Effect of Nigella sativa on pancreatic β-cell damage in streptozotocin-induced diabetic rats: histological and immunohistochemical study

Background:Diabetes mellitus is a metabolic disease characterized by chronic hyperglycemia. Nigella sativa (NS) is a medical plant used as a natural remedy for a variety of illness. Aim of the study:The aim of this study was to demonstrate the effect of NS on pancreatic β-cell damage and serum levels of glucose and insulin in streptozotocin (STZ)-induced diabetic rats and to correlate these effects with the immunohistochemical changes. Materials and methods:Forty-five male albino rats were used in this study. The animals were divided into three groups: group I (control), group II (diabetic), and group III (diabetic with NS). Diabetes was induced in group II and III animals by a single intraperitoneal injection of STZ, 40mg/kg. Group III animals were given NS oil (0.2ml/kg/day) intraperitoneally for 4 weeks. Five rats from each group were sacrificed 2 days, and 2 and 4 weeks after STZ injection. Blood samples were collected for detection of serum glucose and insulin levels. Paraffin sections of the pancreas were prepared and stained with H E stain and immunohistochemical stain using anti-insulin antibody. Results:After STZ injection, the pancreatic islets appeared shrunken and showed degenerative changes and negative or weak positive insulin immunoreactivity. The serum level of insulin was decreased with elevation in the serum glucose concentration. NS injection improved the morphology of the islets, which nearly reverted to their normal size and structure with increased insulin immunoreactivity. NS also increased the lowered insulin and decreased the elevated glucose concentrations. Conclusion:NS has a protective effect on pancreatic β-cell damage and improves serum levels of insulin and glucose in STZ-induced diabetic rats.