Methamphetamine facilitates female sexual behavior and enhances neuronal activation in the medial amygdala and ventromedial nucleus of the hypothalamus

Sexual effects of commonly used recreational psychostimulants in women and the female rat model

INTRODUCTION

Recreational psychostimulants have been associated with increased sexual activity or changes in sexual function in women, but every drug in this class has not shown consistent sexual effects in scientific studies. Further, some studies in female animal models may recapitulate the effects observed in humans, while others produce conflicting results. Overall, though, published studies on the sexual effects of recreational stimulants in women are lacking.

OBJECTIVES

The objective of this manuscript was to review the published sexual effects of prominent recreational psychostimulants in women and in the female rat model.

METHODS

Literature searches for "any years" were performed through PubMed and Google Scholar. Keywords for the searches included "amphetamine," "methamphetamine," "MDMA," "ecstasy," "3,4-methylenedioxymethamphetamine," "cocaine," "caffeine," "sex," "sexual," "female," and "women." Studies in humans and using animal models were included.

RESULTS

Older studies have shown that amphetamine produces a positive sexual effect in women, but often the sample size was too small to draw generalizable conclusions. Methamphetamine also has a positive effect on several sexual domains in women, as well as on vaginal lubrication. 3,4-Methylenedioxymethamphetamine may have a negative or positive effect on sexual activity, but often enhances the sensual aspects of sex. Though low doses of cocaine may heighten the sexual experience, most women who use cocaine experience negative sexual effects. Caffeine has been shown to enhance a physiological measure of arousal, vaginal blood flow, but based on our searches, no studies have investigated the subjective sexual effects of the drug.

CONCLUSION

Different recreational psychostimulants produce varying effects on sexual behavior and responses in women and female animal models, but more research is needed to understand these effects better.

Estradiol Influences Adenosinergic Signaling and NREM Sleep Need in Adult Female Rats

Gonadal steroids and gender are risk factors for sleep disruptions and insomnia in women. However, the relationship between ovarian steroids and sleep is poorly understood. In rodent models, estradiol (E2) suppresses sleep in females suggesting that E2 may reduce homeostatic sleep need. The current study investigates whether E2 decreases sleep need and the potential mechanisms that govern E2 suppression of sleep. Our previous findings suggest that the median preoptic nucleus (MnPO) is a key nexus for E2 action on sleep. Using behavioral, neurochemical and pharmacological approaches, we tested whether (1) E2 influenced the sleep homeostat and (2) E2 influenced adenosine signaling in the MnPO of adult female rats. In both unrestricted baseline sleep and recovery sleep from 6-hour sleep deprivation, E2 significantly reduced non-rapid eye movement sleep (NREM)-delta power, NREM-Slow Wave Activity (NREM-SWA, 0.5-4.0Hz), and NREM-delta energy suggesting that E2 decreases homeostatic sleep need. However, coordinate with E2-induced changes in physiological markers of homeostatic sleep was a marked increase in MnPO extracellular adenosine (a molecular marker of homeostatic sleep need) during unrestricted and recovery sleep in E2-treated but not oil control animals. While these results seemed contradictory, systemically administered E2 blocked the ability of CGS-21680 (adenosine A2A receptor agonist) microinjected into the MnPO to increase NREM sleep suggesting that E2 may block adenosine signaling. Together, these findings provide evidence that E2 may attenuate the local effects of the A2A receptors in the MnPO which in turn may underlie estrogenic suppression of sleep behavior as well as changes in homeostatic sleep need.

Sex, Drugs, and the Medial Amygdala: A Model of Enhanced Sexual Motivation in the Female Rat

Methamphetamine (METH) is a psychomotor stimulant that is reported to enhance sexual desire and behavior in both men and women, leading to increases in unplanned pregnancies, sexually-transmitted infections, and even comorbid psychiatric conditions. Here, we discuss our rodent model of increased sexually-motivated behaviors in which the co-administration of METH and the ovarian hormones, estradiol and progesterone, intensify the incentive properties of a sexual stimulus and increases measures of sexually-motivated behavior in the presence of an androgen-specific cue. We then present the neurobiological mechanisms by which this heightened motivational salience is mediated by the actions of METH and ovarian hormones, particularly progestins, in the posterodorsal medial nucleus of the amygdala (MePD), a key integration site for sexually-relevant sensory information with generalized arousal. We finally demonstrate the cellular and molecular mechanisms underlying this facilitation of sexual motivation by METH, including the upregulation, increased phosphorylation, and activation of progestin receptors (PRs) in the MePD by METH in the presence of ovarian hormones. Taken together, this work extends our understanding of the neurobiology of female sexual motivation.

Sexually experienced, but not naïve, female rats show a conditioned object preference (COP) for mating after a single training trial

Female rats with mating experience spend more time with the male rat, exhibit shorter contact-return latency to intromission, and display more proceptive behaviors in the male rat's compartment than during the first mating experience. The present study tested 1) whether mating induced conditioned object preference (COP) is possible with a single conditioning trial and 2) whether a preference is induced for an object associated with the first mating encounter or the fifth mating encounter in female rats. Ovariectomized, Long-Evans female rats were primed with estradiol benzoate + progesterone and either exposed to an empty paced mating chamber for 15 min (Naïve) or received a 15 intromission test of paced mating behavior (Experienced) on four separate occasions before undergoing the COP procedure. Experienced, but not Naïve, female rats developed a COP for a single mating bout, indicating that mating is highly rewarding for sexually experienced female rats. The findings raise questions about the effect of sexual experience on reward regions in the brain, the responsiveness of genital tissue, and learning mechanisms.

