BRADYKININ STIMULATES PREPUBERTAL RAT GERM-CELL PROLIFERATION IN-VITRO

The effect of bradykinin on germ cell proliferation was studied by usi ng in vitro organ cultures of testicular fragments from 3.5- and 4.5-d ay-old rats in the presence of H-3-thymidine. Bradykinin in tested con centrations of 10(-8), 10(-6) and 10(-4) M manifested a significant st imulation of rat prespermatogonial cell, proliferation. The percentage of labeled germ, cells increased up to 3-fold in comparison with the control value especially in 3.5-day-old rat testicular explants. Two k ininase inhibitors: phosphoramidon and captopril were also used in com bination with bradykinin. The percentage of labeled germ cells was sli ghtly increased as compared to the samples treated with bradykinin onl y. Experiments with two agonists and two antagonists of B-1 and B-2 re ceptors for kinins showed that the rat prespermatogonial cell prolifer ation response to bradykinin is probably mediated via B-2 receptors. T he present findings suggest that bradykinin may be an important local testicular factor with paracrine or autocrine role in the regulation o f spermatogonial cell proliferation and germ cell number. (C) 1998 Els evier Science B.V. All rights reserved.