|Reference : Hormones modulate the concentration of cytoplasmic progestin receptors in the brain of m...|
|Scientific journals : Article|
|Human health sciences : Endocrinology, metabolism & nutrition|
Life sciences : Zoology
Social & behavioral sciences, psychology : Neurosciences & behavior
|Hormones modulate the concentration of cytoplasmic progestin receptors in the brain of male ring doves (Streptopelia risoria).|
|Balthazart, Jacques [> > > >]|
|Blaustein, J. D. [> > > >]|
|Cheng, M. F. [> > > >]|
|Feder, H. H. [ > > ]|
|Journal of Endocrinology|
|Society for Endocrinology|
|[en] Animals ; Binding, Competitive ; Brain/drug effects/metabolism ; Castration ; Columbidae/metabolism ; Cytoplasm/metabolism ; Dihydrotestosterone/pharmacology ; Gonadal Steroid Hormones/pharmacology ; Male ; Progestins ; Promegestone/metabolism ; Receptors, Progesterone/drug effects/metabolism|
|[en] A cytoplasmic progestin receptor has been characterized in the brain of castrated ring doves using an in-vitro assay that measures the binding of a synthetic progestin, [3H]17 alpha,21-dimethyl-19-nor-pregna-4,9-diene-3,20-dione(promegestone; R5020). The affinity of the receptor was similar in both the hyperstriatum and the hypothalamus (Kd approximately equal to 4 X 10(-10) mol/l). Its concentration was higher in the anterior hypothalamus-preoptic area (63 +/- 4 fmol/mg (S.E.M.) protein) than in other brain regions (posterior hypothalamus, 33 +/- 5; hyperstriatum, 28 +/- 3; midbrain, 17 +/- 4 fmol/mg protein; n = 7). Progesterone and R5020 competed well for binding but oestradiol and 5 beta-dihydrotestosterone did not. Corticosterone and, to a lesser extent, testosterone and 5 alpha-dihydrotestosterone completed for binding but much higher concentrations were required than for progestins. Injections of testosterone (200 micrograms testosterone propionate daily for 7 days) significantly increased the concentration of progestin receptors in the anterior and posterior hypothalamus without having any significant effect on other brain areas. Shorter treatment, lasting for 2 days, with testosterone propionate (200 micrograms daily), 5 alpha-dihydrotestosterone (200 micrograms daily) or oestradiol benzoate (50 micrograms daily) did not always cause this increase but seven injections of oestradiol benzoate (50 micrograms daily for 7 days) were even more effective than seven injections of testosterone propionate (200 micrograms daily for 7 days). These data suggested that the sensitivity to progesterone of the brain of the bird changes as a consequence of increases in the level of testosterone in the circulation.|
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