Lactation alters neuropeptide-Y and proopiomelanocortin gene expression in the arcuate nucleus of the rat

M (Susan) Smith

Research output: Contribution to journalArticle

164 Citations (Scopus)

Abstract

To identify possible factors associated with lactation that may be involved in the suppression of GnRH neuronal function, we have examined whether lactation induces changes in arcuate nucleus neuronal function, focusing on changes in neuropeptide-Y (NPY) and POMC neuronal activity. Animals were studied during diestrous day 1 of the estrous cycle or during day 10 postpartum. Lactating animals had their litters adjusted to eight pups on day 2 postpartum. Brain tissue was removed to measure NPY peptide content in the median eminence (ME) or the ME-arcuate nucleus (ME-ARC) and to quantify NPY or POMC mRNA by in situ hybridization, using 35S-labeled antisense riboprobes. The NPY peptide content was significantly increased in the ME (1.8-fold) and ME-ARC (1.5-fold) during lactation compared to those on diestrus. The NPY mRNA content throughout the ARC did not differ between diestrous and lactating animals. However, if specific subdivisions of the ARC were examined, a significant increase (1.8-fold) in NPY mRNA in the ARC-C region of the ARC (at the plane of the dorsal medial hypothalamic nucleus) was observed during lactation. Dorsal to the ARC in this same plane, there was also an induction of NPY expression in cells lateral to the dorsal medial hypothalamic nucleus. The increases in NPY mRNA in the ARC-C region of the arcuate nucleus persisted for at least 24 h after removal of the suckling stimulus. The other subdivisions of the ARC did not show any differences in NPY mRNA between diestrus and lactation. The POMC mRNA content was decreased by 20-30% during lactation compared with that on diestrus. The effects of lactation to decrease POMC mRNA content were not specific to any subdivision of the ARC, but were observed throughout the entire ARC. Given that lactation is an estrogen-deficient state, the increase in NPY neuronal activity, as indicated by increased gene expression in the caudal portion of the ARC and increased content in the ME, could play an inhibitory role in the regulation of GnRH secretion. However, the decrease in POMC neuronal activity, as suggested by the decrease in gene expression throughout the ARC, would not appear to be involved in the suppression of GnRH neuronal activity. These changes in ARC neuronal function could be related to hormonal changes or metabolic signals regulating food intake during lactation.

Original languageEnglish (US)
Pages (from-to)1258-1265
Number of pages8
JournalEndocrinology
Volume133
Issue number3
StatePublished - Sep 1993
Externally publishedYes

Fingerprint

AIDS-Related Complex
Pro-Opiomelanocortin
Arcuate Nucleus of Hypothalamus
Neuropeptide Y
Lactation
Gene Expression
Median Eminence
Messenger RNA
Diestrus
Gonadotropin-Releasing Hormone
Mediodorsal Thalamic Nucleus
Postpartum Period
Peptides
Estrous Cycle

ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Lactation alters neuropeptide-Y and proopiomelanocortin gene expression in the arcuate nucleus of the rat. / Smith, M (Susan).

In: Endocrinology, Vol. 133, No. 3, 09.1993, p. 1258-1265.

Research output: Contribution to journalArticle

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