Aging alters in a region-specific manner serotonin transporter sites and 5-HT1A receptor-G protein interactions in hamster brain

Marilyn J. Duncan, Julie G. Hensler

Research output: Contribution to journalArticlepeer-review

15 Scopus citations

Abstract

Key proteins regulating serotonergic activity, specifically the serotonin transporter and 5-HT1A receptor, were examined in the midbrain raphe nuclei of young (3-4 months) and old (17-19 months) hamsters (N=7-10/group). An age-related decrease in the maximal density of serotonin transporter sites labelled with [3H]paroxetine (fmol/mg protein, Old: 396±13; Young: 487±27) was observed in the dorsal raphe nucleus (DRN) but not the median raphe nucleus (MRN), without affecting the affinity of [3H]paroxetine. In the DRN and MRN, the stimulation of [35S]GTPγS binding by the 5-HT1A receptor agonist 8-OH-DPAT, or the number of 5-HT1A receptor sites labeled with [3H]MPPF, was not different in old versus young animals. Thus in the DRN, aging decreased serotonin transporter sites without changing 5-HT1A receptor activation of G proteins or 5-HT1A receptor density. In the CA1 region of hippocampus, 8-OH-DPAT-stimulated [35S]GTPγS binding was increased in the older animals (% above basal, Old: 141±21; Young: 81±17) without changing specific [3H]MPPF binding sites, suggesting that the capacity of 5-HT1A receptors to activate G proteins is enhanced. Aging also appears to enhance this capacity in the dentate gyrus, because this region exhibited a constant level of 8-OH-DPAT-stimulated [35S]GTPγS binding in spite of an age-related decrease in the number of [3H]MPPF binding sites (fmol/mg protein, Old: 203±21; Young: 429±51).

Original languageEnglish (US)
Pages (from-to)36-44
Number of pages9
JournalNeuropharmacology
Volume43
Issue number1
DOIs
StatePublished - Jul 1 2002

Keywords

  • Autoradiography
  • CA
  • Dentate gyrus
  • Dorsal raphe nucleus
  • Hippocampus
  • Median raphe nucleus
  • [H]MPPF binding
  • [H]paroxetine binding
  • [S]GTPγS binding

ASJC Scopus subject areas

  • Pharmacology
  • Cellular and Molecular Neuroscience

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