ObjectiveTo explore the protective effect of rapamycin on pancreatic damage in severe acute pancreatitis (SAP) and further to explain its protective mechanism.MethodsNinety selected SPF males SD rats were randomly divided into 3 groups: sham-operated group (SO group), SAP group, and rapamycin group (RAPA group), with 30 rats in each group. Then each group of rats were randomly divided into 3 subgroups of 24 h, 36 h, and 48 h, 10 rats in each subgroup. Rats in each group underwent laparotomy, the model was prepared by retrograde injection of solutions into biliopancreatic duct, rats of the SO group were injected with 0.9% normal saline, rats of the SAP group and RAPA group were injected with 5% sodium taurocholate solution, but rats of the RAPA group were injected with rapamycin at 30 min before the injection of 5% sodium taurocholate. All the survival rats in corresponding subgroup were killed at 24 h,36 h, and 48 h after operation respectively, then serum and pancreas tissues of rats were collected, serum inflammatory factors content of IL-1β, IL-6, and TNF-α were detected by ELISA method, expression levels of p-mTOR and p-S6K1 in pancreas were detected by Western blot, pancreas tissues were stained by Hematoxylin-Eosin Staining and pathological changes of pancreas were scored under light microscope.Results① At the timepoint of 24 h, 36 h, and 48 h, the order of the expression levels of p-mTOR and p-S6K1 in pancreatic tissues of 3 groups were all as follows: SO group<RAPA group<SAP group, there were significant difference among any 2 groups (P<0.05). ② IL-1β: at the timepoint of 48 h, the order of the content of IL-1β in 3 groups were as follows: SO group<RAPA group<SAP group, there were significant differences among any 2 groups (P<0.05); IL-6: at the timepoint of 36 h and 48 h, the order of the content of IL-6 in3 groups were as follows: SO group<RAPA group<SAP group, there were significant differences among any 2 groups (P<0.05); TNF-α: at the timepoint of 48 h, the order of the content of TNF-α in 3 groups was as follows: SO/RAPA group<SAP group (P<0.05), but there was no significant difference between the SO group and RAPA group (P>0.05). ③ Pancreatic histological score: at the timepoint of 24 h, 36 h, and 48 h, the order of the pancreatic histological score in3 groups was all as follows: SO group<RAPA group <SAP group, there were significant differences among any 2 groups (P<0.05). ④ The expression levels of p-mTOR and p-S6K1 in pancreatic tissue were positively correlated with the pathological scores of pancreatic tissue (r=0.97, P<0.01; r=0.89, P<0.01).ConclusionRapamycin can reduce the degree of pancreatic damage in SAP and has protective effect on pancreatic tissue.
Objective To explore the protective effect of rapamycin on brain tissues injury in severe acute pancreatitis (SAP) and its possible mechanism in experimental rats. Methods Ninety SPF males SD rats were randomly divided into 3 groups by random envelope opening method: sham operation group (SO group), SAP group, and rapamycin group (RAPA group), then the rats of each group were divided into 24 h, 36 h, and 48 h 3 subgroups by random number table method. Rats in each group underwent laparotomy, the model was prepared by retrograde injection of solutions into biliopancreatic duct, rat of the SO group was injected with 0.9% normal saline (2 mL/kg), rats of the SAP group and the RAPA group were injected with 5% sodium taurocholate solution (2 mL/kg), but rat of the RAPA group was injected with rapamycin (1 mg/kg) at 30 min before narcosis. All survival rats in each subgroup were killed at 24 h, 36 h, and 48 h respectively, then the pancreas and brain tissues of rats were collected, pancreas and brain tissues were stained by hematoxylin-eosin staining, brain tissues were stained by Luxol fast blue additionally, pathological changes of brain tissues were scored under light microscope. The protective effect of rapamycin on brain tissues injury was determined by comparing the differences in the degree of brain tissues among 3 groups. The phosphorylated mammaliantarget of rapamycin (p-mTOR) and phosphorylated ribosomal 40S small subunitS6 protein kinase (p-S6K1) expression levels in brain tissues were detected by Western blot. In addition, the correlations between the expression levels of p-mTOR and p-S6K1 in brain tissues and the degree of brain tissues injury were analyzed to further explore the possible mechanism of rapamycin’s protective effect on brain tissues injury in SAP. Results① At the point of 24 h, 36 h, and 48 h, the order of the relative expression levels of p-mTOR and p-S6K1 in brain tissues of three groups were all as follows: the SO group < the RAPA group < the SAP group (P<0.05). ② At the point of 24 h, 36 h, and 48 h, the order of brain histological score in three groups were all as follows: the SO group < the RAPA group < the SAP group (P<0.05). ③ The relative expression levels of p-mTOR and p-S6K1 in brain tissues were positively correlated with pathological scores of brain tissues (r=0.99, P<0.01; r=0.97, P<0.01). ConclusionRapamycin plays a protective role in pancreatic brain tissues injure by down-regulating the expression levels of p-mTOR and p-S6K1 in mTOR signaling pathway.
Objective To study value of severe acute pancreatitis (SAP) rat model induced by retrograde pancreaticobiliary duct infusion of methylene blue in combination with sodium taurocholate. Methods The SPF 90 SD rats, 45 male rats and 45 female rats of them, were randomly divided into control group (C group), sodium taurocholate group (ST group) and methylene blue in combination with sodium taurocholate group (MBST group), which were retrogradely infused with the 0.9% normal saline, sodium taurocholate plus DAPI, and methylene blue plus sodium taurocholate plus DAPI respectively into the pancreaticobiliary duct. The success rate of puncture, degree necrosis of pancreas tissue, range of pancreatic lesions, and the incidence of bile or intestinal leakage were compared among the three groups. Results ① The success rate of puncture in the MBST group was significantly higher than that in the ST group (P=0.003) and the C group (P=0.006), which had no significant difference between the ST group and the C group (P=0.782). ② The necrosis degree of pancreas tissues in the MBST group and ST group became more and more severe with the extension of time (P<0.050), which in the MBST group was more serious than that in the ST group (P<0.050). ③ The point of pancreatic lesions range in the MBST group was significantly higher than that in the ST group (P=0.003). ④ The incidence of bile or intestinal leakage in the MBST group was significantly lower than that in the C group (P=0.008) and the ST group (P=0.004). Conclusions Retrograde pancreaticobiliary duct infusion of methylene blue in combination with sodium taurocholate can improve success rate of puncture, aggravate necrosis degree of pancreatic tissue, increase lesion scope of pancreatic tissue, and reduce rate of bile or intestinal leakage, which can provide a stable animal model for basic research of SAP.