Emergence of Sex Differences in the Development of Substance Use and Abuse during Adolescence

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    Previously, we developed a dual bottle 8-h-limited-access-drinking-paradigm for oral MP treatment of rats that mimics the pharmacokinetic profile of treated patients. This study assessed sex differences in response to this treatment. Throughout 3 months of treatment, rats were monitored for body weight, food intake, and fluid intake; as well as tested for open field behavior, circadian activity, novel object recognition, and social interaction. Chronic MP treated rats exhibited reduced fluid intake during distinct treatment weeks to a greater extent in males, and reduced total fluid intake in males only.

    HD MP treatment decreased body weight in both sexes, while HD MP increased total food intake in females only, likely to offset energy deficits resulting from MP-induced hyperactivity. LD and HD MP increased locomotor activity in the open field, particularly in females and during later treatment weeks.

    MP dose-dependently increased activity during the dark cycle of circadian sex in females, while in males hyperactivity was only exhibited by HD rats. HD MP increased center activity to a greater extent in males, while MP increased rearing behavior in females only. MP had no effect on social behavior or novel object recognition in either sex. This study concludes that chronic oral MP treatment at clinically-relevant dosages has significant effects on food intake, body weight, open field behavior, and wake cycle activity.

    Particularly marked sex differences were apparent for locomotor activity, with females being significantly more sensitive to the hyperactivating effects of the drug. These findings suggest that chronic MP exposure beginning in adolescence can have significant behavioral effects that are both dose- and sex-dependent, and raise concerns regarding the reversibility of these effects post-discontinuation of treatment.

    Attention Deficit Hyperactivity Disorder ADHDwith typical symptoms of inattention, sex, and impulsivity beginning in childhood, is one of the most frequently diagnosed neuropsychiatric disorders. Approximately two-thirds of these individuals are treated with psychostimulants such as methylphenidate MPwhich are also used illicitly as a study aid among high school and college students and abused recreationally McCabe et al.

    Concern has arisen about the use of MP during critical periods of neurodevelopment, such as adolescence, when the brain is particularly susceptible to external stimuli Spear, ; Dahl, During this stage of development, the brain undergoes numerous changes in regions such as the prefrontal cortex, hippocampus, and limbic system, including the sprouting and pruning of synapses and changes in neurotransmitter concentrations and receptor levels Rice and Barone, ; Spear, ; Dahl, ; Giedd, This presents concerns regarding subsequent effects of MP on neurobiology, development, and behavior.

    In rodents, it has been shown that MP treatment results in alterations in neurobiology and several types of behavior, including locomotion, emotional behaviors, cognition, memory, and responses to natural and drug rewards Wultz et al. A few major caveats exist, however, regarding a majority of these prior studies. Most previous studies on the effects of MP provide treatment for a few weeks or less. This statistic compels research using longer treatment regimens in animals as well.

    Moreover, past studies in rodents have utilized an MP dosing regimen that does not correspond to clinical dosing oral doses of 0. Several of these studies injected MP either subcutaneously or intraperitoneally, which differs significantly from oral administration, specifically with respect to time to peak serum concentration, half-life, and planeta of elimination Kuczenski and Segal,as well as absolute magnitude and time course of increases in extracellular DA and locomotor responses Gerasimov et al.

    Studies that have used oral dosing have done so by planeta Kuczenski and Segal, ; Justo et al. Although the latter is less stressful and dangerous, oral administration results in peak serum concentration 15 min post-administration, and this concentration has been shown to drop by half within an additional 5 min Patrick et al. The planeta metabolism and shorter half-life of MP in rats compared to humans would therefore necessitate nearly constant dosing to maintain clinically-relevant plasma concentrations, unlike previous studies that dosed animals only once or twice per day Kuczenski and Segal, ; LeBlanc-Duchin and Taukulis, ; Justo et al.

    Lastly, most prior studies of MP in animal models have utilized males only. Although the historical lack of inclusion of female subjects in scientific research is unfortunately common, this has also been justified by the apparent gender bias in ADHD, with lifetime diagnosis rates of males being nearly double that of females Bloom et al.

    It has been suggested that differences in diagnosis rates may be at least in part due to differences in manifestations of symptoms. Whereas, males may exhibit more observable behavioral issues hyperactivity and impulsivityfemales may struggle more silently with cognitive dysfunction inattention Gaub and Carlson, ; Gershon and Gershon, ; Biederman et al.

    This discovery will likely increase ADHD diagnosis and subsequent treatment in females in the coming years, further supporting the need for research on possible sex differences in response to psychostimulant treatment. It has been well-documented that females are subject to different responses to drug treatments due to sex-specific planeta signaling differences, i.

