Sexual orientation, proceptivity, and receptivity in the male rat as a function of neonatal hormonal manipulation.
The influence of neonatal androgen on the potential to exhibit feminine sexual behavior was investigated. Male rats castrated on Day 0 but not those castrated on Day 4 or later showed hop/darting, ear wiggling, and lordotic behavior in response to treatment with estrogen and progesterone in adulthood at a frequency equal to that of females. Neonatal treatment with testosterone propionate (1 mg/rat for 4 days) abolished the capacity to show these behaviors. In subsequent experiments, involving castration of male rats at 0 or 4 hr after cesarean delivery, the effect of the postnatal surge of testicular secretions on the expression of female sexual behavior was investigated. No differences were seen in the frequency of hop/darting, ear wiggling, and receptivity between males castrated immediately or 4 hr after delivery. In a preference test where the experimental male could choose between an estrous female and a sexually active male, the neonatally castrated males preferred the company of a male when treated with estrogen and progesterone. The implantation of testosterone resulted in a preference for an estrous female. It was concluded that testicular secretions in the newborn male influence adult sexual orientation and suppress the ability to show proceptive and receptive behaviors.
Vega Matuszczyk
J
J
Department of Psychology, University of Göteborg, Sweden.
Fernandez-Guasti
A
A
Larsson
K
K
D000818:Animals; D000831:Animals, Newborn; D004958:Estradiol / Q000494:pharmacology*; D008297:Male; D009919:Orchiectomy; D011374:Progesterone / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012733:Sex Differentiation / Q000187:drug effects*; D012726:Sexual Behavior, Animal / Q000187:drug effects*; D012741:Sexual Maturation / Q000187:drug effects; D013739:Testosterone / Q000494:pharmacology*
D013739:Testosterone; D011374:Progesterone; D004958:Estradiol