Hypothalamic levels of NPY, MCH, and prepro-orexin mRNA during pregnancy and lactation in the rat: role of prolactin.
Pregnancy and lactation provide excellent models of physiological hyperphagia and hyperprolactinemia. To identify possible factors associated with the increased feeding in these situations, we measured hypothalamic mRNA levels of three orexigenic neuropeptides--NPY, MCH, and orexins--in nonpregnant, pregnant, and lactating rats by in situ hybridization. NPY mRNA content in the arcuate nucleus was significantly increased during pregnancy and lactation. However, MCH and prepro-orexin expression was decreased in both states. 48 or 72 h of fasting in pregnant and lactating rats further elevated NPY mRNA levels and increased the low MCH mRNA content. Surprisingly, no effect was observed in prepro-orexin mRNA levels. Finally, we investigated the possible effect of high PRL levels on these orexigenic signals using a model of hyperprolactinemia induced by pituitary graft. NPY mRNA content was unchanged, but MCH and prepro-orexin mRNA levels were significantly decreased. Our results suggest that the increased NPY expression might be partly responsible for the hyperphagia observed during pregnancy and lactation. MCH and prepro-orexin may be involved in the adaptation of other homeostatic mechanisms and their decreased levels in these physiological settings could be mediated by the elevated circulating PRL levels.
García
M C
MC
Department of Physiology, Faculty of Medicine, University of Santiago de Compostela, R/San Francisco s/n, 15782 Santiago de Compostela, Spain.
López
M
M
Gualillo
O
O
Seoane
L M
LM
Diéguez
C
C
Señarís
Rosa Maria
RM
D000818:Animals; D005260:Female; D005786:Gene Expression Regulation; D006963:Hyperphagia / Q000209:etiology* / Q000235:genetics / Q000378:metabolism; D006966:Hyperprolactinemia / Q000209:etiology / Q000235:genetics / Q000378:metabolism; D007028:Hypothalamic Hormones / Q000096:biosynthesis* / Q000235:genetics; D007031:Hypothalamus / Q000166:cytology / Q000378:metabolism*; D017403:In Situ Hybridization; D047908:Intracellular Signaling Peptides and Proteins; D007774:Lactation; D008543:Melanins / Q000096:biosynthesis* / Q000235:genetics; D009478:Neuropeptide Y / Q000096:biosynthesis* / Q000235:genetics; D009479:Neuropeptides / Q000096:biosynthesis* / Q000235:genetics; D000068797:Orexins; D010907:Pituitary Hormones / Q000096:biosynthesis* / Q000235:genetics; D011247:Pregnancy; D011388:Prolactin / Q000097:blood / Q000502:physiology; D011498:Protein Precursors / Q000096:biosynthesis* / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley
D007028:Hypothalamic Hormones; D047908:Intracellular Signaling Peptides and Proteins; D008543:Melanins; D009478:Neuropeptide Y; D009479:Neuropeptides; D000068797:Orexins; D010907:Pituitary Hormones; D011498:Protein Precursors; D012333:RNA, Messenger; C019463:melanin-concentrating hormone; D011388:Prolactin