Electroconvulsive stimuli and brain peptides: effect of modification of seizure duration on neuropeptide Y, neurokinin A, substance P and neurotensin.

We studied the effects of modification of duration of seizures induced by electroconvulsive stimuli (ECS) on the changes in concentration of neuropeptide Y (NPY), neurokinin A (NKA), substance P (SP) and neurotensin (NT)-like immunoreactivity (-LI) in specific rat brain regions. Rats were divided into groups pretreated with saline, indomethacin, flurbiprofen or diazepam prior to either six sham ECSs or six ECSs. After sacrifice by focused microwave irradiation, brains were dissected into frontal cortex, occipital cortex, striatum, hippocampus, pituitary and hypothalamic sections. Peptides were extracted and measured in extract aliquots by specific radioimmunoassays. Repeated ECS increased NPY-LI and NKA-LI in the hippocampus and the occipital cortex. No effect on SP-LI or NT-LI was found. Indomethacin and flurbiprofen had no effect on the tonic seizure time following ECS, and they did not affect the ECS-induced alterations of the brain peptides. Diazepam pretreatment decreased the tonic seizure time following ECS in a dose-dependent manner. However, diazepam did not modify the ECS-induced increase in NPY-LI and NKA-LI concentrations. The results firmly establish that ECS leads to specific peptide increases in discrete rat brain regions and raise the possibility that such changes may not entirely be a consequence of seizures per se.