Age-related decline in multiple unit action potentials of cerebral cortex correlates with the number of lipofuscin-containing neurons.

The present study examined whether there is any obvious correlation between the density of lipofuscin-containing neurons and the spontaneous neuronal action potentials (Multiple Unit Activity, MUA) in the parietal cortex of the aging rat brain. The results showed that MUA counts were decreased with age while the number of lipofuscin-containing neurons was increased. The cortex with the highest percentage of lipofuscin-containing neurons had the lowest MUA counts while the cortex with the lowest percentage of lipofuscin-containing neurons had the highest MUA counts. The inverse correlation between MUA and lipofuscin-containing neuron number was also evident when the population of the lipofuscin-containing neurons was pharmacologically altered in vivo by the administration of anti-lipofuscin drug centrophenoxine. The inverse relationship between MUA and the lipofuscin-containing neuron numbers is consistent with: (i) the correlations of MUA with age-related changes in lipid peroxidation and biochemically measured lipofuscin concentration, and (ii) the oxidative stress-induced impairments of neuronal electrophysiology.