Methamphetamine alters DNMT and HDAC activity in the posterior dorsal medial amygdala in an ovarian steroid-dependent manner

Methamphetamine (Meth) is a psychomotor stimulant associated with increased sexual drive and risky sexual behaviors in both men and women. Females are comparatively understudied, despite the fact that are just as likely as men to use methamphetamine. Importantly, Meth-associated sexual behaviors put female-users at a greater risk for unplanned pregnancies, and increase the risk of psychiatric co-morbidities such as depression. Our work in a rodent model has demonstrated that in the presence of the ovarian steroids, estradiol (EB) and progesterone (P), methamphetamine facilitates the activation of neurons of in the Medial Amygdala (MePD) and Ventromedial Nucleus of the Hypothalamus (VMN), nuclei that are integral to female sexual behavior. As methamphetamine has been previously associated with epigenetic changes in males, we hypothesized that methamphetamine may facilitate sexual motivation in females by modulating the amount of epigenetic enzymatic activity in the VMN and MePD. To test this hypothesis, histone deacetylase (HDAC) and DNA methyltransferase (DNMT) activity was quantitated in both the VMN and MePD in the presence and absence of methamphetamine in femalerats who were ovariectomized (OVX), or OVXed and hormone replaced with EB + P. DMNT1 and DNMT3B protein levels were also assessed. Our results show that methamphetamine alters DNMT and HDAC activity in the MePD in an ovarian steroid-dependent fashion. Both methamphetamine alone and EB + P alone significantly reduce DNMT enzymatic activity in an OVX female, but do not further decrease activity when both are given in combination. In contrast, no changes in HDAC or DNMT activity were seen in the VMN regardless of treatment, but the amount of DNMT3b after methamphetamine was significantly altered depending on the presence or absence of ovarian steroids. Taken together, these results support the hypothesis that methamphetamine induces change on an epigenetic level in female rats in both a hormone and nucleus dependent manner, and suggests epigenetic changes may play a role in methamphetamine's mechanism to facilitate the sexual motivation.

Anhedonia Following Early-Life Adversity Involves Aberrant Interaction of Reward and Anxiety Circuits and Is Reversed by Partial Silencing of Amygdala Corticotropin-Releasing Hormone Gene

BACKGROUND

Anhedonia, the diminished ability to experience pleasure, is an important dimensional entity linked to depression, schizophrenia, and other emotional disorders, but its origins and mechanisms are poorly understood. We have previously identified anhedonia, manifest as decreased sucrose preference and social play, in adolescent male rats that experienced chronic early-life adversity/stress (CES). Here we probed the molecular, cellular, and circuit processes underlying CES-induced anhedonia and tested them mechanistically.

METHODS

We examined functional brain circuits and neuronal populations activated by social play in adolescent CES and control rats. Structural connectivity between stress- and reward-related networks was probed using high-resolution diffusion tensor imaging, and cellular/regional activation was probed using c-Fos. We employed viral-genetic approaches to reduce corticotropin-releasing hormone (Crh) expression in the central nucleus of the amygdala in anhedonic rats, and tested for anhedonia reversal in the same animals.

RESULTS

Sucrose preference was reduced in adolescent CES rats. Social play, generally considered an independent measure of pleasure, activated brain regions involved in reward circuitry in both control and CES groups. In CES rats, social play activated Crh-expressing neurons in the central nucleus of the amygdala, typically involved in anxiety/fear, indicating aberrant functional connectivity of pleasure/reward and fear circuits. Diffusion tensor imaging tractography revealed increased structural connectivity of the amygdala to the medial prefrontal cortex in CES rats. Crh-short hairpin RNA, but not control short hairpin RNA, given into the central nucleus of the amygdala reversed CES-induced anhedonia without influencing other emotional measures.

CONCLUSIONS

These findings robustly demonstrate aberrant interactions of stress and reward networks after early-life adversity and suggest mechanistic roles for Crh-expressing amygdala neurons in emotional deficits portending major neuropsychiatric disorders.

The Role of Ovarian Hormones and the Medial Amygdala in Sexual Motivation

Purpose

Although research into the neurobiology of sexual desire in women is active, relatively little is understood about the origins of sexual motivation in women. The purpose of our review is to discuss factors that influence a central sexual motivate state and generalized arousal as potential drivers of sexual motivation in women and female rats.

Recent Findings

Sexual motivation is the product of interactions of the central motive state and salient sexually-relevant cues. Ovarian hormones and generalized arousal influence the central motive state, and endogenous levels of estradiol and progesterone correlate with sexual motivation and behavior in women. The amygdala is a key integratory site for generalized arousal and sexual sensory stimulation, which could then increase sexual motivation through its downstream projections.

Summary

Our model of enhanced female sexual motivation suggests that the combined effects of dopamine and progesterone receptor activation in the medial amygdala increases the incentive properties of a sexual stimulus. Further study into the interactions of ovarian hormones and mediators of generalized arousal on the processing of sexually-relevant cues informs our understanding of the neurobiology of female sexual motivation and could lead to the development of therapeutics to treat the dysfunctions of sexual desire in women.

Does being drunk or high cause HIV sexual risk behavior? A systematic review of drug administration studies

HIV sexual risk behavior is broadly associated with substance use. Yet critical questions remain regarding the potential causal link between substance use (e.g., intoxication) and HIV sexual risk behavior. The present systematic review was designed to examine and synthesize the existing literature regarding the effects of substance administration on HIV sexual risk behavior. Randomized controlled experiments investigating substance administration and HIV sexual risk behavior (e.g., likelihood of condom use in a casual sex scenario) were included. Across five databases, 2750 titles/abstracts were examined and forty-three total peer reviewed published manuscripts qualified (few were multi-study manuscripts, and those details are outlined in the text). The majority of articles investigated the causal role of acute alcohol administration on HIV sexual risk behavior, although one article investigated the effects of acute THC administration, one the effects of acute cocaine administration, and two the effects of buspirone. The results of this review suggest a causal role in acute alcohol intoxication increasing HIV sexual risk decision-making. Although evidence is limited with other substances, cocaine administration also appears to increase sexual risk, while acute cannabis and buspirone maintenance may decrease sexual risk. In the case of alcohol intoxication, the pharmacological effects independently contribute to HIV sexual risk decision-making, and these effects are exacerbated by alcohol expectancies, increased arousal, and delay to condom availability. Comparisons across studies showed that cocaine led to greater self-reported sexual arousal than alcohol, potentially suggesting a different risk profile. HIV prevention measures should take these substance administration effects into account. Increasing the amount of freely and easily accessible condoms to the public may attenuate the influence of acute intoxication on HIV sexual risk decision-making.

