Dendritic hypertrophy in Purkinje neurons of old Fischer 344 rats after long-term ethanol treatment.

Metric parameters of Purkinje cell dendritic networks in 24- to 26-month-old Fischer 344 rats were determined after 48 weeks of chronic ethanol intake. Measurements included the total number and length of all segments/network, the total number and length of segments within topologically defined segment categories, and the mean length of segments in each category. A main effect of ethanol was expressed as a significant increase in cumulative length within one category of terminal segments. This increase was the result of a significant increase in mean length/segment in that category. Metric changes in other segment categories were not significant, showing that changes in the networks during ethanol treatment were not distributed randomly. Recovery after ethanol treatment was associated with further nonrandom remodeling of these networks. Significant differences in lengths of terminal segments were no longer present, but internal segments in networks of both pair-fed and ethanol-fed rats were significantly longer. Only one category of internal segments showed this change during recovery. The data showed that long term ethanol treatment in old rats, at a time when effects of aging processes were prominent in Purkinje cell networks, was associated with remodeling of those networks through dendritic extension. This effect was interpreted as compensatory growth in surviving networks following ethanol-related neuronal loss and/or damage to the surrounding neuropil. Recovery from dietary treatment produced further internal remodeling of those networks that was not related specifically to ethanol. It could be shown, however, that the restructuring processes that resulted in longer internal segments after dietary recovery were different in the pair-fed and the ethanolfed rats.