Pharmacological approach to functional reorganization: the role of norepinephrine

Pharmacological studies in laboratory animals show that systemically administered drugs that modulate the levels of specific central neurotransmitters can influence post brain injury behavioral recovery. Several lines of evidence support an important role of central norepinephrine. Selective lesions of central noradrenergic pathways impair recovery after a subsequent injury to the cerebral cortex. Drugs that deplete central norepinephrine, block alpha 1-adrenergic receptors, or decrease norepinephrine release (alpha 2-adrenergic receptor agonists) impede recovery whereas drugs that increase norepinephrine release (alpha 2-adrenergic receptor antagonists) or sympathomimetics (amphetamine) facilitate recovery. These studies also provide insights into the potential neurobiological processes underlying these drug effects.