10 Questions
Where are nicotinic acetylcholine receptors found?
Central and peripheral nervous system, muscle, and many other tissues
What is the primary function of nicotinic receptors at the neuromuscular junction?
Control muscle contraction
Why are nicotinic receptors considered cholinergic receptors?
Because they respond to acetylcholine
Which type of transmission involves the release of high concentrations of neurotransmitters acting on immediately neighboring receptors?
Classical synaptic transmission
What can cause a desensitized receptor to revert to a prolonged open state?
An agonist bound in the presence of a positive allosteric modulator
How many vertebrate nAChR subunits have been identified?
17
What is the function of neuronal forms of the nicotinic receptor found pre-synaptically?
Influence the release of multiple neurotransmitters
Which subunits are included in muscle-type nicotinic acetylcholine receptors?
$\alpha1, \beta1, \gamma, \delta$
What effect does the binding of an agonist like nicotine have on nicotinic acetylcholine receptors?
Stabilizes the open and desensitized states
What is the role of snake venom neurotoxins in relation to nicotinic acetylcholine receptors?
Antagonistically bind to nAChRs, inhibiting ion flow and leading to paralysis and death
Study Notes
Nicotinic Acetylcholine Receptors: Structure, Binding, and Effects
- Nicotinic acetylcholine receptors (nAChRs) can use second messengers like metabotropic receptors
- Nicotinic receptors transmit outgoing signals for sympathetic and parasympathetic systems
- Receptors can be antagonized by compounds like hexamethonium, interfering with signal transmission
- Nicotinic receptors have a molecular mass of 290 kDa and are made up of five subunits arranged around a central pore
- Nicotinic receptors are broadly classified into muscle-type and neuronal-type based on their primary sites of expression
- Muscle-type receptors are composed of α1, β1, γ, and δ subunits, while neuronal subtypes include various homomeric or heteromeric combinations of twelve different subunits
- Binding of a chemical messenger like acetylcholine or agonists like nicotine or epibatidine is necessary for opening the nAChR channel pore
- Nicotinic AChRs may exist in different conformational states, and binding of an agonist stabilizes the open and desensitized states
- The channel allows positively charged ions to move across it, with a net flow of positively charged ions inward
- Many neuronal nAChRs can affect the release of other neurotransmitters
- The activation of receptors by nicotine modifies the state of neurons through depolarization of the plasma membrane and entry of calcium, leading to the activation of voltage-gated ion channels and intracellular cascades
- Snake venom neurotoxins antagonistically bind to nAChRs, inhibiting ion flow and leading to paralysis and death
Test your knowledge of Nicotinic Acetylcholine Receptors with this quiz. Explore their structure, binding mechanisms, and physiological effects, including their role in the sympathetic and parasympathetic systems. Gain insights into the diverse subunit compositions and the impact of agonists and antagonists on receptor function.
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