Increase in glutamine content of rat midbrain induced by short-term exposure to toluene and hexane.

A method for quantitative analysis of free amino acids in rat brain was established. Rat midbrain was homogenized in HC104 solution and the supernatant was applied to a high-performance liquid chromatograph attached to a fluorescence detector. Amino acids were separated in an ion exchange column prepared for amino acid analysis and were reacted with o-phthalaldehyde. Fluorescence intensity was linear in a wide range of amounts of authentic amino acids (1.25-12.5 nmoles). Threonine, serine and glutamine were completely separated. Sixty minutes was required for the elution of nine amino acids, which were main components of free amino acids in rat midbrain. An 8-hr exposure of rats to 4000 ppm of toluene or hexane produced significant increase in glutamine content of the midbrain.