ENHANCED SUSCEPTIBILITY OF FOLLICLE-STIMULATING-HORMONE-DEPRIVED INFERTILE BONNET MONKEY (MACACA-RADIATA) SPERMATOZOA TO DITHIOTHREITOL-INDUCED DNA DECONDENSATION IN-SITU

Immunoneutralization of endogenous follicle-stimulating hormone (FSH) of adult male monkeys leads to oligospermia and infertility despite un changed testosterone levels, The inability of these monkeys to impregn ate despite repeated exposures to cycling females appeared to be due t o abnormal alterations in the kinetics of germ cell transformations an d deficient spermiogenesis. Here we investigated the stability of sper m chromatin in oFSH-immunized monkeys as a marker for spermiogenesis. The susceptibility of spermatozoa to in vitro decondensation induced b y dithiothreitol (DTT, 0.05-50 mM) was studied by measuring the nuclea r fluorescence of DTT-treated, ethidium bromide (EB)-stained sperm usi ng flow cytometry. Changes in sperm morphology and binding of thiol-sp ecific C-14-iodoacetamide (C-14-IA) were also monitored under the same conditions. Sperm from the immunized monkeys decondensed at a lower c oncentration of DTT, bound more EB, and decondensed more extensively t han those from control animals. The difference was apparent in sperm f rom all regions of the epididymis. Immunized monkey sperm also bound s ignificantly more C-14-IA at all concentrations of DTT. Overall, the e ffective concentration of DTT required to elicit 50% of maximal decond ensation (ED50) of epididymal and ejaculated sperm was significantly l ower for the immunized monkeys than even the caput sperm of controls. These results suggest that FSH deprivation in monkeys results in produ ction of sperm with limited potential for disulfide formation and redu ced chromatin stability.