TRH in therapeutic vs. nontherapeutic seizures: affective and motor functions

We have modeled some aspects of electroconvulsive therapy (ECT) in rats. In addition to sham-treated controls, one group received two electroconvulsive (ECS) current-doses at grand mal seizure threshold. Two more groups received three additional ECSs at two higher current-doses. Only the two suprathreshold groups showed significant antidepressant (AD) effects in the forced-swim test, but all three seizure groups showed significant increases in TRH and related peptides in anterior cortex (AC), pyriform cortex (PYR), amygdala/entorhinal cortex (AY), and hippocampus (HC). In motor cortex (MC), TRH appeared to be increased only in the lower dose suprathreshold ECS condition. No condition increased TRH in striatum (STR). These results fell short of directly implicating limbic TRH in AD effects, but in HC, MC, and STR, correlations of peptide levels with individual swim scores raise the possibility that this peptidergic system might be involved in motor as well as affective functions. Other peptides related to TRH might also be implicated in affective regulation and antidepressant effects.