Effects of serotonin receptor antagonists and agonists on the tail-flick response in mice involve altered tail-skin temperature.
Tail-flick latency and tail-skin temperature were measured in mice after administration of serotonin (5-HT) receptor antagonists (metergoline and metitepin) and agonists [5-methoxy-N,N-dimethyltryptamine (5-MeODMT) and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT)]. Metergoline (4 mg/kg) and metitepin (0.5 mg/kg) reduced the tail-flick latencies and increased the tail-skin temperatures, but the effect on the tail-flick latencies was non-significant when the effect of temperature was taken into account. Both 5-MeODMT (3 mg/kg) and 8-OH-DPAT (1 mg/kg) reduced the tail-skin temperature but only 5-MeODMT increased the tail-flick latencies. The effect of 5-MeODMT on tail-flick latencies was still highly significant when the effect of temperature was taken into account. The results show that the apparent hyperalgesia elicited by 5-HT receptor antagonists in the tail-flick test in the mouse is secondary to increased tail-skin temperature and not due to increased nociceptive sensitivity. The antinociceptive effect of 5-MeODMT in the tail-flick test can, however, not be explained by effects of temperature.
Eide
P K
PK
Department of Physiology, University of Bergen, Norway.
Tjølsen
A
A
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin; D000818:Animals; D007036:Hypothermia, Induced; D008297:Male; D008711:Metergoline / Q000494:pharmacology; D008719:Methiothepin / Q000494:pharmacology; D008732:Methoxydimethyltryptamines / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D011930:Reaction Time / Q000187:drug effects*; D011985:Receptors, Serotonin / Q000187:drug effects*; D012881:Skin Temperature / Q000187:drug effects*; D013764:Tetrahydronaphthalenes / Q000494:pharmacology
D008732:Methoxydimethyltryptamines; D011985:Receptors, Serotonin; D013764:Tetrahydronaphthalenes; D008711:Metergoline; D008719:Methiothepin; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin