T. Kozuru et al., Chronic electroconvulsive shock decreases (+/-) 1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane hydrochloride (DOI)-induced wet-dog shake behaviors of dexamethasone-treated rats, LIFE SCI, 66(13), 2000, pp. 1271-1279
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.