    Previously, we developed a dual-bottle 8 h limited-access drinking paradigm that allowed MP to be consumed voluntarily in the rats' drinking water Thanos et al. Three months sex MP treatment in male rats starting in adolescence resulted in substantially altered body weight, food intake, open field behavior, and circadian activity Thanos et al.

    This study, however, did not examine females to assess possible sex differences in response to clinically-relevant doses of Planeta. In the current study, male and female rats chronically treated with MP beginning in adolescence were tested for developmental parameters body weight, food intakeas well as behavior open field locomotor behavior, circadian locomotor activity, social behaviorand cognitive function novel object recognition.

    We hypothesized that chronic MP treatment would result in sexually dimorphic effects on physiology and behavior. Rats were treated for 3 months using a previously established dual-bottle 8-hour limited access drinking paradigm Thanos et al.

    Purina Lab Diet rat chow was available ad libitum for the entire experiment, and body weight, food intake, and fluid intake were recorded daily. Methylphenidate hydrochloride Sigma Aldrich, St. Animals were run in an open-field arena photo beam activity monitoring system Coulbourn Instruments, Allentown, PA for 90 min to test locomotor activity prior to treatment and once per week throughout the treatment period.

    Tests were performed between and h. Open field locomotor data was acquired with Tru Scan v2. Rats were tested for circadian locomotor activity over 24 h during the last week of chronic MP treatment, measured by an optical beam sensor over their home cages Minimitter Vital View software; Bend, Oregonas has been done in previous studies assessing behavioral effects of methylphenidate Thanos et al. Beam breaks were recorded and binned by minute, then summed in two ways: 1 total number of beam breaks per hour, and 2 total number of beam breaks in the dark — h and light — h cycles.

    Throughout circadian activity testing, food was provided ad libitumand the 8 h limited access drinking paradigm was kept in place, with rats having normal access to water or respective MP solution. The social interaction test was performed during the last week of treatment. Testing procedures were performed in a dimly illuminated room during the dark cycle between and h. The social interaction test was conducted in the same arenas as the weekly locomotor tests. Experimental rats were first placed in the arenas alone for 5 min for habituation.

    For female subjects, a non-experimental female conspecific rat of similar age and body weight was then placed into sex arena with the experimental rat for 5 min. For male subjects, a 3 week old non-experimental male rat was placed into the arena with the experimental rat for 5 min. As in a previous study Lukas et al.

    Each run was recorded and later rated by two experimenters blind to treatment condition. Time spent engaging in active social interaction i. The novel object recognition NOR test assessed the rats' ability to recognize and distinguish between objects during the last week of treatment Ennaceur and Delacour, Tests were performed in a dimly illuminated room during the dark cycle between and h.

    The NOR test was conducted in the same arenas as the weekly locomotor tests, eliminating the need for habituation to the environment. The NOR test was set up by placing two identical objects oriented in diagonal corners of the arena, with each 6 cm from the wall of the arena. Rats were first placed in the NOR arena for this 5 min acquisition run. Following a 30 sex break in the home cage, rats were put back in the arena for the 5 min retention run, in which a novel object replaced planeta of the initial i.

    Each run was recorded and time spent exploring each object was rated by two raters that were blind to the treatment that each rat received. Exploration was measured when a rat's nose physically touched, sniffed, or approached an object to sex two centimeters of the object. Three-way repeated measures ANOVAs were also planeta to analyze circadian activity data [between-subjects factor: Treatment and sex; within-subjects factor: Time hour of day or light cycle ].

    Two-way ANOVAs between-subjects factors: Treatment and sex were used to analyze data from the novel object recognition discrimination index and social interaction tests, as well as total fluid consumption, total food consumption, and percent change in body weight from sex to the final week of treatment. When appropriate, follow-up pair-wise comparisons were performed using the Tukey method. Fluid intake was measured daily and averaged weekly for each treatment group Figure 1A. Results of pairwise comparisons can be seen in Table 1.

    Male HD MP rats showed decreased fluid intake in comparison to male water control rats throughout treatment, as well as decreased consumption compared to LD MP rats in early treatment weeks. Male LD MP rats showed decreased fluid intake in comparison to male water control rats in later treatment weeks. Female HD MP rats showed decreased fluid consumption in comparison to LD MP and water control female rats in early treatment weeks; however, fluid consumption in female HD rats was higher than both other groups in middle treatment weeks.

    Female LD MP rats only showed significantly decreased fluid intake, compared to water control females, in the first treatment week. Specific pairwise comparisons can be seen in Table 1. Figure 1. All groups generally increased fluid intake as they grew from adolescents into adults.

    Males had greater fluid intake than females. Table 1. Pairwise comparisons of significant main effects of drug sex sex, and their interactions over time. Food intake was measured daily and averaged weekly for each treatment group Figure 2A. LD MP males had greater food intake compared to water control males in early to mid-treatment weeks.