Place preferences associated with pups or cocaine change the expression of D2R, V1aR and OTR in the NAcc and MeA and the levels of plasma AVP, OT, T and E2 in mandarin vole fathers

Drug abuse often has negative impacts on parenting behavior. The dopamine (DA), arginine vasopressin (AVP) and oxytocin (OT) systems are involved in paternal behavior and drug-induced behaviors. Mandarin voles (Microtus mandarinus) are socially monogamous rodents with high levels of paternal behavior. The aims of this study were to examine the protein expression levels of the DA 2-type receptor (D2R), AVP receptor 1A(V1aR) and OT receptor (OTR) in the nucleus accumbens (NAcc) and medial amygdala (MeA) as well as the plasma hormone responses after mandarin vole fathers were conditioned with their pups or cocaine. Our experimental models are based on the conditioned place preference (CPP) paradigm. We observed CPP in response to either pup- or cocaine-associated cues in the mandarin vole fathers. Fathers that were conditioned to either pups or cocaine had a lower expression of D2R and V1aR in the NAcc than did controls. Fathers that were conditioned to pups had higher levels of OTR expression in the MeA and higher plasma levels of AVP, OT, estradiol (E2), and lower plasma levels of testosterone (T) than did controls. Fathers that were conditioned to cocaine exhibited lower levels of plasma AVP and T. These results indicate that the reward effects of pup and cocaine are both mediated by D2R, V1aR and OTR in the NAcc and MeA and that there are subtle differences between the pup and cocaine reward mechanisms that are associated with altered plasma AVP, OT, T and E2.

The ventromedial hypothalamic nucleus in the zebra finch (Taeniopygia guttata): Afferent and efferent projections in relation to the control of reproductive behavior

Sex-specific mating behaviors occur in a variety of mammals, with the medial preoptic nucleus (POM) and the ventromedial hypothalamic nucleus (VMH) mediating control of male and female sexual behavior, respectively. In birds, likewise, POM is predominantly involved in the control of male reproductive behavior, but the degree to which VMH is involved in female reproductive behavior is unclear. Here, in male and female zebra finches, a combination of aromatase immunohistochemistry and conventional tract tracing facilitated the definition of two separate but adjacent nuclei in the basal hypothalamus: an oblique band of aromatase-positive (AR+) neurons, and ventromedial to this, an ovoid, aromatase-negative (AR-) nucleus. The AR- nucleus, but not the AR+ nucleus, was here shown to receive a projection from rostral parts of the thalamic auditory nucleus ovoidalis and from the nucleus of the tractus ovoidalis. The AR- nucleus also receives an overlapping, major projection from previously uncharted regions of the medial arcopallium and a minor projection from the caudomedial nidopallium. Both the AR- and the AR+ nuclei project to the intercollicular nucleus of the midbrain. No obvious sex differences in either the pattern of AR immunoreactivity or of the afferent projections to the AR- nucleus were observed. The significance of these results in terms of the acoustic control of avian reproductive behavior is discussed, and a comparison with the organization of VMH afferents in lizards suggests a homologous similarity of the caudal telencephalon in sauropsids.

Methamphetamine and Ovarian Steroid Responsive Cells in the Posteriodorsal Medial Amygdala are Required for Methamphetamine-enhanced Proceptive Behaviors

Methamphetamine (Meth) is a psychomotor stimulant strongly associated with increases in sexual drive and impulse in both men and women. These changes in sexual motivation have a greater impact on women due to their likelihood of facing the greater burden of unplanned pregnancies, as well as increased risk for psychiatric co-morbidities such as depression. We have previously established a rodent model of Meth-induced increases in sexual motivation. Using this model, we have identified the posteriodorsal medial amygdala (MePD) via excitotoxic lesion studies as a necessary nucleus in Meth-facilitated female sexual motivation. While lesion studies give us insight into key nuclei that may be targets of Meth action, such an approach does not give insight into the identity of the specific MePD neurons or neural circuitry involved in Meth-induced increases in proceptive behaviors. Using the DAUN02 inactivation method, a recently established technique for removing behaviorally relevant cell populations, we present evidence that the ovarian steroid/Meth responsive cells in the MePD are necessary for Meth-induced facilitation of proceptive behaviors. These findings form the basis for future work that will allow for the classification of neuronal subtypes involved in the MePD’s modulation of proceptive behavior as well as a stronger understanding of the neurocircuitry of female sexual motivation.

Androgen-primed castrate males are sufficient for methamphetamine-facilitated increases in proceptive behavior in female rats

Methamphetamine (MA) is a psychomotor stimulant associated with increases in sex drive in both men and women. Women, however, are far more likely to face social disadvantages as a consequence of MA use, and their increased sexual motivation poses additional health concerns such as unplanned pregnancies. To better understand the mechanisms underlying MA-facilitated sexual motivation in females, we previously established a rodent model where a "binge"-type administration paradigm of MA to sexually receptive female rats significantly increases proceptive behavior in the presence of a sexually active, gonadally-intact male. Our previous work with this model has led us to consider whether the increases in proceptive behavior are truly indicative of increased sexual motivation, or instead a consequence of heightened motor responsivity. Here, we test whether MA-induced increases in proceptive behaviors are specific to a sexually relevant stimulus. Females' sexual, social, exploratory behaviors, and interaction times were scored during the exposure to stimulus males, including castrates, and dihydrotestosterone (DHT)-treated castrates. MA-treated females demonstrated significant increases in proceptive behaviors toward DHT-treated castrate males but not toward castrate males. While the non-MA-treated females did display proceptive behavior, there was no significant difference between behaviors elicited by DHT-CX males compared to CX males. Our results support the hypothesis that MA facilitates proceptive behavior only in response to specific, androgen mediated sexually-relevant cues.

