Reduction of neuropeptide Y binding sites in the rat hippocampus after electroconvulsive stimulations

Repetitive electroconvulsive stimulations (ECSs) increase neuropeptide Y (NPY) synthesis in hippocampal neurons, but whether NPY release and the density of NPY receptors are affected is unknown. In rats exposed to 14 daily ECSs, the concentration of NPY specific binding sites in hippocampal membranes was reduced by about 75% compared with sham, but was unchanged in membranes isolated from the cerebral cortex and the thalamus. In accordance with this, in vitro autoradiography revealed a similar reduction in binding in the dentate gyrus and the CA1 and CA3 regions, but not in the parietal cortex, the entorhinal cortex or the thalamus. These results show significant changes in NPY receptor binding after repeated ECSs, suggesting that NPYergic neurotransmission, most likely within the hippocampus, is strongly affected by ECSs.