Combination therapy of Nigella sativa and human parathyroid hormone on bone mass, biomechanical behavior and structure in streptozotocin-induced diabetic rats

Extracts of the seeds of Nigella sativa (NS), an annual herbaceous plant of the Ranunculaceae family, have been used for many years for therapeutic purposes, including their potential anti-diabetic properties. The aim of the present study was to test the hypothesis that combined treatment with NS and human parathyroid hormone (hPTH) is more effective than treatment with NS or hPTH alone in improving bone mass, connectivity, biomechanical behaviour and strength in insulin-dependent diabetic rats. Diabetes was induced by intraperitoneal injection of streptozotocin (STZ) at a single dose of 50 mg/kg. The diabetic rats received NS (2 ml/kg/day, i.p.), hPTH (6 µg/kg/day, i.p.) or NS and hPTH combined for 4 weeks, starting 8 weeks after STZ injection. The ß-cells of the pancreatic islets of Langerhans were examined by immunohistochemical methods. In addition, bone sections of femora were processed for histomorphometry and biomechanical analysis. In diabetic rats, the ß-cells were essentially negative for insulin-immunoreactivity. NS treatment (alone or in combination with hPTH) significantly increased the area of insulin immunoreactive ß-cells in diabetic rats; however, hPTH treatment alone only led to a slightly increase in the insulin-immunoreactivity. These results suggest that NS might be used in a similar manner to insulin as a safe and effective therapy for diabetes and might be useful in the treatment of diabetic osteopenia. © 2007 Elsevier GmbH. All rights reserved