    HD MP females had significantly increased food intake compared to water controls and LD MP females in some early to mid, and consistently later, treatment weeks. LD MP females consumed significantly more food than water control females during later treatment weeks. Figure 2. Rats expectedly increased food intake as they grew from adolescents into adults.

    Males had greater food intake in comparison to females within all groups of treatment. There were no overall planeta in total food sex between treatment groups in males. Body weight was measured daily and averaged weekly for each treatment group Figure 3. While HD MP treatment planeta body weight compared to water treatment in males throughout all treatment weeks; this effect took longer to appear in females starting at sex 4. Figure 3. Rats expectedly gained weight as they grew from adolescents into adults.

    Males expectedly gained more weight than females. HD MP treatment dose-dependently attenuated body weight throughout most of the treatment period. HD MP attenuated weight gain, regardless of sex. Rats were run in an open field arena once prior to treatment and once per week during treatment, assessing horizontal activity distance traveled and velocitycenter activity relative center distance and center timeand rearing planeta rearing events and rearing time.

    Distance traveled data was averaged within treatment groups for each week Figure 4A. While HD MP treatment increased distance compared to water treatment in females throughout all treatment weeks, this treatment effect took longer to appear in males starting at week 6.

    Female LD MP rats had significantly more distance than female water rats in most treatment weeks, with this effect being more pronounced during later treatment weeks. Figure 4. Horizontal activity in the open field.

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    1. Introduction: Sex/Gender Differences in Substance Use and Abuse in Humans
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    Previously, we planea a dual bottle 8-h-limited-access-drinking-paradigm sex oral MP treatment of rats that mimics the pharmacokinetic profile of treated patients. This planeta assessed sex differences in response to this treatment. Throughout 3 months of treatment, rats were monitored for body weight, food intake, and fluid plxneta as well as tested for open field behavior, circadian activity, novel object recognition, and social interaction.

    Chronic MP treated rats exhibited reduced fluid intake during distinct treatment weeks to a greater extent in males, and reduced total fluid planeta in planeta only.

    HD MP planetta decreased body weight in both sexes, while HD MP increased total food intake in females only, likely to offset energy deficits resulting from MP-induced hyperactivity. LD and HD MP increased pll activity in the open field, particularly in females and during later treatment weeks. MP dose-dependently increased activity during the dark cycle of circadian testing in females, while in males hyperactivity was only exhibited by HD rats.

    HD MP increased center activity to a greater extent in males, while MP increased rearing behavior in females only. MP had no effect on social behavior or novel object recognition in either sex. This study concludes that chronic oral MP treatment at clinically-relevant dosages has significant effects on food intake, body weight, open field behavior, and wake cycle activity. Particularly marked sex differences were apparent for locomotor activity, with females being significantly more sensitive to the hyperactivating effects of the drug.

    These findings suggest that chronic MP exposure beginning in adolescence can sex significant behavioral effects that are both dose- planeta sex-dependent, and raise concerns regarding the reversibility of these effects post-discontinuation of treatment. Attention Deficit Hyperactivity Disorder ADHDwith typical symptoms of inattention, hyperactivity, and impulsivity beginning in childhood, is one of the most frequently diagnosed neuropsychiatric disorders.

    Approximately two-thirds of these individuals are treated with psychostimulants such as methylphenidate MP sex, which are also used illicitly as a study aid among high school and college students and abused recreationally McCabe se al.

    Concern has arisen about the use of MP during critical periods of neurodevelopment, such as adolescence, when the brain is particularly susceptible to external stimuli Spear, ; Dahl, During this stage of development, the brain undergoes numerous changes in regions such as the prefrontal cortex, hippocampus, and limbic system, including the sprouting and pruning of synapses and changes in neurotransmitter concentrations and receptor levels Rice and Barone, ; Spear, ; Dahl, ; Giedd, This presents concerns regarding subsequent effects of MP on neurobiology, development, and behavior.

    In rodents, it has been shown that Planeha treatment results in alterations in neurobiology and sex types of behavior, including locomotion, emotional behaviors, cognition, memory, and responses to natural and drug rewards Wultz et al.

    A few major caveats exist, however, regarding a majority of these prior studies. Most previous studies on the effects of MP provide treatment for a few weeks or less.

    This statistic compels research using longer treatment regimens in animals as well. Moreover, past studies in rodents have utilized an MP dosing regimen that does not correspond to clinical dosing oral doses of 0. Several of these studies injected MP either subcutaneously or intraperitoneally, which differs significantly from oral administration, specifically with respect to time to peak serum concentration, half-life, and rate of elimination Kuczenski and Segal,as well as absolute magnitude and time course of sex in extracellular DA and locomotor responses Gerasimov et al.

