比格犬胃底腺组织学和超微结构的增龄变化

Effect of Aging on Histology and Ultrastructure of Gastric Fundic Gland in Beagle Dogs

背景：研究发现老年人胃底腺泌酸功能相关结构无明显退化表现,但人体标本易受环境因素影响,因此需采用标准动物以尽量减少环境因素的影响,对该结果作进一步验证。目的：研究比格犬胃底黏膜组织学和胃底腺超微结构的增龄变化。方法：19只健康比格犬分为中青年组（1~5岁,n=8）、低龄老年组（6~8岁,n=5）和高龄老年组（≥9岁,n=6）,取胃底组织标本,光镜下观察胃底黏膜,测定固有膜厚度、胃底腺体实质占固有膜面积的比率,计数壁细胞、主细胞和内分泌细胞;电镜下观察胃底腺细胞超微结构,测定相关细胞器面积分数。结果：比格犬胃底固有膜厚度随增龄呈降低趋势,但各年龄组间差异无统计学意义（P〉0.05）,高龄老年组腺体密度明显降低,间质明显增加。三组间壁细胞数及其线粒体和微管泡系统面积分数无明显差异（P〉0.05）,高龄老年组主细胞数及其酶原颗粒面积分数、颈黏液细胞黏原颗粒面积分数显著减少（P〈0.05）,内分泌细胞数随增龄逐渐增多（P〈0.05）。结论：比格犬胃底黏膜与泌酸功能有关的壁细胞及其相应细胞器无明显增龄相关退化表现,分泌组胺、胃泌素、生长抑素等以刺激胃酸分泌的内分泌细胞数量明显增多,这可能是老年胃维持良好泌酸功能的代偿机制。

Background： It has been demonstrated that acid secretion-related gastric fundic structures do not degenerate in elderly individuals. As specimens obtained from human body are greatly influenced by environmental factors,the results need to be further verified by standard animals. Aims： To investigate the aging-related changes of histology of gastric fundus and ultrastructure of fundic gland in beagle dogs. Methods： Nineteen healthy beagle dogs were divided into three age groups,8 in younger group（ aged 1-5 years）,5 in junior elderly group（ aged 6-8 years） and 6 in senior elderly group（ aged ≥9 years）. Gastric specimens obtained from the fundus were examined by light microscope,the thickness of lamina propria and percentage of parenchymal area of fundic gland in lamina propria were measured,and the parietal cells,chief cells and endocrine cells were counted. Ultrastructure of fundic gland cells were observed by electron microscopy,and the area percentages of related organelles were calculated. Results： The thickness of lamina propria in gastric fundus of beagle dogs showed a decline tendency with aging,but no significant differences were found among the three age groups（ P〈0. 05）; in senior elderly group,a marked decrease in density of fundic gland was observed and with an increase of interstitial tissues. The amount of parietal cells and the area percentages of mitochondria and tubulovesicle in parietal cells showed no aging-related reduction（ P〈0. 05）,while the amount of chief cells,area percentages of zymogen granule in chief cells,and mucous granule in mucous neck cells were significantly decreased in senior elderly group（ P〈0. 05）. The amount of endocrine cells increased gradually with aging（ P〈0. 05）. Conclusions： Aging-related degeneration is not existed in acid secretion-related parietal cells and organelles in gastric fundus of beagle dogs. Furthermore,endocrine cells which secret histamine,gastrin,and somatostatin,etc. for stimulating acid secretion even increased. These changes might be a compensatory mechanism for acid secretion in elderly individuals.