The effect of intraperitoneal administration of hydroalcoholic extracts of heated and unheated and hexanic extract of heated Cannabis sativa flowers on pain in rats

Background and Objective: Cannabis sativa can produce phytocannabinoids such as tetrahydrocannabinolic acid and cannabidiolic acid, they are of the most important of these compounds that affect the endocannabinoid system and result in nervousness, epilepsy and nausea. This research was to investigate effects of hexanic and hydroalcoholic extracts of female Cannabis sativa flowers which have the maximum amount of cannabinoids, on thermal and chemical pains. In addition, the effect of heat on physiological effects of phytocannabinoids on pain was examined. Materials and Methods: In this experimental study, male Wistar rats (200-250g) were categorized into control, sham, hydro-alcoholic extract of heated flowers in 1, 10 and 50 mg/kg doses, hydro-alcoholic extract of unheated flowers in 50 mg/kg dose and hexanic extract of heated flower in 50 mg/kg dose groups. In order to evaluate the chemical pain, formalin test was used and to investigate thermal pain, tail flick test was performed. Results: Intraperitoneal injection of 50 mg/kg hexanic extract of heated flowers respect to other extracts exerted a significant reduction on first and second phases of formalin test and threshold of thermal pain. Conclusion Decarboxylated cannabinoids, which are extracted in more amounts by hexane, probably have more affinities to CB1 and TRPV1 receptors of pain pathway and respectively cause release of mediators involved in process of pain and making pain receptors non-sensitive. They also inhibit factors involved in severance of endocannabinoids.