PURPOSE: The present study investigated the effects of oral treatment with M. pumilum var. alata (MPA) extracts on the estrogen receptor, metabolic characteristics and insulin signaling pathway in pancreas and liver of ovariectomised nicotidamide streptozotocin-induced diabetes in female rats.
MATERIALS AND METHODS: Ovariectomised diabetic (OVXS) Sprague-Dawley rats were orally administered with either aqueous leaf extract and ethanol (50%) stem-root extract of MPA (50 or 100 mg/kg) respectively for 28 days. Metabolic parameters were evaluated by measuring fasting blood glucose, serum insulin, oral glucose and insulin tolerance test. Distribution and expression level of insulin, oxidative stress and inflammatory marker in the pancreatic islets and liver were evaluated by immunohistochemistry and western blot, respectively.
RESULTS: Oral treatment with aqueous leaf and ethanol (50%) stem-root extracts of MPA (100 mg/kg) significantly reversed the elevated fasting blood glucose, impaired glucose and insulin tolerance. The protein expression of insulin, glucose transporter (GLUT-2 and GLUT-4) increased in the pancreatic islets and liver. Furthermore, marked improvement in the tissue morphology following treatment with MPA was observed. Similarly, the western blots analysis denotes improved insulin signaling in the liver and decreased reactive oxygen species producing enzymes, inflammatory and pro-apoptotic molecules with MPA treatment.
CONCLUSIONS: Taken together, this work demonstrate that 100 mg/kg of aqueous leaf extract and ethanol (50%) stem-root extract of MPA improves β-cell function and insulin signaling in postmenopausal diabetes through attenuation of oxidative stress and partially mediated by oestrogen receptor stimulation.
METHODS: Two parameters were measured (i) rate of glucose uptake by 3T3-L1 adipocyte cells in-vitro (ii) degree of pancreatic destruction in streptozotocin-nicotinamide induced male diabetic rats receiving M. pumilum aqueous extract (M.P) (250 and 500mg/kg/day) as reflected by levels of pancreatic oxidative stress, inflammation and apoptosis. In the meantime, phyto-chemical compounds in M.P were also identified by using LC-MS.
RESULTS: M.P was found able to enhance glucose uptake by 3T3-L1 adipocyte cells in-vitro while its administration to the male diabetic rats causes decreased in the fasting blood glucose (FBG), glycated haemoglobin (HbA1c), total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL) levels but causes increased in insulin and high-density lipoprotein (HDL) levels, to near normal. Levels of oxidative stress in the pancreas as reflected by levels of lipid peroxidation product (LPO) decreased while levels of anti-oxidantive enzymes (SOD, CAT and GPx) in pancreas increased. Additionally, levels of inflammation as reflected by NF-κB p65, Ikkβ and TNF-α levels decreased while apoptosis levels as reflected by caspase-9 and Bax levels decreased. Anti-apoptosis marker, Bcl-2 levels in pancreas increased.
CONCLUSIONS: The ability of M.P to enhance glucose uptake and reduces pancreatic complications could account for its beneficial effects in treating DM.
METHODS: Blood and pancreas were collected from adult male diabetic rats receiving 28days treatment with VVSAE orally. Fasting blood glucose (FBG), glycated hemoglobin (HbA1c), insulin and lipid profile levels and activity levels of anti-oxidative enzymes (superoxide dismutase-SOD, catalase-CAT and glutathione peroxidase-GPx) in the pancreas were determined by biochemical assays. Histopathological changes in the pancreas were examined under light microscopy and levels of insulin, glucose transporter (GLUT)-2, tumor necrosis factor (TNF)-α, Ikkβ and caspase-3 mRNA and protein were analyzed by real-time PCR (qPCR) and immunohistochemistry respectively. Radical scavenging activity of VVSAE was evaluated by in-vitro anti-oxidant assay while gas chromatography-mass spectrometry (GC-MS) was used to identify the major compounds in the extract.
RESULTS: GC-MS analyses indicated the presence of compounds that might exert anti-oxidative, anti-inflammatory and anti-apoptosis effects. Near normal FBG, HbAIc, lipid profile and serum insulin levels with lesser signs of pancreatic destruction were observed following administration of VVSAE to diabetic rats. Higher insulin, GLUT-2, SOD, CAT and GPx levels but lower TNF-α, Ikkβ and caspase-3 levels were also observed in the pancreas of VVSAE-treated diabetic rats (p<0.05 compared to non-treated diabetic rats). The extract possesses high in-vitro radical scavenging activities.
CONCLUSION: In conclusions, administration of VVSAE to diabetic rats could help to protect the pancreas against oxidative stress, inflammation and apoptosis-induced damage while preserving pancreatic function near normal in diabetes.