Metabolism of monoamine neurotransmitters in the evolution of infarction in ischemic striatum.

The time course of changes in monoamine metabolism in ischemic striatum was assessed by measurement of levels of dopamine (DA), dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), serotonin (5-HT) and 5-hydroxy-indole-acetic acid (5-HIAA) 2, 4, 7 and 16 hours after irreversible unilateral carotid ligation in Mongolian gerbils with stroke. DA was reduced to 30% of the level in the contralateral non-ischemic striata by 2 hours after stroke, but DOPAC was significantly elevated (p less than 0.01) to 227%, while HVA remained equal to control. At 4 hours after stroke, DOPAC was 86% of the contralateral non-ischemic striata but HVA had risen to 130%. At 7 hours after stroke, DOPAC in the ischemic striata was 148% of control, while HVA remained at 133%. By 16 hours after stroke, DA, DOPAC and HVA were depleted from the ischemic striata, corresponding to the time course for irreversible damage to the neurotransmitter uptake function of nerve terminals. 5-HT levels in the ischemic striata were 30% of control at 2 hours, 46% at 4 hours, 30% at 7 hours and 21% at 16 hours, while 5-HIAA remained equal to control throughout the time course. These studies indicate that monoamine metabolism continues in ischemic striatum for up to 8 hours after the onset of stroke following irreversible unilateral carotid ligation in the Mongolian gerbil, but metabolism of DA is disrupted by 16 hours after stroke while metabolism of 5-HT continues.