Hypersexuality Addiction and Withdrawal: Phenomenology, Neurogenetics and Epigenetics

Hypersexuality has been defined as abnormally increased sexual activity. Epidemiological and clinical studies have shown that this non-paraphilic condition consists of "excessive" sexual behaviors and disorders accompanied by personal distress and social and medical morbidity. It is a very controversial and political topic in terms of how best to categorize it as similar or not similar to addictive behaviors including substance abuse. Hypersexual disorder is conceptualized as a non-paraphilic sexual desire disorder with impulsivity. Pathophysiological perspectives include dysregulation of sexual arousal and desire, sexual impulsivity, and sexual compulsivity. The nucleus accumbens, situated within the ventral striatum, mediates the reinforcing effects of drugs of abuse, such as cocaine, alcohol, nicotine, and food as well as music. Indeed, it is believed that this structure mandates behaviors elicited by incentive stimuli. These behaviors include natural rewards like feeding, drinking, sexual behavior, and exploratory locomotion. An essential rule of positive reinforcement is that motor responses will increase in magnitude and vigor if followed by a rewarding event. Here, we are hypothesizing that there is a common mechanism of action (MOA) for the powerful effects drugs, music, food, and sex have on human motivation. The human drive for the three necessary motivational behaviors "hunger, thirst, and sex" may all have common molecular genetic antecedents that, if impaired, lead to aberrant behaviors. We hypothesize that based on a plethora of scientific support hypersexual activity is indeed like drugs, food, and music that activate brain mesolimbic reward circuitry. Moreover, dopaminergic gene and possibly other candidate neurotransmitter-related gene polymorphisms affect both hedonic and anhedonic behavioral outcomes. There is little known about both the genetics and epigenetics of hypersexuality in the current literature. However, we anticipate that future studies based on assessments with clinical instruments combined with genotyping of sex addicts will provide evidence for specific clustering of sexual typologies with polymorphic associations. There have been some studies using electrophysiological techniques that do not support the view that hypersexuality is indeed similar to substance abuse and other behavioral addictions. The authors are also encouraging both clinical and academic scientists to embark on research using neuroimaging tools to examine natural dopaminergic agonistic agents targeting specific gene polymorphisms to "normalize" hypersexual behavior.

Lithium modulates the production of peripheral and cerebral cytokines in an animal model of mania induced by dextroamphetamine

OBJECTIVES

Several recent studies have suggested that the physiopathology of bipolar disorder (BD) is related to immune system alterations and inflammation. Lithium (Li) is a mood stabilizer that is considered the first-line treatment for this mood disorder. The goal of the present study was to investigate the effects of Li administration on behavior and cytokine levels [interleukin (IL)-1β, IL-4, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α)] in the periphery and brains of rats subjected to an animal model of mania induced by amphetamine (d-AMPH).

METHODS

Male Wistar rats were treated with d-AMPH or saline (Sal) for 14 days; on Day 8 of treatment, the rats were administered Li or Sal for the final seven days. Cytokine (IL-1β, IL-4, IL-6, IL-10, and TNF-α) levels were evaluated in the cerebrospinal fluid (CSF), serum, frontal cortex, striatum, and hippocampus.

RESULTS

The present study showed that d-AMPH induced hyperactivity in rats (p < 0.001), and Li treatment reversed this behavioral alteration (p < 0.001). In addition, d-AMPH increased the levels of IL-4, IL-6, IL-10, and TNF-α in the frontal cortex (p < 0.001), striatum (p < 0.001), and serum (p < 0.001), and treatment with Li reversed these cytokine alterations (p < 0.001).

CONCLUSIONS

Li modulates peripheral and cerebral cytokine production in an animal model of mania induced by d-AMPH, suggesting that its action on the inflammatory system may contribute to its therapeutic efficacy.

Hypersexuality Addiction and Withdrawal: Phenomenology, Neurogenetics and Epigenetics

Hypersexuality is now part of the DSM-V and has been defined as abnormally increased sexual activity. Epidemiological and clinical studies have shown that this non-paraphilic condition consists of “excessive” sexual behaviors and disorders accompanied by personal distress and social and medical morbidity. Hypersexual disorder is conceptualized as primarily a non-paraphilic sexual desire disorder with impulsivity. Pathophysiological perspectives include dysregulation of sexual arousal and desire, sexual impulsivity, sexual addiction, and sexual compulsivity. The nucleus accumbens, situated within the ventral striatum, mediates the reinforcing effects of drugs of abuse, such as cocaine, alcohol, nicotine, and food as well as music. Indeed, it is believed that this structure mandates behaviors elicited by incentive stimuli. These behaviors include natural rewards like feeding, drinking, sexual behavior, and exploratory locomotion. An essential rule of positive reinforcement is that motor responses will increase in magnitude and vigor if followed by a rewarding event. Here, we are hypothesizing that there is a common mechanism of action (MOA) for the powerful effects drugs, music, food, and sex have on human motivation. The human drive for the three necessary motivational behaviors “hunger, thirst, and sex” may all have common molecular genetic antecedents that, if impaired, lead to aberrant behaviors. We hypothesize that based on a plethora of scientific support hypersexual activity is indeed like drugs, food, and music that activate brain mesolimbic reward circuitry. Moreover, dopaminergic gene and possibly other candidate neurotransmitter-related gene polymorphisms affect both hedonic and anhedonic behavioral outcomes. There is little known about both the genetics and epigenetics of hypersexuality in the current literature. However, we anticipate that future studies based on assessments with clinical instruments combined with genotyping of sex addicts will provide evidence for specific clustering of sexual typologies with polymorphic associations. The authors are also encouraging both clinical and academic scientists to embark on research using neuroimaging tools to examine natural dopaminergic agonistic agents targeting specific gene polymorphisms to “normalize” hyper- or hyposexual response.

