Mechanisms of Action of Noradrenaline in the Brain
The noradrenaline (NA) innervation of the brain has been studied extensively over the past decade. Early views suggested that the nucleus locus coeruleus (LC) has a widespread, diffuse, slow conducting projection system with little anatomical or functional specificity. These views were supported by the observations that (a) the LC projects into nearly every brain structure in a rather diffuse manner, (b) LC fibers are small, unmyelinated and slowly conducting and therefore unlikely to convey specific information (c) action potential discharge rates of LC neurons vary considerably with sleep-wakefulness cycles being nearly silent in REM sleep and (d) iontophoretic application of NA produces in nearly every brain area a long lasting beta receptor-mediated suppression of spontaneous firing rates. It is now clear, however, that these conclusions represent an oversimplification of the actual evidence and that LC functions might be more specific and complex. LC innervation of the for-ebrain is actually quite heterogeneous with some structures being heavily invested with NA fibers while others are relatively devoid of them. Furthermore, within a given structure, e.g. the neocortex, there is a distinct laminar distribution of NA fibers and receptors.
KeywordsVisual Cortex Locus Coeruleus Medial Septum Spike Discharge Hippocampal Pyramidal Cell
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- Aston-Jones, G. and Bloom, F.E., 1981, Norepinephrine-containing locus coeruleus neurons in behaving rats exhibit pronounced responses to non noxious environmental stimuli. J. Neurosci. 1:887.Google Scholar
- Foote, S.L., Bloom, F.E. and Aston Jones, G., 1983, Nucleus Locus coeruleus: new evidence of anatomical and physiological specificity. Physiol. Rev., 63:844.Google Scholar
- Hoffer, B.J., Siggins, G.R., Oliver, A.P. and Bloom, F.E., 1973, Activation of the pathway from locus coeruleus to rat cerebellar purkinje neurons: pharmacological evidence of noradrenergic central inhibition. J. Pharmacol. Exp. Ther., 184:553.Google Scholar
- Madar, Y., 1983, The noradrenergic action in the visual cortex. Unpublished Ph.D. dissertation. The Weizmann Institute of Science, Rehovot.Google Scholar
- Madar, Y. and Segal, M., 1980, The functional role of the noradrenergic system in the visual cortex. Activation of the noradrenergic pathway. Exp. Brain Res.. 41:A14.Google Scholar
- Marshall, K.C., 1983, Catecholamines and their actions in the spinal cord, in: “Spinal Cord Pharmacology”, R.A. Davidoff, ed., Dekker, N.Y.Google Scholar
- Sara, S.J., 1985, Memory disfunction: an integration of animal and human research from preclinical and clinical perspectives. D.S. Olton, E. Gamzu and S. Corkin (Eds.) Ann. New York Acad. Sci, in press.Google Scholar
- Segal, M., 1976, Brainstem afferents to the rat medial septum. J. Physiol. (Lond), 261:617.Google Scholar
- Woodward, D.J., Moises, H.C., Waterhouse, B.D., Hoffer, B.J. and Freedman, R., 1979, Modulatory actions of norepinephrine in the central nervous system. Fed. Proc., 38:2109.Google Scholar