[3H]D-ASPARTIC ACID RELEASE IN BRAIN-SLICES OF ADULT AND AGED FISCHER 344 RATS

Alterations in glutamate content and uptake have been reported to occur in aged animals. The present studies used [H-3]D-Aspartic acid ([H-3]-D-ASP) release as a marker for glutamate neuro-transmission. Frequency dependent [H-3]-D-ASP release was measured in adult (8 month) and aged (28-30 month) Fischer 344 rats. Relatively high stimulation frequencies (> 10 Hz) were required to induce [H-3]-D-ASP release in both adult and aged F344 rats in temporal cortex and hippocampus. In both brain areas aged animals showed significantly more [H-3]-D-ASP release than adult animals. Kainic acid 1 mM failed to induce the release of [H-3]-D-ASP in either temporal cortex or hippocampus. Omega conotoxin GVIA (5 X 10(-9)M) a N and L type voltage sensitive calcium channel antagonist failed to inhibit [H-3]-D-ASP stimulated release. These results demonstrate an increase in [H-3]-D-ASP release in aged compared to adult F344 rats. The data also suggest a novel calcium channel may be involved in [H-3]-D-ASP release.