Methamphetamine-enhanced female sexual motivation is dependent on dopamine and progesterone signaling in the medial amygdala

Methamphetamine (METH) is a psychomotor stimulant strongly associated with increases in sexual drive and impulsive sexual behaviors that often lead to unsafe sexual practices. In women METH users, such practices have been associated with increases in unplanned pregnancies and sexually transmitted diseases. Despite this significant heath concern, the neural mechanisms underlying this drug-sex association are not known. We previously established a rodent model of METH-facilitated female sexual behavior in which estradiol and progesterone interact with METH to increase motivational components of female behavior and neuronal activation in the posterodorsal medial amygdala (MePD) (Holder et al., 2010; Holder and Mong, 2010). The current study more directly examines the mechanisms underlying the drug-sex interaction. Here, we hypothesize that METH-induced increases in MePD dopamine signaling bridge the METH-hormone interaction. In support of this hypothesis, we found that excitotoxic lesions targeted to the MePD attenuated the METH-induced increases in proceptive behavior. Furthermore, infusion of a D1 agonist into the MePD increased proceptive behavior, while infusion of a D1 antagonist blocked the ability of METH to increase proceptive behaviors. Additionally, we found that METH-treatment increased progesterone receptor (PR) immunoreactivity in the MePD, suggesting an interaction between dopamine and progesterone signaling. Indeed, infusions of the PR antagonist, RU486, prevented METH-induced increases in sexual behavior. Thus, taken together, the current findings suggest that dopamine in the MePD modulates enhanced sexual motivation via an amplification of progesterone signaling and contributes to a better understanding of the neurobiology of drug-enhanced sexual behaviors.

Neural response to visual sexual cues in dopamine treatment-linked hypersexuality in Parkinson's disease

Hypersexuality with compulsive sexual behaviour is a significant source of morbidity for patients with Parkinson's disease receiving dopamine replacement therapies. We know relatively little about the pathophysiology of hypersexuality in Parkinson's disease, and it is unknown how visual sexual stimuli, similar to the portrayals of sexuality in the mainstream mass media may affect the brain and behaviour in such susceptible individuals. Here, we have studied a group of 12 patients with Parkinson's disease with hypersexuality using a functional magnetic resonance imaging block design exposing participants to both sexual, other reward-related and neutral visual cues. We hypothesized that exposure to visual sexual cues would trigger increased sexual desire in patients with Parkinson's disease with hypersexuality that would correspond to changes in brain activity in regions linked to dopaminergically stimulated sexual motivation. Patients with Parkinson's disease with hypersexuality were scanned ON and OFF dopamine drugs, and their results were compared with a group of 12 Parkinson's disease control patients without hypersexuality or other impulse control disorders. Exposure to sexual cues significantly increased sexual desire and hedonic responses in the Parkinson's disease hypersexuality group compared with the Parkinson's disease control patients. These behavioural changes corresponded to significant blood oxygen level-dependent signal changes in regions within limbic, paralimbic, temporal, occipital, somatosensory and prefrontal cortices that correspond to emotional, cognitive, autonomic, visual and motivational processes. The functional imaging data showed that the hypersexuality patients' increased sexual desire correlated with enhanced activations in the ventral striatum, and cingulate and orbitofrontal cortices. When the patients with Parkinson's disease with hypersexuality were OFF medication, the functional imaging data showed decreases in activation during the presentation of sexual cues relative to rest. These deactivations were not observed when the patients were ON medication, suggesting that dopamine drugs may release inhibition within local neuronal circuits in the cerebral cortex that may contribute to compulsive sexual behaviour. The findings of this study have implications with respect to the potential influence of cue exposure via exposure to mass media in enhancing libido, which in this group of vulnerable patients can lead to devastating social consequences and occasionally, custodial sentences. Stimulation through exposure to sexual visual cues in patients with Parkinson's disease with hypersexuality provides a motivational impetus for seeking this reward behaviour through activations and deactivations of cerebral cortex.

Fetishism due to methamphetamine (glass) abuse: a case report

BACKGROUND

Fetishism is a type of paraphilia. The focus of sexual arousal in fetishism is oriented towards inanimate objects. Sexual arousal and craving are some of the reasons the youth resort to crystal (glass). Drug abuse may cause disorders in sexual function.

CASE REPORT

The patient was a 41 years old man. He married in age 22 years and experienced frequent intercourses with his wife from which he gained pleasure and it was his preferable method. Her wife left ten years ago. The patient started crystal administration through insufflations since seven months ago. Simultaneous with crystal abuse, wearing women's underwear was the only medium through which the patient reached sexual orgasm.

DISCUSSION

A lot of psychological symptoms related to new substances (for example glass) are new to psychiatrists treating dependency in medical clinics. Fetishism may coexist with addiction as comorbidity. Another point to be mentioned is that, symptoms of fetishism increased and decreased with more and less glass administration, indicating that symptoms of paraphilia emerge as a result of glass use. In addition, prior to glass use, the patient maintained normal sexual tendencies, had experienced sexual intercourse and did not suffer from any type of paraphilia.

Is it really crystal clear that using methamphetamine (or other recreational drugs) causes people to engage in unsafe sex?

