Evaluation of agonist-antagonist properties of nitrogen mustard and cyano derivatives of Delta(8)-tetrahydrocannabinol

Abstract

Delta(8)-Tetrahydrocannabinol (Delta(8)-THC) is a naturally occurring cannabinoid with a characteristic pharmacological profile of in vivo effects. Previous studies have shown that modification of the structure of Delta(8)-THC by inclusion of a nitrogen-containing functional group alters this profile and may alkylate the cannabinoid receptor, similar to the manner in which beta-funaltrexamine (beta-FNA) alkylates the mu-opioid receptor. Two novel analogs of Delta(8)-THC were synthesized: a nitrogen mustard analog with a dimethylheptyl side chain (NM-Delta(8)-THC) and a cyano analog with a dimethylpentyl side chain (CY-Delta(8)-THC). Both analogs showed high affinity for brain cannabinoid receptors and when administered acutely, produced characteristic Delta(9)-THC-like effects in mice, including locomotor suppression, hypothermia, antinociception and catalepsy. CY-Delta(8)-THC shared discriminative stimulus effects with CP 55,940; for NM-Delta(8)-THC, these effects also occurred, but were delayed. Although both compounds attenuated the effects of Delta(9)-THC in the mouse behavioral tests, evaluation of potential antagonist effects of these compounds was complicated by the fact that two injections of Delta 9-THC produced similar results, suggesting that acute tolerance or desensitization might account for the observations. NM-Delta(8)-THC, but not CY-Delta(8)-THC, attenuated the discriminative stimulus effects of CP 55,940 in rats several days following injection. Hence, addition of a nitrogen-containing functional group to a traditional cannabinoid structure does not eliminate agonist effects and may produce delayed attenuation of cannabinoid-induced pharmacological effects. (C) 1997 Elsevier Science Ltd