DYNAMIC CHANGES OF BRAIN-DERIVED NEUROTROPHIC FACTOR PROTEIN-LEVELS IN THE RAT FOREBRAIN AFTER SINGLE AND RECURRING KINDLING-INDUCED SEIZURES

Regional levels of brain-derived neurotrophic factor protein were meas ured in the rat brain using enzyme immunoassay following seizures evok ed by hippocampal kindling stimulations. One stimulation, which induce d a brief, single episode of epileptiform activity in hippocampus and piriform cortex but not in parietal cortex or striatum, gave rise to a transient increase of brain-derived neurotrophic factor levels in den tate gyrus and CA3 region and a decrease in piriform cortex. After 40 rapidly recurring seizures, with epileptiform activity also involving parietal cortex and striatum, increases were observed in dentate gyrus , CA3 and CA1 regions, piriform cortex and striatum. Maximum levels we re reached at 2-24 h and brain-derived neurotrophic factor then return ed to baseline except in dentate gyrus, where elevated protein content was sustained for four days. The differential regulation of brain-der ived neurotrophic factor protein levels in various forebrain structure s, which only partly correlates to messenger RNA changes, could indica te regional differences in protein release, antero- or retrograde tran sport, or brain-derived neurotrophic factor promoter activation. The d ynamic changes of brain-derived neurotrophic factor levels in regions involved in the generation and spread of seizure activity may regulate excitability and trigger plastic responses in the post-seizure period . (C) 1997 IBRO. Published by Elsevier Science Ltd.