Influence of prolactin on the metabolism of steroid hormones in rat liver and adrenals

The influence of prolactin treatment on the hepatic metabolism of 4 [4-¹⁴C] androstene 3,17 dione (in the microsomal and 105,000 x g supernatant fractions) and 5α [4-¹⁴C] androstane 3α,17β diol (in the microsomal fraction) and on the adrenal metabolism of 4 [4-¹⁴C] androstene 3,17 dione was studied in intact and castrated male and female rats with and without concomitant treatment with testosterone propionate. Whereas prolactin gave a significant and specific decrease in the activity of adrenal 5α reductase by about 20-30% in both male and female rats no specific effects were noted in the metabolism of steroids in the liver. Neither did prolactin compensate for the relative androgen unresponsiveness characteristic of neonatally castrated male rats. These results suggest that prolactin does not play any significant role in mediating the recently discovered hypophyseal control of sexual differentiation of hepatic steroid metabolism in the rat whereas it may have a function in maintaining sexual differences in adrenal 5α reductase activity.