Differential alteration of dopamine, acetylcholine, and glutamate release during anoxia and/or 3,4-diaminopyridine treatment.

The potassium-stimulated release of acetylcholine (ACh), glutamate (GLU) and dopamine (DA) from mouse striatal slices was studied during anoxia and/or 3,4-diaminopyridine (DAP) treatment. Anoxia, in the presence of calcium, increased DA and GLU release, but depressed ACh release. Omission of calcium from an anoxic incubation further stimulated GLU and DA release and impaired ACh release. Under normoxic conditions, DAP (100 microM) increased the release of all three neurotransmitters; the sensitivity of the slices to DAP changed with the presence or absence of an acetylcholinesterase inhibitor in the preincubation media. During an anoxic incubation, DAP did not ameliorate the anoxic-induced, K+-stimulated impairment of ACh release, but significantly reduced the K+-stimulated release of GLU and DA. These results are consistent with the hypothesis that hypoxia induces a presynaptic deficit that may underlie postsynaptic ischemic-induced changes. Amelioration of these presynaptic alterations in neurotransmitter release may be an effective approach to preventing hypoxic-induced damage.