Effects of acute intoxication with hydrogen sulfide on central amino acid transmitter systems.

The acute effects of hydrogen sulfide (H2S) on brain amino acid levels were examined in five regions of the rat brain following administration of either saline (controls), or 10 or 30 mg/kg i.p. of sodium hydrosulfide (NaHS). These doses represented sublethal (0.66 x LD50) as well as lethal (2 x LD50) amounts. No significant changes in amino acid levels were found in the cerebral cortex, striatum or hippocampus. In the cerebellum, aspartate and glycine levels declined at 10 mg/kg NaHS. The region showing the greatest change was the brainstem where aspartate, glutamate, glutamine, GABA, glycine and taurine and alanine all increased. It would appear then, that acute intoxication results in substantial changes in brainstem amino acid levels. As some of these amino acids have been implicated in the neuronal control of breathing, one of the underlying causes of death following H2S may be the alteration of amino acid neurotransmitter levels and metabolism resulting in the arrest of central respiratory drive.