Antinociceptive Effects of Eugenol Evaluated in a Monoiodoacetate-induced Osteoarthritis Rat Model

The aim of the present study was to evaluate whether eugenol, the main constituent of clove oil, has the capacity to provide analgesia in the monoiodoacetate-induced rat model of osteoarthritis. Animals (n?=?6/group) received either eugenol (20 or 40?mg/kg) or a vehicle by gavage. Daily administrations were initiated 2?days post osteoarthritis induction and continued for the duration of the study (4?weeks). Gait analysis was performed using the CatWalk method and secondary mechanical allodynia was assessed with von Frey filaments. Selected spinal cord peptides (substance P, calcitonin gene-related peptide and dynorphin) were quantified by mass spectrometry. Significant changes were identified in dynamic gait parameters (swing speed, swing phase duration and duty cycle) of the affected limb following 40?mg/kg eugenol treatment compared with the vehicle (p?