OBJECTIVE: The objective of this study was to determine the effects of T3 derivatives, σ-T3, γ-T3 and α-T3 on insulin secretion of rat pancreatic islets in a dynamic culture.
METHOD: Pancreatic islets isolated from male Wistar rats were treated with T3 for 1 h at 37°C in a microfluidic system with continuous operation that provided a stable cell culture environment. Glucose (2.8 mM and 16.7 mM, as basal and stimulant, respectively) and potassium chloride (KCl) (30 mM) were added to the treatment in calcium free medium. The supernatant was collected for insulin measurements.
RESULTS: Short-term exposure (1 h) of σ-T3 to β cells in the stimulant glucose condition significantly potentiated insulin secretion in a dose-dependent manner. γ-T3 and α-T3 also displayed dosedependent effect but were less effective in the activation of insulin secretion. Essentially, KCl, a pancreatic β cell membrane depolarizing agent, added into the treatment further enhanced the insulin secretion of σ-T3, γ-T3 and α-T3 with ED50 values of 504, 511 and 588 µM, respectively.
CONCLUSION: The findings suggest the potential of σ-T3 in regulating glucose-stimulated insulin secretion (GSIS) in response to the intracellular calcium especially in the presence of KCl.
METHODS: SLBH at 1 and 2g/kg/b.w. was given orally to streptozotocin (STZ)-nicotinamide-induced male diabetic rats for 28days. Metabolic parameters (fasting blood glucose-FBG and lipid profiles-LP and serum insulin) were measured by biochemical assays. Distribution and expression level of insulin, oxidative stress marker i.e. catalase, inflammatory markers i.e. IKK-β, TNF-α, IL-1β and apoptosis marker i.e. caspase-9 in the pancreatic islets were identified and quantified respectively by immunohistochemistry. Levels of NF-κβ in pancreas were determined by enzyme-linked immunoassay (ELISA).
RESULTS: SLBH administration to diabetic male rats prevented increase in FBG, total cholesterols (TC), triglyceride (TG) and low density lipoprotein (LDL) levels. However, high density lipoprotein (HDL) and serum insulin levels in diabetic rats receiving SLBH increased. Additionally, histopathological changes and expression level of oxidative stress, inflammation and apoptosis markers in pancreatic islets of diabetic rats decreased with increased expression level of insulin in the islets. LC-MS analysis revealed the presence of several compounds in SLBH that might be responsible for these effects.
CONCLUSIONS: SLBH has great potential to be used as agent to protect the pancreas against damage and dysfunction where these could account for its anti-diabetic properties.
MATERIALS AND METHODS: Purified islets were treated with serum-free, serum, IBMX, tocopherol, or IBMX and tocopherol media. Quantitative polymerase chain reaction and Western blotting were carried out to compare the expression levels of PDX1 in treated purified islets cultured with different media.
RESULTS: Islets treated with IBMX/tocopherol exhibited the highest fold change in the relative expression of PDX1 on day 5 post-treatment (relative expression: 6.80±2.08), whereas serum-treated islets showed the lowest fold changes in PDX1 expression on day 5 post-treatment (0.67±0.36), as compared with the expression on day 1 post-treatment. Insulin production and viability tests of purified islets showed superiority of islet at supplemented serum-free media with IBMX/tocopherol compared to other cultures (53.875%±1.59%).
CONCLUSIONS: Our results indicated that supplemented serum-free medium with tocopherol and IBMX enhances viability and PDX1 gene expression compared to serum-added and serum-free media.
METHODS: Forty healthy male SD rats were induced to diabetes with a single dose intra-peritoneal administration of STZ (60 mg/kg b.w.) - NAD (120 mg/kg b.w.). Diabetic rats were orally administered with 1 mL of pomegranate fresh juice (PJ) or 100 mg pomegranate seed powder in 1 mL distilled water (PS), or 5 mg/kg b.w. of glibenclamide every day for 21 days. Rats in all groups were sacrificed on day 22. The obtained data was analyzed by SPSS software (v: 22) using One-way analysis of variance (ANOVA).
RESULTS: The results showed that PJ and PS treatment had slight but non-significant reduction of plasma glucose concentration, and no impact on plasma insulin compared to diabetic control (DC) group. PJ lowered the plasma total cholesterol (TC) and triglyceride (TG) significantly, and low-density lipoproteins (LDL) non-significantly compared to DC group. In contrast, PS treatment significantly raised plasma TC, LDL, and high-density lipoproteins (HDL) levels compared to the DC rats. Moreover, the administration of PJ and PS significantly reduced the levels of plasma inflammatory biomarkers, which were actively raised in diabetic rats. Only PJ treated group showed significant repairment and restoration signs in islets of Langerhans. Besides, PJ possessed preventative impact against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals almost 2.5 folds more than PS.
CONCLUSIONS: Our findings suggest that active constituents with high antioxidant properties present in PJ are responsible for its anti-hyperlipidemic and anti-inflammatory effects, likewise the restoration effect on the damaged islets of Langerhans in experimental rats. Hence, the pharmacological, biochemical, and histopathological profiles of PJ treated rats obviously indicated its helpful effects in amelioration of diabetes-associated complications.