Hormonal dependency of neural cadherin in the binding of round spermatids to Sertoli cells in vitro.

The procession of round spermatids through stages VII and VIII of the rat spermatogenic cycle is critically dependent on testosterone (T). When intratesticular T levels are reduced, round spermatids appear to slough from the seminiferous epithelium, resulting in the disappearance of elongated spermatids. We hypothesized that T-dependent cell adhesion molecules are involved in Sertoli cell-round spermatid interactions. This study examined the hormonal regulation of one candidate cell adhesion molecule, N-cadherin, in vitro and its participation in Sertoli cell-round spermatid adhesion in coculture. Sertoli cells were isolated from 20-day-old Sprague-Dawley rats; treated with FSH and T, alone or in combination; and incubated for 48 h before determination of N-cadherin concentrations in Sertoli cell extracts by RIA. Both FSH and T significantly increased the cellular content of N-cadherin (3.7-fold), whereas FSH or T alone had no effect. Round spermatids were isolated from adult rats, and their adhesion to Sertoli cells was assessed in a 48-h coculture in the presence of FSH, T, or FSH plus T. Adherent round spermatids were quantitated by histological evaluation after staining with the periodic acid-Schiff reaction. A dose-dependent increase in round spermatid density (number of round spermatids bound per 10,000-microns2 Sertoli cell culture surface area) was observed with increasing T doses (7-28 ng/ml) in the presence of FSH (1 microgram/ml), whereas FSH and T alone at these doses produced no effect. T also increased the N-cadherin content of the cocultures in a dose-dependent manner in the presence of FSH. Addition of an N-cadherin antiserum to the Sertoli cell-round spermatid coculture in the presence of FSH and T significantly (P < 0.0001) reduced round spermatid density by 65%. It is concluded that both the production of N-cadherin by Sertoli cells and the binding of round spermatids to Sertoli cells are stimulated in a synergistic manner by T and FSH. Furthermore, the immunoneutralization data suggest the active involvement of N-cadherin in round spermatid-Sertoli cell adhesion in vitro. N-Cadherin may be one of the factors that subserve the androgen-dependent process of round to elongated spermatid maturation.