"We found that the combination of a marijuana-like compound with either the mild pain medication ibuprofen or rofecoxib provides more pain relief than each of them given alone," says study author Pierre Beaulieu, MD, PhD, of the University of Montreal in Canada .
The marijuana-like compound that researchers tested in the study is called anandamide, a natural internal chemical that activates the same system as marijuana. Nonsteroidal anti-inflammatory drugs such as ibuprofen and rofecoxib inhibit a specific enzyme that prevents the degradation of anandamide. This led researchers to suspect that supplements of anandamide could create even greater pain relief effects.
In the study, researchers injected the drugs into the back paw of rats. Then 15 minutes later, researchers injected the compound formalin into the same paw, which creates a persistent inflammatory pain condition locally.
"We found that compared to a separate administration of drugs, anandamide combined with either ibuprofen or rofecoxib doubled the animals' pain relief," says Beaulieu. "Also since the compounds were injected locally, into the paw, we believe that the treatment would avoid some of the deleterious psychoactive effects seen with marijuana."
Marijuana and marijuana-like compounds can act on receptors in the brain and the periphery, but only the brain ones contribute to the psychoactive effects.
As a next step, the researchers are testing the treatment strategy in animals that model a particularly hard-to-treat, persistent pain condition that can result from nerve injury, termed neuropathic pain.
Another new animal study supports the development of treatments that target the cannabinoid system for those with obesity. "We found that a compound that bloc
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Contact: Leah Ariniello
dawn@sfn.org
202-462-6688
Society for Neuroscience
26-Oct-2004