Many studies have found associations between unsafe sexual behaviour and use of crystal methamphetamine (and many other recreational drugs). Researchers and authors of relevant articles in popular media have often interpreted these associations as meaning that using ‘crystal’ directly causes people to engage in unsafe sex, and that interventions should aim to reduce crystal use in order to reduce the prevalence of sexually transmissible infections such as HIV. There is consistent evidence that crystal users are a high-risk group in terms of sexual behaviour. However, most relevant studies have provided only circumstantial evidence regarding a causal relationship. Promoting the idea that a particular recreational drug is a major direct cause of unsafe sex may have the unintended adverse effect of creating an excuse for engaging in unsafe sex, thereby increasing its use, and may incur opportunity costs by preventing limited available health promotion resources from being directed more usefully. This paper examines the limitations, in terms of demonstrating causality, of various types of study that have been published on this topic in relation to crystal use in particular. Researchers who investigate relationships between recreational drug use and behaviour, including sexual behaviour, should be careful about the wording of their conclusions and recommendations, and should consider the possibly counterproductive ways in which their findings might be represented in the media.

Chronic pre-exposure to methamphetamine following 31 days of withdrawal impairs sexual performance but not sexual conditioning in male Japanese quail

In the current study, male quail were administered methamphetamine (3.0 or 5.6 mg/kg IP) or saline once daily for 10 days and locomotor activity was assessed. Following a 31-day withdrawal period, sexual conditioning trials were conducted such that a conditioned stimulus (CS) was presented prior to a copulatory opportunity with a female quail. Male quail treated with methamphetamine (5.6 mg/kg) showed a decrease in locomotor activity from Trial 1 to Trial 10 suggesting a potential tolerance effect. Following the 31-day withdrawal period, all male quail that received the CS paired with a copulatory opportunity showed enhanced approach to the CS, regardless of treatment history. Thus, chronic pre-exposure to methamphetamine did not alter sexual conditioning. In contrast, chronic pre-exposure to methamphetamine (3.0 mg/kg) decreased the frequency of successful copulations suggesting that it impaired sexual performance. The findings suggest that methamphetamine may differentially affect the neural circuitry involved in motivational systems compared with those involved in consummatory aspects of sexual behavior. These effects may last long after drug cessation.

Concurrent exposure to methamphetamine and sexual behavior enhances subsequent drug reward and causes compulsive sexual behavior in male rats

Methamphetamine (Meth) users report having heightened sexual pleasure, numerous sexual partners, and engaging in unprotected sex due to loss of inhibitory control. This compulsive sexual behavior contributes to increased prevalence of sexually transmitted infections, but the neural basis for this is unknown. We previously established a paradigm for compulsive sexual behavior in male rats in which visceral illness induced by lithium chloride was paired with sexual behavior (Davis et al., 2010; Frohmader et al., 2010a). The current study examined the effects of repeated Meth administration on sexual performance, compulsive sexual behavior, and sex or Meth reward. First, results demonstrated that seven daily administrations of 2 mg/kg, but not 1 mg/kg, Meth increased latencies to initiate mating. This impairment was evident 30 min after last Meth administration, but dissipated after 1 or 7 d of subsequent drug abstinence. Repeated 1 mg/kg Meth exposure resulted in compulsive sex-seeking behavior 2 weeks following last Meth administration. This effect was dependent on Meth administration being concurrent with sexual experience and was not observed in sexually experienced animals that received Meth alone. Moreover, concurrent Meth and sexual experience enhanced conditioned place preference (CPP) for Meth, and for concurrent Meth and mating compared with Meth or mating alone. In contrast, CPP for mating alone was decreased. Together, these data indicate that the association between drug use and mating may be required for expression of compulsive sexual behavior and is correlated with increased reward seeking for concurrent Meth exposure and mating.

A single administration of methamphetamine to mice early in the light period decreases running wheel activity observed during the dark period

Repeated intermittent administration of amphetamines acutely increases appetitive and consummatory aspects of motivated behaviors as well as general activity and exploratory behavior, including voluntary running wheel activity. Subsequently, if the drug is withdrawn, the frequency of these behaviors decreases, which is thought to be indicative of dysphoric symptoms associated with amphetamine withdrawal. Such decreases may be observed after chronic treatment or even after single drug administrations. In the present study, the effect of acute methamphetamine (METH) on running wheel activity, horizontal locomotion, appetitive behavior (food access), and consummatory behavior (food and water intake) was investigated in mice. A multi-configuration behavior apparatus designed to monitor the five behaviors was developed, where combined measures were recorded simultaneously. In the first experiment, naïve male ICR mice showed gradually increasing running wheel activity over three consecutive days after exposure to a running wheel, while mice without a running wheel showed gradually decreasing horizontal locomotion, consistent with running wheel activity being a positively motivated form of natural motor activity. In experiment 2, increased horizontal locomotion and food access, and decreased food intake, were observed for the initial 3h after acute METH challenge. Subsequently, during the dark phase period decreased running wheel activity and horizontal locomotion were observed. The reductions in running wheel activity and horizontal locomotion may be indicative of reduced dopaminergic function, although it remains to be seen if these changes may be more pronounced after more prolonged METH treatments.

How generalized CNS arousal strengthens sexual arousal (and vice versa)

Heightened states of generalized CNS arousal are proposed here to facilitate sexual arousal in both males and females. Genetic, pharmacologic and biophysical mechanisms by which this happens are reviewed. Moreover, stimulation of the genital epithelia, as triggers of sex behavior, is hypothesized to lead to a greater generalized arousal in a manner that intensifies sexual motivation. Finally, launched from histochemical studies intended to characterize cells in the genital epithelium, a surprising idea is proposed that links density of innervation with the efficiency of wound healing and with the capacity of that epithelium to stimulate generalized CNS arousal. Thus, bidirectional arousal-related mechanisms that foster sexual behaviors are envisioned as follows: from specific to generalized (as with genital stimulation) and from generalized to specific.

