[Concentration and forms of prolactin in circulating blood and lymph of lactating goats during milking and injections of exogenous hormone].

Using the radioimmunological method, the dynamics of concentration as well as the content of monomeric and dimeric prolactin forms in the blood and lymph of the goat mammary gland were studied in the course of milking and after i.v. administration of exogenous hormone. The maximum prolactin concentration in lymph was lower than that in blood by 57.7 +/- 0.9 ng/ml. This difference is due to disappearance of the monomeric prolactin form, possibly as a result of binding of the hormone with receptors. The injections of 0.4 mg prolactin caused a two-fold increase in the peak of hormone concentration in comparison with that usually observed during milking. After 3-4 hormone injections the ratio of the maximum prolactin concentrations in lymph and blood approximated 1. This effect is associated with the negative regulation of prolactin receptors. When injecting prolactin between milkings, the difference of the maximum prolactin concentrations in lymph and in blood was two times lesser than during milking.