AGE-RELATED-CHANGES IN THE MORPHOLOGY OF PREGANGLIONIC NEURONS PROJECTING TO THE RAT HYPOGASTRIC GANGLION

The aim of this study was to investigate age-related changes in pregan glionic neurons of the lumbar and sacral spinal cord of the male rat t hat may underlie impaired control of the urogenital system in old age. Preganglionic sympathetic and parasympathetic neurons of 4- and 24-mo nth-old rats were identified by retrograde axonal tracing with cholera toxin subunit-B followed by immunocytochemistry Labelled preganglioni c neurons were scanned on the confocal microscope. Measurements were m ade of soma area, number of primary dendrites, number of dendritic bra nch points and total dendritic length. There were significant decrease s in the number of dendritic branch points and total dendritic length of sympathetic preganglionic neurons in the aged rats compared to the adult group. The soma area and number of primary dendrites were not si gnificantly different. Some cells exhibited signs of degeneration, suc h as swelling of the soma and distension of the proximal part of prima ry dendrites. No significant differences were found in any of the para meters measured for the parasympathetic neurons. The changes in dendri tic morphology of sympathetic preganglionic neurons may reflect altere d central and peripheral control of pelvic viscera in old age.