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Lactation alters neuropeptide-Y and proopiomelanocortin gene expression in the arcuate nucleus of the rat.
Endocrinology. 1993 Sep; 133(3):1258-65.E

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.

Authors+Show Affiliations

Department of Physiology, University of Pittsburgh School of Medicine, Pennsylvania 15261.

Pub Type(s)

Comparative Study
Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8365368

Citation

Smith, M S.. "Lactation Alters neuropeptide-Y and Proopiomelanocortin Gene Expression in the Arcuate Nucleus of the Rat." Endocrinology, vol. 133, no. 3, 1993, pp. 1258-65.
Smith MS. Lactation alters neuropeptide-Y and proopiomelanocortin gene expression in the arcuate nucleus of the rat. Endocrinology. 1993;133(3):1258-65.
Smith, M. S. (1993). Lactation alters neuropeptide-Y and proopiomelanocortin gene expression in the arcuate nucleus of the rat. Endocrinology, 133(3), 1258-65.
Smith MS. Lactation Alters neuropeptide-Y and Proopiomelanocortin Gene Expression in the Arcuate Nucleus of the Rat. Endocrinology. 1993;133(3):1258-65. PubMed PMID: 8365368.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Lactation alters neuropeptide-Y and proopiomelanocortin gene expression in the arcuate nucleus of the rat. A1 - Smith,M S, PY - 1993/9/1/pubmed PY - 1993/9/1/medline PY - 1993/9/1/entrez SP - 1258 EP - 65 JF - Endocrinology JO - Endocrinology VL - 133 IS - 3 N2 - 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. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/8365368/Lactation_alters_neuropeptide_Y_and_proopiomelanocortin_gene_expression_in_the_arcuate_nucleus_of_the_rat_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/endo.133.3.8365368 DB - PRIME DP - Unbound Medicine ER -