Reemphasis of the Role of 5-Hydroxytryptamine in Cerebral Ischemia

Cortical monoamine changes during ischemic episodes of up to one hour were studied in the gerbil. Norepinephrine (NE) levels decreased after 60 minutes in the occluded hemisphere of animals with stroke, but dopamine (DA) levels were unaltered. 5-Hydroxytryptamine (5-HT) levels became bilaterally reduced in animals with and without stroke as soon as 5 minutes after occlusion. Abnormal motor activity suggestive of seizure developed in some animals that exhibited signs of stroke. Accordingly, the influence of seizure activity on cortical monoamine changes was studied in a second experiment. Reduction of DA and NE was only observed when seizures occurred in association with stroke. 5-HT levels were reduced bilaterally in animals with and without signs of stroke and reduced further in animals with stroke plus seizure. We concluded that seizure activity must be taken into account when examining the mechanism of disordered catecholamine metabolism in the gerbil stroke model. However, 5-HT metabolism appears disordered in ischemic brain independent of seizure activity.