[Brain serotonin metabolism in experimental cerebral ischemia and the effect of coenzyme Q administration]

Bilateral ligation of common carotid arteries of male Wistar rats was produced during fasting for the periods of 15, 30 and 60 min. Thereafter the animals were killed by decapitation, and the brain was divided into the forebrain (ischemic portion), and the brain stem and the cerebellum (blood flow maintained portions by the vertebrobasilar artery system). The above three portions were subjected to fluorophotometry of serotonin (5-HT) and 5-hydroxindole acetic acid (5-HIAA) according to the method described by Curzon. In the different series of the studies, rats pretreated with coenzyme Q (CoQ) were exposed to bilateral ligation of common carotid arteries for 60 min, and the CoQ effect upon the serotonin metabolism was investigated. The results obtained were as follows; 1. The 5-HT levels in the forebrain progressively reduced starting at 15 min (p less than 0.01), and reached to 80.2% of the control value at 60 min (p less than 0.001), while those of the brain stem and the cerebellum showed no significant changes. 2. The time-course changes of 5-HIAA levels up to 60 min were not remarkable in the forebrain and the cerebellum, while those of brain stem revealed a decreasing tendency. 3. CoQ pretreatment to sham-operated rats disclosed a gross increasing trend of 5-HT and 5-HIAA concentrations in the brain stem. 4. CoQ preadministrated brains, of which bilateral common carotid arteries were ligated for 60 min, showed a statistically significant elevation of the 5-HT in the brain stem (p less than 0.01) and in the cerebellum (p less than 0.05), while the 5-HIAA level of CoQ preadministrated brains was higher only in the brain stem as compared to that of shamoperated rats (p less than 0.05). 5. The above results would lead to the hypothesis that CoQ treatment could activate brain serotonin metabolism in case of cerebral infarct.