Increased sensitivity to serotonergic agonists after repeated electroconvulsive shock in rats.
The effect of single and repeated electroconvulsive shock (ECS) (once daily for 7 days) on head twitches produced by 5-HT agonists (LiCl, 5-hydroxytryptophan; 5-HTP and 5-methoxytryptamine; 5-MT) was investigated 1 hr, 24 hr, 5 days and 10 days after the last ECS, while locomotor activity induced by serotonergic agonists (fenfluramine, 3-chlorophenylpiperazine; m-CPP) and antagonists (metergoline, cyproheptadine) was only investigated after 24 hr. 5HT and 5-HIAA concentrations were measured 0.5, 1 and 24 hr after a single ECS and up to 10 days after repeated ECS. Head twitches induced by LiCl were significantly depressed 1 hr after both single and repeated ECS. The number of head twitches produced by LiCl, 5-HTP or 5-MT given 24 hr after single or repeated ECS did not change but it rose significantly 5 and 10 days after the last shock. Repeated ECS increased locomotor activity 24 hr after the last shock. This increase was significantly enhanced by serotonergic antagonists. Biochemical assays showed that a single ECS did not significantly change brain 5-HT and 5-HIAA concentrations 0.5, 1 or 24 hr after the ECS. On the other hand, repeated ECS raised brain 5-HIAA 0.5, 1 and 24 hr or 5 and 10 days and 5-HT 0.5 hr after the final ECS. It is concluded that a single or repeated ECS both depress the serotonergic system response to LiCl but repeated ECS facilitates the response to serotoninomimetics.
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D006916:5-Hydroxytryptophan / Q000494:pharmacology; D008735:5-Methoxytryptamine / Q000494:pharmacology; D000818:Animals; D001921:Brain / Q000502:physiology*; D002712:Chlorides / Q000494:pharmacology; D003533:Cyproheptadine / Q000494:pharmacology; D004597:Electroshock; D005277:Fenfluramine / Q000494:pharmacology; D008094:Lithium / Q000494:pharmacology; D018021:Lithium Chloride; D008297:Male; D008711:Metergoline / Q000494:pharmacology; D009043:Motor Activity / Q000187:drug effects; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D012701:Serotonin / Q000502:physiology*; D009435:Synaptic Transmission / Q000187:drug effects*
D002712:Chlorides; D010879:Piperazines; D008711:Metergoline; D005277:Fenfluramine; D003533:Cyproheptadine; D012701:Serotonin; D008735:5-Methoxytryptamine; D008094:Lithium; D006916:5-Hydroxytryptophan; D018021:Lithium Chloride; C015068:1-(3-chlorophenyl)piperazine