Aging selectively suppresses vasoactive intestinal peptide messenger RNA expression in the suprachiasmatic nucleus of the Syrian hamster

Marilyn J. Duncan, Jana M. Herron, Stephanie A. Hill

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


Aging leads to many changes in the expression of circadian rhythms, including reduced amplitude, altered relationship to the environmental illumination cycle, and reduced sensitivity to phase resetting signals. Neuropeptide synthesizing neurons in the suprachiasmatic nucleus (SCN), the principal circadian pacemaker in mammals, play a role in regulating pacemaker function and in coupling the pacemaker to overt circadian rhythms. Aging may alter the activity of neuropeptide neurons in the SCN, which could be reflected in changes in mRNA expression. Therefore, this study investigated whether aging alters the level or rhythm of expression of neuropeptide mRNAs in the SCN of male Syrian hamsters, a well established model for the study of age-related changes in circadian rhythms. Three age groups of hamsters (young [3-5 months old], middle-aged [12-15 months old] and old [19-22 months old] were sacrificed at five times of day. Their brains were dissected and sections through the suprachiasmatic nucleus were prepared and used for in situ hybridization for mRNAs for vasoactive intestinal peptide (VIP), arginine vasopressin (AVP) and somatostatin (SS). Aging selectively decreased the SCN expression of VIP mRNA without affecting AVP mRNA or SS mRNA. Also, only AVP mRNA expression exhibited a robust 24-h rhythm, in contrast to previous findings in other species that VIP mRNA and SS mRNA, as well as AVP mRNA, exhibit 24-h rhythms in the SCN. The present findings suggest that age-related reductions in VIP mRNA expression may contribute to the alterations in entrainment and attenuated sensitivity to phase resetting signals that are characteristic of aging. Furthermore, the results demonstrate that neuropeptide gene expression in the SCN is differentially regulated by aging and varies among species.

Original languageEnglish
Pages (from-to)196-203
Number of pages8
JournalMolecular Brain Research
Issue number2
StatePublished - Mar 5 2001

Bibliographical note

Funding Information:
We thank Anthony Deveraux for assistance with these experiments and Dr Kathryn Scarbrough for helpful consultation concerning in situ hybridization for VIP mRNA expression. NIH Grant AG-13418 supported these studies.


  • Circadian rhythm
  • In situ hybridization
  • Somatostatin
  • Vasoactive intestinal peptide
  • Vasopressin

ASJC Scopus subject areas

  • Molecular Biology
  • Cellular and Molecular Neuroscience


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