Age-induced changes in the enteric nervous system in the mouse

The enteric nervous system of the murine gut was investigated by immunocytochemistry in 1-, 3-, 12- and 24-month-old mice, using protein gene product 9.5, a general marker for nerve elements. Myenteric and submucosal plexi were quantified by computerized image analysis. In antrum, there were significantly fewer neurones per ganglion in both myenteric and submucosal ganglia of 12- and 24-month-old mice than in 3-month-old animals. The same was true of duodenum and colon. The relative volume density of nerve fibres in antral muscularis propria was significantly greater in the 1-, 12- and 24-month-old mice than in the 3-month-old mice. In colon, there were fewer submucosal ganglia per millimetre baseline in 1-month-old mice than in 3-month-old mice. The colonic myenteric ganglion in 1-, 12- and 24-month-old mice was smaller than in 3-month-old mice. There was no statistical difference between females and males regarding the number of ganglia per millimetre baseline, ganglionic area, number of neurones per ganglion or the relative volume density of nerve fibres in either the myenteric or submucosal plexi. As the enteric nervous system is responsible for coordinating and integrating the motility of the gut, the ageing-related changes reported here may well be of some relevance for the increased gastrointestinal motility dysfunction in the elderly persons.