The effects of cyanide on the extracellular levels of dopamine, 3,4-dihydroxyphenylacetic acid, homovanillic acid, 5-hydroxyindoleacetic acid and inositol phospholipid breakdown in the brain.

The effects of sodium cyanide on the extracellular levels of dopamine and the main brain metabolites of dopamine and 5-hydroxytryptamine were studied in awake, freely moving rats using microdialysis technique. Already 20 min after the administration of cyanide (2 mg/kg; ip) the extracellular level of striatal dopamine was increased and after 40 min an enhancement of the homovanillic acid level was observed. Slight but significant decreases of 3,4-dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid were also observed. The increased extracellular levels of dopamine and homovanillic acid could indicate an increased release of dopamine. An alternative explanation could be an extracellular leakage of dopamine due to neuronal damage caused by cyanide. Cyanide has also been reported to induce marked changes in cytosolic brain Ca2+. We examined the effect of cyanide on inositol phospholipid breakdown in rat cerebral cortex and pig striatum in vitro. This breakdown was not affected by sodium cyanide and appears therefore not to be responsible for the reported changes of cytosolic Ca2+ induced by sodium cyanide.