Testosterone self-administration in female hamsters

Abstract

Abuse of anabolic-androgenic steroids (AAS) is a growing public health concern. In addition to their anabolic effects, steroids are also reinforcing as demonstrated by testosterone self-administration in male hamsters. However, steroid use in women lags behind that in men. Are androgens also rewarding in females? We determined if female hamsters voluntarily consume testosterone by intracerebroventricular (i.c.v.) self-administration in an operant chamber. Twelve ovary-intact female hamsters self-administering testosterone (1.0 microg/microl) i.c.v. for 19.1 +/- 2.3 days developed a significant preference (P < 0.05) for the active nose-poke (31.5 +/- 6.1 nose-pokes/4 h) over the inactive nose-poke (12.5 +/- 1.1 nose-pokes/4 h). Operant behavior in females was similar to that reported previously for male hamsters. Estrous cycles became irregular 9.6 +/- 2.3 days after the start of self-administration. Regular cycles resumed 13.7 +/- 2.6 days after testosterone was discontinued. To determine the effect of ovarian steroids on androgen self-administration, females were ovariectomized (OVX) and allowed to self-administer testosterone for 10.8 +/- 0.5 days. Afterwards, estrogen was replaced, and self-administration continued for an additional 9.7 +/- 0.6 days. OVX females maintained their preference for the active (23.9 +/- 7.0 nose-pokes/4 h) over the inactive nose-poke (12.6 +/- 3.4 nose-pokes/4 h, P < 0.05), and estrogen had no effect on responding for androgen (active: 25.8 +/- 6.5 nose-pokes; inactive: 8.2 +/- 2.0 nose-pokes/4 h, P < 0.05). Estrous female hamsters did not show a significant preference for stimulus males or females when mating was blocked, and testosterone self-administration did not alter partner preference. However, activity in the preference chamber predicted subsequent androgen intake (R(2) = 0.66, P < 0.05). These findings are consistent with the idea that anabolic steroids have inhibitory effects on female reproduction. Moreover, they suggest that sex differences in androgen reward do not underlie sex differences in AAS abuse in humans.