In vivo studies on prolactin function in the female rat: divergent effects of treatment with bromergocryptine and antisera to rat prolactin.

The effect of suppression of prolactin (PRL) serum levels on early pregnancy and lactation in the rat by means of either bromergocryptine (BEC) or rabbit antiserum to rat PRL has been examined. BEC terminated early pregnancy when given on any day from 1 to 6 and significantly impaired lactation performance when injected during the lactation period. Antibodies against rat PRI, however, showed no effect on either early pregnancy or lactation, although the sera of the treated rats contained free PRL antibodies as evidence for sufficient dosage of antiserum. This finding can be explained in two ways: either the antibodies are not able to neutralize the biological activity of the bound PRL, or the effect of BEC is not mediated by PRL-suppression alone but requires a second component not provided by the specific antiserum.