Photoperiod and Testosterone Regulate Androgen Receptor Immunostaining in the Siberian Hamster Brain

• Published in: Biology of reproduction Vol. 69; no. 3; pp. 876 - 884
• Main Authors: BITTMAN, Eric L, EHRLICH, David A, OGDAHL, Justyne L, JETTON, Amy E
• Format: Journal Article
• Language: English
• Published: Madison, WI Society for the Study of Reproduction 01-09-2003
• Subjects: Analysis of Variance; Animals; Biological and medical sciences; Castration; Circadian Rhythm; Cricetinae; Follicle Stimulating Hormone - blood; Fundamental and applied biological sciences. Psychology; Immunohistochemistry; Lighting; Luteinizing Hormone - blood; Male; Neurosecretory Systems - metabolism; Neurosecretory Systems - radiation effects; Phodopus; Photoperiod; Prolactin - blood; Prosencephalon - metabolism; Prosencephalon - radiation effects; Receptors, Androgen - metabolism; Receptors, Androgen - radiation effects; Reproduction - physiology; Steroid hormones. Cholecalciferol derivatives; Testis - physiology; Testis - radiation effects; Testosterone - physiology; Vertebrates: endocrinology; Nuclear receptor; Androgen; Rodentia; Central nervous system; Environmental factor; Castrated animal; Exposure; Photoperiod; Encephalon; Testosterone; Vertebrata; Mammalia; Androgen receptor; Hormonal regulation; Testicular hormone; Sex steroid hormone; Hamster; Biological receptor; Hormonal receptor; Quantitative analysis
• ISSN: 0006-3363; 1529-7268
• DOI: 10.1095/biolreprod.102.010900

Day length regulates the effects of gonadal steroids on gonadotropin secretion and behavior in seasonal breeders. To determine
whether this influence of photoperiod results from changes in androgen receptor expression in Siberian hamster brain regions
that regulate neuroendocrine function, androgen receptor immunostaining was examined in castrated animals given either no
androgen replacement or one of three doses of testosterone (T) resulting in physiological serum concentrations. Half of the
animals were housed under inhibitory photoperiod conditions, and immunostaining was quantified 11 days later. Measurement
of serum gonadotropin and prolactin concentrations confirmed that androgen exerted graded effects on pituitary function but
that the animals were killed before photoperiodic influences had fully developed. T significantly increased the numbers of
androgen receptor-immunoreactive cells in every brain region examined. Photoperiod exerted no significant influence on androgen
receptor-immunoreactive cell number in the arcuate nucleus, bed nucleus of the stria terminalis (BNST), medial preoptic nucleus,
or in medial amygdala. An interaction between T and photoperiod was observed in the BNST and in the rostral and middle portions
of the arcuate nucleus. Although increasing concentrations of T resulted in more intense cellular immunostaining in the BNST
and arcuate, this effect was not influenced by day length. These results indicate that relatively short-duration (11 days)
exposure to inhibitory photoperiod triggers localized and regionally specific changes in androgen receptor expression.