Antinociceptive effect of black seed feeding in streptozotocin-diabetic rats

  Abstract  Introduction: Diabetic rats display exaggerated hyperalgesic behavior in response to noxious stimuli that may resemble and model aspects of painful diabetic neuropathy in humans. This study was designed to investigate the effect of Nigella sativum (NS) on formalin-induced nociceptive responses (standard formalin test) in streptozotocin (STZ)-induced diabetic rats.  Methods: For this purpose, STZ-diabetic rats received Nigella sativum mixed with standard rat chow at a weight ratio of 6.25% orally for a period of one month.  Results: It was found out that NS treatment did cause a significant reduction in blood glucose in diabetic rats and NS-treated diabetic rats exhibited a lower nociceptive score as compared to untreated-diabetic ones. Meanwhile, NS treatment reduced the nociceptive score in both phases of the formalin test. In contrast, sodium salicylate as positive control only reduced this score in the second phase of the test.  Discussion: The results suggest therapeutic potential of NS feeding for treating painful diabetic neuropathy.