title: Up-regulation of neuropeptide Y levels and modulation of glutamate release through neuropeptide Y receptors in the hippocampus of kainate-induced epileptic rats.
abstract: Kainate-induced epilepsy has been shown to be associated with increased levels of neuropeptide Y (NPY) in the rat hippocampus. However, there is no information on how increased levels of this peptide might modulate excitation in kainate-induced epilepsy. In this work, we investigated the modulation of glutamate release by NPY receptors in hippocampal synaptosomes isolated from epileptic rats. In the acute phase of epilepsy, a transient decrease in the efficiency of NPY and selective NPY receptor agonists in inhibiting glutamate release was observed. Moreover, in the chronic epileptic hippocampus, a decrease in the efficiency of NPY and the Y(2) receptor agonist, NPY13-36, was also found. Simultaneously, we observed that the epileptic hippocampus expresses higher levels of NPY, which may account for an increased basal inhibition of glutamate release. Consistently, the blockade of Y(2) receptors increased KCl-evoked glutamate release, and there was an increase in Y(2) receptor mRNA levels 30 days after kainic acid injection, suggesting a basal effect of NPY through Y(2) receptors. Taken together, these results indicate that an increased function of the NPY modulatory system in the epileptic hippocampus may contribute to basal inhibition of glutamate release and control hyperexcitability.
authors.affiliation: Center for Neuroscience and Cell Biology, University of Coimbra, Portugal.
authors.forename: Ana P
authors.initials: AP
authors.lastname: Silva
authors.forename: Sara
authors.initials: S
authors.lastname: Xapelli
authors.forename: Paulo S
authors.initials: PS
authors.lastname: Pinheiro
authors.forename: Raquel
authors.initials: R
authors.lastname: Ferreira
authors.forename: Joana
authors.initials: J
authors.lastname: Lourenço
authors.forename: Armando
authors.initials: A
authors.lastname: Cristóvão
authors.forename: Eric
authors.initials: E
authors.lastname: Grouzmann
authors.forename: Cláudia
authors.initials: C
authors.lastname: Cavadas
authors.forename: Catarina R
authors.initials: CR
authors.lastname: Oliveira
authors.forename: João O
authors.initials: JO
authors.lastname: Malva
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004347:Drug Interactions; D004827:Epilepsy / Q000139:chemically induced / Q000378:metabolism*; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D007608:Kainic Acid; D008297:Male; D009478:Neuropeptide Y / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D010446:Peptide Fragments / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017208:Rats, Wistar; D017476:Receptors, Neuropeptide Y / Q000037:antagonists & inhibitors / Q000145:classification / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
chemical_list: D009478:Neuropeptide Y; D010446:Peptide Fragments; D012333:RNA, Messenger; D017476:Receptors, Neuropeptide Y; C062924:neuropeptide Y (13-36); C062259:neuropeptide Y, Leu(31)-Pro(34)-; D018698:Glutamic Acid; D011189:Potassium Chloride; D007608:Kainic Acid