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Role of 5-HT and NA in spinal dopaminergic analgesia.
- Source :
-
European journal of pharmacology [Eur J Pharmacol] 1982 Dec 17; Vol. 86 (1), pp. 65-70. - Publication Year :
- 1982
-
Abstract
- Spinal rats and rats with an intact neuraxis given the dopamine (DA) agonist R-apomorphine (0.31-1.75 mumol/kg) in the lumbar subarachnoid space by intrathecal injection were tested 5 and 10 min later for spinal analgesia (increased tail-flick response latency). Apomorphine produced analgesia in spinal rats but not in rats with an intact neuraxis. However, pretreatment of intact rats with the serotonergic (5-HT) receptor antagonist methysergide, the noradrenergic (NA) receptor antagonist phentolamine or the two antagonists together led to a dose-dependent analgesia following apomorphine. Intact rats pretreated with the monoamine depleting drug reserpine, the 5-HT synthesis inhibitor p-chlorophenylalanine (PCPA) or the NA synthesis inhibitor FLA 63 also showed analgesia to apomorphine. On the other hand, pretreatment with the catecholamine depleting agent alpha-methyl-p-tyrosine (AMPT), the beta-adrenergic receptor blocker propranolol or the opioid receptor antagonist naloxone failed to produce DA analgesia. The present findings suggest that both 5-HT and NA descending fiber systems exert tonic inhibitory effects on spinal DA nociceptive processes.
Details
- Language :
- English
- ISSN :
- 0014-2999
- Volume :
- 86
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- European journal of pharmacology
- Publication Type :
- Academic Journal
- Accession number :
- 6297926
- Full Text :
- https://doi.org/10.1016/0014-2999(82)90397-1