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). W hen intratesticular T levels are reduced, round spermatids appear to s lough from the seminiferous epithelium, resulting in the disappearance of elongated spermatids. We hypothesized that T-dependent cell adhesi on molecules are involved in Sertoli cell-round spermatid interactions . This study examined the hormonal regulation of one candidate cell ad hesion molecule, N-cadherin, in vitro and its participation in Sertoli cell-round spermatid adhesion in coculture. Sertoli cells were isolat ed 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-ca dherin 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 rou nd spermatids were quantitated by histological evaluation after staini ng with the periodic acid-Schiff reaction. A dose-dependent increase i n round spermatid density (number of round spermatids bound per 10,000 -mu m(2) Sertoli cell culture surface area) was observed with increasi ng T doses (7-28 ng/ml) in the presence of FSH (1 mu g/ml), whereas FS H 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 c ell-round spermatid coculture in the presence of FSH and T significant ly (P < 0.0001) reduced round spermatid density by 65%. It is conclude d that both the production of N-cadherin by Sertoli cells and the bind ing of round spermatids to Sertoli cells are stimulated in a synergist ic manner by T and FSH. Furthermore, the immunoneutralization data sug gest the active involvement of N-cadherin in round spermatid-Sertoli c ell adhesion in vitro. N-Cadherin may be one of the factors that subse rve the androgen-dependent process of round to elongated spermatid mat uration.