Age-associated histological changes of gastric fundal mucosa and ultrastructure of gastric chief cells in human and Beagle dogs

Abstract

Objective To investigate the effect of aging on gastric pepsinogen secretion through observing histological changes of gastric fundal mucosa and ultrastructure of gastric chief cells in human and Beagle dogs at different ages. Methods Fifty middle-aged and elderly indigestion patients with gastroscopy were selected as study objects and divided into young and middle age group (age 20-59 years, n=19), junior elderly group (age 60-69 years, n=11), middle elderly group (age 70-79 years, n=10), and senior elderly group (no less than 80 years, n=10). In addition, nineteen healthy Beagle dogs were also selected as study objects and divided into young and middle age group (age between 1 to 5 years, n=8), junior elderly group (age six to eight years, n=5), and senior elderly group (no less than 9 years, n=6). The histology and morphology of gastric fundal mucosa of human and Beagle dogs were observed under light microscope. Then the thickness of lamina propria was measured and the number of gastric chief cells was counted. The ultrastructure of gastric chief cells was observed under electron microscope, and the area percentages of secretory granule(also called mucous granule)area in cytoplasm of chief cell was calculated.The data was analyzed by one-way analysis of variance. Results No significant histological and morphological changes of gastric fundal mucosa were observed in human and Beagle dogs at different ages.There was no significant difference in the thickness of lamina propria among different ages in human and Beagle dogs (all P>0.05). The number of human chief cells of young and middle age group, junior elderly group, middle elderly group and senior elderly group was 71.79±16.85, 52.73±16.60, 57.10±20.21 and 43.70±16.89/high power field (HPF), respectively, which decreased as age increased (F=6.431, P=0.001). The numbers of chief cells of young and middle age group, junior elderly group, and senior elderly group of Beagle dogs were 328.38±32.36, 341.20±42.49 and 225.67±52.19/HPF, respectively, which decreased as age increased (F=13.647, P<0.01). Aging-related degeneration was founded in ultrastructure of gastric chief cells in human and Beagle dogs including rough endoplasmic reticulum dilation, ribosomes missing, secretory granule decreasing and so on. The area percentages of secretory granule area in cytoplasm of human chief cells of young and middle age group, junior elderly group, middle elderly group and senior elderly group were (67.28±3.79)%, (66.88±4.84)%, (65.63±7.10)% and (56.25±8.47)%, respectively, which decreased as age increased (F=6.069, P=0.002). The area percentages of secretory granule area in cytoplasm of Beagle dogs′ chief cells of young and middle age group, junior elderly group, and senior elderly group were (58.83±3.07)%, (52.34±4.73)% and (39.89±4.46)%, respectively, which decreased as age increased (F=38.837, P<0.01). Conclusion As age increased, the ability of pepsinogen secretion of fundal gland decreased, which may be one of the reasons of functional dyspepsia in the eldly. Key words: Chief cells, gastric; Ultrastructure; Aging; Pepsinogens; Beagle dog