POSITRON EMISSION TOMOGRAPHY STUDIES OF HEALTHY-VOLUNTEERS - NO EFFECTS ON THE DOPAMINE TERMINALS AND SYNTHESIS AFTER SHORT-TERM EXPOSURE TO TOLUENE

Despite extensive research, the mechanisms for the effects of organic solvents on the central nervous system are still unknown. One mechanis m proposed is that solvents interfere with the synthesis of neurotrans mitters. In the present study 11 male healthy volunteers were exposed during 15 min to 100 p.p.m. toluene at light physical exercise, and th e dopamine decarboxylase activity and number of terminals in putamen w ere measured before and after exposure by positron emission tomography . Two different tracers were used, [beta-C-11]L-DOPA for decarboxylase activity during the in vivo synthesis of dopamine, and [C-11] nomifen sine to estimate the number of terminals. Although there was a slight increase in the rate of dopamine synthesis in the putamen after the ex posure, this difference was not statistically significant (P=0.4). No effect was observed with regard to the uptake of nomifensine. There wa s nb significant relationship between the dose of toluene and rate of dopamine synthesis, and no significant correlation between the time fr om end of exposure to start of the PET-camera and DOPA. Our findings i ndicate that short term exposure to 100 p.p.m. of toluene does not aff ect the rate of dopamine synthesis or the number of presynaptic termin als.