THE EFFECT OF SUMATRIPTAN ON BRAIN MONOAMINES IN RATS

Clinical data suggests that sumatriptan is effective in the acute trea tment of migraine. The vascular effects of the drug have been invoked to explain this antimigraine efficacy. However, the affect of sumatrip tan on brain monoamines has not previously been investigated. In order to study these hypothetical effects, we administered the drug to 24 m ale rats, subcutaneously, at three doses (0.3, 0.6, and 0.9 mg/kg of b ody weight), and 30 minutes later, all animals were decapitated. Dopam ine, serotonin, and their metabolites 3,4 dihydroxyphenylacetic acid, 5-hydroxyindoleacetic acid, and homovanillic acid concentrations were measured in the frontal cortex, hypothalamus, striatum, and hippocampu s, by high performance liquid chromatography. Plasma concentrations of the drug were also determined. The control group was treated with NaC l 0.9%, given subcutaneously. Sumatriptan, at the dose of 0.3 mg/kg di d not alter the brain monoamine concentrations; however, at the dose o f 0.6 mg/kg, sumatriptan decreased serotonin concentration in the hypo thalamus and increased the turnover of dopamine and serotonin in the h ypothalamus and striatum, while at the dose of 0.9 mg/kg, it augmented only the turnover of serotonin in the hypothalamus. No dose- dependen t effect of the drug was found. This subcortical antidopaminergic and antiserotoninergic effect of sumatriptan may be involved in its antimi graine action.