Autoradiography of L-type and N-type calcium channels in aged rat hippocampus, entorhinal cortex, and neocortex

The present study examined blains from 6 17, and 32 month old male (F344X B N)F1 rats to determine whether there was any age-related change in the dist ribution or density of L-type and N-type Ca2+ channels in hippocampus, ento rhinal cortex, and neocortex, areas commonly involved in the generation of epileptic seizures. The L-type channel antagonist PN200-110 and the N-type channel antagonist omega -conotoxin GVIA were used to determine specific bi nding densities and the autoradiographic distribution of ligand binding was quantified by computer-assisted densitometry. One-way ANOVA noted a signif icant variance in the mean value of binding density between different age g roups only in neocortex laminae TV-VI for [H-3]PN200-110 binding (P < 0.05) . Post-hoc testings indicated that the mean value of the 17 month old group was significantly less than those of the 6 and 32 month old groups (P ( 0. 05). These results indicate no overall age-related change in the number of L-type and N-type Ca2+ channels in brain areas frequently involved in seizu re activity and suggest that age-related changes in brain Ca2+. physiology may be associated with changes in voltage-gated Ca2+ channel function rathe r than channel number. (C) 2001 Elsevier Science Inc, All rights reserved.