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      Influence of Photoinhibition, Photostimulation and Prolactin on Pituitary and Hypothalamic Nuclear Androgen Receptors in the Male Hamster

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          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.

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          Author and article information

          Journal
          NEN
          Neuroendocrinology
          10.1159/issn.0028-3835
          Neuroendocrinology
          S. Karger AG
          0028-3835
          1423-0194
          1990
          1990
          03 April 2008
          : 52
          : 5
          : 511-516
          Affiliations
          aDepartment of Obstetrics and Gynecology, Michael Reese Hospital and Medical Center, University of Illinois School of Medicine, Chicago, Ill.; bDepartment of Physiology, Southern Illinois University, Carbondale, Ill., USA
          Article
          125636 Neuroendocrinology 1990;52:511–516
          10.1159/000125636
          2126358
          © 1990 S. Karger AG, Basel

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          Page count
          Pages: 6
          Categories
          Original Paper

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