Diurnal modulation of rat hypothalamic gonadotropin-releasing hormone release by melatonin in vitro

1993 ◽  
Vol 16 (1) ◽  
pp. 1-7 ◽  
Author(s):  
D. D. Rasmussen
Keyword(s):  
Gonadotropin Releasing Hormone ◽  
Hormone Release ◽  
Releasing Hormone

Estrogen stimulates gonadotropin-releasing hormone release from rat hypothalamus independently through catecholamine and histamine in vitro

1989 ◽  
Vol 120 (5) ◽  
pp. 644-648 ◽  
Author(s):  
Shirou Ohtsuka ◽  
Takamichi Nishizaki ◽  
Keiichi Tasaka ◽  
Akira Miyake ◽  
Osamu Tanizawa ◽  
...  
Keyword(s):  
Bovine Serum Albumin ◽  
Gonadotropin Releasing Hormone ◽  
Female Rats ◽  
Hormone Release ◽  
Mediobasal Hypothalamus ◽  
Releasing Hormone ◽  
Gnrh Release ◽  
Perifusion System ◽  
Made In

Abstract. Estradiol is known to stimulate gonadotropin-releasing hormone release from the rat mediobasal hypothalamus. Studies were made in an in vitro perifusion system on whether catecholamine and/or histamine was involved in estradiol-induced GnRH release. Normal cycling female rats were decapitated in diestrus II and their medio-basal hypothalami were combined and, perifused with Earl's balanced salt solution containing 0.01% bovine serum albumin bubbled with 95% O2 and 5% CO2. The levels of norepinephrine, dopamine, and histamine and of GnRH in the effluent were measured by HPLC and radioimmunoassay, respectively. Administration of 10−6 mol/l estradiol resulted in releases of norepinephrine, dopamine, histamine and GnRH at levels of 98, 70, 91 and 288%, respectively, of initial values. Administration of 10−6 mol/l norepinephrine or dopamine resulted in no increase in histamine release, and administration of 10−6 mol/l histamine did not increase release of norepinephrine or dopamine. These data suggest that estradiol stimulates the releases of GnRH, catecholamine and histamine from the rat medio-basal hypothalamus, and that it increases GnRH release independently through catecholamine and histamine. As we found previously that norepinephrine or histamine stimulates GnRH release from the mediobasal hypothalamus, we conclude that estradiol stimulates releases of norepinephrine and histamine, resulting in GnRH release from the medio-basal hypothalamus.

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