Further studies on the antinociceptive effects of delta 6-THC-7-oic acid.

The antinociceptive effects of delta 6-THC-7-oic (THC-7-oic) acid have been investigated further with particular regard to the influence of certain experimental parameters in the hot plate test. These included the degree of the thermal stimulus, the nature of the vehicle and a possible role for copper in the response. A temperature effect similar to that seen with nonsteroidalantiinflammatory drugs (NSAIDs) was observed, 55 degrees produced observable antinociception, however, at a surface temperature of 58 degrees C no drug effect was seen. Non-aqeous vehicles such as peanut oil increased the potency of THC-7-oic acid. Finally, the substitution of purified water for tap water reduced the drug response which could be partially restored by adding copper to the purified drinking water. An increase in the inhibitory effect when copper was added was also seen in vitro in a cell culture model where the acid reduced prostaglandin synthesis induced by THC. Our findings suggest that THC-7-oic acid probably acts by mechanisms similar to the NSAIDs and that the above mentioned experimental conditions can greatly influence the outcome of studies with this agent.