Intracerebroventricular Self-Administration of Commonly Abused Anabolic-Androgenic Steroids in Male Hamsters (Mesocricetus auratus): Nandrolone, Drostanolone, Oxymetholone, and Stanozolol

Performance- and image-enhancing drug use in the community: use prevalence, user demographics and the potential role of wastewater-based epidemiology

Performance- and image-enhancing drug (PIED) misuse is a significant public health issue. Currently, seizure data, surveys, anti-doping testing, and needle service provider data are used to estimate PIED use in populations. These methods are time consuming, single point-in-time measurements that often consist of small sample sizes and do not truly capture PIED prevalence. Wastewater-based epidemiology (WBE) has been used globally to assess and monitor licit and illicit drug consumption within the general community. This method can objectively cover large populations as well as specific subpopulations (gyms, music festivals, prisons), and has potential as a complementary monitoring method for PIED use. Information obtained through WBE could be used to aid public health authorities in developing targeted prevention and education programmes. Research on PIED analysis in wastewater is limited and presents a significant gap in the literature. The focus is on anabolic steroids, and one steroid alternative currently growing in popularity; selective androgenic receptor modulators. This encompasses medical uses, addiction, prevalence, user typology, and associated public health implications. An overview of WBE is described including its benefits, limitations and potential as a monitoring method for PIED use. A summary of previous work in this field is presented. Finally, we summarise gaps in the literature, future perspectives, and recommendations for monitoring PIEDs in wastewater.

Efeitos dos anabolizantes sobre a densidade de neurônios dos núcleos da base

RESUMO Objetivos: Pouco se sabe sobre a atuação dos esteroides androgênicos anabolizantes (EAA) no cérebro humano e, por isso, resolvemos estudar a perda neuronal causada pelo uso e abuso de EAA em camundongos. Métodos: Utilizamos 60 camundongos da linhagem Swiss, sendo 30 machos e 30 fêmeas, divididos em três grupos: 20 animais foram tratados com Deposteron® (cipionato de testosterona); outros 20 animais foram tratados com Winstrol Depot® (stanozolol); os últimos 20 animais foram tratados com solução salina. Todos foram submetidos à natação por 15 minutos. Finalizado o tratamento, os animais foram sacrificados pelo método de inalação de Halotano. Os encéfalos foram retirados e armazenados em solução de formaldeído a 4% por 24 horas. De cada encéfalo foram retiradas amostras homotípicas da região média do cérebro em cortes frontais para que pudéssemos avaliar as áreas estabelecidas para este estudo. Resultados: As análises da estimativa dos perfis celulares mostraram que houve uma diminuição do número de perfis no núcleo pálido dos animais machos tratados com Winstrol Depot®. Conclusão: Esses resultados nos permitem inferir que o uso inadequado e sem orientação médica de EAA pode levar a degenerações celulares.

Mad men, women and steroid cocktails: a review of the impact of sex and other factors on anabolic androgenic steroids effects on affective behaviors

RATIONALE

For several decades, elite athletes and a growing number of recreational consumers have used anabolic androgenic steroids (AAS) as performance enhancing drugs. Despite mounting evidence that illicit use of these synthetic steroids has detrimental effects on affective states, information available on sex-specific actions of these drugs is lacking.

OBJECTIVES

The focus of this review is to assess information to date on the importance of sex and its interaction with other environmental factors on affective behaviors, with an emphasis on data derived from non-human studies.

METHODS

The PubMed database was searched for relevant studies in both sexes.

RESULTS

Studies examining AAS use in females are limited, reflecting the lower prevalence of use in this sex. Data, however, indicate significant sex-specific differences in AAS effects on anxiety-like and aggressive behaviors, interactions with other drugs of abuse, and the interplay of AAS with other environmental factors such as diet and exercise.

CONCLUSIONS

Current methods for assessing AAS use have limitations that suggest biases of both under- and over-reporting, which may be amplified for females who are poorly represented in self-report studies of human subjects and are rarely used in animal studies. Data from animal literature suggest that there are significant sex-specific differences in the impact of AAS on aggression, anxiety, and concomitant use of other abused substances. These results have relevance for human females who take these drugs as performance-enhancing substances and for transgender XX individuals who may illicitly self-administer AAS as they transition to a male gender identity.

