Abstract
Background: The extent of metabolic disruption and the usefulness of drugs and supplements, such as medicinal plants, in patients with diabetes may be impacted by the severity of the disease. Method: Nicotinamide + STZ together and STZ alone were used to induce early- and late-stage diabetes type 2 (ET2D and LT2D, respectively) in rats. Glucose tolerance test (GTT) was performed because the stage of disease was considered compatible with the magnitude of deviation from normal glucose tolerance test (GTT), as well as the level of FBS. Three main groups of the study were nondiabetic, early-stage diabetic, and late-stage diabetic rats. Each group was divided into two sub-groups, one of which received Citrullus colocynthis seed aqueous extract (CCAE, 90mg/kg BW) for 28 days. Weekly FBS and body weights were recorded during the study. At the end of 28 days, the serum levels of ALT, AST, ALP, TG, urea, creatinine, uric acid, cholesterol, HDL, LDL, c-peptide, and HbA1c were measured; the hepatic mRNA expression of several enzymes of glucose and fat metabolic pathways were also determined by Real-Time PCR. The accumulation of fat in the hepatic tissue was visualized by measuring the TG content and by H&E and Oil-Red staining and the degree of oxidative stress was measured by protein carbonyl content (PCC).Results: The LT2D rats showed maximal deviations from normal GTT. GTT for control and ET2D rats were similar, yet the area under curve (AUC) for ET2D rats was significantly higher. Urea, ALT, and ALP levels were high in diabetic rats compared to control and significantly different from each other.Serum TG dropped and ALT, ALP, HDL and LDL significantly improved after treatment with CCAE. Different patterns of G6Pase and PEPCK expression in ET2D and LT2D suggested their similarity to short- and long-term fasting states, respectively. While the reduction of FBS levels in ET2D could be explained by an inhibition of G6Pase expression and therefore glycogenolysis, the level of PEPCK expression was not significantly lowered by CCAE in LT2D. H&E staining of liver tissue showed steatoses of varying morphology in both ET2D and LT2D rats. CCAE led to up-regulated PPARα and down-regulated CPT1 expressions.Conclusion: As PEPCK activity is necessary for the continuation of the TG/FA cycle during fasting, it is possible that in LT2D, CCAE directed the PEPCK activity more towards glyceroneogenesis than gluconeogenesis to ensure the persistence of the TG/FA cycle. The enhanced glyceroneogenesis together with an up-regulated PPARa expression and down-regulated CPT1 expression probably led to lower blood and hepatic TG. More research is needed to establish the effect of CCAE on PEPCK expression and its course of activity.
Short- and long-term effects of various Citrullus colocynthis seed extracts in normal and streptozotocin-induced diabetic rats
