| Part1 The change and significance of hormone sensitive lipase in the islets of diabetes ratsObjectiveTo explore the roles of hormone sensitive lipase(HSL)in lipids metabolism of islet in type 2 diabetes by observing the change of HSL and triglyceride(TG) in the islets of diabetes rats.MethodDiabetes rats were induced by feeding the fat fat rich food and injecting the streptozotocin (25mg·kg-1). According to the result of blood glucose and insulin lever, the rats were divided into two groups: diabetes with high blood glucose group (DM) and diabetes with normal blood glucose group (DN),normal rats(NC) and rats fed with fat rich food(HF) were provided as controls. Body weight, blood glucose, plasma insulin, plasma lipids and TG in islet were measured. Islet Morph and insulin content used HE staining and SABC method were evaluated. The expression of HSL gene and protein was tested by RT-PCR and western blotting method. The free fatty acid released from islet was represented the activity of HSL.ResultThe blood glucose was no difference between HF group and NC group rats, but plasma insulin and plasma lipids in HF group rats were significant elevated compared with NC group(p <0.05或p<0.01). The blood glucose and plasma lipids in DM group rats were significantly increased(p <0.05或p<0.01). The plasma insulin in DM group rats was similar to that in NC group. In DN group, the blood glucose was retrieved, at the same time, plasma insulin was increased and plasma lipids were decreased.HE and SABC staining showed that the islet morph of HF group rats was regulation. Compared with NC group, expression of insulin of HF group rats was no change, but the islet volume of HF group rats was overtly increased. The islet morph of DM group rats was irregulation. The expression of insulin and the islet volume of DM group rats were markedly decreased(p<0.01). Compared with DM group,the islet morph of DN group rats was more irregulation, but the islet volume and expression of insulin of DN group rats were increased(p<0.05).Compared with NC group, TG in the islets of rat in HF group was significantly increased(p <0.05), TG accumulation in the islets of diabetes rats was more severity, approximately was as 2.15 times as that of NC group(p <0.01). Insulin treatment made islets TG content decreased, but it was still higher than that in NC group(p<0.01).At the same time, the expression of HSL in HF and DM group significantly increased(p<0.01), compared with NC group. Normalization of blood glucose made the expression of HSL fall(p <0.05),but still more than NC group. Compared with NC group, the activity of HSL in HF and DM group was markedly increased(p <0.05). Compared with DM group, the activity of HSL in DN group was decreased(p <0.05).ConclusionThe raise of glucose and lipases may be upregulated HSL in islet, so the expression and activity of HSL in the islets of diabetes rats increased, which could be a compensation mechanism to alleviate the TG content in islet and farther to keep the metabolism balance of glucose and lipids.Par2 The effects of intervention in vitro on hormone sensitive lipase in NIT-1 cellObjectiveTo observe the effects of glucose, palmitinic acid and insulin on hormone sensitive lipase in NIT-1 insulinoma cells in vitro, and to investigate the role of HSL in disorder of glucose and lipids metabolism ofβcell .MethodsNIT-1 cells were exposed to various concentrations of glucose(5 mmol/L,10 mmol/L,15mmol/L,20 mmol/L,25mmol/L,30mmol/L), palmitinic acid(0.125 mmol/L,0.25 mmol/L,0.5 mmol/L) and insulin(with or without 25ng/ml) for 24 hours, 48 hours, 72 hours. The content of triglyceride, the expression of HSL mRNA and protein, the activity of HSL were examined. Reverse transcription- polymerase chain reaction (RT-PCR) and western blot were applied in this study.ResultThe content of triglyceride in NIT-1 cells was increased in dose-and time-dependent manner, when they were cultured in different concentrations of glucose. It reached approximately 1.5-fold in 30mmol/L glucose after 72 hours, compared with in 5mmol/L glucose. Long-term exposure of NIT-1 cells to high concentrations glucose caused an inverse"v"-like induction of HSL expression. HSL expression firstly increased, and then decreased. The induction was paralleled at the level of enzyme activity, protein, and mRNA expression.Palmitinic acid intervention showed that the content of triglyceride in NIT-1 cells was slightly elevated following the increase of palmitinic acid concentration and the extension of intervention time. At the same time, palmitinic acid also promoted the expression of HSL mRNA and protein(p<0.05), but change of HSL activity was not significant(p>0.05).The content of triglyceride in NIT-1 cells with high glucose(25 mmol/L) and high palmitinic acid(0.25 mmol/L) was more than that in NIT-1 cells with 5mmol/L glucose,high glucose or high palmitinic acid(p<0.05). triglyceride accumulation was further aggravated with insulin(p<0.05). High glucose and high palmitinic acid induced the expression and activity of HSL(p<0.05), but the induction of high glucose and high palmitinic acid together was lower than that of high glucose or high palmitinic acid along(p<0.05). There was no significant effect of insulin on HSL expression and activity.ConclusionThe triglyceride accumulation in NIT-1 cells was aggravated in dose-and time-dependent manner within the glucose and palmitinic acid, while HSL was regulated bilaterally by high glucose and high palmitinic acid. So HSL plays a critical role in the regulation of intracellular triglyceride levels inβ-cells, and that downregulation of HSL might be part of the defense against glucose and FFA-induced islet dysfunction...
|
PDF Full Text Request