Effects of anabolic-androgens on brain reward function

Androgens are mainly prescribed to treat several diseases caused by testosterone deficiency. However, athletes try to promote muscle growth by manipulating testosterone levels or assuming androgen anabolic steroids (AAS). These substances were originally synthesized to obtain anabolic effects greater than testosterone. Although AAS are rarely prescribed compared to testosterone, their off-label utilization is very wide. Furthermore, combinations of different steroids and doses generally higher than those used in therapy are common. Symptoms of the chronic use of supra-therapeutic doses of AAS include anxiety, depression, aggression, paranoia, distractibility, confusion, amnesia. Interestingly, some studies have shown that AAS elicited electroencephalographic changes similar to those observed with amphetamine abuse. The frequency of side effects is higher among AAS abusers, with psychiatric complications such as labile mood, lack of impulse control and high violence. On the other hand, AAS addiction studies are complex because data collection is very difficult due to the subjects' reticence and can be biased by many variables, including physical exercise, that alter the reward system. Moreover, it has been reported that AAS may imbalance neurotransmitter systems involved in the reward process, leading to increased sensitivity toward opioid narcotics and central stimulants. The goal of this article is to review the literature on steroid abuse and changes to the reward system in preclinical and clinical studies.

'Roid rage in rats? Testosterone effects on aggressive motivation, impulsivity and tyrosine hydroxylase

In humans and animals, anabolic-androgenic steroids (AAS) increase aggression, but the underlying behavioral mechanisms are unclear. AAS may increase the motivation to fight. Alternatively, AAS may increase impulsive behavior, consistent with the popular image of 'roid rage. To test this, adolescent male rats were treated chronically with testosterone (7.5mg/kg) or vehicle and tested for aggressive motivation and impulsivity. Rats were trained to respond on a nose-poke on a 10 min fixed-interval schedule for the opportunity to fight in their home cage with an unfamiliar rat. Although testosterone increased aggression (6.3±1.3 fights/5 min vs 2.4±0.8 for controls, p<0.05), there was no difference in operant responding (28.4±1.6 nose-pokes/10 min for testosterone, 32.4±7.0 for vehicle). This suggests that testosterone does not enhance motivation for aggression. To test for impulsivity, rats were trained to respond for food in a delay-discounting procedure. In an operant chamber, one lever delivered one food pellet immediately, the other lever gave 4 pellets after a delay (0, 15, 30 or 45 s). In testosterone- and vehicle-treated rats, body weights and food intake did not differ. However, testosterone-treated rats chose the larger, delayed reward more often (4.5±0.7 times in 10 trials with 45 s delay) than vehicle controls (2.5±0.5 times, p<0.05), consistent with a reduction in impulsive choice. Thus, although chronic high-dose testosterone enhances aggression, this does not include an increase in impulsive behavior or motivation to fight. This is further supported by measurement of tyrosine hydroxylase (TH) by Western immunoblot analysis in brain regions important for motivation (nucleus accumbens, Acb) and executive function (medial prefrontal cortex, PFC). There were no differences in TH between testosterone- and vehicle-treated rats in Acb or PFC. However, testosterone significantly reduced TH (to 76.9±3.1% of controls, p<0.05) in the caudate-putamen, a brain area important for behavioral inhibition, motor control and habit learning.

Neurochemical consequence of steroid abuse: stanozolol-induced monoaminergic changes

