Reduced feeding response to muscimol and neuropeptide Y in senescent F344 rats

Jessica D. Coppola, Barbara A Horwitz, Jock Hamilton, James E. Blevins, Roger B. McDonald

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


Many mammals experience spontaneous declines in their food intake and body weight near the end of life, a stage we refer to as senescence. We have previously demonstrated that senescent rats have blunted food intake responses to intracerebroventricular injections of neuropeptide Y (NPY). In the present study, we tested the hypothesis that responsiveness to GABA, a putative potentiator of NPY's effect, is also diminished. Young and old male F344 rats received injections of NPY, muscimol, (MUS, a GABA-A receptor agonist), combinations of these two agents, and vehicle [artificial cerebrospinal fluid (aCSF)] into the hypothalamic paraventricular nucleus (PVN). Both young and old presenescent rats increased their food intake in response to NPY, MUS, and the combination of the two (in comparison to injections of aCSF). The combination treatment was generally more effective than either NPY or MUS alone. These data are consistent with suggestions that both NPY and GABA play a role in the regulation of feeding behavior. Senescent rats exhibited an attenuated NPY-induced food intake, no increase in response to MUS, and a response to NPY + MUS that was no larger than that of NPY alone. We conclude that PVN injections of GABA, as well as NPY, are less effective in stimulating feeding in senescent rats and suggest that alterations in their signaling pathways play a role in the involuntary feeding decrease seen near the end of life.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Issue number6 57-6
StatePublished - Jun 2005


  • Anorexia of aging
  • Brain
  • Food intake control
  • Hypothalamus

ASJC Scopus subject areas

  • Physiology


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