Acetylcholine is a neurotransmitter, or brain chemical, that is used by your body to contract skeletal muscle and the smooth muscle that lines blood vessels, airways and other structures that can constrict without conscious control. Abnormal release or heightened sensitivity of acetylcholine plays a factor in asthma attacks because it causes your trachea to narrow slightly, making it difficult to breath. As such, some newer asthma drugs contain anticholinergics, which block the action of acetylcholine.
Acetylcholine
Acetylcholine is widely used, both centrally and peripherally, throughout your entire nervous system, including your autonomic and somatic systems, according to "Medical Biochemistry: Human Metabolism in Health and Disease." In other words, acetylcholine is needed to contract all the muscles you consciously control and most of the ones you can't, with the exception of your heart. Within your brain, acetylcholine is the main component of the cholinergic system, which tends to cause anti-excitatory actions. As such, it is related to stimulating REM sleep, sustained concentration and memory.
Asthma
Millions of people worldwide suffer from asthma, which is a constriction of your airways caused by some allergen in your diet or in the environment. Pollen and dust mites are common environmental triggers that can lead to symptoms from mild wheezing to severe difficulty breathing. In the initial asthmatic response, allergens are recognized by mast cells, which release chemicals that cause your airways, primarily your trachea, to narrow. In the later phase asthmatic response, which can last for up to 24 hours, acetylcholine may play a role. Steroids are the main prescribed treatment for asthma, although they are not effective for everyone and they can lead to side effects.
Research
A British study on mice and rats published in a 2011 edition of the journal "Thorax" discovered evidence that the late asthmatic response occurs because allergen-triggered sensory nerves cause the release of more acetylcholine, which causes the airways to narrow. The researchers believe that the same process happens in people who are asthmatic, and that adding anticholinergics to asthma medication may be beneficial.
Cautions
Acetylcholine can be overproduced in your body in response to industrial chemicals. According to the American Academy of Allergy, Asthma and Immunology, inhaling some substances in aerosol form can directly lead to the buildup of histamine or acetylcholine within your lungs, which can trigger asthma attacks (Reference 3). The scientists at the academy note that inhaling insecticides, in particular, can cause a buildup of acetylcholine, which causes your airway muscles to contract and tighten.
References
- "Medical Biochemistry: Human Metabolism in Health and Disease"; Miriam D. Rosenthal, et al.; 2009
- "Thorax"; A Role for Sensory Nerves in the Late Asthmatic Response; K. Raemdonck, et al.; July 2011
- American Academy of Allergy, Asthma and Immunology; Occupational Asthma: Tips to Remember
