Neuroscience letters
September 1, 1980
O G Berge, K Hole, H Dahle
34 citations
Injecting 5-methoxy-N,N-dimethyltryptamine into the brain's ventricles altered pain sensitivity in rats, measured by the tail-flick test. Low doses (1.6 to 25 micrograms) reduced tail-flick latencies by 13-24%, indicating hyperalgesia (increased pain sensitivity), likely from decreased activity in descending serotonergic neurons. Moderate doses (50 and 100 micrograms) produced a biphasic response: initial hyperalgesia followed by analgesia. The highest dose (400 micrograms) increased latencies by 28-39%, indicating analgesia, probably by stimulating spinal postsynaptic serotonergic receptors.
European journal of pharmacology
June 3, 1983
O G Berge, D Chacho, K Hole
20 citations
5-MeO-DMT, a psychedelic compound, inhibits the reuptake of serotonin in rat brain tissue at concentrations between 0.5 and 500 micromolar, affecting the striatum, hippocampus, and hypothalamus. At higher concentrations (10 micromolar), it also inhibits dopamine reuptake and triggers the release of both serotonin and dopamine from nerve endings. These findings suggest that 5-MeO-DMT's effects as a serotonin agonist may involve blocking reuptake, not just directly stimulating receptors as previously thought.
Neuroscience letters
July 19, 1988
P K Eide, K Hole
11 citations
Injecting substance P into the spinal cord of mice temporarily caused a behavioral syndrome but no lasting toxic effects or changes in pain sensitivity measured by tail-flick response to heat. However, when given 30 minutes later, the pain-suppressing effect of the serotonin receptor agonist 5-MeODMT was markedly reduced. Skin temperatures were nearly identical between substance P and control groups, ruling out temperature changes as a confound. These results indicate a functional interaction between substance P and serotonin in spinal pain processing, suggesting that intrathecal substance P modulates serotonin receptor function.
Journal of neural transmission
January 1, 1989
P K Eide, K Hole
9 citations
Repeated administration of the psychedelic compound 5-MeODMT in mice reduces its own pain-killing effect and that of a related drug, 8-OH-DPAT, in tail-flick and hot-plate tests. The behavioral responses to spinal injections of serotonin and substance P—vigorous biting, licking, and scratching—were also weakened after repeated 5-MeODMT treatment. The findings suggest that repeated 5-MeODMT downregulates serotonin receptors involved in pain relief, and the rapid desensitization to both serotonin and substance P may indicate a functional interaction between these two signaling molecules in the spinal cord's modulation of pain.