title: Functional activation of somatostatin- and neuropeptide Y-containing neurons in the entorhinal cortex of chronically epileptic rats.
abstract: The in vitro release of somatostatin and neuropeptide Y, their tissue concentration and immunocytochemical pattern were examined in the entorhinal cortex of chronically epileptic rats. A systemic administration of 12 mg/kg kainic acid causing generalized tonic-clonic seizures for at least 3 h after injection was used to induce, 60 days later, a chronically enhanced susceptibility to seizures in the rats. The release of both peptides under depolarizing conditions was significantly reduced by 15% on average from slices of the entorhinal cortex two days after kainic acid-induced status epilepticus. At 60 days, the spontaneous and 30 mM KCl-induced release of somatostatin was significantly enhanced by 30% on average. The release induced by 100 mM KCl was raised by 70%. The spontaneous, 30 mM and 100 mM KCl-induced release of neuropeptide Y from the same slices was increased, respectively, by 120%, 76% and 36%. The late changes were associated with an increased tissue concentration of neuropeptide Y but not of somatostatin. This was confirmed by immunocytochemical evidence showing that neuropeptide Y-, but not somatostatin-immunoreactive neurons were increased in the entorhinal cortex of kainic acid-treated rats. These results indicate that neurotransmission mediated by somatostatin and neuropeptide Y, two peptides previously shown to play a role in limbic epileptogenesis, is enhanced in the entorhinal cortex of chronically epileptic rats.
authors.affiliation: Istituto di Ricerche Farmacologiche Mario Negri, Milano, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Vezzani
authors.forename: R
authors.initials: R
authors.lastname: Monhemius
authors.forename: P
authors.initials: P
authors.lastname: Tutka
authors.forename: R
authors.initials: R
authors.lastname: Milani
authors.forename: R
authors.initials: R
authors.lastname: Samanin
mesh_terms: D000818:Animals; D002452:Cell Count; D018728:Entorhinal Cortex / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D004827:Epilepsy / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D018690:Excitatory Amino Acid Agonists / Q000633:toxicity; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000633:toxicity; D008297:Male; D009474:Neurons / Q000378:metabolism / Q000502:physiology*; D009478:Neuropeptide Y / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013004:Somatostatin / Q000378:metabolism*; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology
chemical_list: D018690:Excitatory Amino Acid Agonists; D009478:Neuropeptide Y; D013004:Somatostatin; D007608:Kainic Acid