title: Long-term persistence of male copulatory behavior in castrated and photo-inhibited Siberian hamsters.
abstract: Gonadal steroids are essential for the long-term maintenance of the full repertoire of sexual behavior in male rodents. Typically, all individuals of several species cease to display the ejaculatory reflex within a few weeks of castration. The present study documents the persistence of the ejaculatory reflex 19 weeks after orchidectomy in 40% of male Siberian hamsters maintained in long or short day lengths; testosterone was undetectable in the circulation of these animals. Intact hamsters transferred from a long to a short photoperiod underwent gonadal regression: 50% of these animals continued to display mating behavior culminating in ejaculation throughout 25 weeks of testing. The remaining animals failed to ejaculate after approximately 11 weeks of short day treatment but resumed mating coincident with spontaneous gonadal recrudescence. Activation of sex behavior in the latter cohort appears to depend on gonadal steroids and is in contrast to the copulatory behavior of the substantial proportion of the study population that sustains the full sexual repertoire in the long-term absence of gonadal steroids. Sex behavior of the latter animals may be dependent on nongonadal steroids or mediation by steroid-independent mechanisms.
authors.affiliation: Department of Psychology, University of California, Berkeley, CA 94720, USA. jhp@socrates.berkley.edu
authors.forename: Jin Ho
authors.initials: JH
authors.lastname: Park
authors.forename: Nana
authors.initials: N
authors.lastname: Takasu
authors.forename: Maria I
authors.initials: MI
authors.lastname: Alvarez
authors.forename: Kathryn
authors.initials: K
authors.lastname: Clark
authors.forename: Rahim
authors.initials: R
authors.lastname: Aimaq
authors.forename: Irving
authors.initials: I
authors.lastname: Zucker
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002369:Castration; D006224:Cricetinae; D004542:Ejaculation / Q000502:physiology* / Q000528:radiation effects*; D005260:Female; D008027:Light; D008297:Male; D017111:Phodopus; D017440:Photoperiod; D012726:Sexual Behavior, Animal / Q000502:physiology* / Q000528:radiation effects*; D013737:Testis / Q000502:physiology / Q000528:radiation effects; D013997:Time Factors