Cholinergic pathway

Nicoll, RA (1985) The septo-hippocampal projection a model cholinergic pathway. Trends Neurosci. 8 533-536. 

It is important to emphasise that a lesion of the reticular system disrupts a number of afferent inputs to the cortex. Particularly important in this respect are the mono-aminergic (especially noradrenaline, 5-HT and histamine) and cholinergic pathways. When the ascending inputs from these neurons are destroyed, sleep is passive and not at all like natural sleep which, as detailed above, has distinct phases and depends on brainstem influences on cortical function. How these different neurotransmitters might influence sleep and arousal will be considered next. 

Overall, there are compelling reasons to believe that cholinergic pathways not only play a part in arousal but also contribute to the induction of the arousal-like features of REM sleep. 

Hernandez-Peon, R., Chavez-Ibarra, G., Morgane, P. J. Timo-Iaria, C. (1963). Limbic cholinergic pathways involved in sleep and emotional behavior. Exp. Neurol. 8, 93-111. 

Figure 13.2. The major cholinergic pathways of the human brain.

K. Nakamura, M. Shirane, Activation of the Reticulothalamic Cholinergic Pathway by the Major Metabolites of Aniracetam , Eur. J Pharmacol. 1999, 380, 81-89. 

The cholinergic pathways in the mammalian brain are extremely diffuse and arise from cell bodies located in the hindbrain and the midbrain. Of these areas, there has been considerable interest of late in the nucleus basalis magnocellularis of Meynert because this region appears to be particularly affected in some patients with familial Alzheimer s disease. As the projections from this area innervate the cortex, it has been speculated... 

Other cholinergic pathways in the brain include a network of intrinsic neurons in the striatum, and also various nuclei in the lower brain stem which project to the cerebellum are the origins of the cranial nerves. Striatal cholinergic neurons project mainly to spiny neurons which are the principal locus for the relay of cortical information flowthrough the basal ganglia (Calabresi et al.. 

The parasympathetic cholinergic pathway emanating from the vagus nerve exerts the main neuronal control in human airways. The cholinergic efferent nerves synapse in ganglia within the airways, and from there,... 

Neuroanatomical findings on the localization of memory and attentional functions fit with findings on the distribution of cholinergic pathways. The... 

Anticholinergics, like atropine and its derivative ipratropium bromide block cholinergic pathways that cause airway constriction. They may provide added bronchodi-lator effect in patients who are receiving beta -adrenergic agents for asthma. 

A number of pathways contain acetylcholine, including neurons in the neostriatum, the medial septal nucleus, and the reticular formation. Cholinergic pathways appear to play an important role in cognitive functions, especially memory. Presenile dementia of the Alzheimer type is reportedly associated with a profound loss of cholinergic neurons. However, the specificity of this loss has been questioned because the levels of other putative transmitters, eg, somatostatin, are also decreased. 

To discuss the role of acetylcholine pharmacology and cholinergic pathways in mediating memory functions. 

The second section on clinical science has been increased by two chapters to accommodate the increase in the numbers of drugs and advances in knowledge about psychiatric disorders. Three new neurotransmitter systems are introduced and illustrated substance P and the neurokinin family nitric oxide and the endocannabi-noids such as anandamide (the brain s own marijuana ). Also amplified is coverage of the classical neurotransmitter systems, especially intercommunications now illustrated between serotonin and dopamine and between norepinephrine/noradrenaline and serotonin. Also included are numerous new illustrations of noradrenergic and cholinergic pathways. 

Mesulam, M. M., Guillozet, A., Shaw, P., Levey, A., Duysen, E. G. and Lockridge, O. (2002) Acetylcholinesterase knockouts establish central cholinergic pathways and can use butyrylcholinesterase to hydrolyze acetylcholine. Neuroscience 110, 627-639. 

Many AD patients have damage to other neurotransmitter pathways as much as to their cholinergic pathways thus, they would not be helped much by manipulating only ACh levels in their brains. 

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