Suckling-induced serum prolactin levels are modified by interference with milk ejection in lactating rats.
The aim of this study was to determine whether suckling-induced prolactin (PRL) levels were modified when milk ejection was impaired. Milk ejection impairment was achieved in two experimental models: a) depriving the dam of sleep during suckling and b) increasing the nonsuckling intervals in lactating dams. Sleep deprivation blocked milk ejection and enhanced suckling-induced PRL levels in dams that had been previously separated from their pups. When milk ejection is blocked in litter-deprived dams, mammary glands are not evacuated and they remain engorged. Suckling stimuli were not the cause of the difference in suckling-induced serum PRL levels in control and sleep-deprived dams. The engorgement of the mammary glands may play a role, as a maximum suckling-induced PRL increase was not observed in nonseparated SD dams with nonengorged mammary glands. Moreover, suckling-induced PRL levels were decreased when engorged mammary glands of SD dams were evacuated through an oxytocin injection. A parallel increase between suckling-induced PRL levels and mammary gland weight was observed in the experiments in which milk ejection was impaired through an increase in the intervals of nonsuckling, providing additional support for a relationship between mammary gland engorgement and the regulation of suckling-induced PRL levels.
Instituto de Neurobiología, Buenos Aires, Argentina. fuacta@ssdnet.com.ar
L M
LM
Voloschin
M G
MG
Gallardo
J H
JH
Tramezzani
D000818:Animals; D005260:Female; D007774:Lactation / Q000502:physiology*; D008893:Milk Ejection / Q000502:physiology*; D010121:Oxytocin / Q000494:pharmacology; D011388:Prolactin / Q000097:blood*; D051381:Rats; D012892:Sleep Deprivation; D013997:Time Factors; D014886:Weaning
D010121:Oxytocin; D011388:Prolactin