Repeated electroconvulsive stimuli: changes in neuropeptide Y, neurotensin and tachykinin concentrations in time.

1. The effects of repeated electroconvulsive stimuli (ECS) on neuropeptide Y (NPY)-, neurokinin A (NKA)-, substance P (SP)- and neurotensin (NT)- like immunoreactivity (-LI) levels in specific rat brain regions were studied in order to establish changes in peptide tissue concentrations in time after the last ECS. 2. The rats were sacrificed 15 minutes, 60 minutes, 1 day, 7 days or 15 days after the sixth sham ECS or ECS, using focused microwave irradiation. 3. Following dissection of the brains, peptides were extracted and measured in extract aliquots by radioimmunoassays. 4. ECS increased NPY-LI in both right and left hippocampus, frontal cortex and occipital cortex at 15 min, 60 min and 1 day after the treatments. Seven days following the last treatment, NPY-LI concentrations were elevated in the left hippocampus and occipital cortex but not in the corresponding right structures. Fifteen days following the last ECS treatment no changes in NPY concentrations were seen. 5. Also NKA-LI was increased in both the right and left hippocampus; the duration of changes was identical to those of NPY-LI. 6. No effects on SP- or NT-LI were found. 7. These results are in line with our hypothesis that one of the ECT's mechanisms of action might involve its effects on NPY and NKA.