CHANGES IN GLUCOCORTICOID RECEPTOR IMMUNOREACTIVITY AFTER ADRENALECTOMY AND CORTICOSTERONE TREATMENT IN THE RAT TESTIS

The distribution of glucocorticoid receptor (GR) in the rat testis was investigated by means of immunocytochemistry (IR) and computer-assist ed image analysis. A monoclonal antibody against rat liver GR showed t he presence of GR IR selectively in the nuclei of interstitial and tub ular cells. The semiquantitative microdensitometry of GR IR revealed t hat 77% of the specific staining was localized in the tubular compartm ent of rat testis. After adrenalectomy, GR IR was greatly reduced both in interstitial and tubular cells, roughly at the same degree. Cortic osterone treatment (50 mg/kg, for 5 d) of adrenalectomized animals yie lded a recovery of nuclear immunopositivity without changing the cellu lar distribution of GR, as observed in control rats. Nevertheless, the high dose of corticosterone administered produced a significant (p<0. 01) decrease of GR IR with respect to control rats. These results prov ide evidence for a prevalent nuclear binding of GR in the tubular comp artment in basal conditions. On the other hand, adrenalectomy or repea ted corticosterone treatment seem to affect GR similarly in all positi ve cells without changing significantly the proportion of GR IR in the different testicular compartments. This uneven distribution of GR IR suggests that tubular cells can be a major target of corticosterone wh en affecting directly testicular functions in the rat.