Gonadal regulation of corticotropin-releasing factor immunoreactivity in hypothalamus.
The effect of gonadectomy and subsequent gonadal steroid administration on hypothalamic corticotropin-releasing factor immunoreactivity (CRF-ir) in male and female rats was determined using a radioimmunoassay specific for rat CRF. When compared to appropriate controls, gonadectomy resulted in significantly decreased CRF-ir in both males and females (p less than 0.025). Short-term replacement with testosterone or estradiol did not significantly alter hypothalamic CRF-ir. Acute IC administration of gonadotropin-releasing hormone to male rats significantly decreased CRF-ir in the median eminence 15 minutes later. Chronic administration of estradiol for 3 weeks significantly reduced CRF-ir in ovariectomized rats (p less than 0.005). This decrease was shown not to correlate to the marked increase in anterior pituitary weight (r2 = 0.063, not significant). Chronic administration of estradiol to hypophysectomized female rats significantly decreased hypothalamic CRF-ir (p less than 0.01), an effect localized to the median eminence (p less than 0.005). These data imply that the gonadectomy-induced reduction in hypothalamic CRF-ir was not directly mediated by the loss of gonadal steroids. Chronic estradiol treatment decreased hypothalamic CRF-ir, by a non-pituitary mechanism. These data show significant effects of the gonadal axis in the regulation of CRF in the hypothalamus in both sexes.
Haas
D A
DA
Department of Medicine, University of Toronto, Ontario, Canada.
George
S R
SR
D000818:Animals; D003346:Corticotropin-Releasing Hormone / Q000378:metabolism*; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D007016:Hypophysectomy; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009919:Orchiectomy; D010052:Ovariectomy; D010053:Ovary / Q000378:metabolism / Q000502:physiology*; D010903:Pituitary Gland, Anterior / Q000378:metabolism / Q000502:physiology; D010906:Pituitary Hormone-Releasing Hormones / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D013737:Testis / Q000378:metabolism / Q000502:physiology*; D013739:Testosterone / Q000494:pharmacology
D010906:Pituitary Hormone-Releasing Hormones; D013739:Testosterone; D004958:Estradiol; D003346:Corticotropin-Releasing Hormone