Effects of acute and chronic electroconvulsive stimuli on cAMP and cGMP efflux in the rat striatum and hippocampus

The effects of acute and chronic electroconvulsive stimuli (ECS) on extrace llular concentrations of the cyclic nucleotides, cAMP and cGMP, from the st riatum and hippocampus of awake rats were studied with in vivo microdialysi s in conjunction with radioimmunoassay. Acute ECS, but not acute sham-ECS, significantly increased cAMP and cGMP efflux from the striatum by about 75 and 50%, respectively. Chronic ECS did not influence significantly basal ef flux of cAMP or cGMP from the striatum or the hippocampus in comparison to control animals receiving chronically sham-ECS. Administration of a challen ge ECS in animals treated chronically with sham-ECS resulted in an increase in cAMP and cGMP concentrations in the striatum by 20%, but it failed to a ffect significantly efflux of these nucleotides in animals treated chronica lly with ECS. Similarly, in the hippocampus, administration of a challenge ECS in animals treated chronically with sham-ECS resulted in an increase in cAMP and cGMP concentrations by about 40 and 65%, respectively, whereas it failed to affect significantly efflux of these nucleotides in animals heat ed chronically with ECS. Thus, acutely administered ECS increases cAMP and cGMP efflux in the striatum and hippocampus of rats, an effect that is grea tly diminished in animals chronically receiving ECS. These findings suggest changes in the cAMP and cGMP signal transduction mechanisms in response to acute and chronic ECS that may be related to the therapeutic effects of th is antidepressant and antipsychotic treatment. (C) 2000 Elsevier Science B. V. All rights reserved.