Age-related changes in the nadph-diaphorase-positive dendrites in the dorsolateral neuronal column of the periaqueductal gray in rat

The effects of age on the dendritic tree of reduced nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d)-positive neurons in the dorsolateral neuronal column of the periaqueductal gray (DLPAG) in the rat were examined, using NADPH-d histochemistry and computer-assisted analysis. In 26-month-old rats some of the neurons exhibited considerably branched dendrites, while others show amputation stumps, or local swellings in the initial dendritic portion. Quantitative analysis demonstrated that the number of dendritic segments in DLPAG increased with advancing age. The mean segment length and the mean length of the terminal segment significantly increased in 12-month-old rats compared to 3-month-old rats and decreased in 26-month-old rats in comparison to 12-month-old, as the reduction was significant for the terminal segments only. The total dendritic length of NADPH-d-stained neurons increased with aging. The increase was more pronounced in 12-month-old rats compared to 3-month-old rats and the difference was significant in 26-month-old rats. The number of the nodal vertices, Va and Vb, significantly increased between 12- and 26-month of age. The dendritic reorganization was considered a sign of compensatory mechanism counteracting the degenerative changes.