Changes in synaptosomal ectonucleotidase activities in two rat models of temporal lobe epilepsy

Adenosine has been proposed as an endogenous anticonvulsant which can play an important role in seizure initiation, propagation and arrest. Besides th e release of adenosine per se, the ectonucleotidase pathway is an important metabolic source of extracellular adenosine. Here we evaluated ATP diphosp hohydrolase and 5'-nucleotidase activities in synaptosomes from hippocampus and cerebral cortex at different periods after induction of status epilept icus (SE) by intraperitoneal administration of pilocarpine or kainate. Ecto nucleotidase activities from synaptosomes of hippocampus and cerebral corte x of rats were significantly increased at 48-52 h, 7-9 days and 45-50 days after induction of SE by pilocarpine. In relation to kainate model, both hi ppocampal. enzymes were enhanced at 7-9 days and 45-50 days, but only 5'-nu cleotidase remained elevated at 100-110 days after the treatment. In cerebr al cortex, an increase in ATP diphosphohydrolase was observed at 48-52 h, 7 -9 days and 45-50 days after induction of SE by kainate. However, 5'-nucleo tidase activity only presented significant changes at 45-50 and 100-110 day s. Our results suggest that SE can induce late and prolonged changes in ect onucleotidases activities. The regulation of the ectonucleotidase pathway m ay play a modulatory role during the evolution of behavioral and pathophysi ological changes related to temporal lobe epilepsy. (C) 2000 Elsevier Scien ce B.V. All rights reserved.