title: Photoperiodic regulation of substance P immunoreactivity in the mating behavior pathway of the male golden hamster.
abstract: Mating behavior in the male golden hamster is regulated by both gonadal steroids and photoperiod. Gonadal steroids may regulate mating behavior by actions on the medial nucleus of the amygdala, bed nucleus of the stria terminalis, and medial preoptic area. Neurons in these areas actively accumulate gonadal steroids and lesions of these nuclei disrupt mating behavior in male hamsters. Photoperiodic regulation of mating behavior is regulated, at least in part, by decreased responsiveness to gonadal steroids. Therefore, we sought to determine if the changes induced by changes in gonadal steroids would mimic those induced by changes in photoperiod. The number of substance P-containing neurons in these areas decrease following castration and are restored with testosterone treatment suggesting that this peptide may mediate steroidal regulation of male mating behavior. To determine the effect of photoperiod on substance P, peptide containing neurons were counted in (1) enucleates (n = 6), (2) enucleated castrates treated with testosterone (n = 6), (3) castrates treated with testosterone (n = 4), and (4) intact controls (n = 6). Bilateral enucleation caused a decrease in the number of substance P neurons in the medial nucleus, bed nucleus of the stria terminalis, and medial preoptic area (P less than 0.05). Testosterone treatment prevented this decrease (P less than 0.05). Thus, a decrease in daylength causes a decrease in substance P in the medial nucleus of the amygdala, the medial bed nucleus of the stria terminalis and the medial preoptic area that is mediated by changes in testosterone levels.
authors.affiliation: Department of Biological Sciences, Rutgers State University, Newark, NJ 07102.
authors.forename: J M
authors.initials: JM
authors.lastname: Swann
authors.forename: N
authors.initials: N
authors.lastname: Macchione
mesh_terms: D000679:Amygdala / Q000737:chemistry; D000818:Animals; D001921:Brain / Q000378:metabolism*; D002552:Cerebral Ventricles / Q000737:chemistry; D006224:Cricetinae; D015353:Eye Enucleation; D007124:Immunoenzyme Techniques; D008297:Male; D008647:Mesocricetus; D009474:Neurons / Q000737:chemistry; D017440:Photoperiod; D011301:Preoptic Area / Q000737:chemistry; D012726:Sexual Behavior, Animal / Q000502:physiology* / Q000528:radiation effects; D013373:Substance P / Q000378:metabolism*; D013493:Suprachiasmatic Nucleus / Q000737:chemistry; D013739:Testosterone / Q000502:physiology*
chemical_list: D013373:Substance P; D013739:Testosterone