Effects of prolactin and the suckling stimulus on implantation and LH secretion in rats.
Litter removal during lactation led to an increase in serum LH concentration, an effect which was completely reversed by prolactin injections. Lactating rats receiving ergocryptine also showed increased serum LH but not to the extent found during litter removal, suggesting that both prolactin and suckling are important factors in the maintenance of lactational anoestrus. The early implantation induced by removal of the litter from rats concurrently lactating and pregnant was not prevented by prolactin. Implantation occurred early in similar rats with serum prolactin levels reduced by ergocryptine treatment and the effect was reversed by prolactin. However, early implantation led to failure of the pregnancy to reach term. These results show that, although prolactin is involved, the suckling stimulus is also essential to prevent implantation in rats with concurrent lactation and pregnancy.
D000818:Animals; D010064:Embryo Implantation / Q000187:drug effects; D004971:Estrus / Q000187:drug effects; D005260:Female; D007774:Lactation; D007986:Luteinizing Hormone / Q000097:blood / Q000378:metabolism*; D011247:Pregnancy; D011388:Prolactin / Q000494:pharmacology / Q000502:physiology*; D051381:Rats; D013391:Sucking Behavior / Q000502:physiology*
D011388:Prolactin; D007986:Luteinizing Hormone