Physiology & behavior
January 1, 1987
T Archer, E Arweström, B G Minor et al.
32 citations
In rats and mice, two drugs that activate serotonin receptors (8-OH-DPAT and 5-MeODMT) reliably produced pain relief in three different tests (tail-flick, hot-plate, and shock-titration). However, when the animals were pretreated with a toxin that destroys noradrenaline neurons (DSP4) given systemically, or with 6-hydroxydopamine injected directly into the spinal cord, the pain-relieving effects of both drugs were eliminated. In the tail-flick test, 8-OH-DPAT actually caused increased pain sensitivity after spinal cord noradrenaline depletion. Biochemical measurements confirmed that the toxins severely reduced noradrenaline in the spinal cord. The findings suggest that the pain relief from these serotonin drugs depends on intact noradrenaline nerve endings in the spinal cord, pointing to a critical interaction between noradrenaline and serotonin systems in spinal pain processing.
British journal of pharmacology
October 1, 1986
T Archer, W Danysz, G Jonsson et al.
16 citations
In rats, drugs that block alpha-2 adrenoceptors (yohimbine and phentolamine) injected into the spinal cord prevented or reduced the pain-relieving effects of a serotonin-like drug (5-MeODMT) in three different pain tests (hot-plate, tail-flick, and shock titration). A different blocker (prazosin) reduced the pain relief in two of the tests but not the third. Yohimbine alone lowered pain thresholds in a dose-dependent way. The results indicate that alpha-2 adrenoceptors interact with serotonin-induced pain relief at the spinal level.
Journal of neural transmission
January 1, 1988
B G Minor, M L Persson, C Post et al.
7 citations
In rats, destroying spinal norepinephrine (NA) neurons with 6-hydroxydopamine eliminated the pain-relieving effect of the serotonin receptor agonist 5-MeODMT in three different pain tests. Replacing NA directly into the spinal cord restored the analgesic effect. Chemical analysis confirmed a 95% loss of NA in the spinal cord. Destroying serotonin neurons with 5,7-DHT reduced the analgesic effect in one test. The findings show that NA is necessary for 5-MeODMT to produce analgesia and further clarify how NA modulates serotonin-related pain relief.
Behavioral and neural biology
July 1, 1986
W Danysz, G Jonsson, B G Minor et al.
6 citations
Two experiments on rats show that depleting noradrenaline or serotonin in specific brain and spinal cord regions blocks or reduces pain relief from a drug called 5-MeODMT. Destroying noradrenaline-producing neurons in the locus coeruleus or spinal cord completely eliminated the drug's analgesic effect in three pain tests. Destroying serotonin-producing neurons in the nucleus raphe magnus or spinal cord only partly reduced the effect in two of the tests. The findings indicate that descending noradrenergic and serotonergic pathways interact, likely within the spinal cord, to produce this pain relief.