Effects of ovariectomy and ovarian steroids on binding of 3H-mepyramine, an H1-histamine antagonist, in rat hypothalamus.
The effects of ovariectomy and ovarian steroids on 3H-mepyramine binding, a histamine antagonist considered as a suitable ligand for H1-histamine receptors, were studied. Saturation binding assays and Scatchard plot analyses were performed in membranes from hypothalamus of adult female rats. In the hypothalamus of ovariectomized (OVX) rats, a decrease of the Bmax and a lowering of Kd values as compared to diestrous rats, were found. Estradiol administration to OVX rats as a single SC injection (25 micrograms), or by means of SC Silastic capsules (500 micrograms/ml estradiol benzoate; 10 mm/100 g b.wt.), reversed the effects of OVX, increasing both Bmax and Kd. The addition of progesterone (25 mg) blunted the effects of estradiol (50 micrograms). The present results suggest that hypothalamic H1-histamine receptors may be modulated by the ovarian steroids and provide further evidence of a possible role of histamine in female gonadotropin regulation.
Seltzer
A M
AM
Laboratorio de Investigaciones Cerebrales, Facultad de Ciencias Médicas, U.N.C., Mendoza, Argentina.
Donoso
A O
AO
D000631:Aminopyridines / Q000378:metabolism*; D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D007031:Hypothalamus / Q000187:drug effects / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000097:blood; D010052:Ovariectomy; D011374:Progesterone / Q000494:pharmacology*; D011738:Pyrilamine / Q000378:metabolism*; D011863:Radioimmunoassay; D011869:Radioligand Assay; D051381:Rats; D011969:Receptors, Histamine H1 / Q000187:drug effects* / Q000378:metabolism
D000631:Aminopyridines; D011969:Receptors, Histamine H1; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D011738:Pyrilamine