Ergot drugs suppress plasma levels of prolactin (PRL) but not growth hormone (GH), luteinizing hormone (LH) or corticosterone (CORT) in parturient mice.

Plasma levels of prolactin (PRL), growth hormone (GH), luteinizing hormone (LH), and corticosterone (CORT) were measured in parturient Rockland-Swiss (R-S) albino mice following the daily administration for 10 days of 0.5 mg ergocornine (ERGO), 0.5 mg bromocriptine (BROMO), or sesame oil (OIL). The dams were provided with replete foster young on a daily basis so as to prevent the decline in suckling activity that normally occurs in undernourished pups of ergot-treated dams. Circulating PRL levels were significantly reduced by both ergot drugs but plasma levels of the other hormones measured were not altered. Thus, ergot drugs have relatively specific effects on PRL even in parturient animals receiving sustained high levels of suckling stimulation.