Chronic electroconvulsive shock decreases (+/-) 1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride (DOI)-induced wet-dog shake behaviors of dexamethasone-treated rats

Electroconvulsive shock (ECS) therapy is considered to be an effective trea tment for depression, but its mechanism of action is still unknown. We inve stigated the effect of chronic ECS in rats treated for 14 days with dexamet hasone (Dex), a glucocorticoid receptor agonist. Chronic injection of sesam e oil decreased body weight change and increased serotonin (5-HT)-2A recept or number and DOI (5-HT-2A, 2C receptor agonist)-induced wet-dog shake (WDS ) behaviors. Dex treatment for 14 days decreased body weight of rats, but r epeated ECS did not reverse this decrease. Dex also abolished plasma cortic osterone levels, and ECS failed to restore these levels. These results indi cate that chronic ECS does not antagonize the effect of Dex. The treatment with Dex increased 5-HT-2A receptor binding density of rat frontal cortex a nd the number of DOI-induced WDS behaviors. Chronic ECS reduced the enhance d WDS behaviors by Dex but had little effect on receptor density. These res ults suggest that chronic ECS might suppress 5-HT-2A receptor function at t he postreceptor signaling level rather than at the receptor itself, without changing HPA axis function in Dex-treated rats.