大鼠胰腺组织学及超微结构的增龄改变研究

Age-related changes in pancreatic histology and ultrastructure in rats

目的探讨Sprague-Dawley(SD)大鼠胰腺组织结构及超微结构的增龄改变,为阐明老年胰腺相关疾病高发提供理论依据。方法SPF级雄性6月龄SD大鼠30只,在大鼠饲养至6月龄、12月龄、18月龄和25月龄时,随机选取5只处死、取材,制作组织学(HE染色)和电镜切片,对比观察胰腺组织学和超微结构的增龄变化。结果大鼠胰腺组织随月龄增加出现纤维化,并以导管周围为著,胰腺组织脂肪浸润随月龄增加逐渐加剧(H=15.88,P=0.001);随月龄增加,胰岛的数量(密度)逐渐减少(F=3.55,P=0.039),但胰岛的平均截面积逐渐增大(F=7.76,P=0.002),其形态由类圆形、类椭圆形逐渐变得不规则。随月龄增加,大鼠胰腺腺泡细胞和胰岛β细胞胞质内均出现细胞核固缩,线粒体脱水、肿胀,粗面内质网扩张且排列松散等改变;随月龄增加,大鼠胰腺腺泡细胞顶部酶原颗粒数量逐渐减少(F=9.73,P<0.001),酶原颗粒数平均面积和总面积显著降低(F=6.51,P=0.001;F=22.18,P<0.001);腺泡细胞胞质内非衰老线粒体及衰老线粒体数量均增加(H=8.22,P=0.045;H=32.95,P<0.001);胰岛β细胞内胰岛素原数量降低(F=16.20,P<0.001)。结论随月龄增加,SD大鼠胰腺出现了一系列退化表现(间质增生、脂肪组织浸润、腺泡细胞内的酶原颗粒数量减少而衰老线粒体数量增加、胰岛数量和胰岛β细胞内胰岛素原数量减少等),同时也存在一些代偿现象(胰岛增大、非衰老线粒体数量增加等)。

Objective To investigate age-related histological and ultrastructural changes of the pancreas in Sprague-Dawley(SD)rats,and to provide a theoretical basis for the high incidence of pancreatic diseases in the elderly.Methods Thirty 6-month-old specific pathogen-free male SD rats were fed until 6,12,18 and 25 months of age.Five rats of each age group were randomly selected,killed and then sampled to make histological(HE staining)and electron microscopic sections to observe age-related changes in pancreatic histology and ultrastructure.Results The pancreatic tissue of rats showed increasing fibrosis with age,especially around the duct.Fat infiltration of the pancreatic tissue also increased with age(H=15.88,P=0.001).With the increase of age,the number(density)of pancreatic islets decreased gradually(F=3.55,P=0.039),but the average cross-sectional area of islets increased significantly(F=7.76,P=0.002),and the round and oval islets became irregular.Nuclear pyknosis,mitochondrial dehydration,mitochondrial swelling,and dilatation and loose organization of rough endoplasmic reticula were observed in the cytoplasm of pancreatic acinar cells and islet beat cells in aged rats.With the increase of age,the number of zymogen granules at the apical pole of pancreatic acinar cells of rats decreased(F=9.73,P<0.001),and the average area and total area of granules were significantly decreased(F=6.51,P=0.001;F=22.18,P<0.001);The number of non-senescent mitochondria and senescent mitochondria in the cytoplasm of acinar cells increased significantly(H=8.22,P=0.045;H=32.95,P<0.001);The amount of proinsulin in islet beta cells was significantly decreased(F=16.20,P<0.001).Conclusions With aging,the rat pancreas exhibits a series of degenerative manifestations(stromal hyperplasia,adipose tissue infiltration,decreased numbers of zymogen granules in acinar cells,increases in the number of senescent mitochondria,reduced islets and reduced proinsulin in islet beta cells),while there are some compensatory phenomena(increasing numbers of islets and non-senescent mitochondria).