Tissue distribution of prolactin receptor mRNA during late stage embryogenesis of the chick

Serum prolactin increases during late embryogenesis. In order to elucidate the function of prolactin at this period, tissue distribution of prolactin receptor mRNA was examined by RNase protection assay. The mRNA was detected strongly in the kidney, intestine, and allantoic membrane; weakly detected in the brain; but not detected in the liver. The expression levels of the prolactin receptor mRNA in the kidney, intestine, and allantoic membrane were retained at constant levels during later stages of,embryogenesis: (Days 17 and 19) and posthatch periods (2 and 28 d after hatching). These results suggest that prolactin is mainly involved in the osmoregulation during the later stage,of embryogenesis and that the expression of prolactin receptor: mRNA in,the kidney, intestine, and allantoic membrane is regulated by a serum prolactin-independent manner.