Abstract ▼ AI-Helper

In doing repeated screening for natural resources which were regarded to have the efficacy of reducing blood sugar, Opuntia ficus-indica was one of those which drew attention. One of its mixture complexes (OCC) was taken up for examining its effects on blood glucose level, plasma insulin level, gluc...

In doing repeated screening for natural resources which were regarded to have the efficacy of reducing blood sugar, Opuntia ficus-indica was one of those which drew attention. One of its mixture complexes (OCC) was taken up for examining its effects on blood glucose level, plasma insulin level, glucose tolerance, plasma triglyceride, plasma NEFA, plasma cholesterol, plasma GOT, plasma GPT, histopathological appearance of pancreatic islet in streptozotocin-induced diabetic rats, db/db mice and C57 mice. In the first experiment that was run for 3 weeks, 32 male Sprague-Daweley rats were assigned to non-diabetic control (NC), diabetic control (DC), diabetic OCC of 2% (OCC-2), diabetic OCC of 5% (OCC-5) groups. Diabetes was induced by intraperitoneal injection of streptozotocin. Weight gain and food efficiency ratio decreased with higher feed and water intake for all diabetic groups as compared to NC. OCC-2 and OCC-5 lowered fasting plasma glucose and insulin level and improved glucose tolerance. Plasma total cholesterol, triglyceride, NEFA, LDL-cholesterol and VLDL-cholesterol concentrations were also lower in OCC-2 and OCC-5 groups, although HDL- cholesterol level was little affected by experimental diets. Plasma GOT and GPT were lower in OCC-2 and OCC-5 groups. OCC-2 and OCC-5 groups also showed lower fecal excretion of bile acid. Histopathological observation of pancreatic islet for OCC-2 and OCC-5 groups showed hyperplasia which was very similar to NC. Increased number of β-cell was found in OCC-2 and OCC-5 groups. The mRNA expression of HMG-CoA (3-hydroxy-3- methylglutaryl-coenzyme A) reductase, LDL-receptor and CYP7A1 increased in OCC-2 and OCC-5 groups. In the second experiment that was conducted for 4 week period, 24 mice (db/db mice and C57 mice) were divided into OCC-treated group and untreated group. Body weight and total diet intake of OCC group were significantly lower than untreated group (p<0.05), whereas total water intake of OCC group significantly increased (p<0.05). Blood glucose level was lower for mice fed on OCC. Plasma insulin level and glucose tolerance for OCC-fed mice showed a similar trend to normal group. Plasma total cholesterol, triglyceride, LDL-cholesterol and VLDL-cholesterol concentrations became lower with OCC feeding, although HDL-cholesterol level was little affected by experimental diet. Plasma GOT and GPT showed lower activities in OCC group. Fecal excretion of bile acid was reduced in OCC group. Histopathological study of pancreatic islet for db-OCC group showed a similar hyperplasia observed normal group. Insulin-immunostaining of pancreatic islet showed an increased β-cell number while glucagon-immunostaining exhibited a decrease of α-cells. Ki-67-immunostaining of pancreatic islet also indicated a cell generation. LDL-receptor and CYP7A1 mRNA expression were increased in OCC group. However, HMG-CoA reductase mRNA expression was low in OCC group. Overall results of the conducted experiments supported clinical evidences for anti-diabetic effects of OCC. KEY WORDS: Opuntia ficus-indica, blood glucose, plasma insulin, glucose tolerance, plasma triglyceride, total cholesterol, HDL, LDL, VLDL, pancreatic islets, HMG-CoA reductase, LDL-receptor, CYP7A1