Evidence for an action of araboascorbic acid on dopaminergic pathways of the corpus striatum

The relative decrease in the 2 h accumulation of administered [3H]-spiperone (SPI)-2 muCi/kg, 0.0004 mg/kg, s.c. - in mouse corpus striatum, a brain area with a high dopaminergic input (specific plus nonspecific dopamine receptor ligand binding) and the cerebellum, a brain area with little, if any, dopaminergic input (an index of nonspecific dopamine receptor ligand binding) were used to compare the influence of araboascorbic acid (AraA) with ascorbic acid (AsA) on the dopamine receptor. The abilities of these compounds to potentiate haloperidol-induced catalepsy were also investigated. Pretreatment for 30 min with AraA (1000 or 2000 mg/kg, i.p.) produced the same dose-dependent decrease in SPI accumulation in corpus striatum as observed with AsA. Accumulation in cerebellum was unaffected by either agent. Furthermore, as previously shown for AsA in rats and monkeys, AsA (1000 mg/kg) potentiated the cataleptogenic effect of haloperidol (0.2 mg/kg, s.c.). AraA was at least as effective as AsA in potentiating catalepsy produced by the neuroleptic. Thus, it would appear that AraA influenced the dopamine receptor in a manner not unlike that already shown for AsA. Because both agents have almost identical redox potentials but divergent antiscorbutic activities, their reductive properties might be more pertinent to the observed effects than their antiscorbutic properties.