頁籤選單縮合
題名 | Difference in the in Vivo Influence of Serotonin[feb5]坧 Autoreceptors on Serotonin Release in Prefrontal Cortex and Dorsal Hippocampus of the Same Rat Treated with Fluoxetine= |
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作者 | Li,Xi-ming; Perry,Kenneth W.; Wong,David T.; |
期刊 | 中國生理學雜誌 |
出版日期 | 19990600 |
卷期 | 42:2 1999.06[民88.06] |
頁次 | 頁53-59 |
分類號 | 361.1 |
語文 | eng |
關鍵詞 | Fluoxetine; WAY 100635; Monoamines; Prefrontal cortex; Dorsal hippocampus; A dualprobe microdialysis procedure; |
英文摘要 | Recent studies have demonstrated that antagonism of somatodendritic serotonin□ (5-HT□) autoreceptors can potentiate the increase of extracellular 5-HT concentrations induced by selective serotonin reuptake inhibitors including fluoxetine. The present study was conducted to uncover any functional difference between the 5-HT□ autoreceptors located on the cell bodies of 5-HT neurons in the dorsal (DRN) and median (MRN) raphe nuclei. The investigational approach used in the present study was to detect extracellular 5-HT concentrations in two terminal areas, prefrontal cortex ( Pfc) and dorsal hippocampus (Dhp), which are mainly innervated by the 5-HT neurons located in the DRN and MRN respectively. To avoid possible variation between individual animals a dualprobe microdialysis procedure was applied to determine 5-HT concentrations in both brain areas of the same rat. Fluoxetine (10 mg/kg, s.c.) alone produced a smaller increase in the extracellular 5-HT concentration in the Pfc than Dhp of the same rat ( maximal 5-HT concentrations were 183% and 223% of the baseline values in Pfc and Dhp respectively). However, an antagonist of 5-HT□ receptors, WAY 100635, subsequently injected (s.c.) at 1 mg/kg brought the 5-HT concentrations to similar levels in the Pfc (332%) and Dhp (308%). Since the 5-HT concentrations immediately before the injection of WAY100635 were lower in the PFc (102%) than Dhp (186%), WAY100635 induced a larger 5-HT net increase in the Pfc ( 332%-102%=230%) than Dhp (308%-186%=122%). On the other hand, WAY100635 alone did not significantly change the extracellular 5-HT concentrations in both areas. Furthermore, extracellular concentrations of dopamine (DA) and two DA metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, in both areas were not altered by the administrations of fluoxetine and WAY100635. In conclusion, the present study demonstrated that the antagonist of 5-HT□ receptors, WAY100635, produced a more robust potentiation in the fluoxetine-induced 5-HT increases in the Pfc than Dhp. Since Pfc and Dhp are predominately innervated by 5-HT neurons located in the DRN and MRN respectively, this result may indicate a functional difference between the 5- HT□ autoreceptors located on the cell bodies of 5-HT neurons in the DNR and MRN. |
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