Salvia divinorum, an unusual psychoactive sage described by a Brookhaven National Lab scientist as “probably one of the most potent hallucinogens known,” is currently on brisk sale throughout lower Manhattan, as well as most of the rest of the country where it is currently legal. The plant has gained some popularity over the years, and scientists are trying to learn more about its interaction with the brain.
Hooker [Jacob Hooker, chemist at Brookhaven and lead author of the study –ed.] and fellow researchers used positron emission tomography, or PET scanning, to watch the distribution of salvinorin A in the brains of anesthetized primates. In this technique, the scientists administer a radioactively labeled form of salvinorin A (at concentrations far below pharmacologically active doses) and use the PET scanner to track its site-specific concentrations in various brain regions.
Within 40 seconds of administration, the researchers found a peak concentration of salvinorin A in the brain – nearly 10 times faster than the rate at which cocaine enters the brain. About 16 minutes later, the drug was essentially gone. This pattern parallels the effects described by human users, who experience an almost immediate high that starts fading away within 5 to 10 minutes.
High concentrations of the drug were localized to the cerebellum and visual cortex, which are parts of the brain responsible for motor function and vision, respectively. Based on their results and published data from human use, the scientists estimate that just 10 micrograms of salvia in the brain is needed to cause psychoactive effects in humans.
Salvia doesn’t cause the typical euphoric state associated with other hallucinogens like LSD, Hooker said. The drug targets a receptor that is known to modulate pain and could be important for therapies as far reaching as mood disorders.
“Most people don’t find this class of drugs very pleasurable,” Hooker said. “So perhaps the main draw or reason for its appeal relates to the rapid onset and short duration of its effects, which are incredibly unique. The kinetics are often as important as the abused drug itself.”
The Brookhaven team plans to conduct further studies related to salvia’s abuse potential. The scientists also hope to develop radioactive tracers that can better probe the brain receptors to which salvia binds. Such studies could possibly lead to therapies for chronic pain and mood disorders.
Press release: Brookhaven Scientists Explore Brain’s Reaction to Potent Hallucinogen
PET images (color) of [11C]-salvinorin A in the baboon brain overlaid on MRI template (black and white) summed from 3-7 minutes post-injection. High concentrations (red) were observed in the cerebellum and activity was seen throughout cortical and subcortical regions. The maximum concentration of [11C]-salvinorin A in the brain occurs in 40 seconds and clears with a half-life of only 8 minutes, matching the pharmacological duration of action.