Changes in the amounts of neurotransmitters released from the striatum and spontaneous motor activity in rats exposed to high doses of toluene.

Abstract

We studied the neurotoxicological effects of high-dose toluene exposure by measuring neurotransmitter release from the striatum and spontaneous motor activity in freemoving Tokai High Avoider (THA) male rats. The rats were exposed to 1,000, 2,000, and 4,000ppm toluene for 4 hours. During the 4-hour exposure period and each one hour pre- and post-exposure periods, acetylcholine (ACh), 3, 4-dihydroxyphenylacetic acid (DOPAC), homovanilic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA) in the microdialysate from kthe striatum of each rat were measured continuously using microdialysis. Simultaneously, spontaneous motor activity of each rat was monitored using an Aimex device. The amounts of neurotransmitters released and spontaneous motor activity showed similar changes for every concentration of toluene exposure during those periods. Although minimal changes in neurotransmitters and motor activity were observed in the 1,000 ppm group, increases in neurotransmitter release and motor activity were observed in the 2,000 ppm group during the entire exposure period and also in the 4,000 ppm group during the early period of exposure. On the other hand, decreases in neurotransmitter release and motor activity were observed in the 4,000 ppm group during the late period of exposure. These findings indicate that the striatum influences motor activity via changes in the amounts of neurotransmitters released during the period of high-dose toluene exposure.