Synthesis of LH-RH by Rat Hypothalamic Tissue in vitro. II. Effect of Short-Term Orchiectomy and Estradiol Benzoate Therapy

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Abstract
Normal, castrate and estradiol benzoate (EB; 1 µg/100 g b.w. × 6d, s.c.)-treated castrate male rats were utilized to study the short term effects of these treatments upon the incorporation of 3H-glycine into LH-RH in vitro. The rise in serum LH and FSH observed in the untreated castrates was prevented by EB therapy. The treatments had no significant effect upon serum LH-RH levels or the incorporation of 3H-gly into LH-RH. EB treatment markedly (p < 0.01) increased the hypothalamic LH-RH concentration and significantly lowered the specific activity (nCi/ng) of the 3H-gly-LH-RH (p < 0.05). These results suggest that EB acts both on the pituitary and hypothalamus to suppress gonadotropin (Gn) release, but that, at the time period studied, neither castration or EB-treatment had any apparent effect upon hypothalamic LH-RH synthesis.