Behavioural and glial cell effects of inhalation exposure to styrene vapour with special reference to interactions of simultaneous peroral ethanol intake.

Male Wistar rats were exposed to 300 p.p.m. of styrene vapour with simultaneous ethanol ingestion for 4 to 17 weeks. The effects on behaviour were analyzed after 4, 9 and 13 weeks of the experiment. The most manifest behavioural effects were found in rats exposed to the combination, and the changes included increased preening time at the 4th week and increased ambulation and rearing at the end of the exposure. The ethanol ingestion affected also the accumulation of the solvent burden by delaying the peak solvent concentration in the perirenal fat to the 8th week of exposure. The fat solvent concentration did not differ from each other in the two groups at the end of the experiment, and they were similar as compared the concentration found in phenobarbital-pretreated rats exposed for reference. The styrene exposure had almost no effects on cerebral glial cells whereas ethanol induced unexpectedly increased protein destruction in them throughout the experiment. Co-exposure to ethanol and styrene decreased the magnitude of protein destruction in the glial cells. Withdrawal of the rats after an 8-week exposure showed that the styrene effects were largely abolished in two weeks of exposure-free period as analyzed by the determination of brain RNA and acid proteinase activity. Brain RNA was lower than control after two weeks of ethanol deprivation. The present data indicate that marked metabolic interactions between ethanol and styrene take place in agreement with experience on other similar solvent combinations.