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 language | English (US) |
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Pages (from-to) | 36-44 |
Number of pages | 9 |
Journal | Neuropharmacology |
Volume | 43 |
Issue number | 1 |
DOIs | |
State | Published - Jul 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