Researchers at Brown University have shown that the brain produces anandamide, a naturally occuring cannabinoid substance that functions as a pain suppressor. Anandamide is similar pharmacologically to delta-9-tetrahydrocannabinol (THC), a compound found in marijuana.
In the study, researchers electrically stimulated the periaqueductal gray area (PAG) of anesthetized rats. PAG is a part of the brainstem that is involved in pain suppression and is found in mammals. The rats were also injected with a chemical irritant called formalin, a substance that causes prolonged pain.
The researchers measured the amount of anandamide in the PAG region using an atmospheric pressure-chemical ionization mass spectrometry machine. This very sensitive instrument allowed the scientists to measure extremely small quantities of the anandamide compound.
Researchers discovered that when the PAG area was stimulated, there was an increase in the release of anandamide. When injections of formalin were administered, even greater amounts of anandamide were released. These findings suggest that the brain uses a cannabinoid substance, anandamide, to control pain sensitivity.
The use of cannabinoids to control pain is not new. Recently there has been much controversy over whether cannabis, also called marijuana, should be used to alleviate pain. Researchers in this study believe these findings prove that cannabinoids, including marijuana, are definitely useful in controlling pain. They also stress the importance of additional studies and clinical trials with cannabinoids.