Evaluation of the Effect of Chronic Oral Administration of Withania somnifera Root on Pain Score in Male Diabetic Rats

Hyperalgesia is considered as one of the marked signs of subchronic diabetes mellitus that could affect the life style of the patients. Considering the anti-diabetic potential effect of the medicinal plant Withania somnifera (WS) (Ashwagandha), this study was designed to investigate the analgesic effect of WS on formalin-induced nociceptive responses in diabetic rats. Rats were divided into six groups: non-treated control, WS-treated control, streptozocin (STZ)-induced diabetic, sodium salicylate (SS)-treated control, diabetic and WS-treated diabetic groups. For induction of diabetes, STZ (60 mg/Kg, i.p.) was administered as a single dose. The treatment groups received orally Withania somnifera -mixed rat pellet (6.25%) for two months. The results showed that diabetic rats exhibited a higher score of pain at both phases of the formalin test and WS-treated diabetic rats exhibited a lower nociceptive score at both phases of the test (p<0.05). While, SS administration significantly reduced pain score only at chronic phase of the test in the diabetic group (p<0.01). Taken together, these results indicate that two-month administration of Withania somnifera could attenuate nociception in an experimental model of diabetes mellitus and this may be considered as a treatment for painful diabetic neuropathy.