Follicle-stimulating hormone and testosterone stimulation of immature and mature sertoli cells in vitro: Inhibin and N-cadherin levels and round spermatid binding

The in vitro response of Sertoli cells isolated from adult rat testes to te stosterone (T) and follicle-stimulating hormone (FSH) treatment was investi gated. Sertoli cells from >70-day-old Sprague-Dawley rats were isolated by a combined enzymatic treatment followed by the removal of the majority of c ontaminating germ cells with immobilized peanut agglutinin lectin. Sertoli cells were then cultured for 6-10 days, forming a confluent layer with a ce ll viability of >83% and 74-77% purity. The contaminating cells were peritu bular cells (4-6%), pachytene spermatocytes (4-5%), round spermatids (<2%), elongated spermatids (<1%), and degenerating germ cells (14.8%). The propo rtion of degenerating germ cells decreased from 14.8% to 8.6% between days 6 and 10 in culture. After a prestimulation culture period of 4 days, FSH t reatment over a 2-day period resulted in a dose-related increase of inhibin with a median effective dose (ED50) value of 36.7 +/- 20.4 ng/ml in com pa rison with an ED50 value of 4.4 +/- 0.9 ng/ml obtained with immature Sertol i cell cultures from 20-day-old rats. Mature Sertoli cells, in contrast to immature Sertoli cells, were unresponsive to combined FSH + T treatment for the production of the cell adhesion protein N-cadherin. FSH treatment prom oted the in vitro binding of round spermatids isolated from adult testis to adult Sertoli cells in coculture. It is concluded that mature Sertoli cell s in culture are responsive to FSH in terms of inhibin production and round -spermatid binding. The lack of an FSH + T-induced increase in N-cadherin o r round spermatid binding is attributed to either a reduced sensitivity, or an alteration in the regulation of mature Sertoli cells by FSH + T.