Effect of phorbol ester and phospholipase C on LH‐stimulated steroidogenesis in purified rat Leydig cells

Abstract

When the phorbol ester, 4β‐phorbol‐12‐myristate‐13‐acetate (PMA) or bacterial phospholipase C (PL‐C) is added to a preparation of purified adult rat Leydig cells, containing 2 mM CaCl₂, a time‐ and dose‐dependent decrease of LH‐stimulated testosterone production is observed. After a 3 h stimulation with oLH (100 ), PMA (100 ) and PL‐C (1.6 ) do not affect the cell viability or the hCG specific binding, while cAMP accumulation is significantly reduced; cAMP‐stimulated steroidogenesis is diminished only in the presence of PL‐C. These observations suggest that in vitro: (i) activated Ca²⁺‐ and phospholipid‐dependent protein kinase is implicated in the regulation of rat Leydig cell steroidogenesis by LH at a step before the adenylate cyclase; (ii) phospholipids play an important role in cAMP‐stimulated testosterone synthesis.