The brain M2 ACh receptor
is known to contribute to impaired cognitive function, including a deficit in behavioral flexibility, working memory, and hippocampal plasticity [139, 140].
It is possible that the alteration of ACh receptor
might have taken place in neuronal plexus which are nicotinic type.
Abnormal contracture knots may be initiated by a synaptic dysfunction at the motor endplate with the excessive acetylcholine (ACh)  release and changes in ACh receptor
(AChR)  or acetylcholinesterase (AChE)  activities.
Afterward, DRC to Ach were performed in vessels pre-incubated for 30 min with Atropine (At, [10.sup.-5]M), an Ach receptor
antagonist; and indomethacin (IND, [10.sup.-5] M), a cyclooxygenase (COX) inhibitor.
Since the lesioning procedure did not ensure a precise and complete removal of the efferent system, a genetically altered mouse ([euro]9 Ach receptor
subunit knockout) was developed in which the peripheral cochlear Ach receptor
sites were deleted.
Consolidating evidence for a role of nicotinic receptors also emerges from studies in which IT or speed of information processing measures have been assessed in patients with nicotinic Ach receptor
ACh travels across the synapse and binds with specialized ACh receptor
sites (AChR) on the postsynaptic muscle cell membrane, called the motor end plate.
Afterwards, DRC to Ach were performed in vessels pre-incubated for 30 min with At, [10.sup.-5M,] an Ach receptor
antagonist; and indomethacin IND, [10.sup.-5] M, a cyclooxygenase (COX) inhibitor.
Fishes also have been used to evaluate the effects of neurotoxins, such as the case of anatoxin-a, a nicotinic agonist produced by cyanobacteria that blocks cholinergic neurotransmission to compete for the ACh receptor
. This toxin can cause death in humans and other animals.
AChE is responsible for the rapid cleavage of the neurotransmitter ACh in the synapse, thereby regenerating the ACh receptor
and the excitability of the postsynaptical membrane.