The effects of prolactin and corticosterone on insulin binding to rat Leydig cells.

The influence of prolactin (PRL) and corticosterone on insulin binding to purified rat Leydig cells was assessed in vitro. The lowest dose of PRL (50 ng/ml) increased (p<0.05) and the remaining PRL concentrations (100, 150, 200, 250 ng/ml) decreased (p<0.05) the insulin binding to Leydig cells. All doses of corticosterone (150, 200, 250, 300 ng/ml) except the lowest one (100 ng/ml) decreased the insulin binding. In conclusion, hyperprolactinemia or excess glucocorticoids associated with an impairment of testicular steroidogenesis may be mediated by a defective insulin binding to Leydig cells.