Cortical ablation reduces veratridine evoked release of endogenous glutamate from superfused substantia nigra slices.

A brain slice superfusion system and HPLC coupled to fluorometric detection were used to study depolarization-evoked release of endogenous glutamate (Glu) and aspartate (Asp) from substantia nigra (SN) slices. Veratridine (15-25 microM) and K+ (50 mM) evoked both a Ca2(+)-dependent and Ca2(+)-dependent release of Glu and Asp. However, the pattern of Glu release was different from that of Asp. In addition, cortical ablation significantly reduced the evoked release of Glu but not that of Asp. There results indicate the existence in SN of functional Glu- and Asp-releasing nerve terminals. Some of the Glu-enriched nerve terminals might belong to a cortico-nigral neuronal pathway.