The use of antiserum to rat prolactin to evaluate its role as luteotrophin in the hamster.

Rabbit antisera to rat prolactin was found to cross-react with the hamster pituitary extract by double diffusion and quantitative precipitin techniques. Short term neutralization of prolactin by antiserum to rat prolactin either in early or late stages of gestation did not have any deleterious effects. Prolonged administration of rat prolactin antiserum resulted in an increase in the incidence of resorptions, but pregnancy was still maintained followed by normal parturition. This is in marked contrast to the abortive effects of an antiserum of ICSH. It was concluded that prolactin does not play a major role in maintaining pregnancy of the hamster.