Antidepressant-Like Effect of tramadol and its Enantiomers in Reserpinized Mice: Comparativestudy with Desipramine, Fluvoxamine, Venlafaxine and Opiates:

Tramadol is a centrally acting analgesic that demonstrates opioid and monoaminergic properties. Several studies have suggested that tramadol could play a role in mood improvement. Moreover, it has previously been shown that tramadol is effective in the forced swimming test in mice and the learned helplessness model in rats, two behavioural modelspredictive of antidepressant activity. The aim of the present study was to test tramadol and its enantiomers in the reserpine test in mice, aclassical observational test widely used in the screening of antidepressant drugs. This test is a non-behavioural method where only objective parameters such as rectal temperature and palprebral ptosis are considered. Moreover, we compared the effects of tramadol and itsenantiomers with those of antidepressants (desipramine, fluvoxamine and venlafaxine) and opiates [morphine (–)-methadone and levorphanol]. Racemic tramadol, (–)-tramadol, desipramine and venlafaxine reversed the reserpine syndrome (rectal temperature and ptosi...