Comparison of LH stimulated testosterone release from Mongolian gerbil and mouse whole testes and isolated interstitial cells in vitro: difference in response and sensitivity.

The in vitro steroidogenic response of gerbil and mouse whole testes and isolated testicular interstitial cells to stimulation with gonadotrophic hormones was compared. The testosterone release during incubation in vitro with LH/FSH was measured radioimmunologically. In whole testes incubation, basal testosterone release after 4 h was significantly lower in gerbil as compared to mouse testes, but the testosterone release on maximal LH-stimulation was not significantly different. The increment in the testosterone production from basal to stimulated levels was greater in gerbil, the production per gram testis was greater in mouse testes. Mechanically dispersed interstitial cell preparations from gerbil and mouse released comparable amounts of testosterone during in vitro incubation. The lowest effective standard-concentration was 1.1 microIU LH/vial in gerbil and 35.9 microIU LH/vial in mouse interstitial cell incubations. Half-maximum testosterone release (ED50) occurred at 8-15 microU LH/vial for gerbil and 86-200 microIU LH/vial (ranges) for mouse interstitial cells. The difference in sensitivity to LH stimulation of gerbil and mouse interstitial cells is approximately 13-fold allowing the application of the gerbil interstitial cell assay to studies dealing with very small samples or little bioactive LH-concentrations.