Medications That Affect Acetylcholine
The aim of the investigation is to test the pharmacological properties of drugs which affect the autonomic nervous system and the cardiovascular system. In this experiment the heart rate and blood pressure from an anaesthetised cat was monitored. The purpose of the tests was to gain experience of in-vivo experimentation and to understand the difficulty in drug, dosage and administration which can have significant effects on the animal if wrongly selected. Drugs used in this experiment were noradrenaline, adrenaline, acetylcholine, propranolol and atropine. Drugs which affect the heart can be categorised into autonomic neurotransmitters, antidysrhythmic drugs and cardiac glycosides/other inotropic drugs.
Alzheimer’s disease is the most common cause of dementia among older adults, according to the National Institute on Aging. Its symptoms include severe memory loss and problems with the ability to think that interfere with daily life. There is no cure for Alzheimer’s disease. Experts do not know what causes Alzheimer’s disease. However, they know that many people with the condition have lower levels of acetylcholine. Alzheimer’s disease damages cells that produce and use acetylcholine. Certain medications can increase levels of acetylcholine. They do this by blocking the action of enzymes that break down the neurotransmitter. The primary enzyme in this group is called acetylcholinesterase (AChE), and drugs that make these enzymes less active are called AChE inhibitors or cholinesterase inhibitors. AChE inhibitors can help with symptoms related to thought processes such as language, judgment, and memory. Imbalances in levels of acetylcholine play a role in some neurological conditions. People who have Alzheimer’s disease and Parkinson’s disease tend to have low levels of acetylcholine. There is no proven way to maintain ideal levels of acetylcholine and prevent neurological diseases. However, researchers are developing advanced treatments to help people with these health conditions live longer, healthier lives.
Muscarinic acetylcholine receptors (mAChRs) have been found to regulate many diverse functions, ranging from motivation and feeding to spatial navigation, an important and widely studied type of cognitive behavior. Systemic administration of non-selective antagonists of mAChRs, such as scopolamine or atropine, have been found to have adverse effects on a vast majority of place navigation tasks. However, many of these results may be potentially confounded by disruptions of functions other than spatial learning and memory (Nicolelis MAL, 2009). Although studies with selective antimuscarinics point to mutually opposite effects of M1 and M2 receptors, their particular contribution to spatial cognition is still poorly understood, partly due to a lack of truly selective agents. Furthermore, constitutive knock-outs do not always support results from selective antagonists. For modeling impaired spatial cognition, the scopolamine-induced amnesia model still maintains some limited validity, but there is an apparent need for more targeted approaches such as local intracerebral administration of antagonists, as well as novel techniques such as optogenetics focused on cholinergic neurons and chemogenetics aimed at cells expressing metabotropic mAChRs (McNaughton BL, 2006).
Summing up, acetylcholine can be found in all motor neurons, where it stimulates muscles to contract. From the movements of the stomach and heart to the blink of an eyelash, all of the body's movements involve the actions of this important neurotransmitter. It is also found in many brain neurons and plays an important role in mental processes such as memory and cognition. Severe depletion of acetylcholine is associated with Alzheimer's disease
McNaughton BL, Battaglia FP, Jensen O, Moser EI, Moser M-B. Path integration and the neural basis of the “cognitive map”. Nat Rev Neurosci (2006)
Nicolelis MAL, Lebedev MA. Principles of neural ensemble physiology underlying the operation of brain-machine interfaces. Nat Rev Neurosci (2009)
Hafting T, Fyhn M, Molden S, Moser M-B, Moser EI. Microstructure of a spatial map in the entorhinal cortex. Nature (2005)