Effects of cyanide on the striatal dopamine receptor binding in the rat

Abstract

In previous studies we have shown that sodium cyanide decreases the striatal dopamine levels within 60 s compared with the controls. Treatment with sodium cyanide also increases the naturally occuring 3,4-dihydroxy-L-phenylalanine (L-DOPA) in the striatum, but not in any other region studied. An increase in the in vivo synthesis of dopamine in cyanide-treated rats has also been observed. In order to further elucidate the effects on the central dopaminergic pathways the effects of sodium cyanide on the striatal dopamine D 1 and dopamine D 2 receptor binding were studied in vitro and after administration of sodium cyanide. In the rats injected with sodium cyanide (2.0 mg/kg, i.p.) the B max of the striatal dopamine D 1 receptor binding was significantly decreased 15 min and 1 h after the treatment. The striatal dopamine D 2 receptor binding was decreased only at 1 h after the cyanide administration. Neither sodium cyanide nor its metabolite sodium thiocyanate did significantly change the striatal dopamine D 1 and D 2 receptor binding in vitro. Accordingly sodium cyanide and sodium thiocyanate do not have direct effects on the dopamine receptors studied. The effects of cyanide on dopamine D 1 and D 2 receptors are probably in part due to the effect of cyanide on the release of dopamine.