Activity of the Hypothalamic Melanocortin System Decreases in Middle-Aged and Increases in Old Rats

Nóra Füredi, Alexandra Mikó, Balázs Gaszner, Diána Feller, Ildikó Rostás, Judit Tenk, Margit Solymár, Márta Balaskó, Erika Pétervári

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3 Citations (Scopus)

Abstract

Appearance of middle-aged obesity and aging anorexia both in humans and rodents suggests a role for regulatory alterations. Hypothalamic melanocortin agonist, α-melanocyte-stimulating hormone (α-MSH) produced in the arcuate nucleus (ARC), reduces body weight via inducing hypermetabolism and anorexia mainly through melanocortin 4 receptors (MC4Rs) in the paraventricular nucleus (PVN). Orexigenic ARC-derived agouti-related protein (AgRP) is an inverse agonist on MC4R in the PVN. Previously, we demonstrated that characteristic age-related shifts in the catabolic effects of α-MSH may contribute both to middle-aged obesity and aging anorexia. Responsiveness to α-MSH decreases in middle-aged rats compared with young adults, whereas in old age it rises again significantly. We hypothesized corresponding age-related dynamics of endogenous melanocortins. Therefore, we quantified mRNA gene expression and peptide or protein level of α-MSH, AgRP, and MC4R in the ARC and PVN of male Wistar rats of five age groups (from young to old). Immunofluorescence and quantitative reverse transcriptase polymerase chain reaction were applied. α-MSH and MC4R immunoreactivities in the ARC and PVN declined in middle-aged and increased together with their expressions in aging rats. AgRP gene expression but not its immunoreactivity increased in aging rats. Our results demonstrate that age-dependent changes of endogenous melanocortins contribute to middle-aged obesity and aging anorexia.

Original languageEnglish
Pages (from-to)438-445
Number of pages8
JournalJournals of Gerontology - Series A Biological Sciences and Medical Sciences
Volume73
Issue number4
DOIs
Publication statusPublished - Mar 14 2018

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Keywords

  • Aging anorexia
  • Brain aging
  • Hormones
  • Metabolism
  • Obesity

ASJC Scopus subject areas

  • Ageing
  • Geriatrics and Gerontology

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