Muscarinic M1, M3, Nicotinic,GABAA and GABAB Receptor ...

there is overlap in function among the regions. Spatial learning, contextual
learning, associative learning, and reorganization of sensory fields are some
examples. Cholinergic septohippocampal pathway appears to contribute to its role
in memory.
Muscarinic receptors
Muscarinic receptors are a family of G protein-coupled receptors that have
a primary role in central cholinergic neurotransmission. Specific agonists, which
activate postsynaptic muscarinic receptors, stimulate cholinergic signaling
(Valentin et al., 2006). These receptors are widely distributed throughout the body
and subserve numerous vital functions in both the brain and autonomic nervous
system (Hassal et al., 1993). In the brain, muscarinic receptors participate in many
important functions such as learning, memory and the control of posture. In the
periphery, among other effects, muscarinic receptors mediate smooth muscle
contraction, glandular secretion and modulation of cardiac rate and force. In the
CNS there is evidence that muscarinic receptors are involved in motor control,
temperature regulation, cardiovascular regulation and memory. Interest in the
classification of muscarinic receptors involved in functions at different locations
has been heightened by the potential therapeutic application of selective agents in
areas such as AD, Parkinson’s disease, asthma, analgesia and disorders of
intestinal motility, cardiac and urinary bladder function (Caulfield & Birdsall,
1998).
Classification of Muscarinic receptors
Muscarinic receptors are G protein coupled receptors (Hulme et al., 1990).
Molecular cloning studies have revealed the existence of five molecularly distinct
mammalian muscarinic receptor proteins (Bonner, 1989). Muscarinic receptors,
widely distributed throughout the central and peripheral nervous system have
critical functions in learning and memory, attention and motor activity (Weiner et
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