Leydig cell heterogeneity as judged by quantitative cytochemistry of 3 beta-hydroxysteroid dehydrogenase activity in...

3 beta-Hydroxysteroid dehydrogenase (3 beta-HSD) is one of the key enzymes involved in the steroidogenic pathway of Leydig cells. In this study, quantitative cytochemistry was used to detect the 3 beta-HSD staining intensity in individual rat Leydig cells. The measurement of the intensity of staining was a reliable method reflecting the relative amount of 3 beta-HSD activity. The objective was to determine the presence, basal and hCG-mediated effect of 3 beta-HSD activity in individual Leydig cells. 3 beta-HSD cytochemistry was performed in both, 8 and 12 microns diameter rat Leydig cells. The results showed that both populations of Leydig cells have different basal 3 beta-HSD activity. The 8 microns cells showed a greater basal 3 beta-HSD activity than the 12 microns cells when their optical density values were normalized to their size. A difference in regulation of the enzymatic activity by LH/hCG was observed in the two types of Leydig cells. Incubation of the whole population of Leydig cells with hCG (1IU), decreased the 3 beta-HSD activity in the 8 microns cells, but increased the activity in the 12 microns cells. The results describe for the first time that the 3 beta-HSD activity may be differentially regulated by LH/hCG in Leydig cells.