An extensive literature has documented adverse effects on mental health in anabolic androgenic steroids (AAS) abusers. Depression seems a common adverse reaction in AAS abusers. Recently it has been reported that in a rat model of AAS abuse stanozolol induces behavioural and biochemical changes related to the pathophysiology of major depressive disorder. In the present study, we used the model of AAS abuse to examine possible changes in the monoaminergic system, a neurobiological substrate of depression, in different brain areas of stanozolol-treated animals. Wistar rats received repeated injections of stanozolol (5mg/kg, s.c.), or vehicle (propylene glycol, 1ml/kg) once daily for 4weeks. Twenty-four hours after last injection, changes of dopamine (DA) and relative metabolite levels, homovanilic acid (HVA) and 3,4-dihydroxy phenylacetic acid (DOPAC), serotonin (5-HT) and its metabolite levels, 5-hydroxy indolacetic acid (5-HIAA), and noradrenaline (NA) amount were investigated in prefrontal cortex (PFC), nucleus accumbens (NAC), striatum (STR) and hippocampus (HIPP). The analysis of data showed that after chronic stanozolol, DA levels were increased in the HIPP and decreased in the PFC. No significant changes were observed in the STR or in the NAC. 5-HT and 5-HIAA levels were decreased in all brain areas investigated after stanozolol exposure; however, the 5-HIAA/5-HT ratio was not altered. Taken together, our data indicate that chronic use of stanozolol significantly affects brain monoamines leading to neurochemical modifications possibly involved in depression and stress-related states.

Testosterone as a discriminative stimulus in male rats

Testosterone and other anabolic-androgenic steroids (AAS) are reinforcing in animals, as determined by conditioned place preference or self-administration. Most drugs of abuse produce subjective effects on mood and perception that initiate and maintain drug taking. Whether AAS have similar effects is not known. Food-restricted male Sprague-Dawley rats (n=9) were tested for their ability to discriminate an injection of testosterone from the β-cyclodextrin vehicle using a standard two-lever operant paradigm. In drug discrimination, animals use the subjective effects of drug or vehicle to select the appropriate lever to obtain food pellets under an FR10 schedule of reinforcement. All rats demonstrated vigorous responding for food (1415.1±76.1 responses/20 min) with 94.9% of responses on the active lever. For the first 30 days, rats received 1mg/kg testosterone sc 30 min before testing. On Day 14, one rat achieved the discrimination criteria of 9/10 consecutive days with >90% responses on the active lever and ≤5 responses on the inactive lever before the first reinforcement. Subsequently, rats were tested with testosterone at different doses (2, 7.5, 15 mg/kg at 30 min before testing) and times (2mg/kg at 30 or 60 min before testing), each for 20 days. One additional rat demonstrated successful discrimination at Day 54 with 2mg/kg testosterone 60 min before testing. The remaining 7 rats failed to discriminate testosterone within 110 days. When analyzed according to less-stringent standards, 4 additional rats met criteria for testosterone discrimination. However, continued performance was not stable. Thus, testosterone was unable to consistently support drug discrimination. We conclude that testosterone does not produce rapid interoceptive effects (NIH DA12843 to RIW).

The acute effects of a low and high dose of oral l-arginine supplementation in young active males at rest

l-arginine (2-amino-5-guanidinovaleric acid) is a conditionally essential amino acid. Intravenous (IV) administration of l-arginine invokes a large metabolic (nitrate/nitrite (NOx)) and hormonal (growth hormone (GH), insulin-like growth factor 1 (IGF-1), and insulin) response; however, research examining oral l-arginine supplementation is conflicting, potentially owing to dose. The purpose of this study was examine a low and high dose of oral l-arginine on blood l-arginine, NOx, GH, IGF-1, and insulin response. Fourteen physically active males (age: 25 ± 5 years; weight: 78.0 ± 8.5 kg; height: 179.4 ± 4.7 cm) volunteered to be in a randomized, double-blind, repeated-measures study. Following an overnight fast, an IV catheter was placed in a forearm vein and a resting blood sample was drawn at ∼0800 hours. Each subject was then provided 1 of 3 treatment conditions (placebo, low (0.075 g·kg–1 of body mass), or high (0.15 g·kg–1 of body mass of l-arginine)). Blood samples were drawn at 30, 60, 90, 120, and 180 min after consumption. l-arginine plasma concentrations significantly increased (p < 0.001) to a similar level at any time point in both the low- and high-dose conditions; there was no change over time in the placebo condition. There was no significant difference between conditions for NOx, GH, IGF-1, or insulin. Based on these findings, a low dose of l-arginine was just as effective at increasing plasma l-arginine concentrations as a high dose; however, neither dose was able to promote a significant increase in NOx, GH, IGF-1, or insulin at rest.

