Actions of tramadol on micturition in awake, freely moving rats
Article first published online: 29 JAN 2009
2003 British Pharmacological Society
British Journal of Pharmacology
Volume 139, Issue 4, pages 741–748, June 2003
How to Cite
Pandita, R. K., Pehrson, R., Christoph, T., Friderichs, E. and Andersson, K.-E. (2003), Actions of tramadol on micturition in awake, freely moving rats. British Journal of Pharmacology, 139: 741–748. doi: 10.1038/sj.bjp.0705297
- Issue published online: 29 JAN 2009
- Article first published online: 29 JAN 2009
- (Received January 20, 2003, Revised March 19, 2003, Accepted March 26, 2003)
- monoamine reuptake;
(±)-Tramadol, a widely used analgesic, is a racemate stimulating opioid receptors and inhibiting reuptake of noradrenaline and serotonin, that is, pharmacological principles previously shown to influence rat micturition.
We studied both (±)-tramadol and its enantiomers in conscious Sprague–Dawley rats undergoing continuous cystometry. The effects of these agents were compared to those of morphine (μ-opioid receptor agonist) and tested after pretreatment with naloxone (μ-opioid receptor antagonist). Cystometries were evaluated before and after intravenous (i.v.), intraperitoneal (i.p.) and intrathecal (i.t.) drug administrations.
The most conspicuous effects of i.v. (±)-tramadol (0.1–10 mg kg−1) was an increase in threshold pressure and an increase in micturition volume.
These effects were mimicked by (+)-tramadol (0.1–5 mg kg−1 i.v.), whereas (−)-tramadol (5 mg kg−1 i.v.) did not influence threshold pressure and micturition volume.
The effects of (±)-tramadol 5 mg kg−1 on micturition volume were blocked by pretreatment with naloxone 0.3 mg kg−1. Morphine (0.3–10 mg kg−1 i.p.) increased threshold pressure but did not significantly increase micturition volume in doses not resulting in overflow incontinence.
(±)-Tramadol 10 mg kg−1 increased urine production, an effect blocked by desmopressin 25 ng kg−1.
(±)-Tramadol effectively inhibits micturition in conscious rats by stimulating μ-opioid receptors. A synergy between opioid receptor stimulation and monoamine reuptake inhibition may contribute to the micturition effects.
British Journal of Pharmacology (2003) 139, 741–748. doi:10.1038/sj.bjp.0705297