Effects of prenatal morphine exposure on rat heterotypical sexual behavior

Prenatal exposure to morphine inhibits ovarian steroid-dependent lordosis b ehavior in female rats, and enhances certain components of male sexual beha vior in male rats. In the present study, the effects of mid to late gestati onal morphine exposure on male sexual behavior in females and on female sex ual behavior in males were examined in adult offspring. Gonadectomized male rats were injected at weekly intervals with 30 or 60 mu g estradiol benzoa te and 1.0 mg progesterone and tested for female sexual behavior with stimu lus males on 2 consecutive weekly tests. Ovariohysterectomized (OVX) female s were injected with 500 mu g testosterone propionate (TP) dairy for 15 day s and tested for male sexual behavior with stimulus females on the last day of TP injection and 1 week later, after TP withdrawal. Prenatal morphine e xposure increased the expression of male sexual behaviors in female rats, b ut it did not increase lordosis behavior in male rats. Thus, exposure to mo rphine during gestation alters male and female sexual behavior in young adu lt animals. Because prenatal morphine exposure both defeminized and masculi nized adult sexual behavior in female rats, it is possible that female brai n development is more vulnerable to prenatal insult such as opiate exposure . (C) 1999 Elsevier Science Inc.