Hypothalamic levels of NPY, MCH, and prepro‐orexin mRNA during pregnancy and lactation in the rat: role of prolactin

Aug 2, 2003FASEB journal : official publication of the Federation of American Societies for Experimental Biology

Changes in hunger-related brain signals during pregnancy and breastfeeding in rats linked to prolactin

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Abstract

NPY mRNA content in the arcuate nucleus was significantly increased during pregnancy and lactation.

Increased feeding behavior occurs during pregnancy and lactation, associated with changes in specific neuropeptides.
Both MCH and prepro-orexin mRNA levels decreased in pregnant and lactating rats.
Fasting for 48 or 72 hours elevated NPY mRNA levels and increased MCH mRNA content in these states.
No changes were observed in prepro-orexin mRNA levels following fasting.
In a model of hyperprolactinemia, NPY mRNA levels remained unchanged, while MCH and prepro-orexin mRNA levels decreased.
Increased NPY expression may contribute to hyperphagia during pregnancy and lactation, while decreased MCH and prepro-orexin levels could be linked to elevated prolactin.

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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.

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Hypothalamic levels of NPY, MCH, and prepro‐orexin mRNA during pregnancy and lactation in the rat: role of prolactin

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