The Effect of in Vitro and in Vivo Toluene Exposure on Rat Erythrocyte and Synaptosome Membrane Integral Enzymes

Abstract

The mechanism of the anaesthetic effect of toluene on the central nervous system (CNS) was studied by using rat erythrocyte and synaptosome membranes as nerve cell models both in vitro and in vivo. The activities of the membrane-bound integral enzymes acetylcholinesterase (AChE), total adenosine triphosphatase (total ATPase) and magnesium-activated adenosine triphosphatase (Mg2+-ATPase) were determined. A short-term exposure to 2000 p.p.m. of toluene had an inhibitory effect on the enzyme activities studied. The degree of inhibition in erythrocyte membranes in vitro and in vivo, and in synaptosome membranes in vitro were in good correlation. In in vivo conditions, the synaptosome-bound enzymes were, however, significantly more inhibited by toluene, which indicates that membranes in vivo are even more vulnerable to the toxic effects of organic solvents than they are as isolated membranes in vitro. However, our results show that in vitro experiments can be used to predict the toxic nerve cell membrane effects of organic solvents. Toluene caused similar enzyme inhibitions both in neural cell membranes and in erythrocyte membranes. Thus, even peripheral non-excitable cell membranes, like erythrocytes, can be used as nerve cell membrane models in studies on the mechanism of the anaesthesia caused by solvents.

Effect of toluene and cresols on Na+,K+-ATPase, and serotonin in rat brain

“…The most outstanding are Korpela and Tahti's (1988), who suggest that toluene (highly lipophylic) acts on membrane lipids. On the other hand Lebel and Schatz (1990), propose that the eVect is speciWcally on phospholipids, and Franks and Lieb (1987) suggest that organic solvents act on membrane proteins.…”

“…This is an important catecholamine for brain biochemical metabolism with antioxidant activity in the presence of free radicals, which generate oxidative stress (Lehotssky et al, 1999). The enzyme Na + ,K + -ATPase reduces its activity up to 50% due to oxidative stress (Gutteridge and Halliwell, 1990;Korpela and Tahti, 1988), even though its mechanism of action has not been entirely deWned. Lipid peroxidation is a marker of oxidative stress that facilitates the evaluation of the damage caused by free radicals on membrane lipids (Lebel and Schatz, 1990), particularly the unsaturation of the biomolecules that make up the lipid double-layer.…”

Impact of gasoline inhalation on some neurobehavioural characteristics of male rats

“…The inhibition of the plasma membrane Na + , K + -ATPase might have been attributed to a direct effect of the solvents and alcohols in the gasoline on the membrane causing dissolving the its bilayers. The most outstanding are toluene (highly lipophylic) acts on membrane lipids and the effect is specifically on phospholipids and on the other hand the organic solvents act on membrane proteins [34,41,42]. Also as the functional hydroxyl group (OH - ) moves away from the functional methyl group (CH 3 ) attached to the aromatic ring of the solvents, the biogenic amines, lipid peroxidation, and Na + , K + -ATPase and total ATPase enzyme activity tend to suffer important changes, indicating that the stearic impediment effect and the inductive effect produced at the aromatic ring of the solvents play an important role in the response of biogenic amine metabolism, together with the enzymes and lipid peroxidation of animal brain membranes [39].…”

Toluene-induced oxidative stress in several brain regions and other organs

“…Several neurological deficits have been described in experimental animals following inhalation or intraperitoneal injection, including modified levels of enzymes (Korpela and Tahti, 1988), lipids (Kyrklund et al, 1987), and specific neurotransmitter receptors (Yamawaki et al, 1982;Von Euler et al, 1988). Behavioral and electroencephalic changes have also been reported (Naaslund, 1986;Rees et al, 1989).…”