Nerve terminal damage in cerebral ischemia: Greater susceptibility of catecholamine nerve terminals relative to serotonin nerve terminals

The energy-dependent uptake of (3H)-dopamine (DA), (3H)-norepinephrine (NE) and (3H)-serotonin (5-HT) was measured in synaptosomes isolated from either the whole cerebral hemispheres or the striata of gerbils after cerebral ischemia. Ischemic stroke was induced in the Mongolian gerbil by left common carotid ligation. Uptake values in the affected hemisphere (expressed as a percent of the corresponding control hemisphere) were 32.6% for DA, 35.1% for NE, and 52.0% for 5-HT, 16 hours after stroke. The differential reduction in uptake of the catecholamines relative to 5-HT was significant (p less than 0.005). This differential persisted when measures were made on isolated striata from the ischemic and control hemispheres. In the latter measurements, uptake of DA was 20.7% of control and uptake of 5-HT was 44.7% of control. Uptake of both DA and NE were significantly reduced in animals exhibiting milder circling behavior, while uptake of 5-HT was not. There was no significant reduction of uptake in animals subjected to left common carotid ligation not exhibiting signs of stroke. These studies indicate a selective sensitivity of catecholamine nerve terminals to damage in ischemic stroke.