IN-VITRO STUDY OF THE CATECHOLAMINERGIC METABOLISM OF LOCUS-COERULEUSNEURONS BY DIFFERENTIAL NORMAL PULSE VOLTAMMETRY

The aim of the present work was to measure, by voltammetry, the catech olaminergic metabolic activity of rat locus coeruleus (LC) neurones in brain slices. For this new experimental approach, we used an optimize d protocol of slice preparation intended to prevent neuronal damages d ue to brain ischaemia. Our results show that the LC neurones exhibit i n vitro a stable spontaneous catecholaminergic metabolic activity and that, as in vivo, 3,4-dihydroxyphenylacetic acid (DOPAC) is likely to be the main contributor to the recorded signal. This catecholaminergic metabolic activity can be pharmacologically altered by administering carbachol and clonidine to the superfusion fluid. We also determined t he values of bath temperature and superfusion flow rate providing, in our methodological conditions, an optimal catecholaminergic metabolic activity. Finally, we took advantage of both the direct accessibility to the LC and the compactness of this nucleus to determine the spatial resolution of differential normal pulse voltammetry. In conclusion, t he study of the subregional mechanisms controling the catecholaminergi c metabolism in LC neurones can be performed in brain slices by differ ential normal pulse voltammetry.