Membrane androgen receptors may mediate androgen reinforcement

Anabolic-androgenic steroid (AAS) abuse is widespread. Moreover, AAS are reinforcing, as shown by self-administration in rodents. However, the receptors that transduce the reinforcing effects of AAS are unclear. AAS may bind to classical nuclear androgen receptors (ARs) or membrane receptors. We used two approaches to examine the role of nuclear ARs in AAS self-administration. First, we tested androgen self-administration in rats with the testicular feminization mutation (Tfm), which interferes with androgen binding. If nuclear ARs are essential for AAS self-administration, Tfm males should not self-administer androgens. Tfm males and wild-type (WT) littermates self-administered the non-aromatizable androgen dihydrotestosterone (DHT) or vehicle intracerebroventricularly (ICV) at fixed-ratio (FR) schedules up to FR5. Both Tfm and WT rats acquired a preference for the active nose-poke during DHT self-administration (66.4+/-9.6 responses/4 h for Tfm and 79.2+/-11.5 for WT responses/4 h), and nose-pokes increased as the FR requirement increased. Preference scores were significantly lower in rats self-administering vehicle (42.3+/-5.3 responses/4 h for Tfm and 19.1+/-4.0 responses/4 h for WT). We also tested self-administration of DHT conjugated to bovine serum albumin (BSA) at C3 and C17, which is limited to actions at the cell surface. Hamsters were allowed to self-administer DHT, BSA and DHT-BSA conjugates for 15 days at FR1. The hamsters showed a significant preference for DHT (18.0+/-4.1 responses/4 h) or DHT-BSA conjugates (10.0+/-3.7 responses/4 h and 21.0+/-7.2 responses/4 h), but not for BSA (2.5+/-2.4 responses/4 h). Taken together, these data demonstrate that nuclear ARs are not required for androgen self-administration. Furthermore, androgen self-administration may be mediated by plasma membrane receptors.

Treatment of anabolic-androgenic steroid dependence: Emerging evidence and its implications

Currently, few users of anabolic-androgenic steroids (AAS) seek substance abuse treatment. But this picture may soon change substantially, because illicit AAS use did not become widespread until the 1980s, and consequently the older members of this AAS-using population - those who initiated AAS as youths in the 1980s - are only now reaching middle age. Members of this group, especially those who have developed AAS dependence, may therefore be entering the age of risk for cardiac and psychoneuroendocrine complications sufficient to motivate them for substance abuse treatment. We suggest that this treatment should address at least three etiologic mechanisms by which AAS dependence might develop. First, individuals with body image disorders such as "muscle dysmorphia" may become dependent on AAS for their anabolic effects; these body image disorders may respond to psychological therapies or pharmacological treatments. Second, AAS suppress the male hypothalamic-pituitary-gonadal axis via their androgenic effects, potentially causing hypogonadism during AAS withdrawal. Men experiencing prolonged dysphoric effects or frank major depression from hypogonadism may desire to resume AAS, thus contributing to AAS dependence. AAS-induced hypogonadism may require treatment with human chorionic gonadotropin or clomiphene to reactivate neuroendocrine function, and may necessitate antidepressant treatments in cases of depression inadequately responsive to endocrine therapies alone. Third, human and animal evidence indicates that AAS also possess hedonic effects, which likely promote dependence via mechanisms shared with classical addictive drugs, especially opioids. Indeed, the opioid antagonist naltrexone blocks AAS dependence in animals. By inference, pharmacological and psychosocial treatments for human opioid dependence might also benefit AAS-dependent individuals.

Anabolic-androgenic steroid dependence? Insights from animals and humans

Anabolic-androgenic steroids (AAS) are drugs of abuse. They are taken in large quantities by athletes and others to increase performance, with negative health consequences. As a result, in 1991 testosterone and related AAS were declared controlled substances. However, the relative abuse and dependence liability of AAS have not been fully characterized. In humans, it is difficult to separate the direct psychoactive effects of AAS from reinforcement due to their systemic anabolic effects. However, using conditioned place preference and self-administration, studies in animals have demonstrated that AAS are reinforcing in a context where athletic performance is irrelevant. Furthermore, AAS share brain sites of action and neurotransmitter systems in common with other drugs of abuse. In particular, recent evidence links AAS with opioids. In humans, AAS abuse is associated with prescription opioid use. In animals, AAS overdose produces symptoms resembling opioid overdose, and AAS modify the activity of the endogenous opioid system.

