Substance P-induced inhibition of Leydig cell steroidogenesis in primary culture.

The effect of substance P (SP) on hamster Leydig cell steroidogenesis in primary culture was investigated. Purified Leydig cells were cultured with or without SP for 24 h. The levels of testosterone and progesterone in the culture media were 174 +/- 20 pg ml-1 and 105 +/- 12 pg ml-1, respectively. In the presence of SP (10(-7) mol l-1), testosterone concentration significantly decreased to 123 +/- 19 pg ml-1, e.g. with 29.3%. By contrast, at the concentration used, SP had no effect on progesterone secretion. The possible molecular mechanism of the SP action on Leydig cell function was discussed. The reported results indicate that SP can modulate Leydig cell steroidogenesis in culture.