Remodeling of neuronal dendritic networks with aging and alcohol.

Chronic ethanol treatment and aging processes produce significant changes in neuronal dendritic morphometry, but the precise patterns of change are different for these two factors. Furthermore, the morphometric effects of long term ethanol treatment on neuronal structure may be expressed in different ways at different times during the life span. When rats were treated with ethanol chronically from 12 months of age for 24 or 48 weeks, the predominant morphometric change in surviving cerebellar Purkinje neurons was a nonrandom elongation of terminal segments in the dendritic arbors. The results suggested that the synaptic circuitry in the cerebellar cortex of these rats was altered in an ethanol-specific and nonrandom pattern by selective compensatory growth of a particular category of terminal segments. During normal aging between 12 and 18 months, Purkinje cell networks in rats underwent regression of terminal dendritic segments, but after 18 months localized regrowth of proximal terminal dendritic segments coincided with regression of distal terminal segments, a pattern of dendritic change that was markedly different from that induced by ethanol.