The anabolic androgenic steroid nandrolone decanoate affects mRNA expression of dopaminergic but not serotonergic receptors

The abuse of anabolic androgenic steroids (AASs) at supratherapeutic doses is a problem not only in the world of sports, but also among non-athletes using AASs to improve physical appearance and to become more bold and courageous. Investigations of the possible neurochemical effects of AAS have focused partially on the monoaminergic systems, which are involved in aggressive behaviours and the development of drug dependence. In the present study, we administered nandrolone decanoate (3 or 15 mg/kg/day for 14 days) and measured mRNA expression of dopaminergic and serotonergic receptors, transporters and enzymes in the male rat brain using quantitative real-time polymerase chain reaction. Expression of the dopamine D1-receptor transcript was elevated in the amygdala and decreased in the hippocampus while the transcript level of the dopamine D4-receptor was increased in the nucleus accumbens. No changes in transcriptional levels were detected among the serotonin-related genes examined in this study. The altered mRNA expression of the dopamine receptors may contribute to some of the behavioural changes often reported in AAS abusers of increased impulsivity, aggression and drug-seeking.

Reduced activity of monoamine oxidase in the rat brain following repeated nandrolone decanoate administration

Anabolic androgenic steroids (AAS) are known as doping agents within sports and body-building, but are currently also abused by other groups in society in order to promote increased courage and aggression. We previously showed that 14 days of daily intramuscular injections of the AAS nandrolone decanoate (15 mg/kg) reduced the extracellular levels of the dopaminergic metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the nucleus accumbens shell using microdialysis. The aim of the present study was to investigate whether the same dose regimen of nandrolone decanoate may affect the activities of the dopamine-metabolizing enzymes monoamine oxidases A and B (MAO-A and MAO-B). A radiometric assay was used to determine the activities of MAO-A and MAO-B in rat brain tissues after 14 days of daily i.m. nandrolone decanoate injections at the doses 3 and 15 mg/kg. Gene transcript contents of MAO-A, MAO-B and cathecol-O-methyltransferase (COMT) were measured with quantitative real-time reverse transcription PCR. 3 mg/kg of nandrolone decanoate significantly reduced the activity of both MAO-A and -B in the caudate putamen. 15 mg/kg of nandrolone decanoate significantly reduced the activity of MAO-A in the amygdala and increased the gene transcript level of MAO-B in the substantia nigra. In conclusion, imbalanced MAO activities may contribute to explain the impulsive and aggressive behaviour often described in AAS abusers. The reduced MAO activities observed are in line with our previously presented findings of decreased extracellular levels of DOPAC and HVA in the rat brain, indicating decreased monoaminergic activity following repeated AAS administration.

Testosterone and nucleus accumbens dopamine in the male Syrian hamster

Most drugs of abuse increase dopamine (DA) in nucleus accumbens (Acb). However, the effects of anabolic androgenic steroids (AAS) on Acb DA have not been examined. We determined the effects of subcutaneous (sc) testosterone (T) on Acb DA in male hamsters. The effects of sc amphetamine were also examined for comparison. In addition, Acb DA was evaluated during intracerebroventricular (ICV) T infusion, designed to mimic T intake during ICV T self-administration in drug-naïve and drug-preexposed animals. Acb DA was measured using in vivo microdialysis and HPLC-EC. T (7.5 or 37.5 mg/kg), amphetamine (1 or 5 mg/kg), or vehicle was injected sc and Acb DA monitored for 4h. In the ICV experiment, T (1 or 2 microg/infusion) or vehicle was infused ICV every 6 min for 4h and Acb DA monitored. ICV T preexposure was accomplished by repeating the same ICV T infusion (1 microg/infusion) daily for 14 days, and T infusion was accompanied by microdialysis on 15th day. Neither sc nor ICV T administration increased Acb DA. At high dose (2 microg/infusion), ICV T decreased Acb DA. Likewise, daily ICV infusion of T for 15 days did not alter Acb DA. In contrast, sc amphetamine significantly increased Acb DA at both doses. Therefore, unlike many drugs of abuse, AAS does not increase Acb DA levels. The reduction in DA at high T doses is likely due to autonomic depressant effects of AAS. We suggest that AAS act via mechanism distinct from those of stimulants, but may share neural substrates with other drugs of abuse.

