To investigate the antihyperglycemic potent of thymoquinone (TQ), this study has been conducted in streptozotocin-induced diabetic male rats.Diabetes was induced by single injection with streptozotocin (60 mg/kg b.w., i.p.). Rat ≥ 200 mg/dl of blood glucose was used as diabetic.Sixty five adult male rats (aged 56 days and weighted 138±8.8g) were divided into five groups, non-diabetic control (were drenched with drinking water) and four diabetic groups(DM, TQ50,TQ100, and DMI) were drenched with drinking water,TQ (50 mg/kg, bw), TQ (100 mg/kg, bw), and injected with insulin (4 IU/animal), respectively, for 42 days. During the experiment,body weight gains were recorded and blood samples were obtained weekly for assessment of plasma glucose and insulin concentrations. TQ treated male rats showed normal activity and body health throughout the experiment. Significant decrease of body weight gain has been recorded in untreated diabetic (DM) and insulin treated diabetic (DMI) groups as compared with that of intact control (C) and TQ treated diabetic (TQ50 and TQ100) groups, started from the fourth day of experiment, while DM group registered the lowest body weight gain among the experimental groups. Results of blood glucose concentrations referred to significant elevation in diabetic groups as compared with intact control. While in comparison between the diabetic groups, blood glucose concentration decreased significantly TQ50, TQ100, and DMI groups compared with DMI group. It has been found that insulin treated (DMI) and TQ treated (TQ50 and TQ100) male rats recorded no significant difference in serum insulin concentration when compared with each other but they were significantly lower than that of intact control male rats (C), but the average means of these four groups were significantly higher than that of non-treated diabetic male rats (DM).These changes were time dependent during the studied experimental period. It can be concluded that drenching of 100 mg/kg of TQ has potent hypoglycemic effect in experimentally-induced diabetic male rats.

The present study has been conducted to investigate the potency of thymoquinone (TQ) in ameleorating the pathological changes of pancreas, liver, and kidneys in streptozotocin-induced diabetic male rats. Sixty five adult male rats (aged 56 days and weighted 138±8.8g) were subjected to five equal groups (13 male rats each), non-diabetic control and four diabetic groups. Diabetes was induced by single injection with streptozotocin (60 mg/kg b.w., i.p.). Rats ≥ 200 mg/dl of blood glucose were used as diabetic. Diabetic groups (DM, TQ50, TQ100, and DMI) were drenched with drinking water, TQ (50 mg/kg, bw), TQ (100 mg/kg, bw), or injected with insulin (4 IU/animal), respectively, for 6 weeks. Twenty four hours after the last day of experiment, male rats has been anaesthesized, sacrificed, and pancreatic, liver, and kidney tissues were removed and fixed in formalin (10%) for histopathological examination. Histological findings of thymoquinone treated (TQ50 and TQ100 groups) pancreases revealed normal cellularity of islets of Langerhans and normal exocrine tissue except few congestion, whereas those obtained from non treated diabetic rats (DM group) showed complet impairment of some islands and highly destructed of others. Normal hepatic architecture with the appearance of radiating shape around the central vein, has been shown in the section obtained from thymoquinone treated diabetic rats (TQ50 and TQ100 groups) except few congestion, obvious regeneration and mitotic division in the nuclei of hepatocytes. Sections obtained from non treated diabetic male rats (DM group) showed sever congestion, large thrombi in the hepatic tissue, and loss of hepatic architecture with sever hemorrhage, degeneration in hepatocytes, and dilation of sinusoids. Section obtained from kidneys of thymoquinone treated diabetic rats (TQ50 and TQ100 groups) reveales normal renal convoluted tubules with normal epithelium of the tubules and high cellularity of glomeruli. Whearas those obtained from non treated diabetic male rats (DM group) revealed dilation of renal convoluted tubules with necrosis in the epithelium of the tubules and sever hemorrhage in the renal tissue. It can be concluded that drenching of 100 mg/kg of TQ for 6 weeks has potent ameliorating and regenerative effect of pancreas, liver, and kidneys in experimentally-induced diabetic male rats.