EVALUATION OF CAMPHOR ON MECHANICAL HYPERALGESIA INDUCED BY GP120

Introduction: Camphor is a bicyclic monoterpene ketone (C10H16O), obtained by the camphor laurel’s wood (Cinnamomum camphora)1,2. This plant of the family of Laureacea is native to eastern Asia and it has been popularized since ancient times due to its aromatic properties and medical uses1,2. Among its known therapeutic properties, it has antipyretic and anti-inflammatory actions, antisepsis and mild local analgesia, besides being used as an expectorant, repellent and antimicrobial substance1,2,3,4. Objectives: The present work has investigated the analgesic properties of the Camphor in the model of mechanical hyperalgesia induced by intrathecal injection of gp120 in mice. Material and Methods: Male Swiss mice were separated in two groups: a control group (n=7), which received sterile saline (0,9%), and a group (n=6) treated orally with Camphor (30mg/kg). One hour after, 5 ?l of gp120 was injected with the aid of a Hamilton’s micro-syringe (25 ?L) between the L5 and L6 vertebrae through intact skin. The animals were then housed individually in acrylic boxes for habituation. The evaluation of mechanical hyperalgesia was performed by the right hind paw withdraw threshold using an electronic von Frey apparatus (InSight®, Ribeirao Preto, Brazil), 2 and 3 hours after intrathecal administration of gp120. The maximum pressure tolerated by the animal was determined in grams, after the paw withdraw. Results: Heightened algesia was observed throughout the period in the control group, however, Camphor did not reduce pain sensitivity induced by gp120 at 2 and 3 hours after intrathecal injection. It is important to emphasize that the results did not reach statistical significance (p <0,05). Discussion and Conclusion: Oral treatment with Camphor did not demonstrate analgesic effects in the model of mechanical hyperalgesia induced by gp120 in mice. New studies, therefore, should be done.