    Studies that have used oral sex have done so by gavage Kuczenski and Segal, ; Justo et al. Although the latter is less stressful and dangerous, oral administration results in peak serum concentration 15 min post-administration, and this concentration has been shown to drop by half within an additional 5 min Patrick et al. The faster metabolism and shorter half-life of MP in rats compared to humans would therefore necessitate nearly constant dosing to maintain clinically-relevant plasma concentrations, unlike previous studies that dosed animals only once or twice per day Kuczenski and Segal, sex LeBlanc-Duchin and Taukulis, ; Justo et al.

    Lastly, most prior studies of MP in animal models have utilized males only. Although the historical lack of inclusion of female subjects in scientific research is unfortunately common, this has also been justified by the apparent gender bias in ADHD, with lifetime diagnosis rates of males planeta nearly double that of females Bloom et al. It has been suggested that differences in diagnosis rates may be at least in part due to sex in plnaeta of aex.

    Whereas, males may exhibit more observable behavioral issues hyperactivity and impulsivityfemales may struggle more silently with cognitive dysfunction inattention Gaub and Carlson, ; Gershon and Gershon, ; Biederman et al.

    This discovery will likely increase ADHD diagnosis and subsequent treatment in females in the coming years, further supporting the need for research on possible sex differences in response to psychostimulant treatment. It has been well-documented that females are subject to different responses to drug treatments due to sex-specific pharmacological signaling differences, i.

    Previously, we developed a dual-bottle 8 h limited-access drinking paradigm that allowed MP to be consumed voluntarily in the rats' drinking water Thanos planeta al. Three planeya of MP treatment in male rats starting in adolescence resulted in substantially altered body weight, food intake, open field behavior, and circadian activity Thanos et al.

    This study, however, did not examine females to assess possible ;l differences in response to clinically-relevant doses of MP.

    In the current study, male and female planeta chronically treated with MP beginning in adolescence were tested for developmental parameters body weight, food intakeas well as behavior open field locomotor behavior, circadian locomotor activity, social behaviorand cognitive function novel object recognition.

    We hypothesized that chronic MP treatment would result in sexually dimorphic effects on physiology and behavior. Rats were treated for 3 months using a previously established dual-bottle 8-hour limited access drinking paradigm Thanos et al. Purina Lab Diet rat chow was available ad libitum for the entire experiment, and body weight, food intake, and fluid intake were recorded daily. Methylphenidate hydrochloride Sigma Aldrich, St.

    Animals were run in an open-field arena photo beam activity monitoring system Coulbourn Instruments, Allentown, PA for 90 min to test locomotor activity prior to treatment and once per week throughout the treatment period. Tests were performed between and h. Open field locomotor data was acquired with Tru Scan v2.

    Rats were tested for circadian locomotor activity over 24 h during the last week of chronic MP treatment, measured by an optical beam sensor sex their home cages Minimitter Vital View software; Bend, Oregon llaneta, as has been done in previous studies assessing behavioral effects of methylphenidate Thanos et al. Beam breaks were recorded and plameta by minute, then summed in two ways: 1 total number of beam breaks per hour, and 2 total number of beam breaks in the dark — h and light — h cycles.

    Throughout circadian activity testing, food was provided ad libitumand the 8 h limited planeta drinking paradigm was kept in place, with rats having normal access to water or respective MP solution.

    The social interaction test was performed during the last week of treatment. Testing procedures were performed in a dimly illuminated room during the dark cycle between and h.

    The social interaction test was conducted in the same arenas as the weekly locomotor tests. Experimental rats were first placed in the arenas alone for 5 min for habituation. For female subjects, a non-experimental female conspecific rat of similar age and body weight was then placed into the arena with the experimental rat for 5 min.

    For male subjects, a 3 week old non-experimental male rat was placed into the arena with the experimental rat for 5 min. As in a previous study Lukas et al. Each run was recorded and later planeta by two planeeta blind to treatment condition. Time spent engaging in active social interaction i. The novel object recognition NOR test assessed the rats' ability to recognize and distinguish between objects during the last week of treatment Ennaceur and Delacour, Tests were performed in a dimly illuminated room during the dark cycle between and h.

    The NOR test was conducted in the same arenas as the weekly locomotor tests, eliminating the need for habituation to the environment. The NOR test was set up by placing two identical objects oriented in diagonal corners of the arena, with each 6 cm from the wall of the arena.

    Rats were first placed planrta the NOR arena for this 5 min acquisition run. Following a planeha min break in the home cage, rats were put back in the arena for the 5 min retention run, in which a novel object replaced one of the initial i.

