The Effect of Aging on the Structure of the Colon of Rat with Reference to Interstitial Cells of Cajal

Abstract Introduction Aging process is a driving force behind the age associated diseases. The gastrointestinal tract (GIT), including the colon, is affected by the aging process. Constipation, fecal incontinence, and fecal impaction are common complaints of geriatric patients, probably reflecting colonic dysmotility. Interstitial cells of Cajal might be involved in this process, however, there is little known about changes in these cells and gastrointestinal tract with aging. Aim The objective of this work was to study the effect of aging on the structure of the colon of male albino rats. Age associated changes of the Interstitial Cells of Cajal (ICC) was also investigated. Materials and Methods Thirty male albino rats were equally divided into three groups: Group I (young): included rats aged six weeks. Group II (adult): included rats aged 16 weeks. Group III (senile): included rats aged two years. The specimens from the colon (one cm above the ileo- ceacal valve) of all rats were obtained and processed for light and electron microscopic examinations. Specimens were subjected to hematoxylin and eosin, toluidine blue, Alcian blue-PAS technique, Masson’s trichome, c-kit, and CD 34 immunohistochemical stain as well as transmission electron microscopic examination. Morphometric and statistical studies were also done. Results Aging altered the microscopic structure of the different layers of the colon. Focal mucosal corrugation or disruption, epithelial discontinuity, mononuclear cellular infiltration and alteration in the mucous content of goblet cells were found in aged rats. Increased collagen deposition in all colonic layers was also observed. Significant decrease of Nissls’ granules in the neurons of myenteric plexus and the number of goblet cells were also detected. Colonocytes of senile rats showed focal loss of microvilli, vacuolated cytoplasm, swollen mitochondria with irregular cristea and irregular nuclei. Change in nuclear shape and chromatin distribution, mitochondrial swelling and endoplasmic reticulum dilatation were also detected in ICCs in senile rats. Moreover, there was a significant decrease in area percentage of ICCs and telocytes (Tcs). Conclusions Aging caused profound alteration in the histological structure of the colon of senile rats. Moreover, ICC showed age related ultrastructural changes. These changes might contribute to age associated gastrointestinal diseases.