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 wer e studied in a wake, 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 mi n an enhancement of the homovanillic acid level was observed. Slight b ut significant decreases of 3,4-dihydroxyphenylacetic acid and 5-hydro xyindoleacetic acid were also observed. The increased extracellular le vels of dopamine and homovanillic acid could indicate an increased rel ease 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 Ca 2+. We examined the effect of cyanide on inositol phospholipid breakdo wn in rat cerebral cortex and pig striatum in vitro. This breakdown wa s not affected by sodium cyanide and appears therefore not to be respo nsible for the reported changes of cytosolic Ca2+ induced by sodium cy anide. (C) 1995 Intox Press, Inc.