Protective Effects Of Baicalin On Severe Acute Pancreatitis

Background:Acute pancreatitis is a common disease with great variability in severity, whose manifestation is mostly characterized with conflagration abdominal pain and increased serum amylase. Patients with mild acute pancreatitis can be fully recovered by fasting, fluid replacement and other measures. Whereas about >20% acute pancreatitis is severe acute pancreatitis (SAP), which mortality rate can reach up to 30%-50%. The pathogenetic condition of SAP is very complicated and aggravates quickly. During the past few years,along with people's living habit changing—excessive drinking, binge overeating and gradually increasing biliary tract diseases, the incidence of SAP has increased year by year. Since the cause and pathogenesis of SAP has still not been fully understood, there are no specific measures for SAP. Once SAP progressed to acute inflammation reaction stage, the progress could not be interrupted. So the research about acute pancreatitis's pathogenesis and therapeutic measures is still a hot spot. It has been proved that mediators of inflammation interacting with each other can result in system inflammatory response syndrome(SIRS)and cause multiple organ failure (MOF), which is the most common death causes for patients with SAP. Therefore, mediators of inflammation take important part in the development of SAP. The effect of oxidative stress is important in organ injury and SIRS. Mass oxygen radicals can participate in the progress of lipid peroxidation, formation of nitrotyrosine and DNA injury, which will modulate inflammatory response ultimately. Therefore, inhibition of oxidative stress and inflammatory response will limit the development of SAP.Chaiqinchengqitang and Qingyitang, which are representative prescription of traditional Chinese medicine for the treatment of acute pancreatitis. Extensive clinical practice has also shown its sound therapeutic effects on acute pancreatitis. Scutellaria baicalensis georgi is the main material in Qingyitang. As one of the effective ingredients in Scutellaria baicalensis georgi (Labiatae) and a glucur, Baicalin, could take protective effects on the development of SAP. However, the protective mechanism has not been fully understood. Therefore, in present study, we investigated the change of oxidative stress and inflammatory response in acute pancreatitis and their roles in the development of acute pancreatitis. Then we investigated the antioxidative and antiinflammatory effects of Baicalin in acute pancreatitis.Aims:To investigate the changes of oxidative stress and inflammatory response in the development of rat SAP model induced by retrograde injection 3.5% sodium taurocholate; and to investigate the protective effects and mechanisms of Baicalin on pancreatic injury of rats with SAP.Methods:The improved Aho method was adopted to prepare SAP rat models via retrograde injection of 3.5% sodium taurocholate to the pancreatic duct. Fourty five SD rats were randomly assigned to the model group, Baicalin-treated group and sham operation group, 15 rats for each group. Rats in sham operation group only received abdomen opening surgery. The three groups were then randomly divided into 3 h, 6 h and 12 h groups with 5 rats in each group, 10 min after successful modeling, the Baicalin-treated group was first injected with 5% Baicalin injection at a dose of 10 mg/100 g via femoral vein passage followed by continuous intravenous administration (10 mg/h/100 g) by microinfusion pump. The sham operation group and model group were injected with saline of equivalent volume at the corresponding time points after operation. The following observations were carried out 3h, 6h and 12 h after operation: (1) the pancreatic pathological changes according to the relevant requirements after HE staining; (2) serum content of amylase and lipase; (3)pancreatic content of malonaldehyde (MDA), IL-6 and tumor necrosis factor alpha (TNF-α);(4) SOD activity; (5)staining for PAR and nitrotyrosine, (6) upregulation/formation of ICAM-1, (7) neutrophil infiltration, (8) expression of TGF-β.Results:1) Retrograde injection of 35 g/L sodium taurocholate in rats resulted in SAP characterized by oedema, mass neutrophil infiltration, erythrocytes exudation, necrosis and elevated serum amylase and lipase level. The pancreatic injury aggravated with time after adminstration of sodium taurocholate. In the model group,the pancreatic structure was obviously damaged with definite acinus edema, mass neutrophilic infiltration and a little erythrocytes exudation at 3 h; and the intensive necrosis and bleeding was found in pancreatic tissue at 6 h. Cmpared with rats in sham operation group,rats in the model group had significant increased amylase and lipase serum levels and pancreatic tissue MDA, TNF-αand IL-6 contents(p<0.01);and a significant decreased activity of SOD (P<0.01). Immunohisto-chemisty staining for nitrotyrosine, PAR, ICAM-1, TGF-βwas positive in pancreatic tissue of the model group. However, there was negative staining in pancreatic tissue of the sham operation group.2) In Baicalin-treated group,pancreatic tissue structure was intact with slightly edema and a little neutrophilic infiltration,but no obvious bleeding and necrosis. Compared with model group,the pathological change of pancreatic tissue was obviously improved and the serum amylase and lipase levels were significantly decreased (at 3 h, 6h and 12h) (P<0.01).3) At all time pionts, the pancreatic tissue MDA content of Baicalin-treated group was lower than that in the model group (P<0.01); and the SOD activity of Baicalin-treated group was higher than that in the model group (P<0.05). Compared with model group, immunohistochemisty staining of nitrotyrosine and PAR in pancreatic tissue markedly reduced in Baicalin-treated group.4) Compared with model group,the contents of tissue TNF-αand IL-6 were significantly decreased in Baicalin treated group at all time pionts (P<0.05). Compared with model group, immunohistochemisty staining of ICAM-1 and TGF-βmarkedly reduced in pancreatic tissue of Baicalin-treated group.Conclusion:In the present study, we confirmed the change of oxidase stress and inflammatory response in pancreatic tissue of rat with acute pancreatitis induced by sodium taurocholate;and the protective effects of Baicalin on the development of acute pancreatitis. We found Baicalin can take protective effects by markedly reducing the 1) pancreatic inflammation and tissue injury (histological score), 2) lipid peroxidation, 3) formation of PAR and nitrotyrosine, 4) upregulation/ formation of ICAM-1, 5) neutrophil infiltration, 6) production of proinflammatory cytokines TNF-αand IL-6 and 7) expression of TGF-β, and increasing SOD activity. The present study provides a better insight into the molecular biology of protective effects of Baicalin on acute pancreatitis. The antiinflammatory, antioxidative and lipidperoxidation preventive effects of Baicalin participate in the protective effects in the development of acute pancreatitis coordinately.