Comparing the relative amount of testosterone required to restore sexual arousal, motivation, and performance in male rats

It is well established that male rat reproductive behaviors including sexual arousal, motivation, and performance are dependent on circulating levels of testosterone (T). The present study was designed to (1) compare the relative amount of T required to restore these different aspects of behavior in castrated rats, and (2) create an animal model for clinical populations with sexual impairments. Twenty-nine male Long-Evans rats were tested before and after castration for sexual performance (copulation), motivation (partner preference), and arousal (50 kHz ultrasonic vocalizations; measured together with scent marking). Sexual arousal was also inferred from copulation data. Rats were then assigned to one of four groups, and T was re-introduced via Silastic capsule implants varying in length and content: No T (empty capsules), Low T (2mm capsules), Medium T (5mm capsules), or High T (two 10mm capsules). The highest dose was intended to restore physiological levels. Results indicate that High T is required for 50 kHz vocalizations, while Medium T was sufficient for the restoration of copulation, partner preference, and scent marking. These data suggest that sexual arousal may be most sensitive to reductions in testosterone. The role of T levels in measures of generalized and specific (sexual) arousal is discussed in the context of other reproductive behaviors. Furthermore, because the Low T group showed impairments across all behaviors during post-implant tests, we propose that these animals may provide a good animal model for studying clinical conditions marked by reduced motivation and arousal, including Hypoactive Sexual Desire Disorder.

Methamphetamine enhances sexual behavior in female rats

The present study evaluated the effects of methamphetamine (MA) on sexual behavior in female rats. In Experiment 1, ovariectomized, hormone-primed rats were injected with MA (1.0mg/kg, i.p.) or saline prior to a test for mate choice wherein females could mate with two males simultaneously. Female rats treated with saline returned to their preferred mate faster after receiving intromissions and visited their preferred mate at a higher rate than their non-preferred mate. In contrast, MA-treated female rats spent a similar amount of time with their preferred and non-preferred mate and failed to return to their preferred mate faster than to their non-preferred mate following intromissions. Two weeks later, the females received the same drug treatment but were tested for partner preference wherein females could spend time near a male or female stimulus rat. All subjects spent more time near the male stimulus than the female stimulus. However, the MA-treated rats visited the male stimulus more frequently and spent less time near the female stimulus than the saline-treated rats. Similar to Experiment 1, female rats in Experiment 2 were tested for mate choice and then two weeks later tested for partner preference; however, females received three daily injections of MA (1.0mg/kg, i.p.) or saline. Females treated chronically with MA returned to both males faster following intromissions than females treated with saline, independent of preference (i.e., preferred mate and non-preferred mate). Furthermore, MA-treated rats were more likely to leave either male (i.e., preferred or non-preferred mate) than saline-treated rats after receiving sexual stimulation. Although MA-treated subjects spent more time near the male stimulus than the female stimulus, they spent less time near either when compared to saline-treated subjects. The present results demonstrate that MA affects sexual behavior in female rats partly by increasing locomotion and partly by directly affecting sexual behavior.

Systemically administered oxytocin decreases methamphetamine activation of the subthalamic nucleus and accumbens core and stimulates oxytocinergic neurons in the hypothalamus

Recent preclinical evidence indicates that the neuropeptide oxytocin may have potential in the treatment of drug dependence and drug withdrawal. Oxytocin reduces methamphetamine self-administration, conditioned place preference and hyperactivity in rodents. However, it is unclear how oxytocin acts in the brain to produce such effects. The present study examined how patterns of neural activation produced by methamphetamine were modified by co-administered oxytocin. Male Sprague-Dawley rats were pretreated with either 2 mg/kg oxytocin (IP) or saline and then injected with either 2 mg/kg methamphetamine (IP) or saline. After injection, locomotor activity was measured for 80 minutes prior to perfusion. As in previous studies, co-administered oxytocin significantly reduced methamphetamine-induced behaviors. Strikingly, oxytocin significantly reduced methamphetamine-induced Fos expression in two regions of the basal ganglia: the subthalamic nucleus and the nucleus accumbens core. The subthalamic nucleus is of particular interest given emerging evidence for this structure in compulsive, addiction-relevant behaviors. When administered alone, oxytocin increased Fos expression in several regions, most notably in the oxytocin-synthesizing neurons of the supraoptic nucleus and paraventricular nucleus of the hypothalamus. This provides new evidence for central actions of peripheral oxytocin and suggests a self-stimulation effect of exogenous oxytocin on its own hypothalamic circuitry. Overall, these results give further insight into the way in which oxytocin might moderate compulsive behaviors and demonstrate the capacity of peripherally administered oxytocin to induce widespread central effects.

Effects of methamphetamine on sexual performance and compulsive sex behavior in male rats

RATIONALE

Methamphetamine (Meth) is a highly addictive psychostimulant associated with enhanced sexual desire, arousal, and sexual pleasure. Moreover, Meth abuse is frequently linked with the practice of sexual risk behavior and increased prevalence of human immunodeficiency virus. Currently, there is a lack of studies investigating the effects of Meth on maladaptive sexual behavior under controlled experimental settings in animal studies.

OBJECTIVE

The overall objective of the current study was to examine the effects of Meth on various aspects of male sexual behavior including maladaptive sex-seeking behavior.

METHODS

First, a dose-response curve of the effects of Meth (0, 1, 2, and 4 mg/kg; s.c.) on sexual motivation and performance was conducted in sexually naïve and experienced male rats. Next, the effects of Meth (1 mg/kg; s.c.) on inhibition of maladaptive sexual behavior was tested using a sex aversion conditioning paradigm, in which visceral illness induced by lithium chloride (LiCl) was paired with sexual behavior.

RESULTS

Meth administration inhibited sexual performance in a dose-dependent matter as evidenced by the decreased percentages of males that mated and increased latencies to initiate sexual behavior when injected with 2 or 4 mg/kg Meth. Moreover, an acute dose of Meth prior to or following sex aversion conditioning resulted in disrupted conditioned inhibition of sexual behavior.

