Increase of noradrenaline metabolism following electrical stimulation of the Locus coeruleus in the rat.

A sensitive gas–liquid chromatography method is described for measuring both free and conjugated 4-hydroxy-3-methoxyphenyl glycol (HMPG) in brain, which is applied to study the turnover of noradrenaline (NA) in brain when one Locus coeruleus (LC) is stimulated electrically. Stimulation was found to produce a rise in total HMPG on the ipsilateral side of brain when the current was sufficiently low to obviate current spread to the opposite LC. This suggests an increase in turnover of NA on electrical stimulation.