A Comparison of Mitragyna Speciosa and Mitragynine Against Opioids on Thermal Nociception in Rats

The purpose of this experiment is to compare Mitragyna speciosa (M. speciosa) and its active component, mitragynine, a known µ-opioid receptor (MOR) agonist, against well-known and commonly abused opioids, morphine and oxycodone. Another goal of this research is to determine if these compounds are also active when administered orally as is typical in human users. Male Sprague-Dawley rats were administered M. speciosa and mitragynine both intraperitoneally (IP) and orally and their antinociceptive effects were evaluated on the hotplate. Mitragynine exhibited antinociceptive effects similar to oxycodone when administered both IP and orally. M. speciosa exhibited a trend towards antinociceptive effects when administered both IP and orally. This research demonstrates that M. speciosa possesses properties like oxycodone and raises the possibility of an abuse liability which might warrant consideration for restrictions on the consumer marketplace