Darracq L, Gervasoni D, Soulière F, Lin J S, Fort P, Chouvet G, Luppi P H
Département de Médecine Expérimentale, INSERM U52, CNRS ERS 5645, Faculté de Médecine, Lyon, France.
Neuroreport. 1996 Dec 20;8(1):351-5. doi: 10.1097/00001756-199612200-00069.
The noradrenergic neurones of the locus coeruleus (LC) discharge tonically during wakefulness, decrease their activity during slow wave sleep and are virtually quiescent during paradoxical sleep. We recently demonstrated an inhibitory glycinergic input to the locus coeruleus and proposed that this could be responsible for inhibition of the LC during paradoxical sleep. To test this proposal, we developed a method combining polygraphic recordings, iontophoresis and single-unit extracellular recordings in the unanaesthetized head-restrained rat. Iontophoretically applied strychnine, a specific glycine antagonist, induced strong excitation of LC neurones during paradoxical sleep, but also during slow wave sleep and wakefulness. These results suggest that glycine tonically inhibits noradrenergic LC neurones throughout the entire sleep-waking cycle and not only during paradoxical sleep.
