Testicular denervation-induced nuclear changes in Leydig cell of hemicastrated adult rats

In the adult male rat, hemicastration (HC) induces a remarkable enhancement of testosterone secretion from the Leydig cells of the remaining testis. We have observed previously that the denervation of inferior spermatic nerves inhibits this enhancement. The present experiments were designed to assess morphometrically whether or not this change had a cytological correlate in Leydig cells. At least five testes from each group (denervation plus HC, sham denervation plus HC and intact rats) were prepared for both optical and electron microscopy studies. The results showed that after 24 h of denervation, the nuclear volume of the Leydig cells in denervation plus HC rats was smaller (p < 0.01) than those of sham denervation plus HC (196.56 +/- 16.53 vs. 280.71 +/- 13.37), whereas both the volume density of heterochromatin (19.84 +/- 3.14 vs. 10.03 +/- 2.47%) and the heterochromatin index (expressed as periphery heterochromatin area divided by nuclear perimeter, 0.149 +/- 0.046 vs. 0.094 +/- 0.026) were significantly (p < 0.01) higher in denervation plus HC rats than in its sham groups. No changes in Leydig cell numbers or cytoplasmic organelles were detected. The results suggest that some nuclear and heterochromatin-associated cellular activity might be inhibited by testicular denervation in hemicastrated rats.