Neurochemical effects of electrically and chemically induced seizures: an in vivo microdialysis study in the rat hippocampus.
This study examined the effects of electroconvulsive shock (ECS) on interstitial concentrations of serotonin (5-HT), its metabolite 5-hydroxyindoleacetic acid (5-HIAA), acetylcholine and choline, and the dopamine metabolite homovanillic acid (HVA) in the hippocampus of freely moving rats using online brain microdialysis. The effects of ECS on 5-HT, 5-HIAA, and HVA were compared to the effects of seizures induced by the convulsant agent flurothyl. Interstitial concentrations of 5-HT increased several fold in response to ECS and this increase was accompanied by a significant increase in the concentration of HVA. Acetylcholine and choline concentrations were also increased significantly by ECS. The ECS-induced increase in interstitial 5-HT was markedly reduced when the voltage-dependent sodium channel blocker tetrodotoxin (1 mumol/L) was added in the perfusion solution, indicating that the observed increase was of neuronal origin. Interstitial concentrations of 5-HT also increased in response to flurothyl-induced seizures and this increase was accompanied by a significant increase in the concentration of HVA. These results provide direct in vivo evidence that interstitial concentrations of 5-HT increase several fold in response to both ECS- and flurothyl-induced seizures. These observations are discussed in relation to the hypothesized role of 5-HT in ECS-induced memory deficits.
Zis
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AP
Department of Psychiatry, University of British Columbia, Vancouver, Canada.
Nomikos
G G
GG
Brown
E E
EE
Damsma
G
G
Fibiger
H C
HC
D000109:Acetylcholine / Q000032:analysis; D000704:Analysis of Variance; D000818:Animals; D003956:Dialysis / Q000379:methods; D004597:Electroshock; D005481:Flurothyl; D006624:Hippocampus / Q000737:chemistry* / Q000503:physiopathology; D006719:Homovanillic Acid / Q000032:analysis; D006897:Hydroxyindoleacetic Acid / Q000032:analysis; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D012640:Seizures / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology; D012701:Serotonin / Q000032:analysis
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D005481:Flurothyl; D000109:Acetylcholine; D006719:Homovanillic Acid