EFFECT OF SUMATRIPTAN ON CEREBRAL BLOOD-FLOW IN THE BABOON MODEL

Changes in cerebral blood flow are implicated to be important in the p athophysiology of migraine. Furthermore, serotonin (5-HT) is known to be the most important substance in the etiology of migraine. Sumatript an (CAS 103628-46-2), a 5-HTID receptor agonist was recently introduce d in the treatment of migraine. In the present study a baboon model wa s used to investigate the changes in cerebral blood flow due to anaest hesia and pharmacological interventions using Tc-99m-labelled hexameth ylpropylene amine oxime Tc-99m-HMPAO) and single photon emission compu ted tomography (SPECT). The effect of sumatriptan on cerebral blood fl ow was investigated after 10 min and again after 23 min, with the anim al under anaesthesia, i.e. induction with ketamine and maintenance on thiopental. Sumatriptan did not alter the cerebral blood flow during t he 10 min procedure. However, sumatriptan reversed the increased cereb ral blood flow due to the prolonged anaesthesia (23 min), lowering mor e than 20%. No significant changes in the biochemical parameters (bloo d pressure, heart rate pO(2) and pCO(2)) were observed. These results also suggest that sumatriptan reverses the increased cerebral blood fl ow most likely via 5-HTID receptor stimulation.