Toxic effects of peroral o-cresol intake on rat brain.

Male Wistar rats were given o-cresol in their drinking water (0.3 g/l) for 20 weeks. The ingested cumulative dose exceeded the acute LD50 at the fourth week of the experiment. O-cresol induced an increased drinking rate initially which decreased significantly below the drinking rate of the controls at the end of the experiment. The biochemical effects in the cerebral homogenate were inconspicuous, and they included increased RNA content initially, and reduced glutathione concentration and azoreductase activity at the end of experiment. Glial cells displayed significant increases in the acid proteinase and 2',3'-cyclic nucleotide 3'-phosphohydrolase activities at the 20th week of exposure.