Nanomolar concentrations of anabolic-androgenic steroids amplify excitotoxic neuronal death in mixed mouse cortical cultures

The use of anabolic-androgenic steroids (AASs) in the world of sport has raised a major concern for the serious, sometimes life-threatening, side effects associated with these drugs. Most of the CNS effects are of psychiatric origin, and whether or not AASs are toxic to neurons is yet unknown. We compared the effect of testosterone with that of the AASs, 19-nortestosterone (nandrolone), stanozolol, and gestrinone, on excitotoxic neuronal death induced by N-methyl-d-aspartate (NMDA) in primary cultures of mouse cortical cells. In the most relevant experiments, steroids were applied to the cultures once daily during the 4 days preceding the NMDA pulse. Under these conditions, testosterone amplified excitotoxic neuronal death only at very high concentrations (10 muM), whereas it was protective at concentrations of 10 nM and inactive at intermediate concentrations. Low concentrations of testosterone became neurotoxic in the presence of the aromatase inhibitors, i.e. anastrozole and aminoglutethimide, suggesting that the intrinsic toxicity of testosterone was counterbalanced by its aromatization into 17beta-estradiol. As opposed to testosterone, nortestosterone, stanozolol and gestrinone amplified NMDA toxicity at nanomolar concentrations; their action was insensitive to aromatase inhibitors, but was abrogated by the androgen receptor antagonist, flutamide. None of the AASs were toxic in the absence of NMDA. These data suggest that AASs increase neuronal vulnerability to an excitotoxic insult and may therefore facilitate neuronal death associated with acute or chronic CNS disorders.

Self-administration of 3α-androstanediol increases locomotion and analgesia and decreases aggressive behavior of male hamsters

Androgens, such as testosterone (T), can have reinforcing effect, which may be due in part to actions of T's metabolite, 3alpha-androstanediol (3alpha-diol). To investigate rewarding effects of 3alpha-diol, gonadally intact adult male hamsters were given a two-bottle choice test to determine the amount of 3alpha-diol that would be self-administered over 4 days of exposure. After 2 days of habituation and 4 days of monitoring of consumption, hamsters were tested in an activity monitor and the open field (locomotion/exploration), paw lick (analgesia) and resident-intruder (aggression) tasks. Hamsters consumed significantly more 3alpha-diol than vehicle in the two-bottle choice test. Hamsters that were allowed to self-administer 3alpha-diol made significantly more beam breaks and total entries in the open field had increased latencies to pawlick, and engaged in significantly fewer attacks, than did hamsters with access to vehicle alone. Hamsters that self-administered 3alpha-diol had higher levels of 3alpha-diol in serum, hippocampus, prefrontal cortex, striatum and midbrain than did hamsters with access to vehicle alone. Together, these data suggest that 3alpha-diol may have rewarding effects.

Altered extracellular levels of DOPAC and HVA in the rat nucleus accumbens shell in response to sub-chronic nandrolone administration and a subsequent amphetamine challenge

Associated with acts of violence and polydrug use, abuse of anabolic androgenic steroids (AAS) is an increasing problem in society. The aim of the present study was to elucidate whether sub-chronic treatment with the AAS nandrolone decanoate affects dopamine release and dopamine metabolism in the rat nucleus accumbens shell, before and after an amphetamine challenge. Male Sprague-Dawley rats received daily i.m. injections of nandrolone decanoate (15 mg/kg) or vehicle for 14 days. On day 15, the animals were anaesthetized and a microdialysis probe was implanted into the nucleus accumbens shell. Extracellular fluid was collected 1h before and 3h after a single amphetamine injection (5 mg/kg). The samples were then analyzed regarding the content of dopamine, and its metabolites 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), using HPLC with electrochemical detection. Two weeks of nandrolone decanoate administration caused a significant decrease of the basal DOPAC and HVA levels, which remained low during the first hour following the amphetamine challenge. Dopamine levels did not differ significantly between groups, neither after the nandrolone pre-treatment nor the amphetamine challenge. In conclusion, these novel findings indicate that AAS alter the metabolism of dopamine in a brain region involved in the development of drug dependence.

