Differential role of 5-HT(1A) and 5-HT (1B) receptors on the antinociceptive and antidepressant effect of tramadol in mice
by
Berrocoso E, Rojas-Corrales MO, Mico JA.
Pharmacology and Neuroscience Research Group,
Department of Neuroscience (Pharmacology and Psychiatry),
School of Medicine,
University of Cadiz, Plaza Falla 9, 11003, Cadiz, Spain,
juanantonio.mico@uca.es.
Psychopharmacology (Berl). 2006 Sep;188(1):111-8.

ABSTRACT

RATIONALE: Tramadol, (1RS,2RS)-2-[(dimethylamine)-methyl]-1-(3-methoxyphenyl)-cyclohexanol hydrochloride, is an atypical analgesic which binds weakly to i-opioid receptors and enhances the extra-neuronal concentration of noradrenaline and serotonin by interference with both the uptake and release mechanisms. OBJECTIVES: The present study was undertaken to evaluate the potential role of 5-HT(1A) and 5-HT(1B) receptors on the analgesic and antidepressant-like effect of tramadol. METHODS: The effect of either a selective 5-HT(1A) receptor antagonist (WAY 100635; N-2-[4-(2-methoxyphenyl-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexane carboxamide; 0.2-0.8, 8 mg/kg) or a selective 5-HT(1B) receptor antagonist (SB 216641; N-[3-(3-dimethylamino) ethoxy-4-methoxyphenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-(1,1'-biphenyl)-4-carboxamide; 0.2-0.8, 8 mg/kg) was investigated in mice in combination with tramadol by means of the hot-plate test, a phasic nociceptive model, and the forced swimming test, a paradigm aimed at screening potential antidepressants. RESULTS: The results showed that WAY 100635 enhanced the antinociceptive effect and produced a large decrease in the antidepressant-like effect of tramadol. In contrast, SB 216641 did not significantly modify either the analgesic or the antidepressant-like effects of tramadol. CONCLUSIONS: These findings suggest that 5-HT(1A) receptors modulate the analgesic and the antidepressant-like effects of tramadol in differing ways. The results suggest the involvement of the 5-HT(1A) autoreceptors from the raphe nuclei and spinal 5-HT(1A) receptors in the antinociceptive effect. In contrast, the 5-HT(1A) receptors located in the forebrain may be responsible for the blockade of the antidepressant-like effect of tramadol. 5-HT(1B) receptors seem not to modify these effects in the models investigated.

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Antidepressant
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Tramadol and analgesia
Tramadol: pharmacology
Tramadol as an antidepressant
Tramadol: risk/benefit analysis
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Tramadol : morning or evening?
Methadone for tramadol addicts?
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Pharmacokinetics and pharmacodynamics
Tramadol, depression and Parkinson's disease

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