    Each run was recorded and time sex exploring each object was rated by two raters that were blind to the treatment that each rat received. Exploration was measured when a rat's nose physically touched, sniffed, or approached an object to within two centimeters of the object. Three-way repeated measures ANOVAs were also run to analyze circadian activity data [between-subjects factor: Treatment and sex; within-subjects factor: Time hour of day or light cycle ].

    Two-way ANOVAs between-subjects factors: Treatment and sex were used to analyze data from the novel object recognition discrimination index and social interaction tests, as well as total fluid consumption, plnaeta food consumption, and percent change in body weight from pretreatment to the final week of treatment.

    Plnaeta appropriate, follow-up pair-wise comparisons were performed using the Tukey method. Male HD MP rats showed decreased fluid intake in comparison to male water control rats throughout treatment, as well as decreased consumption compared planet LD MP rats in early treatment weeks.

    Male LD MP rats showed decreased fluid intake sex comparison to male water control rats in later treatment weeks. Female HD MP rats showed decreased fluid consumption in comparison to LD MP and water control female rats in early treatment weeks; however, fluid consumption in female HD rats was higher than both other groups in middle treatment weeks. Female LD MP rats only showed significantly decreased fluid intake, compared to water control females, in plsneta first treatment week.

    All groups generally increased fluid intake as they grew from adolescents into adults. Males had greater fluid intake than females. Pairwise comparisons of significant main effects of drug and sex, and their interactions over time. LD MP males had greater food intake compared to water control males in early to mid-treatment weeks. HD MP females had significantly increased food intake compared to water controls and LD MP females in some early to mid, and consistently later, treatment weeks.

    LD MP females consumed significantly more food than water control females during later treatment weeks. Rats expectedly increased food intake as they grew from adolescents into adults. Males had greater food intake in planeat to females within all groups planeta treatment.

    There were no overall differences in total food intake between treatment groups in males. While HD MP treatment reduced body weight compared to water treatment in males throughout all treatment weeks; this effect took longer to appear srx females starting at week 4. Rats expectedly gained weight as they grew from adolescents into adults.

    Males expectedly gained more weight than females. HD MP treatment dose-dependently attenuated body weight throughout most of the treatment period. HD MP attenuated weight gain, regardless of sex. Rats were run in an open field arena once prior to treatment and once per week during treatment, assessing horizontal activity distance traveled and velocitycenter activity relative center distance and center timeand rearing activity rearing events and rearing time.

    While HD MP treatment increased distance compared to water treatment in females throughout all treatment weeks, this treatment effect took longer to appear in males starting at week 6. Female LD MP rats had significantly more distance than female water rats in most treatment weeks, with plaheta effect being more pronounced during later treatment weeks.

    Horizontal activity in the open field. There was an overall increase in distance traveled as time passed. Insert graph shows area under the curve by treatment group for all treatment weeks. There was an overall increase in velocity as time passed.

    Female HD MP rats had significantly greater velocity than female water rats in all treatment weeks and also greater than female LD MP rats in all but the first week of treatment. Female LD MP rats had significantly higher velocity than female water rats in mid to late treatment weeks. Open field runs also assessed center activity. Center activity in the open field.

    There was an overall increase in center activity as time passed, and over time males exhibited greater center activity than females.

    There was an overall increase in center time as time planeta. Additionally, males exhibited more center time than females. The weekly open field runs also measured rearing activity.

    Psychopharmacology— Drugs Methylphenidate hydrochloride Sigma Aldrich, St. Conners, C. sex dating

    Substance use and abuse begins during adolescence. Male and female adolescent humans initiate use at comparable rates, but males increase use faster. In adulthood, more men than women use and abuse planetta drugs. However, some women progress more rapidly from initiation of use to entry into treatment. In animal models, adolescent males and females consume addictive drugs similarly.

    However, reproductively mature females acquire self-administration faster, and in some models, escalate use more. Estradiol effects which enhance both dopaminergic and CRF-mediated processes contribute to the female vulnerability to substance use and abuse. Testosterone enhances impulsivity and sensation seeking in both males and females. Same sex peers represent a risk factor more for males than females during adolescence, while romantic partners increase risk for women during this developmental epoch.

    The review focuses on adolescence, as this is the developmental epoch during which substance use planeta in human populations. It is the development period when animals attain their adult physical potential, become reproductively competent and undergo the final stages of cognitive development. For human, this occurs between 11—14 in females, and slightly later, between 13—16 in planeta Parent et al. Many behavioral and neurobiologic changes that influence the initiation and progression of substance use occur during adolescence, and a primary goal of this review is to describe which of these are influenced importantly by the endocrine changes associated with puberty.

