Clonidine modulates locus coeruleus metabolic hyperactivity induced by stress in behaving rats.

To assess, under rigorously chronic conditions, whether clonidine would modulate the increased activity engendered by stress in the locus coeruleus (LC), rats implanted for recordings by in vivo voltammetry, were subjected to immobilization (10 min). When injected 30-60 min before stress, clonidine 50-200 micrograms/kg i.p. modulated the increased catechol metabolic activity in a dose-dependent manner. This provides a biochemical basis, obtained in behaving rats, for using clonidine as a stabilizer in syndromes where central noradrenergic or peripheral sympathetic activities are heightened.