1. Lasting Increase in Serotonin 5-HT1A but Not 5-HT4 Receptor Subtypes in the Kindled Rat Dentate Gyrus: Dissociation from Local Presynaptic Effects
- Author
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Alfredo Cagnotto, L. Mancini, Tiziana Mennini, Marco Gariboldi, Annamaria Vezzani, D. Crespi, Maria Laura Presti, and C. Manzoni
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Male ,Serotonin ,medicine.medical_specialty ,Pyridines ,Neurotransmission ,Hippocampal formation ,Tritium ,Serotonergic ,Hippocampus ,Biochemistry ,Functional Laterality ,Piperazines ,Dioxanes ,Iodine Radioisotopes ,Rats, Sprague-Dawley ,Radioligand Assay ,Cellular and Molecular Neuroscience ,Piperidines ,Internal medicine ,Kindling, Neurologic ,medicine ,Animals ,Cerebral Cortex ,Neurons ,8-Hydroxy-2-(di-n-propylamino)tetralin ,Chemistry ,Kindling ,Dentate gyrus ,Electric Stimulation ,Rats ,Endocrinology ,nervous system ,Receptors, Serotonin ,Dentate Gyrus ,Synapses ,Autoreceptor ,Receptors, Serotonin, 5-HT4 ,Serotonin Antagonists ,WAY-100,635 ,Receptors, Serotonin, 5-HT1 ,Neuroscience - Abstract
We examined the effect of kindling on serotonergic neurotransmission in the hippocampus by measuring serotonin (5-HT) release and uptake in hippocampal synaptosomes and 5-HT1A and 5-HT4 receptor subtypes during and at different times after electrical kindling of the dentate gyrus. Using quantitative receptor autoradiography, we found that binding of 8-[3H]hydroxy-2-(di-n-propylamino)tetralin ([3H]8-OH-DPAT) to 5-HT1A receptors was selectively increased by 20% on average (p < 0.05) in the dentate gyrus of the stimulated and contralateral hippocampus 2 days after stage 2 (stereotypes and occasional retraction of a forelimb) and by 100% on average (p < 0.05) 1 week after stage 5 (tonic-clonic seizures) compared with sham-stimulated rats. A 20% increase (p < 0.05) was observed 1 month after the last generalized seizure. No changes were found after a single afterdischarge. 5-HT4 receptors, which colocalize with 5-HT1A receptors on hippocampal neurons, were not modified in kindled tissue. [3H]5-HT uptake and its release as well as the 5-HT1B autoreceptor function did not differ from shams in hippocampal synaptosomes at stages 2 and 5. Systemic administration of 100 and 1,000 microg kg(-1) 8-OH-DPAT or 1,000 microg kg(-1) WAY-100,635, 30 min before each electrical stimulation, did not significantly alter kindling progression or the occurrence of stage 5 seizures in fully kindled rats. The changes in 5-HT1A receptor density in the dentate gyrus are part of the plastic modifications occurring during kindling and may contribute to modulating tissue hyperexcitability. more...
- Published
- 2002
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