Self-administration of estrogen and dihydrotestosterone in male hamsters

Anabolic-androgenic steroids (AAS) are drugs of abuse. Previous studies have shown that male and female hamsters self-administer testosterone (T) and other AAS, suggesting that androgens are reinforcing in a context where athletic performance is irrelevant. AAS are synthetic derivatives of T, which may be aromatizable to estrogen and/or reducible to dihydrotestosterone (DHT). However, we do not know which metabolites of T are reinforcing. To determine if DHT, estradiol (E(2)), or DHT + E(2) are reinforcing, we tested intracerebroventricular (icv) self-administration in male hamsters. The hypothesis was that androgen reinforcement is sensitive to both androgenic and estrogenic T metabolites. If so, hamsters would self-administer DHT, E(2), and DHT + E(2). Twenty four castrated male hamsters (n = 8/group) received icv cannulas and sc T implants for physiologic androgen replacement. One week later, hamsters self-administered DHT (0.1, 1.0, 2.0 microg/microl), E(2) (0.001, 0.01, 0.02 microg/microl), or DHT + E(2), each for 8 days in increasing concentration (4 h/day). Operant chambers were equipped with an active and inactive nose-poke. At the medium concentration, hamsters self-administered DHT (active nose-poke: 47.9 +/- 13.9 responses/4 h vs. inactive: 18.7 +/- 4.8), E(2) (active: 44.8 +/- 14.9 vs. inactive: 16.6 +/- 2.6), and DHT + E(2) (active: 19.1 +/- 2.4 vs. inactive: 10.4 +/- 2.4, P < 0.05). At the highest concentration, males self-administered DHT (active: 28.3 +/- 7.7 vs. inactive: 15.0 +/- 3.5, P < 0.05) and DHT + E(2) (active: 22.6 +/- 3.8 vs. inactive: 11.6 +/- 2.5, P < 0.05), but not E(2). Hamsters did not self-administer the lowest concentrations of DHT, E(2), or DHT + E(2). These results support our hypothesis that both androgenic and estrogenic T metabolites are reinforcing. Together, they do not exert synergistic effects.

Influence of the anabolic-androgenic steroid nandrolone on cannabinoid dependence

The identification of the possible factors that might enhance the risk of developing drug addiction and related motivational disorders is crucial to reduce the prevalence of these problems. Here, we examined in mice whether the exposure to the anabolic-androgenic steroid nandrolone would affect the pharmacological and motivational effects induced by Delta(9)-tetrahydrocannabinol (THC), the principal psychoactive component of Cannabis sativa. Mice received nandrolone using pre-exposure (during 14days before THC treatment) or co-administration (1h before each THC injection) procedures. Both nandrolone treatments did not modify the acute antinociceptive, hypothermic and hypolocomotor effects of THC or the development of tolerance after chronic THC administration. Nandrolone pre-exposure blocked THC- and food-induced conditioned place preference and increased the somatic manifestations of THC withdrawal precipitated by the CB1 cannabinoid antagonist rimonabant (SR141617A). The aversive effects of THC were not changed by nandrolone. Furthermore, nandrolone pre-exposure attenuated the anxiolytic-like effects of a low dose of THC without altering the anxiogenic-like effects of a high dose in the lit/dark box, open field and elevated plus-maze. Biochemical experiments showed that chronic nandrolone treatment did not modify CB1 receptor binding and GTP-binding protein activation in the caudate-putamen and cerebellum. Taken together, our results suggest that chronic nandrolone treatment alters behavioural responses related to cannabinoid addictive properties.