Caryocar villosum attenuates inflammation by inhibiting CXCL1 activation and peripheral hyperalgesia through opioid pathway modulation

The oil of Caryocar villosum is used in Amazonian folk medicine to treat pain and inflammatory conditions. So, we assessed the anti-inflammatory and antinociceptive properties of the ethanolic extract obtained from the fruit peels of this species. The acetic acid-induced writhing, carrageenan-induced mechanical hyperalgesia, formalin, carrageenan-induced paw edema and carrageenan-induced peritonitis tests were used on mice. The C. villosum ethanolic extract significantly inhibited the number of abdominal writhes, mechanical hyperalgesia and paw licking time in the second phase of the formalin test. At a dose of 300 mg kg(-1), the extract also significantly reduced the volume of edema formed in the late phase and reduced the recruitment of leukocytes and neutrophils in the peritoneal cavity, as well as CXCL1 chemokine levels. It is suggested that the extract attenuates the leukocyte recruitment by inhibiting the CXCL1 activation. The peripheral antinociceptive activity occured through opioid pathway modulation because pretreatment with C. villosum ethanolic extract reversed the naltrexone-induced antinociception.