CONCLUSIONS

These data suggest that Meth administration in male rats impairs sexual motivation and performance. In addition, low doses of Meth that do not disrupt sexual function may result in maladaptive seeking of sexual behavior.

Reproductive behaviors: new developments in concepts and in molecular mechanisms progress in brain research, Luciano Martini, editor, January 19, 2010

New developments in the analysis of mechanisms for reproductive behaviors are reviewed. Conceptually, the concept of generalized arousal (GA) of the central nervous system (CNS) is considered. Breeding for high and low GA, we show an impact of GA on sexual arousal of male mice, and also find that the structure of GA in the CNS of males and females is not the same. Further, we propose, theoretically, that among epithelial tissues in humans, there are correlations among their innervation densities and their ability to trigger arousal. In new technical developments, we analyze transcriptional effects of estrogens in the hypothalamic neurons that regulate lordosis behavior. The rapid effect of estradiol to increase acetylation of histones in ventromedial hypothalamic neurons could be tied into transcriptional activation, but the effect of estradiol to increase methylation of histone 3, lysine 9 (H3K9) is puzzling. This work seeks to discover the coactivator dynamics underlying transcriptional effects of estrogens on sex behavior.

Methamphetamine enhances paced mating behaviors and neuroplasticity in the medial amygdala of female rats

Methamphetamine (METH) is a psychomotor stimulant strongly associated with increases in sexual drive and behavior in women and men. Even though men and women are equally as likely to be addicted to or use METH, studies of sexual behavior often focus on male users. The paucity in studies examining the effect of METH in women is of great concern, when one considers the high correlation with sexually transmitted diseases such as HIV/AIDS and unplanned pregnancies. In fact, why METH so profoundly increases sexual drive is unknown. We have demonstrated that repeated exposure to METH enhances both receptivity and proceptivity in hormonally primed female rats. The current study examined whether a repeated exposure to METH enhanced female-initiated sexual behaviors in hormonally primed rats. In a paced mating paradigm, METH treatment significantly decreased the female's return latency following a mount (57%) and an ejaculation (44%), and the likelihood to leave the male following an intromission (37%) compared to controls. The METH-induced changes in paced mating behavior were accompanied by a 60% increase in spinophilin levels in the medial amygdala following hormonal priming and METH treatment. Taken together, these findings suggest that METH increases female sexual motivation and behavior in the rat potentially via changes in the neural substrate that require repeated exposure to the drug.

The role of mesocorticolimbic dopamine in regulating interactions between drugs of abuse and social behavior

The use of addictive drugs can have profound short- and long-term consequences on social behaviors. Similarly, social experiences and the presence or absence of social attachments during early development and throughout life can greatly influence drug intake and the susceptibility to drug abuse. The following review details this reciprocal interaction, focusing on common drugs of abuse (e.g., psychostimulants, opiates, alcohol and nicotine) and social behaviors (e.g., maternal, sexual, play, aggressive and bonding behaviors). The neural mechanisms underlying this interaction are discussed, with a particular emphasis on the involvement of the mesocorticolimbic dopamine system.

Mixing pleasures: review of the effects of drugs on sex behavior in humans and animal models

Drugs of abuse act on the brain circuits mediating motivation and reward associated with natural behaviors. There is ample evidence that drugs of abuse impact male and female sexual behavior. First, the current review discusses the effect of drugs of abuse on sexual motivation and performance in male and female humans. In particular, we discuss the effects of commonly abused drugs including psychostimulants, opiates, marijuana/THC, and alcohol. In general, drug use affects sexual motivation, arousal, and performance and is commonly associated with increased sexual risk behaviors. Second, studies on effects of systemic administration of drugs of abuse on sexual behavior in animals are reviewed. These studies analyze the effects on sexual performance and motivation but do not investigate the effects of drugs on risk-taking behavior, creating a disconnect between human and animal studies. For this reason, we discuss two studies that focus on the effects of alcohol and methamphetamine on inhibition of maladaptive sex-seeking behaviors in rodents. Third, this review discusses potential brain areas where drugs of abuse may be exerting their effect on sexual behavior with a focus on the mesolimbic system as the site of action. Finally, we discuss recent studies that have brought to light that sexual experience in turn can affect drug responsiveness, including a sensitized locomotor response to amphetamine in female and male rodents as well as enhanced drug reward in male rats.

Low doses of cocaine decrease, and high doses increase, anxiety-like behavior and brain progestogen levels among intact rats

There are sex and hormonal differences in response to cocaine that have been demonstrated in people and animal models. Cocaine can alter secretion of progestogens, such as progesterone (P), and its neuroactive metabolite, 5alpha-pregnan-3alpha-ol-20-one (3alpha,5alpha-THP). However, little research has been done on the neuroendocrine effects in the initiation phase of cocaine use. We hypothesize that some sex/hormonal differences in initiation phase responses to cocaine may be related to formation of progestogens. To investigate the role of progestogens in sex differences in response to acute cocaine, male and female rats in the high (proestrous) or low (diestrous) progestogen phase of the estrous cycle were administered cocaine (0, 5, 10, or 20mg/kg, IP). We examined cocaine's acute neuroendocrine effects on P and 3alpha,5alpha-THP levels, as well as its effects on acute psychomotor stimulation, anxiety, and sexual behaviors. Among rats that had P and/or 3alpha,5alpha-THP levels increased in response to cocaine, enhanced acute psychomotor stimulation was observed. Results suggest that cocaine produces U-shaped curves for progestogens, and anxiety-like behaviors. Male rats were less susceptible to these effects of cocaine than were proestrous or diestrous female rats. However, cocaine's disruption of sexual behaviors was similar among males and proestrous females. These data suggest a complex interaction between hormonal milieu and the neuroendocrine and behavioral effects of cocaine.