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Serotonin depletion results in a decrease of the neuronal activation caused by rivastigmine in the rat hippocampus
Birgitte R Kornum1, Pia Weikop, Arne Moller
1Neurobiology Research Unit, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark. birgitte@nru.dk
Brain Research
|January 24, 2006
Summary
Acetylcholine (ACh) influences brain activity, and serotonin (5-HT) plays a role in this process, particularly in the hippocampus. This study shows 5-HT partially mediates ACh-driven neuronal activation in the dentate gyrus.
Area of Science:
- Neuroscience
- Neuropharmacology
- Molecular Psychiatry
Background:
- The serotonergic and cholinergic systems interact and are implicated in major depression and Alzheimer's disease.
- Acetylcholine (ACh) is suggested to enhance serotonin (5-HT) release via nicotinic receptors.
Purpose of the Study:
- To investigate the extent and location of 5-HT's mediation of neuronal responses to ACh release.
- To understand the interplay between ACh and 5-HT in specific brain regions.
Main Methods:
- Neuronal activity was measured in rats with rivastigmine-induced elevated ACh levels.
- Serotonin (5-HT) depletion was achieved using p-chlorophenylalanine and D,L-fenfluramine.
- Neuronal activation was quantified by c-Fos immunoreactivity in the medial prefrontal cortex, septum, hippocampus, and dorsal raphe nucleus.
Main Results:
- Rivastigmine increased c-Fos immunoreactivity in the medial prefrontal cortex and hippocampus.
- 5-HT depletion reduced ACh-induced c-Fos immunoreactivity in the dentate gyrus.
- No significant effect of 5-HT depletion was observed in the septum, dorsal raphe nucleus, or other hippocampal subfields.
Conclusions:
- Serotonin (5-HT) partially mediates ACh-induced neuronal activation in the hippocampus, specifically the dentate gyrus.
- This mediation may involve locally released 5-HT, highlighting its role in cholinergic signaling pathways.