Neurotransmitters: Acetylcholine & Glutamate

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Questions and Answers

Which of the following best describes the composition of nicotinic receptors?

Five subunits consisting of α, β, γ, δ, and ε (correct)

Only α and β subunits

Three subunits including β and γ

Two subunits, α and β

What is a known effect of Botox on facial muscles?

Enhances blood flow to facial muscles

Stimulates muscle growth in the face

Paralyses muscles to prevent wrinkles (correct)

Increases muscle activation to reduce wrinkles

What type of ACh receptors do muscarinic antagonists such as atropine target?

Only nicotinic receptors

Non-selective muscarinic receptors (correct)

Selective for specific subtypes only

Only those found in muscle cells

Which of the following substances is NOT classified as an antagonist of acetylcholine?

Nicotine Signup and view all the answers

What role does edrophonium play in diagnosing myasthenia gravis?

It is a short-acting acetylcholinesterase inhibitor Signup and view all the answers

What specific type of medication was prescribed to the patient diagnosed with Myasthenia Gravis?

Cholinesterase inhibitors Signup and view all the answers

Which of the following is an agonist of acetylcholine receptors?

Muscarine Signup and view all the answers

What laboratory finding contributed to the diagnosis of Myasthenia Gravis in the patient?

High levels of acetylcholine receptor antibodies Signup and view all the answers

What potential hazard is associated with the ingestion of belladonna?

Severe illness or death due to toxicity Signup and view all the answers

Which ion is typically permeable through nicotinic receptors?

Ca2+ Signup and view all the answers

Which neurotransmitter is primarily involved in the pathology of Myasthenia Gravis?

Acetylcholine Signup and view all the answers

What neurological condition is characterized by the action of antibodies attacking acetylcholine receptors?

Myasthenia Gravis Signup and view all the answers

What enzyme is responsible for synthesizing acetylcholine?

Choline acetyltransferase Signup and view all the answers

How is choline primarily obtained in the body?

Dietary fat consumption Signup and view all the answers

What happens to acetylcholine after it is released into the synaptic cleft?

It acts for a brief period before degradation. Signup and view all the answers

Which type of receptors are nicotinic and muscarinic?

Cholinergic receptors Signup and view all the answers

What role does acetylcholine play in the brain?

Modulating memory and sleep Signup and view all the answers

Which statement about choline recycling is accurate?

Choline is pumped back into the presynaptic terminal by a transporter. Signup and view all the answers

What is the significance of acetylcholinesterase in synaptic transmission?

It degrades acetylcholine after action. Signup and view all the answers

What cognitive impairments are associated with excessive use of antimuscarinic drugs?

Memory loss and delirium Signup and view all the answers

What was a noted functional loss experienced by the patient?

Not knowing how to turn off the stove Signup and view all the answers

Which subunits are typically found in conventional NMDA receptors?

2 GluN1 and 2 GluN2 subunits Signup and view all the answers

What is the role of ketamine within the context of NMDA receptors?

It acts as an antagonist of NMDA receptors Signup and view all the answers

Which of the following options best describes unconventional NMDA receptors?

They incorporate GluN3 subunits along with GluN1 or GluN2 Signup and view all the answers

Which of the following statements about the structure of NMDA receptors is true?

They can incorporate three types of subunits in tri-heteromeric receptors Signup and view all the answers

What is necessary for the synthesis of acetylcholine?

Choline and acetyl coenzyme A Signup and view all the answers

What role does acetylcholine play in the neuromuscular junction?

It initiates muscle contraction. Signup and view all the answers

Which type of Ach receptor activates G proteins and cascades?

Muscarinic receptors Signup and view all the answers

What is a treatment approach for managing symptoms of Myasthenia Gravis?

Increasing levels of acetylcholine Signup and view all the answers

Which enzyme is responsible for breaking down acetylcholine in the synaptic cleft?

Acetylcholinesterase Signup and view all the answers

What is a common effect of curare on nicotinic receptors?

It competitively inhibits receptor activity. Signup and view all the answers

What generally deactivates acetylcholine receptors in Myasthenia Gravis?

Binding of antibodies to the receptors Signup and view all the answers

Where is choline primarily sourced from in the body?

Fat in the diet Signup and view all the answers

What is a primary consequence of Botox treatment on muscles?

Muscles become paralyzed and remain relaxed Signup and view all the answers

Which agonist is specifically known for activating M1 muscarinic receptors?

No specific agonist Signup and view all the answers

What symptom can result from excessive use of antimuscarinic drugs?

Cognitive impairment Signup and view all the answers

What is the function of glutamine synthetase in the glutamate cycle?

To convert glutamate back to glutamine Signup and view all the answers

Which of the following receptor types is responsible for conducting ions such as sodium and calcium?

iGluR Signup and view all the answers

When both NMDA and glycine are present, what response is produced?

Channels open and a larger response is produced Signup and view all the answers

What typically occurs when ketamine is applied to NMDA receptors?

