Effect of Ageing on Colonic Endocrine Cell Population in Mouse

Background: Dysmotility in the gastrointestinal tract increases with age. Colonic endocrine cells play an important role in regulating intestinal secretion and motility. The objective was to study possible age-related changes in the colonic endocrine cells of an animal model. Methods: The colonic endocrine cells in four different age groups of mice were investigated by immunocytochemistry and quantified by computerized image analysis. The ages of these groups were 1, 3, 12 and 24 months old. Results: The numbers of peptide YY (PYY), enteroglucagon and serotonin immunoreactive (IR) cells in 1-month-old mice were significantly increased compared with those of 3-month-old mice. Similarly, the numbers of these cells were significantly greater in 12- and 24-month-old mice than in 3-month-old mice. The cell secretory index (CSI) of enteroglucagon and serotonin IR cells was higher in 1-, 12- and 24-month-old mice than in 3-month-old mice. There was no significant difference between the different age groups regarding the CSI of PYY IR cells, nor was there any statistical difference between females and males in all endocrine cell types regarding numbers and CSI. Conclusion: It is suggested that the increase in colonic endocrine cells prior to puberty might reflect the role of gut hormones in the development of the gastrointestinal tract. It is speculated further that the increase in colonic endocrine cells with ageing may compensate for increased receptor resistance and/or weakened response of effector organs. It is suggested that the increase in numbers and unchanged CSI of PYY cells with advancing age may be responsible for the slow colonic transit and constipation, both of which increase with age.