Injecting 100 micrograms of 5-MeODMT into the spinal subarachnoid space of conscious rats reduced nociceptive reflex reaction times, indicating a hyperalgesic effect. Administration into the thoracic region decreased the average percent of control reaction time by 14%, while injection into the lumbosacral region produced a 25% decrease. This facilitatory effect on pain perception mimics tryptamine rather than serotonin, suggesting 5-MeODMT interacts with tryptaminergic receptors in the spinal cord.
In cats, a single injection of LSD increased the dorsal root potential evoked by stimulating the nucleus raphe magnus, while a single injection of 5-MeODMT decreased it. The dose and time course of these electrophysiological changes matched the drugs' known behavioral effects. After four daily LSD injections, complete tolerance developed to LSD's potentiating effect, but the same pretreatment with 5-MeODMT did not alter its acute inhibitory effect. These results parallel the development of behavioral tolerance to LSD and 5-MeODMT, suggesting this system may serve as an electrophysiological model for studying these drugs.