GnRH antagonist treatment affects nuclear size and membrane associated indentations in rat Leydig cells

In semi-thin preparations of rat testis treated with GnRH antagonist (Ac-D2Nal 1, D4ClPhe 2, DTrp 3, DArg 6, DAla 10; GnRH code- 103-289-10, National Institutes of Health, USA) for a period of 5 weeks, Leydig cells showed a reduction of 18% in the mean nuclear area as compared to the controls. The number of cells with nuclear membrane indentations increased by more than 40% as compared to the controls. Nuclear condensation was evident in the form of dark, electron-dense patches of heterochromatin present all along the rough, uneven boundary of the nuclear wall. In some cells, indentations in the nucleus appeared in the form of deep grooves extending into the core of the nucleus. Shrinkage in the cytoplasm of the cells was very much apparent. Circulating levels of LH and testosterone were very low. LH decreased from 29.6 +/- 2.9 ng/ml to 0.55 +/- 0.018 ng/ml and testosterone from 7.8 +/- .29 ng/ml to 0.5 +/- .02 ng/ml. The mean nuclear area of Leydig cells from other groups of rats treated with estradiol 17-beta (1 microgram/rat per day), testosterone (60 micrograms/rat per day) or combinations of testosterone and estradiol or GnRH antagonist and testosterone in the same regime and for the same period remained unaltered. On the other hand, cells appeared normal when testosterone was supplemented (60 micrograms/rat/day) in rats treated with GnRH antagonist. The mean nuclear area of the Leydig cells recovered significantly (p less than 0.001), but was not completely restored.