title: Prenatal naltrexone facilitates male sexual behavior in the rat.
abstract: The involvement of endogenous opiates in the differentiation of sexual behavior was tested by exposing rat fetuses to continuous naltrexone during the last 9 days of gestation. Time-mated female rats received oral naltrexone, 40 mg/kg/day, via their drinking water, from gestational day 13 until parturition. Early motor development, measured by swimming ability in 7-, 9-, and 11-day-old offspring of the treated dams, was unaffected by prenatal naltrexone. Adult male offspring were given three tests of male sexual behavior, then castrated, primed with ovarian hormones, and given two tests of feminine receptivity (lordosis quotient). Prenatal naltrexone facilitated masculine behavior and suppressed feminine receptivity: latencies to first mount and to ejaculation were shorter, mount rate was higher, and lordosis quotient was lower in naltrexone-treated rats, compared with control animals. These findings implicate endogenous opiates in prenatal organization of sex-specific behavioral dispositions.
authors.affiliation: Department of Psychology, Hebrew University of Jerusalem, Israel.
authors.forename: E
authors.initials: E
authors.lastname: Cohen
authors.forename: G
authors.initials: G
authors.lastname: Keshet
authors.forename: Y
authors.initials: Y
authors.lastname: Shavit
authors.forename: M
authors.initials: M
authors.lastname: Weinstock
mesh_terms: D000818:Animals; D004305:Dose-Response Relationship, Drug; D004542:Ejaculation / Q000187:drug effects; D005260:Female; D008297:Male; D009043:Motor Activity / Q000187:drug effects; D009271:Naltrexone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D017288:Pain Threshold / Q000187:drug effects; D011187:Posture / Q000502:physiology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D012733:Sex Differentiation / Q000187:drug effects; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D013550:Swimming
chemical_list: D009292:Narcotic Antagonists; D009271:Naltrexone