Biology of Reproduction, Vol 23, 924-928, Copyright © 1980 by Society for the Study of Reproduction

Stimulatory Effect of Luteinizing Hormone and Human Chorionic Gonadotropin on Testicular Prolactin Receptor Levels

¹ Department of Molecular Endocrinology, Le Centre Hospitalier de l’Université Laval, Quebec G1V 4G2, Canada

A possible effect of LH or hCG on testicular prolactin receptor levels was investigated in hypophysectomized adult rats. Hypophysectomy leads to a progressive decrease of testicular prolactin receptor content to 25% of that of controls 12 days after surgery. In animals injected 3 times a day for 10 days with highly purified preparations of ovine LH or hCG, prolactin receptor levels increased from 21 ± 4 to 41 ± 4 and 71 ± 7 fmol/testis, respectively (P<0.01 for both). The increase in the number of testicular prolactin receptor levels observed after treatment with hCG in hypophysectomized rats could not be duplicated by injection of estradiol-17 (0.5 µg), testosterone (200 µg) or 5-dihydrotestosterone (200 µg) given twice a day for 5 days. Moreover, these steroids do not interfere with the stimulation of prolactin binding induced by hCG. Since treatment with prolactin is well known to stimulate testicular LH binding and steroidogenesis, the present data provide further evidence for a close interaction between prolactin and LH in the control of the testicular levels of receptors for these two hormones and their subsequent role in the control of testicular functions.

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ACKNOWLEDGMENTS This investigation was supported in part by grants from the Medical Research Council of Canada (MRC) and the Conseil de la Recherche en Santé du Quëbec. FL is a MRC Associate.