title: Influence of photoinhibition, photostimulation and prolactin on pituitary and hypothalamic nuclear androgen receptors in the male hamster.
abstract: Testosterone (T) feedback sensitivity is markedly altered in adult male golden hamsters following exposure to short photoperiods (SD). Using a technique which measures total androgen receptors within the cell nucleus, the present study examined pituitary and hypothalamic nuclear androgen receptor levels in animals exposed to (1) long days (LD) or SD in the presence and absence of a constant T level supplied via a Silastic implant, (2) photostimulation following SD-induced testicular regression and (3) short-term prolactin injections following SD-induced testicular regression. Short photoperiods were associated with a drop in nuclear androgen receptor levels which was correlated with a decline in circulating T. When constant T was supplied to gonadectomized hamsters, those exposed to SD possessed higher pituitary and similar hypothalamic nuclear androgen receptor levels than those exposed to LD. As expected, plasma luteinizing hormone (LH) and follicle-stimulating hormone (FSH) levels were greatly reduced in SD-exposed, castrated, T-treated hamsters as compared to LD-exposed, castrated, T-treated animals. Photostimulation of intact SD-exposed hamsters for 5 or 10 days was associated with a decline in pituitary nuclear androgen receptors. Prolactin treatment caused no noticeable change in pituitary or hypothalamic androgen receptors even though plasma LH and FSH levels were significantly increased. These results support the hypothesis that altered T feedback mechanisms controlling LH and FSH release following chronic exposure to SD may be related to an alteration in the amount of androgen receptors present in the anterior pituitary.
authors: Department of Obstetrics and Gynecology, Michael Reese Hospital and Medical Center, University of Illinois School of Medicine, Chicago.
authors: G S
authors: GS
authors: Prins
authors: A
authors: A
authors: Bartke
authors: R W
authors: RW
authors: Steger
mesh_terms: D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects / Q000528:radiation effects*; D006224:Cricetinae; D005246:Feedback; D005640:Follicle Stimulating Hormone / Q000097:blood; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D008027:Light; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008647:Mesocricetus; D009929:Organ Size / Q000187:drug effects / Q000528:radiation effects; D010507:Periodicity; D010775:Photic Stimulation; D010903:Pituitary Gland, Anterior / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D011388:Prolactin / Q000097:blood / Q000494:pharmacology*; D011944:Receptors, Androgen / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects*; D012669:Seminal Vesicles / Q000033:anatomy & histology; D013737:Testis / Q000033:anatomy & histology; D013739:Testosterone / Q000097:blood
chemical_list: D011944:Receptors, Androgen; D013739:Testosterone; D011388:Prolactin; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone