Antinociceptive and Antihyperglycemic Effects of Melissa officinalis Essential Oil in an Experimental Model of Diabetes

Objective: The efficacy of oral administration of Melissa officinalis essential oil (MOEO) on hyperalgesia was investigated using the formalin test in streptozotocin (STZ)-induced diabetic rats. Materials and Methods: Animals were divided into control, MOEO-treated control (0.01, 0.02 and 0.04 mg/ day), diabetic and MOEO-treated diabetic (0.01, 0.02 and 0.04 mg/day) groups. Nociceptive testing was performed onmale adult Wistar rats 4 weeks after the onset of hyperglycemia. At the end of the experiment, all rats were weighed and plasma glucose measurements were performed. Results: Diabetes was associated with significant hyperalgesia during both phases of the formalin test. MOEO (0.04 mg/day) completely reversed hyperalgesia in diabetic rats, while MOEO (0.02 and 0.04 mg/day) caused less intensive nociceptive behaviorsduring both phases of the test in control rats. MOEO at both high doses restored euglycemia and reduced the body weight of treated diabetic animals compared to untreated diabetic animals. The 0.01-mg dose of MOEO did not alter pain responses in the control or diabetic groups compared to their respective controls. Conclusions: This study shows that chronic administration of MOEO displays efficacy in an experimental model of diabetic hyperalgesia. MOEO may therefore show promise as a treatment for painful diabetic neuropathy.