Ocimum gratissimum enhances insulin sensitivity in male Wistar rats with dexamethasone-induced insulin resistance

Purpose

The antidiabetic activities of Ocimum gratissimum (OG) leaf extract are well documented in experimental diabetes induced by beta cell destruction resulting in hypoinsulinemia. There is however paucity of data on its effect in conditions characterized by hyperinsulinemia. This study therefore investigated the effect of OG on insulin resistance induced by dexamethasone in male Wistar rats.

Method

Twenty male Wistar rats grouped as control, normal + OG, Dex and Dex + OG were used. Control and normal + OG received normal saline while Dex and Dex + OG received dexamethasone (1 mg/kg, i.p) followed by distilled water or OG (400 mg/kg) for 10 days. Levels of fasting blood glucose (FBG), insulin, HOMA-IR, liver and muscle glycogen, hexokinase activities, hepatic HMG CoA reductase activity were obtained. Histopathology of pancreas and liver tissues was carried out using standard procedures.

Results

Body weight reduced significantly in the Dex and Dex + OG groups compared with the control. FBG (147.8 ± 9.93 mg/dL), insulin (2.98 ± 0.49 µIU/ml) and HOMA-IR (1.11 ± 0.22) of Dex animals were higher than the control (FBG = 89.22 ± 6.53 mg/dL; insulin = 1.70 ± 0.49 µIU/ml; HOMA-IR = 0.37 ± 0.04). These were significantly reduced in the Dex + OG (FBG = 115.31 ± 5.93 mg/dL; insulin = 1.85 ± 0.11µIU/ml; HOMA-IR = 0.53 ± 0.08) compared with Dex. Glycogen content and hexokinase activities were increased in the Dex + OG. Increased pancreatic islet size, hepatic steatosis and HMG Co A reductase activity were observed in the Dex but reduced in Dex + OG.

Conclusion

OG promotes cellular glucose utilization and reduces hepatic fat accumulation in Wistar rats with insulin resistance induced by dexamethasone. Further study to identify the involved signal transduction will throw more light on the observed effects.

Re-establishing normal diet following high fat-diet-induced obesity reverses the altered salivary composition in Wistar rats

Background Obesity has been implicated in impaired salivary secretion. This study aimed at evaluating the influence of diet-induced obesity on salivary secretion and how re-feeding with normal diet would affect changes in salivary secretion associated with diet-induced obesity. Methods Weaning rats weighing 55-65 g were randomly divided into three groups (control, diet-induced obese, re-fed obese) of seven rats each. The diet-induced obese group was fed a high-fat diet for 15 weeks, whereas the re-fed obese group received normal diet for another 15 weeks following the 15 weeks of high-fat diet. After treatment, blood and stimulated saliva samples were collected for the analyses of total protein, electrolytes, amylase, Immunoglobulin A (IgA), leptin and ghrelin. Tissue total protein, nitric oxide level, expressions of Na+/K+-ATPase, muscarinic (M3) receptor and aquaporin 5 in the submandibular glands were determined. Data were presented as mean±SEM and compared using independent student t-test and ANOVA with Tukey's post-hoc test. Results Results indicated increases in the levels of salivary calcium, phosphate, bicarbonate and leptin, whereas the levels of salivary amylase and ghrelin showed reduction in the obese group compared with the control. Most of these changes were reversed in the re-fed obese group. There were no significant differences in salivary lag time, flow rate, levels of tissue total protein, nitric oxide and the relative expressions of M3 receptor, Na++/K+-ATPase and aquaporin 5 in the submandibular glands between the obese and control groups. Conclusions Diet-induced obesity lead to some changes in salivary factors which were reversed by returning to normal diet.

Aqueous leaf extract of Ocimum gratissimum improves hematological parameters in alloxan-induced diabetic rats via its antioxidant properties

OBJECTIVE

This study was designed to investigate the effects of Ocimum gratissimum (OG) on hematological parameters and oxidative stress in diabetic rats.

MATERIALS AND METHODS

Twenty-five male rats (150-200 g) were randomly grouped into five as control, normal + OG, diabetic untreated, diabetic + OG, and diabetic + glibenclamide groups. Diabetes was induced by 100 mg/kg of alloxan monohydrate in the diabetic untreated and diabetic + OG groups followed by treatment with distilled water and 400 mg/kg OG, respectively, whereas control, normal + OG, and diabetic + glibenclamide groups were treated with distilled water, 400 mg/kg OG, and 5 mg/kg glibenclamide, respectively. Body weight and fasting blood glucose level were monitored weekly. After 28 days of treatments, under anesthesia induced by 50 mg/kg sodium thiopental i.p., blood samples were obtained for hematological analysis, malondialdehyde (MDA) level determination, and superoxide dismutase (SOD) activity. Data were compared using analysis of variance and Student's t-test.

RESULTS

There was a significant decrease in the fasting blood glucose of the diabetic + OG animals compared to the diabetic untreated and the initial reduction in weight observed in this group was reversed at the end of the experiments. Packed cell volume, red blood cell count, and hemoglobin concentration were significantly increased (P < 0.05) in the diabetic + OG when compared with the untreated group. The MDA concentration was significantly lowered (P < 0.01) in the diabetic + OG group when compared with diabetic untreated while SOD activity was significantly reduced in the diabetic untreated group.

CONCLUSION

It was concluded that OG reverses anemia secondary to alloxan-induced diabetes mellitus in rats probably via its antioxidant activity.