The role of spinal cord 5-HT1A and 5-HT1B receptors in the modulation of a spinal nociceptive reflex.
The role of the 5-hydroxytryptamine (5-HT) receptor subtypes in the spinal cord in the regulation of nociception is unknown. This study examined whether administration of different 5-HT1 receptor agonists into the spinal subarachnoid space of mice modulates the nociceptive tail-flick reflex, and whether effects on the tail-flick reflex involve changes in tail skin temperature. The tail-flick latencies (the time needed to evoke the tail-flick reflex by noxious radiant heat) were significantly increased after intrathecal (i. th.) injection of 5-HT (10-20 micrograms), the 5-HT1A/5-HT1B receptor agonist 5-methoxy-N,N-dimethyltryptamine (5-MeODMT, 10-20 micrograms), the selective 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT, 20 micrograms) and after i.th. injection of 1(m-chlorophenyl)piperazine (mCPP, 5-20 micrograms) and 5-methoxy-3(1,2,3,6-tetrahydropyridin-4-yl)-1H-indole (RU 24969, 5-20 micrograms) which have high affinity for the 5-HT1B receptors. None of the 5-HT1 receptor agonists had the ability to change the tail skin temperature. The results show that in the mouse i.th. injection of both 5-HT1A and 5-HT1B receptor agonists has the ability to inhibit the tail-flick reflex without interfering with the tail skin temperature.
Eide
P K
PK
Department of Physiology, University of Bergen, Norway.
Joly
N M
NM
Hole
K
K
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D007211:Indoles / Q000494:pharmacology; D007278:Injections, Spinal; D008297:Male; D008732:Methoxydimethyltryptamines / Q000494:pharmacology; D051379:Mice; D010146:Pain / Q000503:physiopathology*; D010147:Pain Measurement / Q000379:methods; D010879:Piperazines / Q000494:pharmacology; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D011985:Receptors, Serotonin / Q000502:physiology*; D012018:Reflex / Q000187:drug effects / Q000502:physiology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D012881:Skin Temperature / Q000502:physiology; D013116:Spinal Cord / Q000737:chemistry / Q000502:physiology*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
D007211:Indoles; D008732:Methoxydimethyltryptamines; D010879:Piperazines; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D013764:Tetrahydronaphthalenes; C025145:5-methoxy 3-(1,2,3,6-tetrahydro-4-pyridinyl)1H indole; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; C015068:1-(3-chlorophenyl)piperazine