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

during experimental condition. Various anatomical, electrophysiological and
pathological observations provide evidence that ACh plays a major role in the
control of striatal function and in the regulation of motor control (Jabbari et al.,
1989). The results of confocal studies confirmed the alterations of muscarinic M1
and M3 receptor at protein level which mediated neuronal damage during
condition of glucose deprivation induced by hypoglycemia. It is widely accepted
that certain brain regions and specific neuronal cell types express differential
sensitivity to hypoglycemic insults during glucose deprivation and striatal neurons
are particularly prone to develop neuronal damage under energy deprivation
(Haddad & Jiang, 1993). M1 receptors are responsible for the presynaptic
inhibition of GABA release while M3 receptors exert an inhibitory control on the
release of glutamate in the striatum (Sugita et al., 1991). These studies shows the
importance of maintaining synaptic neurotransmission mediated though
muscarinic M1, M3 receptor subtypes which were found to be affected by
recurrent hypoglycemia during diabetes.
CNS mAChRs regulate a large number of important central functions
including cognitive, behavioural, sensory, motor and autonomic processes (Felder
et al., 2000; Eglen, 2005). The striatum also expresses high sensitivity to
hypoglycemic insults. During these pathological conditions, striatal synaptic
transmission is altered depending on presynaptic inhibition of transmitter release
and opposite membrane potential changes occur in neurones and in cholinergic
interneurones (Calabresi et al., 2000) . Involvement of muscarinic M3 receptor in
the presynaptic inhibition of synaptic transmission at excitatory synapses results in
a decrease in neurotransmitter release and synaptic activity (Washburn & Moises,
1992). The high sensitivity of striatal spiny neurons to energy deprivation is
expressed as a disruption of intrinsic membrane properties as well as an alteration
of synaptic characteristics of the recorded cells (Xu, 1995). The present study on
total muscarinic, muscarinic M1, M3 receptor expression levels in corpus striatum
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