A Study on the Potential Hypoglycemic Effect of Feeding Nigella sativa (Black cumin) Seeds in Rats

Abstract

The present study was designed to evaluate the hypoglycemic effect of Nigella sativa(Black cumin) seeds and to explore how the induction of hypoglycemia،by feeding seeds،can modulate glucose metabolism in animals. This effect was compared with a reference of a known hypoglycemic drug Glibenclamide. Thirty female Wister albino rats wereused as experimental animals and divided into five groups (A،B،C،D and E) of six rats each. Each rat was fed 8 g for 30 days as follows: In group A،the rats were fed basal diet and kept as control ،group B was fed Glibenclamide (hypoglycemic drug) at the rate of10 mg/kg body weight،calculated as part from the rat basal diet،group C was fed Nigella sativa(50 mg/day as part from the basal diet)،group D was fed Nigella sativa(50 mg/day + glucose 2g/kg body weight as part from the basal diet) and group E was fed glucose (2g/kg body weight calculated as part from the rat basal diet). Blood glucose levels were measured weekly. Insulin concentration was recorded at days 14 and 28. At the end of the experimental period،blood hemoglobin concentration was measuredand oral glucose tolerance test was conducted for all rats. Glucose-6-phosphate dehydrogenase and Alanine aminotrasferase activities were estimated،and a histophathological examination of the liver and the pancreas was done for all groups. Animal's body weight was reported at the beginning and at the end of the experiment. x

All the treated groups showed significant reduction in blood glucose concentration after one week of treatment،and it was more pronounced in group B. At the second week and until the end of the experiment، significant reduction compared to the control group،were maintained only in groups B and C which received Glibenclamide and N. sativa، respectively. By the end of the experiment،groups D and E showed similar levels of glucose to the control group. In group D،feeding high glucose dose was not associatedwith the application of N. sativato the diet. When insulin concentration was measured after two weeks،no significant increase was observed in all groups except groups D and E. By the end of the experimental period،all treated groups showed significantly higher insulin levels and it was significantly higher in group E. After four weeks of treatment،no significant changes were noticed in Glucose-6-phosphate dehydrogenase activity in all groups،only higher values were found in groups D and E،being two folds higher than group B. The activity of Alanine aminotrasferase was significantly increased in the group receiving N. sativabut was significantlydecreased in the groups treated with Glibenclamide and glucose،respectively. The performance of the groups receiving Glibenclamide or only the N. sativa was similar،when Glucose Tolerance Test was carried out،but addition of extra glucose to the rat basal diet plus the N. sativaabolished this effect. Hemoglobin concentration and animal’s body weight were not influenced by all treatments applied.No histopathological changes were xi

noticed in the liver and pancreas of Nigella sativatreated groups compared with the other groups and the control. The results showed that Nigella sativaat 50 mg/day can exerts potential hypoglycemic effects in rats. The hypoglycemic effect of the seeds may be mediated،at least in part،by decreasing glucose concentration and increasing insulin level. Glucose uptake and absorption were significantly influenced by feeding N. sativato the rats. The increase of Alanine aminotrasferase activity in N. sativatreated groups،with no histopathological changes،may indicate slight effects on the integrity of liver cells