Heterogeneous effects of serotonin in the dorsal horn of rat: the involvement of 5-HT1 receptor subtypes.
The effect of ionophoretically applied serotonin (5-HT) was tested on cutaneous sensory responses of multireceptive dorsal horn neurones in the anaesthetized rat. Three types of 5-HT action were discerned: selective inhibition of nociceptive responses (10/18 cells), non-selective inhibition of responses to both noxious and innocuous stimuli as well as to excitatory amino acids (4/18 cells) and non-selective excitation of evoked responses (1/18 cells). A few cells (3/18) were unaffected by 5-HT. The use of agonists, shown to discriminate between subtypes of 5-HT1 receptor revealed that a 5-HT1A receptor agonist mimicked the non-selective effects of 5-HT, whereas a 5-HT1B receptor agonist mimicked the selective antinociceptive effects of 5-HT. A 5-HT2 receptor agonist, in contrast, was without effect. Both the selective and the non-selective effects were reversed by a 5-HT1 receptor antagonist, but not a 5-HT2 antagonist.
el-Yassir
N
N
Department of Preclinical Veterinary Sciences, Royal (Dick) School of Veterinary Studies, University of Edinburgh, U.K.
Fleetwood-Walker
S M
SM
Mitchell
R
R
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D007211:Indoles / Q000494:pharmacology; D007650:Ketanserin / Q000494:pharmacology; D008297:Male; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology*; D010146:Pain / Q000503:physiopathology; D010812:Physical Stimulation; D010869:Pindolol / Q000031:analogs & derivatives / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology*; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
D007211:Indoles; D011985:Receptors, Serotonin; D013764:Tetrahydronaphthalenes; C025145:5-methoxy 3-(1,2,3,6-tetrahydro-4-pyridinyl)1H indole; D012701:Serotonin; C047975:cyanopindolol; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D007650:Ketanserin; D010869:Pindolol