Compared to liver, bile duct and skeletal muscle garlic (versus normal saline) only enhances pancreas insulin m-RNA transcription that corresponds to islets cellular plasticity and local and circulating hyperinsulinemia in diabetic rats
Abstract Background: Garlic aqueous extract (GE) augments insulin circulating concentration in streptozotocin-induced type-1 diabetes mellitus (STZ-DM) rat model. Objective: This study investigated at 4 stages in a time-line fashion whether modifications in insulin m-RNA transcription occur, and if they do, are they related to accumulative changes in insulin - serum and tissue concentrations and immunohistochemical (IHC) localizations and plasticities as part of the GE-induced insulinogenic mechanism(s) in the pancreas, liver, bile duct and gastrocnemius skeletal muscle (GSM) of STZ-DM rats. Method: The body weight, food and water intake, urine output, fasting blood glucose (FBG), serum insulin (SI), in addition to tissues insulin concentrations, IHC localizations and numerical intensities and m-RNA transcriptions were investigated before (basal level = BL) and after 1, 4 and 8 weeks of oral treatment in normal rats given normal saline (NR-NS), diabetic rats given normal saline (DR-NS) and diabetic rats given GE (DR-GE). The readings collected were compared using two-way ANOVA with LSD post-hoc test (IBM SPSS - V.22) and differences were considered significant when P <0.05.Results: Compared to NR-NS, DR-NS showed typical diabetic biophysical symptoms in addition to significant accumulative increases in FBG and reductions in SI, which corresponded positively with reductions in pancreatic insulin IHC localization and numerical intensity and m-RNA transcription. Conversely, and in comparison to DR-NS, DR-GE showed amelioration of diabetic biophysical symptoms, in addition to significant accumulative decreases in FBG and increases in SI, which corresponded positively with increases in pancreatic insulin IHC localization and numerical intensity and m-RNA transcription. The liver, bile duct and GSM did not show any changes in the targeted parameters (or indicators of insulin synthesis: proinsulin or C-peptide) in response to GE treatment. Conclusion: GE induced increases in circulating insulin concentration could have been due to increases in pancreas insulin concentrations as a result of an enhancement in islets cellular plasticity and m-RNA transcription. Accordingly, garlic insulinogenic action could be partly due to modification of pancreas genetic expression.