Beta-adrenergic receptor binding in different regions of rat brain after various intensities of electroshock: relationship to postictal EEG.

Relationships among different intensities of electroshock treatment (EST), EEG-recordable primary after discharge (PAD), and beta-adrenergic binding in various brain regions were investigated in adult rats. Different intensities of EST (1-2, 6-8, 20-30 mamp) were applied through ear-clip electrodes for 7 consecutive days. A sigmoidal relationship was observed between the PAD and the applied current-intensity. 3H-dihydroalprenolol (DHA) was used as a ligand to evaluate beta-adrenergic receptor binding in membrane preparation of the following brain regions: Cerebral cortex, cerebellum, pons-medulla, and "midregion"-which consisted of the remainder tissue including thalamus, striatum, and midbrain. A significant decrease (28%) in binding was observed in cortex tissue after EST of 6-8 mamp but no changes were observed after either 1-2 mamp or 20-30 mamp. In "midregion," a significant increase (40%) in binding was observed after EST with the subconvulsive intensity (1-2 mamp) whereas no changes were seen at higher intensities. The results suggest that in cortex, the function relating beta-adrenergic binding to current intensities may not be monotonic. The increase in binding seen in the "midregion" after subconvulsive EST may not be associated with changes related to the clinical efficacy of EST.