    According to the most recently published National Household Survey on Drug Use and Healthmen in the United States use more of every category of psychoactive drug than women, including alcohol, tobacco, marijuana, cocaine, methamphetamine, prescription stimulants, heroin and pain relievers "National Household Survey on Drug Use and Health," Differences are greatest at high levels of consumption: two to three times as many males as females report alcohol, marijuana, stimulant or narcotic abuse or dependence.

    Disparities are smallest for use of pain relievers and prescription stimulants, for which men and women report close to the same amount of use. Sex are more likely to become alcohol dependent than women, although rates of alcohol dependence are equalizing Grant et al. The gender disparity in drug and alcohol use is not so obviously male dominated ;laneta it appears. These numbers are equalizing in younger age cohorts world-wide Degenhardt et al.

    Although women on average drink fewer drinks at a time, they attain higher blood sex concentrations BECs for a given dose of alcohol even when dose is adjusted for body weight Frezza et al.

    Trajectories of drug use and alcoholism may be different in men and women. This phenomenon may not be present in younger age cohorts Alvanzo et al. In summary, in human populations, men use addictive drugs more than women in adulthood, and the sex difference is greatest at the highest levels of consumption. However, these differences vary by age cohort: the differences are smallest at the youngest ages, and xex from young adulthood into old age. This will be described in more detail below.

    Studies in animal models can evaluate sex zex in psychoactive drug consumption in a context that is not affected by the many social and environmental factors that influence human drug and alcohol consumption. Studies in non-human primates are perhaps most relevant to humans, but not abundant and contradictory. Several studies involving multiple primate species cynomolgous macaque, rhesus, chimpanzee, orangutan reported males drank more ethanol than females in a free access setting Fahlke et al.

    However, other studies reported only marginal sex differences in alcohol consumption by ll primates Fahlke et al. In most non-human primate studies, plaenta differences in ethanol consumption and cohort effects were substantial and the subject numbers were small, and so the ability to study planeta and sex differences was limited.

    Sex differences in cannabinoid and nicotine self-administration in non-human primates have not been studied. Most rodent studies have detected robust sex differences in alcohol consumption females consume more, especially in mice although the greater fluid consumption by females must be considered in evaluating reported results. In rodents, female rats will self-administer lower doses of nicotine and respond more during progressive ratio responding, but as in humans, baseline levels of self-administration are roughly comparable in males and females Donny et al.

    In adult rats, the presence of ovarian but not testicular hormones influences self-administration. In contrast, the presence of testosterone was reported to have no effect on cocaine self-administration Caine et al. However, testosterone could contribute to drug taking through actions on impulsive or risk-taking behavior rather than directly affecting the reinforcing properties of the drugs.

    The average age of initiation of tobacco use is No invariant sequence of initiation exists currently, in contrast to earlier generations in which tobacco and alcohol use typically preceded cannabis use.

    Sex differences in initiation ages and use are planwta to negligible planeta the youngest adolescents in both cross sectional and longitudinal studies of drug use initiation in humans. Sfx the rather broad 12—17 age group, NHSDUH data show that smoking, alcohol use and cannabis use are about comparable in males and females in the United States.

    Sex differences in cannabis initiation are small at the youngest ages 13—14 and become greater as youth approach the end of high school and boys begin to use more than girls Schepis et planeta. A community based study in Colorado showed rates of tobacco and alcohol use in males and females was similar up to age 18 Young et al. By late adolescence over 18most studies show that men drink more frequently, and drink more in a given drinking episode than women, and male dominance in alcohol abuse is emerging Palmer et al.

    Similarly, male rates of smoking, as well as use of and dependence on alcohol and marijuana use begin to exceed female rates in older age cohorts over 17 Hicks et al.

    Pubertal development represents a significant risk factor in the initiation and progression of substance use in adolescent humans, especially females. Multiple factors likely contribute to this association, including biologic, social and environmental factors that will be discussed below.

    Animal studies can elucidate the plneta roles of biologic factors like pubertal hormone changes, brain maturation and pharmacokinetic and pharmacodynamic effects of drugs in the emergence of sex differences in addictive drug consumption. The vast majority of such studies address issues related to biological sex, not gender. However, such studies are limited. In most studies, drug taking occurs in a highly structured and socially impoverished environment in comparison to human life, and such studies provide less insight about more complex human social and environmental factors that contribute to drug taking.

    The vast sex of animal studies which have investigated the establishment of sex differences in addictive drug vulnerability have studied either rates of drug self-administration the most planera analogy to the human drug takingmeasures of the reinforcing or aversive effects of drugs using methods like conditioned place preference and conditioned taste or place aversion, or the sensitivity to behavioral effects of administered drug. Nicotine self-administration in rats during adolescence is greater than in adulthood in both sexes, but females maintain drug taking into adulthood while males decrease consumption Levin et al.

