Activation of metabotropic glutamate receptors increases neuropeptide Y expression in the rat hippocampus. Immunohistochemical studies.

Neuropeptide Y (NPY), a 36-amino acid peptide, is present in some hippocampal interneurons and nerve terminals and seems to modulate glutamatergic transmission in this structure. Earlier studies of some other authors showed an increase in NPY expression in the hippocampus during seizures and activation of ionotropic glutamate receptors. In the present study the effect of metabotropic glutamate receptor (mGluR) stimulation was investigated in rat hippocampus by immunohistochemical methods. It was found that (1S,3R)1-aminocyclopentane-1,3-dicarboxylic acid (1S,3R-ACPD), a selective agonist of mGluRs injected into the rat lateral ventricle (1 mumol/10 microliters) or hippocampus (0.1 mumol/1 microliter), 24 h before taking the brains for immunohistochemical studies, induced a significant increase in NPY-immunoreactivity in the hippocampus, especially in the hilar region. The obtained results indicate that mGluRs positively modulate the NPY content in the hippocampal neurons.