Variation in the steroidogenic responsiveness of isolated rat Leydig cells.

Isolated Leydig cells were prepared from adult rat testes by (1) mechanical dissection, (2) collagenase dispersion or (3) mechanical dissection followed by collagenase dispersion, and their functional characteristics were assessed. Compared with Methods 2 and 3, mechanical isolation alone resulted in the purest preparation of Leydig cells but the lowest yield. Leydig cells isolated by any of the 3 methods had similar numbers of LH- and LH-RH receptors, but cells isolated by Methods 1 and 3 showed poor testosterone responsiveness compared to cells isolated by Method 2. This reduced response was evident following stimulation with hCG, dibutyryl cyclic AMP or an LH-RH agonist, and could not be accounted for simply on the grounds of diminished cell viability. It is concluded that Leydig cells in the rat testis are particularly sensitive to mechanical intrusion, and this is an important factor to bear in mind when preparing Leydig cells or when comparing results between laboratories.