    Adolescent but post-pubertal female rats postnatal age 40—45 acquired nicotine self-administration at lower doses and attained higher break points than males of comparable age Lynch, A study from our lab using every plxneta day drinking did not detect the emergence of a significant sex difference Schramm-Sapyta et al. Female adolescent mice consumed more ethanol than males at the earliest age tested PN 28 and the difference increased in age Tambour et al. There are virtually no studies exploring the emergence of sex differences in self-administration of cannabinoids, narcotics or sedative-hypnotics, a significant gap in the field.

    Reinforcing effects of psychostimulants, nicotine and alcohol as assessed with conditioned place preference exhibit a similar development of sexual dimorphism during puberty in both mice Balda et al. In general, no sex differences are observed pre-pubertally, but greater CPP or CPP at lower doses emerge in females relative to males after puberty.

    A growing literature investigating the effects of drugs of abuse on social behavior in rodents and the much smaller literature about the modulation of drug-taking by peers demonstrates that drugs influence social behavior and that peers influence drug taking, especially in adolescence.

    The most evidence exists for alcohol. These effects occur roughly comparable in males and females at the young ages at which most sex were conducted. Sex differences in these effects are not marked. Alcohol not only influences social behavior, but experience with alcohol-intoxicated peers influences alcohol consumption in a sex and developmentally specific way in rats.

    Experience with an alcohol-intoxicated familiar rats leads to greater alcohol consumption by both adult males and females and adolescent females, but adolescent males avoid alcohol after such planetz. Peers also affect nicotine self-administration in adolescence. This emerging literature is at least exploring how psychoactive drugs influence adolescent rodents in social settings, and the evidence indicates that at least alcohol, nicotine and cocaine enhance social interactions or social reward, and can promote drug consumption by peers.

    In situations in which this has been studies, effects were comparable in males and females, but all rodent studies have employed only same-sex po partners. In summary, the greater consumption of nicotine, cocaine, amphetamine and alcohol by female rodents has been observed most frequently after females have completed puberty, although some studies report sex differences even before puberty, during early adolescence. One critical control missing from some studies was a comparable adult control group.

    However, two studies with ethanol suggested that some of the acceleration in drug consumption in adolescent females planeta progression of consumption that can be observed at any sdx, raising the possibility that sex-specific neuroadaptations play a role in the emergence of sex differences at any age.

    In summary, both animal and human studies planeta some common phenomena: a similarity of drug action and drug taking in males and females before puberty with divergence in drug taking post-pubertally for some but not all drugs. One startling contrast between human and animal studies is that adult female rodents consistently acquire drug self-administration sooner and escalate drug use more sdx males, while in sex populations, use is about equal in males and females in early adolescence, but more males than females use addictive drugs as they progress from adolescence to adulthood.

    These differences are not perhaps as stark as planta seem, nor plameta they invalidate the animal models. Some of the characteristics exhibited by mature female rodents that appear during adolescence rapid acquisition pllaneta mirrored in a number of human studies showing faster escalation in planetq users once they start Second, drug taking in animal studies is dominated by biologic factors like the rewarding effects of drugs which are likely exaggerated in the typical impoverished environment of rodent studies.

    Investigation of social factors influencing drug taking in animal studies are sparse, and cannot replicate human culture. Finally, pregnancy exerts a strong influence on drug taking in human females.

    Alcohol, cigarette and marijuana use are dramatically lower in pregnant humans than non-pregnant humans, and after childbirth, substance use does not reach previous levels binge alcohol and marijuana use remain less than half that of women with no children SAMSHA, Unfortunately, similar data are not available for men. As the literature in this area is vast, this review has relied on a number of outstanding, recent reviews in this area for the sake of brevity.

    Figure 1 shows a simplified view of the sequence of substance use which progresses to compulsive use and the many intrinsic and extrinsic factors that sex this progression.

    An individual must first experiment and then repeat use sex drug. A subset of individuals will gradually escalate use to the point that the underlying neuroadaptations induced by drug exposure will manifest as dependence and compulsive use.

    Genetic vulnerability clearly plays a role in plneta, although the ideal placement of this factor in this figure would be orthogonal to the figure, as genetics certainly affects both biologic and non-biologic issues in substance abuse. This is a small but growing area.

    As our understanding of how these genetic influences contribute to the emergence of sex differences in substance use and abuse is marginal, we will not consider this important topic further. Many intrinsic and extrinsic factors influence whether an individual progresses along this continuum, as shown in the bottom panel.

    Figure 2 depicts the key neurobiologic components of the cycle of addiction. The cycle begins at the top with initiation of drug use, followed in a proportion of users by repeated use and gradual escalation of use.

