Muscarinic cholinergic autoreceptors

ACh regulates the cortical arousal characteristic of both REM sleep and wakefulness (Semba, 1991, 2000 Sarter Bruno, 1997, 2000). Medial regions of the pontine reticular formation (Figs. 5.2 and 5.7) contribute to regulating both the state of REM sleep and the trait of EEG activation. Within the medial pontine reticular formation, presynaptic cholinergic terminals (Fig. 5.1) that release ACh also are endowed with muscarinic cholinergic receptors (Roth et al, 1996). Autoreceptors are defined as presynaptic receptors that bind the neurotransmitter that is released from the presynaptic terminal (Kalsner, 1990). Autoreceptors provide feedback modulation of transmitter release. Autoreceptor activation... 

Vilaro MT, Palacios JM, Mengod G. 1994. Multiplicity of muscarinic autoreceptor subtypes Comparison of the distribution of cholinergic cells and cells containing mRNA for five subtypes of muscarinic receptors in the rat brain. Mol Brain Res 21 30-46. 

Figure 1.12 Schematic model of a central cholinergic nerve ending indicating possible sites of drug action. Attempts have been made to increase acetycholine synthesis (CAT= choline acetyltransferase) by increasing availability of choline but this has not been successful (1). ACh is stored in vesicles but there are no clinically effective drugs that act at this site (2). There is some evidence that aminopyridines and phosphatidylserines release ACh and may have limited use in Alzheimer s disease patients (3). Muscarinic antagonists are usedfor Parkinson s disease and antipsychotic-induced extrapyramidal side-effects. Presynaptic muscarinic autoreceptors...

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