Tetramethylpyrazine prevents diabetes by activating PI3K/Akt/GLUT-4 signalling in animal model of type-2 diabetes.

AIMS: The present experiment was conceptualised to explore the therapeutic response of tetramethylpyrazine (TMP), a major active constituent of Ligusticum chuanxiong, a Chinese traditional medicinal plant, in high-fat diet (HFD)-streptozotocin (STZ)-induced diabetes in rats and to identify the possible mechanism of action. MAIN METHODS: Dose-reliant effect of oral treatment of TMP (100, 150 and 200 mg/kg/day) for 28 days was evaluated by calculating the alteration in body weight, level of fasting blood glucose (FBG), plasma insulin, homeostasis model assessment (HOMA), serum lipids, oral glucose & intraperitoneal insulin tolerance and glycosylated haemoglobin in HFD-STZ-induced type-2 diabetic (T2D) rats and underlying molecular mechanisms of TMP was also studied. KEY FINDINGS: TMP treatment prominently reduced the level of FBG, glycosylated haemoglobin and revived body weight gain and level of serum insulin dose-dependently in diabetic rats. TMP treatment considerably improved insulin resistance, as observed in oral glucose tolerance and insulin tolerance tests. Moreover, dose-dependent reduction in the level of pro-inflammatory cytokines, C-reactive protein (CRP) and interleukin-6 (IL-6) was observed and their level was found to be significantly reduced in highest dose TMP (200 mg/kg) treated diabetic rats, pointing towards TMP mediated recovery of insulin signalling and a decrease in insulin resistance. The expressions of p-PI3K-p85/p-Akt/GLUT-4 were also significantly up-regulated by TMP (200 mg/kg), suggesting the connection of the PI3K/Akt signal pathway in the anti-hyperglycemic action of TMP. SIGNIFICANCE: These findings suggest that TMP may be used as a potential agent for type-2 diabetes treatment.

Anxiolytic, antidepressant, and antistress activities of the aqueous extract of Cinnamomum tamala Nees and Eberm in rats.

OBJECTIVE: The current study was designed to explore anxiolytic, antidepressant, and antistress actions of Cinnamomum tamala (CT) leaves (aqueous extract) in rats. MATERIALS AND METHODS: Behavioral procedures of anxiety, depression, and stress were assessed in rats. CT (100, 200, and 400 mg/kg) was given once a daily for 7 days via oral route and the efficacy was matched by those elicited by lorazepam (1 mg/kg, p.o.), imipramine (10 mg/kg, p.o.), and Withania somnifera (100 mg/kg, p.o.) for anxiolytic, antidepressant, and antistress studies, respectively. Standard drugs were given 1 time, 30 min preceding the behavioral trials. RESULTS: One-way analysis of variance followed by Newman-Keuls multiple comparison test was employed to analyze the results. P < 0.05 was considered statistically significant as compared to control. CT at 400 mg/kg produced an antianxiety effect equivalent to lorazepam, in the elevated plus maze, open field, and social interaction tests among selected doses of the CT. CT at 400 mg/kg also induced an antidepressant activity similar to imipramine, in the behavioral despair, learned helplessness test, and tail suspension among selected doses of the CT. Moreover, CT at 400 mg/kg produced a significant antistress effect comparable to W. somnifera in water immersion-restraint stress by decreasing ulcer index, adrenal gland weight, and by normalizing the plasma levels of corticosterone, glucose, cholesterol, and triglyceride levels when related to stress control. CONCLUSION: The study shows that among the different CT doses, CT at 400 mg/kg possesses significant anxiolytic, antidepressant, and anti-stress effects and has therapeutic beneficial for the management of psychological ailments.