Anabolic androgens restore mating after sexual satiety in male rats

Anabolic-androgenic steroids and appetitive sexual behavior in male rats

Anabolic-androgenic steroids (AAS) increase libido and sexual behavior, but the underlying behavioral mechanisms are unclear. One way AAS may enhance expression of sexual behavior is by increasing the willingness to work for sex. In the present study, sexually-experienced male rats received daily injections of testosterone at supraphysiologic doses (7.5 mg/kg in water with 13% cyclodextrin) or vehicle and were tested for appetitive sexual behavior measured by operant responding for access to an estrous female. Initially, rats were trained in their home cage to respond on a nose-poke under a 10-min fixed-interval schedule for food reward. Once rats achieved stable response rates, the food was replaced by a female, followed by mating for 10 min. There was no effect of testosterone on operant responding for food (28.1 ± 4.4 responses/10 min for testosterone, 30.6 ± 4.3 for vehicle) or sex (35.0 ± 4.0 responses/10 min for testosterone, 37.3 ± 5.2 for vehicle). However, rats made significantly more responses for sex than for food (p < 0.05), and responses for food and sex were positively correlated among individuals (R(2) = 0.6). Additional groups of rats were trained to respond on a lever for the female under a 2nd-order schedule of reinforcement, where 5 responses opened a door to show the female for 5s. After 15 door openings, the male gained access to the female. There was no effect of testosterone on time to complete 75 responses: 38.4 ± 7.8 min for vehicle controls vs 43.3 ± 6.6 min for testosterone-treated rats (p > 0.05). These findings suggest that chronic high-dose testosterone does not enhance appetitive drive for sexual behavior.

Copulation modifies AR and ERα mRNA expression in the male rat brain

BACKGROUND/AIMS

One day after male sexual behavior [one ejaculation or copulation to satiety (ad libitum copulation during 4h with the same female)] androgen receptor immunoreactivity (AR-ir) is decreased and estrogen receptor alpha immunoreactivity (ERα-ir) increased in various brain areas related with its control. Seven days after sexual satiety there was a limited recovery of sexual behavior accompanied by a partial recuperation in the AR-ir. In this study we evaluated if these changes in AR-ir and ERα-ir were paralleled by variations in their respective mRNA.

METHODS

Sexually experienced male rats were sacrificed at different intervals: immediately, 24h or seven days after sexual satiety or 24h after one ejaculation. The changes in AR and ERα mRNA were analyzed by in situ hybridization using digoxigenine-labeled oligonucleotide probes in the MPOA, LSV and the bed nucleus of the stria terminalis, medial division, anterior (BSTMA).

RESULTS

AR mRNA density was decreased in the MPOA and the LSV immediately and 24h after one ejaculation or sexual satiety. Seven days after copulating to satiety, there was a recovery of AR mRNA. In the BSTMA the different behavioral conditions did not modify the AR mRNA expression. In the MPOA, LSV and BSTMA the ERα mRNA increased after a single ejaculation and at all intervals after sexual satiety.

CONCLUSION

In some brain areas and after some intervals of sexual activity, the changes in steroid protein receptors expression seem to be consequence of parallel changes in the expression of the respective mRNA.

Anabolic steroids have long-lasting effects on male social behaviors

Anabolic androgenic steroids (AAS) use by adolescents is steadily increasing. Adolescence involves remodeling of steroid-sensitive neural circuits that mediate social behaviors, and previous studies using animal models document effects of AAS on male social behaviors. The present experiments tested whether AAS have persistent and more pronounced behavioral consequences when drug exposure occurs during adolescence as compared to exposure in adulthood. Male Syrian hamsters were injected daily for 14 days with either vehicle or an AAS cocktail containing testosterone cypionate (2 mg/kg), nandrolone decanoate (2 mg/kg), and boldenone undecylenate (1 mg/kg), either during adolescence (27-41 days of age) or adulthood (63-77 days of age). As adults, subjects were tested two or four weeks after the last injection for either sexual behavior with a receptive female or male-male agonistic behavior in a resident-intruder test. Compared with vehicle-treated males, AAS-treated males, regardless of age of treatment, displayed fewer long intromissions and a significant increase in latency to the first long intromission, indicative of reduced potential to reach sexual satiety. Increased aggression was observed in males exposed to AAS compared with males treated with vehicle, independently of age of AAS treatment. However, unlike hamsters exposed to AAS in adulthood, hamsters exposed to AAS during adolescence did not display any submissive or risk-assessment behaviors up to 4 weeks after discontinuation of AAS treatment. Thus, AAS have long-lasting effects on male sexual and agonistic behaviors, with AAS exposure during adolescence resulting in a more pronounced reduction in submissive behavior compared to AAS exposure in adulthood.