NMDA receptors cease to produce a response Signup and view all the answers

What differentiates conventional NMDA receptors from unconventional ones?

Conventional consist of 2 GluN2 subunits and 2 GluN1 subunits Signup and view all the answers

What is one primary role of glutamate transporters in the synaptic environment?

Removing glutamate from clefts for recycling Signup and view all the answers

What effect does belladonna have when ingested in excessive amounts?

Can cause delirium and tachycardia Signup and view all the answers

Study Notes

Acetylcholine & Glutamate

Acetylcholine (ACh) synthesis occurs from acetyl CoA and choline. Choline primarily comes from dietary fat and liver production.
Acetyltransferase combines acetyl CoA and choline to form acetylcholine. This enzyme is only present in cholinergic neurons.
ACh is used at the neuromuscular junction (NMJ) to trigger muscle contractions and acts as a neuromodulator in the brain (influencing memory and sleep).
Myasthenia gravis is an autoimmune disease causing muscle weakness, due to antibodies blocking acetylcholine receptors. It can manifest with drooping eyelids, double vision, and facial expression difficulties.
Cholinesterase inhibitors (like neostigmine) can be used to treat symptoms of Myasthenia Gravis, increasing acetylcholine levels in the synapse by inhibiting the enzyme that breaks it down.

Learning Outcomes

Myasthenia Gravis: Symptoms, causes, diagnosis, and treatment
Acetylcholine (ACh): Synthesis, brain nuclei distribution, pathways, receptors, agonists, antagonists
Alzheimer's Disease: Symptoms, treatment, diagnosis
Glutamate: Synthesis, termination of action, receptor types
NMDAR receptors: Subunit expression, function

Cholinergic Pathways

Cholinergic pathways use a network of nuclei in the basal forebrain and brainstem that innervate other parts of the brain, including the hippocampus and neocortex.
Key nuclei in these pathways are the medial septal nucleus, diagonal band nuclei, nucleus basalis of Meynert, pedunculopontine nucleus, and laterodorsal tegmental nucleus.
These pathways are crucial for various cognitive functions and motor control.

ACh Synthesis and Degradation

ACh is packaged into vesicles.
Release occurs upon action potential arrival.
ACh acts briefly on postsynaptic receptors.
Acetylcholinesterase (AChE) degrades ACh.
Choline is recycled back into the presynaptic terminal by transporters.

ACh Receptors

Cholinergic receptors are categorized as nicotinic and muscarinic based on the selective agonists.
Nicotinic receptors are stimulated by nicotine and have a different subunit composition in muscles versus neurons.
Muscarinic receptors are stimulated by muscarine and have subtypes (M1-M5).
The presented material also discusses the use of various agonists and antagonists of both nicotinic and muscarinic acetylcholine receptors, including nicotine, curare, muscarine, and atropine.

NMDA Receptors

Conventional NMDA receptors consist of 2 GluN1 and 2 GluN2 subunits.
Other (non-conventional) NMDA receptor types can include GluN3 subunits.
NMDA receptors can be di-heteromeric or tri-heteromeric.
Conventional receptors require both glutamate and glycine to activate.
Ketamine, a NMDA antagonist, is discussed, noting its role as an anesthetic also.

Glutamate Synthesis and Inactivation

Glutamate is synthesized from glutamine via glutaminase.
Alternatively, glutamate can be made from aspartate via the transamination process.
After release, glutamate is taken up by glial cells and converted back to glutamine. It is then transported out of the glial cells back to the presynaptic terminal to replenish.
Important transporters involved in glutamate uptake include GLT-1, GLAST, and EAAC1.

Glutamatergic Transmission

Glutamate is a major excitatory neurotransmitter in the CNS.
It is involved in many brain functions like learning, memory, and sensory processing.
Glutamate interacts with different receptors, including AMPA, NMDA, and kainate receptors, leading to various cellular responses.
The material describes the different subtypes of glutamate receptors, such as NMDA, AMPA, and Kainate receptors, and their respective roles in the nervous system.

Case Studies

Various case studies are included, including early-onset Alzheimer's disease and myasthenia gravis.
Early onset Alzheimer's : A case study of a female with early-onset Alzheimer's, showing symptoms and treatment that is evident throughout the patient's medical history.
Myasthenia Gravis: A case study of a librarian affected by Myasthenia Gravis. The case details the progression, diagnosis, and treatment of her condition.
Case studies can illustrate symptoms, diagnosis and treatment typical to these diseases.

Inhibition of ACh Release

Botox, a botulinum toxin, inhibits the release of acetylcholine, leading to muscle paralysis and decreased wrinkle formation.

Example Questions

Example multiple-choice questions about agonists and antagonists.
Example question about the highest expression of GluN2C subunits in the adult brain.

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Description

Explore the fascinating roles of acetylcholine and glutamate in the nervous system. This quiz covers synthesis, functions, and related conditions such as Myasthenia Gravis and Alzheimer's Disease. Test your knowledge on neurotransmitter pathways, receptors, and their impact on brain function.