Short-term in vivo regulation of prolactin receptors in the liver, testes, kidneys, and mammary gland of rats.

Infusion of 17-beta-estradiol for 3 h caused a more than 100% increase in the number of PRL receptors (PRL) in the microsomal liver fraction of male rats without affecting the hormone-receptor affinity. A small but significant increase in PRL receptors also was found in testes but not kidneys. Testosterone infusion to female virgin rats for a similar time period resulted in some nonsignificant decreases in PRL receptors in the liver but not the mammary gland or kidneys. Testosterone infusion to males or 17-beta-estradiol infusion to females did not change the number or affinity of PRL and growth hormone receptors. The level of serum PRL was not influenced during infusion with both hormones.