Metabolism of the dorsal cochlear nucleus in rat brain slices

In vitro brain slices of the cochlear nucleus have been used for electrophy siological and pharmacological studies. More information is needed about th e extent to which the slice resembles in vivo tissue, since this affects th e interpretation of results obtained from slices. In this study, some chemi cal parameters of the dorsal cochlear nucleus (DCN) in rat brain slices wer e measured and compared to the in vivo state. The activities of malate dehy drogenase and lactate dehydrogenase were reduced in some DCN layers of incu bated slices compared to in vivo brain tissue. The activities of choline ac etyltransferase and acetylcholinesterase were increased or unchanged in DCN layers of slices. Adenosine triphosphate (ATP) concentrations for in vivo rat DCN were similar to those of cerebellar cortex. Compared with in vivo v alues, ATP concentrations were decreased in the DCN of brain slices, especi ally in the deep layer. Vibratome-cut slices had lower ATP levels than chop per-cut slices. Compared with the in vivo data, there were large losses of aspartate, glutamate, glutamine, gamma-aminobutyrate and taurine from incub ated slices. These amino acid changes within the slices correlated with the patterns of release from the slices. (C) 2000 Elsevier Science B.V. All ri ghts reserved.