| ObjectiveThrough pancreatic duct ligation in mice, resulted in the barrier of partial drainage of pancreatic juice, and finally formed the performance of pancreatitis. Then we observed the sequential changes on body weight and blood sugar, as well as the changes of exocrine and endocrine cells in cell morphology and function. In order to further research the mouse endocrine cells, especially P-cell function, we used stimulus on islet to study theβ-cell regeneration.MethodsWe took male 8-week-old C57BL/6 mice as the experimental subjects, and 48 mice were randomly divided into the pancreatic duct ligation group and the sham operation group, and post-operation 1d,2d,3d,5d,7d, 10d,2w,4w,8w, samples were collected in both two groups to be observed and compared the general view of changes in pancreatic endocrine and exocrine cells as well as histopathological changes, especially the biological characteristics ofβcells, furthermore a series of special antibody's immunohistochemical staining undergoing sequentially. In addition, the mice, which was staying 8 weeks after the surgery of pancreatic duct ligation, were dealt with continuous low-dose streptozocin (STZ) intraperitoneal injection, by which chemical destruction of the P cells, and then the blood glucose increasing slightly were detected, but lower than the diabetes standard, meanwhile feeding with nucleotide analogues (BrdU) in drinking water for marking the proliferative cells, and finally the specimens were stained by corresponding antibody and then we observed the status of P-cell proliferation. All images were managed by image analysis software, Image Pro Plus 6.0, and the results were expressed as mean±SD. Besides, we use statistical software SPSS 15.0, to analyze the data in each group, P<0.05 considered as statistically significant.ResultsMouse pancreas can be divided into three parts:stomach pancreas (stomach lobule), duodenum pancreas (duodenal lobule), and spleen pancreas (splenic lobule). In duct ligation group, the mice weigh 22.5±0.5g before surgery; 1 day postoperation, the body weight drop to the minimum value,20.0±0.7g; but from then on, the body weight gradually increased, recovered after 10 days postoperation,22.3±1.1g, with the similar level of preoperative body weight; they weighing 26.4±0.6g till sacrifice. The sham operation group had a similar trend, but the value of each stage was significantly higher than that in operation group (p<0.05). The level of blood glucose in both groups had no significant difference and there was also no obvious changes before and after surgery (p>0.05). Histopathological changes in exocrine gland tissues:Day 1:pancreatic interstitial edema, expansion of interlobular pancreatic duct and acinar spaces; Day 5: more severe expansion of the pancreatic duct and the acinar cavity, connective tissue and present; Day 7:exocrine gland atrophy apparently, the number of acinar cells decreased, and acinar lumen extremely expansion; Day 28:the volume of pancreas further shrink, exocrine tissue disappear, and replaced by adipose tissue and duct-like structure; Day 56:pancreatic volume increasing, but fatty tissue and fibrous connective tissue replacement, which were around the islet and the main pancreatic duct. However, endocrine tissue had no significant morphological changes pathologically in each stage, and ICAM, Ki67, BrdU, BrdU and insulin double-labeled showed the evidence of p cell proliferation which only occurred in the pancreatic duct ligation group.ConclusionFollowing pancreatic duct ligation, exocrine tissues shrank, even disappeared completely, and finally were replaced by fatty tissue, but the endocrine islet had no morphological changes. Through stimulating, the proliferative ability ofβcell who were subjected to long-term pancreatic duct ligation had been enhanced relatively.
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