AN UNEXPECTED EFFECT OF OESTRADIOL-17β ON LUTEINIZING HORMONE AND TESTOSTERONE

Abstract

Oestrogens cause atrophy of the testes and accessory sex organs, a decrease in pituitary gonadotrophins (Greep, 1961; Price & Williams-Ashman, 1961), and suppress gonadotrophin secretion in gonadectomized males (Gay & Dever, 1971). Since gonadotrophins are essential for stimulation of androgen production, atrophy of the accessory sex organs has been attributed to lack of testosterone production by the testes secondary to decreased circulating luteinizing hormone (LH) (Moore & Price, 1932). These assumptions served as the basis for interpreting results in an investigation of the pituitary-gonadal system (Steinberger, 1971). Experiments reported here were designed to test these assumptions. Male, adult, hooded rats (250–300 g) were used. Experimental animals were injected daily with 50 or 500 μg oestradiol benzoate (OB), s.c. in 0·1 ml sesame oil, and groups of six animals were killed 24 h and 7 days after initiation of treatment. Luteinizing hormone was measured by double-antibody radioimmunoassay (Steinberger, Chowdhury & Steinberger, 1973)