Academic
Publications
Effect of intrathecal serotonin on nociception in rats: influence of the pain test used

Effect of intrathecal serotonin on nociception in rats: influence of the pain test used,10.1007/BF02454144,Experimental Brain Research,L. Bardin,M. Ba

Effect of intrathecal serotonin on nociception in rats: influence of the pain test used   (Citations: 53)
BibTex | RIS | RefWorks Download
The involvement of serotonin (5-HT) in the modulation of nociceptive impulse in the spinal cord has been widely studied. However, its activity, considering the nature of noxious stimuli and the type of 5-HT receptors involved, merits to be further elucidated. The present behavioural study was performed to compare the doseantinociceptive effect relationship of 5-HT in rats, after intrathecal, (i.t.) injection (10 μl/rat), using mechanical (paw pressure), thermal (tail immersion and tail-flick) and chemical (formalin) pain tests. In rats submitted to the paw pressure test, 5-HT was found to possess a dose-dependent antinociceptive activity (0.01, 0.1, 1, 10 and 20 μg/rat) when vocalization threshold was assessed as a pain parameter. A peak effect occurred 5 min after the injection and the effect was maintained for 45 min. The lowest active dose was 0.1 μg (maximum increase in vocalization thresholds, 233%) and a plateau was observed for 10 μg and 20 μg (maximum increase in vocalization thresholds, 727% and 716%, respectively). When paw withdrawal was assessed, 5-HT induced a weak hyperalgesic effect for the highest dose (60μg), while other doses were ineffective. In the tail-immersion (warmth and cold) and tail-flick tests, different doses (0.01, 0.1, 1, 10, 30, 60 and 100 μg/rat), were studied. In the two immersion tests, only the highest doses (60 μg and 100 μg) significantly increased the withdrawal thresholds from 5 to 45 min after the injection. The maximum effect was observed at 5 min (234% and 216% for 60 μg; 273%, and 306% for 100 μg in the warmth and cold immersion test, respectively). In the tail-flick test, the doses of 30, 60 and 100 μg/rat dose-dependently and significantly increased the withdrawal thresholds from 5 to 45 min after the injection, with a maximum effect at 5 min (305% for 30 μg; 376% for 60 μg; and 454% for 100 μg). In the formalin test, 5-HT (10, 25, 50, 75 and 100 μg/rat) produced dose-related antinociception. The nociceptive response (licking of the injected paw) was significantly reduced from 25 μg (−5911%) in the early phase, whereas the lowest active dose in the late phase was 50 μg (−4617%). For both phases, a total inhibition was obtained with 100 μg. It is concluded that the effect of 5-HT on pain tests may differ according to the applied stimulus and the parameter assessed; unspecific effects of 5-HT may modify motor reactions to noxious stimuli. Mechanical test (assessment of vocalization) was the most sensitive to 5-HT. These observations are of importance in order to further study the pharmacological mechanisms involved in 5-HT spinally induced antinociception.
Journal: Experimental Brain Research - EXP BRAIN RES , vol. 113, no. 1, pp. 81-87, 1997
Cumulative Annual
View Publication
The following links allow you to view full publications. These links are maintained by other sources not affiliated with Microsoft Academic Search.
Sort by: