| Objective: To investigate the effects of different dosage of streptozotocin (STZ) on SD rats'blood glucose level and blood glucose stability in order to find out the best dosage of model establishment. By building Type 2 Diabetes Mellitus (T2DM) rats model, this research aims to explore the role of Liver X receptor (LXR ) in the pathological mechanism of T2DM and to observe the intervention effects of different dosage of Marine Collagen Peptide (MCP) in T2DM model establishment and influence on the expression of LXR . Materials and Methods: After one week of acclimation, 10 of the 40 six-week-old SPF male SD rats were randomly selected as normal group (NG) and given basic feed ,other 30 rats were fed with hypercholesterol foods for one month and then randomized into three groups and intraperitoneally injected with small dosage of STZ: Group A: 30mg/kg (10 rats), Group B: 40mg/kg (10 rats), Group C: 50mg/kg (10 rats). Their blood glucose level and blood glucose stability were recorded to see if they are suitable to build models and record success rate and survival rate. Another 40 six-week-old SPF male SD rats were acclimated for a week and 10 of them were randomly selected as normal group (NG) and given basic feed. Other 30 rats were fed with hypercholesterol foods for one month and intraperitoneally injected with STZ to build T2DM SD rats model. Theses 30 rats were then randomized into three groups: T2DM Group (DM), Marine Collagen Peptide Low Dose group (LM) and Marine Collagen Peptide High Dose group (HM). While continued to be fed with hypercholesterol foods, LM and HM were intragastrically administered different dosage (1.5g/kg?d,3.0g/kg?d) of MCP for one month; DM were lavaged with distilled water. No food but only water was given for 12 hours.All rats were anesthetized with an intraperitoneal injection of 10% Chloral Hydrate, collected blood from abdominal aortic, resected the livers. Pathological changes were observed by HE staining. Immunohistochemical method was used to detect the expression of LXR protein in liver tissue. Results: Group B: SD rats injected with STZ 40mg/kg show the best blood glucose stability and highest success rate and survival rate. Compare blood glucose level and weight of HM before and after intervention(P<0.05).Hepatocytes of NG maintain normal biological characteristics without steatosis and are closely arranged; most hepatic cells in the livers of rats in T2DM express fat denaturation. A few hepatic cells in livers of rats in LM and HM express fat denaturation, better than that in T2DM and there is no distinctive difference between LM and HM. Immunohistochemistry: LXR expresses in every group. Only a few tan particles appearing in the liver tissue of rats in Normal Group; there is significant decrease of tan particle in T2DM; LM and HM have more tan particles compared with T2DM, particularly around hepatic sinusoid and in portal areas. Conclusion:1. Hypercholesterol diet and intraperitoneal injection of small dosage of STZ can successfully build Type 2 Diabetes Mellitus rats model. Group B: SD rats injected with 40mg/kg of STZ have the best blood glucose stability and highest success rate and survival rate. 2.In DM group, glucose increased significantly,most hepatic cells express fat denaturation,the expression of LXR are obviously less than that in the normal group, prompting LXR plays a certain regulatory role in type 2 diabetes glucolipid metabolism.3. High dosage (3.0g/ kg?d) of MCP can lower the blood glucose level of T2DM rats, recover weights and improve the situation of hepatocytes steatosis in model group to some degree, its intervention may express LXR to adjust the liver glucolipid metabolism, improve insulin resistance related. |
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