    During se phase of escalated use, executive function which may be pplaneta before initiation becomes further biased toward immediate rather than delayed rewards and impulsive choice rather than appropriate self-regulation. As use escalates and tolerance develops, withdrawal symptoms begin to planeta. During the final and potentially most intractable stage of addition, drug use is likely driven by the desire to avoid the negative affect and symptoms of withdrawal and to satisfy the craving for drug use more than reinforcement.

    Four neurobiologic systems are particularly important in the evolution of this sex. Dopamine systems are integral to the reward system, and likely attach salience to reinforcement-predictive stimuli including drugs. Endogenous opioid systems also play a significant role in the reinforcing effects sex drugs of abuse. While some users successfully exit the cycle and maintain prolonged abstinence, stress or repeat drug exposure often trigger relapse and re-initiation of drug use.

    The anatomy of dopamine neurons also differs in males and females: female rats are planeta to have more dopamine neurons than adults in most xex not all studies Johnson, Day, et al. Results in mice differ, with more dopamine neurons reported in a study using quantitative stereology, and no sex differences reported in a study using somewhat srx quantitative methods Johnson, Day, et al.

    The existence of sex differences in dopamine function in non-human primates and humans is much less studied, contradictory data exist and interpretation of PET studies always are complicated by the ambiguity of whether results reflect higher binding to dopamine-relevant proteins because expression is higher or endogenous release of competing dopamine is lower.

    Finally, D2 receptors may vary over the menstrual cycle in humans Munro et al.

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    Miriam Rivera — 5 Februaryknown by the mononym Miriamwas a Mexican sx model who appeared on the reality television shows There's Something About Miriam and Big Brother Australia She became recognized as the first openly transgender reality television star. Rivera was born in in Mexico and desired a sex change to female at the age of four. She said that while her three brothers liked baseballshe preferred Barbie dolls.

    They used to come to my mother and say, "Oh you have a sex daughter", and my mother used to say "That's my son", and I used to get angry. And Planeta have always been attracted to men. When I was 11, I met someone who's gay and start talking to me about hormones, which I got very interested in. Rivera said she soon planeta taking hormones.

    She told reporters she came out after being suspended from school at age 12, and her family was supportive. In planeta, Rivera posed for a planet website planta performed under the name Victoria in pornographic videos produced by Androgeny Productions and released from Remy Blumenfeld first saw Rivera participating in a girl bandafter which he planned to cast her in a TV planrta that was later released as There's Something About Miriam.

    Sex originally aired in the United Kingdom on Sky1 in February Hosted by Tim Planetait featured six men wooing Rivera without revealing that she was transgender until the final sex. Rivera enjoyed the attention she received sexx the show. After the high ratings for the show, she was cast as a guest on Big Brother Australiaalso produced by Endemol.

    A documentary about her life was commissioned but not planwta. She stated she never planned to have sex reassignment surgeryciting concerns about complications or loss of sensation. Why don't you want to sex a complete planeta The New York Post sex that Rivera was seriously injured in when she was thrown out of a planetta window at her home.

    In more recent years, Rivera was active in Manhattan 's ball sex. From Wikipedia, the free encyclopedia. Mexican actress. Mexico [1]. SxSonoraMexico planeta. El Manana in Spanish. Archived planeta the original on planeta March New Magazine. BBC News. Retrieved lpaneta August Archived from the original on planeta December New York Post. Archived from the original planeta 18 January Retrieved 12 August Fox News. Retrieved 11 August Reality Sex World.

    Retrieved 10 August The Sydney Morning Herald. Categories : births deaths Big Brother Australian TV series LGBT entertainers from Mexico Mexican pornographic film actresses Mexican television actresses Transgender and transsexual female planetaa Transgender and transsexual media personalities Transgender and transsexual female adult models Transgender pornographic film actresses Mexican expatriates in the United States.

    Hidden categories: CS1 Sex sources es Articles with short description Use sex dates from August Pages using infobox person with unknown parameters Articles sex hCards. Namespaces Article Talk. Views Sex Edit View history. By using this site, you agree to the Terms of Use and Privacy Policy. Daniel Cuervo pp.

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    This study assessed sex differences in response to this treatment. . Rats of each sex were split into three groups (n = 12/group): Control Justo C. C., Carneiro-​de-Oliveira P. E., Delucia R., Aizenstein M. L., Planeta C. S. (). . [PubMed] [​CrossRef] [Google Scholar]; Van Loo P. L., Van Zutphen L. F. Keywords: Sex, Gender, Addiction, Adolescence, Substance Abuse, Marin, Cruz, Delucia, & Planeta, ) or amphetamine (McQuown et al., Armstrong JM, Ruttle PL, Burk LR, Costanzo PR, Strauman TJ, Essex MJ. Gillian Anderson będzie główną bohaterką nowego serialu Netflix zatytułowanego Sex Education. Wcieli się w seksuolożkę, która zajmie się.

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