(D-Met2,Pro5) enkephalinamide causes a decrease in plasma prolactin levels of lactating rats continuously suckled and an increase in those deprived of their litter.
The effect of an enkephalin analogue, (D-Met2,Pro5)enkephalinamide (EKNH2) on prolactin (PRL) secretion of lactating rats continuously suckled or separated from their pups was investigated. In rats together with their pups 0.5 mg/kg EKNH2 caused a dramatic decrease, 0.25 mg/kg a mild and short-lasting reduction in plasma PRL levels. In contrast, in lactating rats separated for 4 h from their pups 0.5 mg/kg of the drug induced a slight and 1.0 mg/kg a considerable increase in plasma PRL levels. The data indicate that in lactating rats depending on the circumstances the enkephalin analogue causes opposite effects on PRL secretion.
D000818:Animals; D004744:Enkephalin, Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D007700:Kinetics; D007774:Lactation; D009270:Naloxone / Q000494:pharmacology; D011247:Pregnancy; D011388:Prolactin / Q000097:blood*; D051381:Rats; D011919:Rats, Inbred Strains
D009270:Naloxone; D004744:Enkephalin, Methionine; C021717:enkephalin, Met(2)-ProNH2(5)-; D011388:Prolactin