Effects of desipramine and maprotiline on the coeruleus-cortical noradrenergic system in anaesthetized rats

Desipramine (1-3000 micrograms/kg i.v.) and maprotiline (1-10,000 micrograms/kg i.v.), two selective noradrenaline uptake blockers, inhibited the firing rate of noradrenergic locus coeruleus neurons and induced excitation of the prefronto-cortical neurons. The selective destruction of ascending noradrenergic pathways by intracerebroventricular injection of 6-hydroxydopamine antagonized the excitatory effect of desipramine and maprotiline on the prefronto-cortical neurons. These results suggest that desipramine and maprotiline dose dependently stimulate the electrical activity of prefronto-cortical neurons, probably by acting on noradrenergic cells of the locus coeruleus.