Acetylcholine normal function

Acetylcholine synthesis and neurotransmission requires normal functioning of two active transport mechanisms. Choline acetyltransferase (ChAT) is the enzyme responsible for ACh synthesis from the precursor molecules acetyl coenzyme A and choline. ChAT is the neurochemical phenotype used to define cholinergic neurons although ChAT is present in cell bodies, it is concentrated in cholinergic terminals. The ability of ChAT to produce ACh is critically dependent on an adequate level of choline. Cholinergic neurons possess a high-affinity choline uptake mechanism referred to as the choline transporter (ChT in Fig. 5.1). The choline transporter can be blocked by the molecule hemicholinium-3. Blockade of the choline transporter by hemicholinium-3 decreases ACh release,... 

Acetylcholine is the primary neurotransmitter in the parasympathetic division of the autonomic nervous system, which mainly innervates the gastrointestinal tract, eyes, heart, respiratory tract, and secretory glands. Although its receptors are crucial for maintaining all normal functions of the body, an extremely small number of illnesses can be explained by the dysfunction of cholinergic regions of the peripheral autonomic system. 

Experiments in my laboratory and in others have demonstrated that the appearance of this wave of electrical activity requires the normal function of acetylcholine within your frontal cortex. If the acetylcholine neurons that project into your frontal cortex are destroyed, then this wave cannot fully form and you will have great difficulty paying attention to important things, such as the impending appearance of a masked gunman. An example of such a wave is labeled post in the figure. In this case, the absence of acetylcholine does not allow the wave to fully develop. This research has demonstrated that acetylcholine s job is to instruct the neurons in your frontal cortex to pay attention to important information and be vigilant to... 

Neurons synthesize acetylcholine from choline, which is obtained from the diet, and from acetyl groups that originate in mitochondria from the metabolism of sugar. Here is yet another example of the importance of sugar for your brain s normal function. The synthesis of acetylcholine occurs within the cytoplasm of your neurons, and the product is stored in synaptic vesicles, those small round packets that neurons release to communicate with each other. Neurons pay a lot of attention to the shelf life of their neurotransmitters they prefer to release the most recently produced neurotransmitter molecules first. As you can see, neurons do not behave like your local grocer they do... 

Acetylcholine is the most abundant neurotransmitter in the body and the primary neurotransmitter between neurons and muscles and controls the stomach, spleen, bladder, liver, sweat glands, blood vessels, heart, and others. Dopamine is essential to the normal functioning of the central nervous system. Noradrenaline, or norepinephrine, acts in the sympathetic nervous system and produces powerful vasoconstriction. Serotonin is associated with the sleep cycle. 

In normal circumstances, acetylcholine is hydrolyzed almost immediately by acetylcholinesterase close to receptors in the synaptic cleft at sites of action (see Bowman, 1993). The normal function of acetylcholinesterase is to hydrolyze acetylcholine in the synaptic cleft, parasympathetic effector organ or neuromuscular junction, in order to terminate... 

As would be expected from the interruption of acetylcholine neuromuscular transmission, electrophysiological studies show smaller than normal motor unit potentials in the victim s muscles. The only specific treatment available is passive immunization with an antitoxin. This will not reverse the paralysis but can help to stabilize the decline. The antitoxin available is from an equine source and thus there can be complications for the patient such as anaphylaxis. The main therapy is supportive care - often involving maintenance of ventilation - over the longer term until normal functions recover. 

Parkinsonism is associated with a number of degenerative changes in both the structure and the chemistry of the basal ganglia. The relationship between the symptoms of the disease and these changes is dependent upon what is the normal function in the extrapyramidal motor system of such substances as dopamine, noradrenaline, serotonin, and the melanins, as well as others such as acetylcholine whose levels appear to be normal in Parkinsonism. Nevertheless, normal levels do not exclude disordered function since dynamic systems can involve different rates of turnover with no apparent change in concentrations. Synaptic transmission in the central nervous system has been extensively reviewed [59-61] and only those factors relevant to Parkinsonism will be discussed here. 

Choline, an essential nutrient for humans, is consumed in many foods. It is part of several major phospholipids (including phosphatidylcholine - also called lecithin) that are critical for normal membrane structure and function. Also, as the major precursor of betaine it is used by the kidney to maintain water balance and by the liver as a source of methyl groups for the removal of homocysteine in methionine formation. Finally, choline is used to produce the important neurotransmitter acetylcholine (catalyzed by choline acetyltransferase in cholinergic neurons and in such non-nervous tissues as the placenta). Each of these functions for choline is absolutely vital for the maintenance of normal function. 

Acetylcholine is one of the fundamental neurotrans-mitters involved in a wide variety of normal regulatory functions. A number of disease states that may be... 

Both the G- and V-agents have the same physiological action on humans. They are potent inhibitors of the enzyme acetylcholinesterase (AChE), which is required for the function of many nerves and muscles in nearly every multicellular animal. Normally, AChE prevents the accumulation of acetylcholine after its release in the nervous system. Acetylcholine plays a vital role in stimulating voluntary muscles and nerve endings of the autonomic nervous system and many structures within the CNS. Thus, nerve agents that are cholinesterase inhibitors permit acetylcholine to accumulate at those sites, mimicking the effects of a massive release of acetylcholine. The major effects will be on skeletal muscles, parasympathetic end organs, and the CNS. 

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