Biochemistry of Neurotransmitters
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Questions and Answers

What role do SNAREs play in the process of synaptic transmission?

  • They bind neurotransmitters to neuroreceptors.
  • They directly transmit electrical signals between neurons.
  • They facilitate the fusion of lipid bilayers during neurotransmitter release. (correct)
  • They serve as receptors for ions in gap junctions.

    • What is a characteristic feature of chemical synapses?

  • They allow for faster signal transmission.
  • They are bi-directional in communication.
  • They allow direct ion flow through gap junctions.
  • They involve the release of neurotransmitters. (correct)

    • How do electrical synapses differ from chemical synapses?

  • Electrical synapses are uni-directional.
  • Electrical synapses require complex protein interactions.
  • Electrical synapses use a slower mode of signal transmission.
  • Electrical synapses do not involve neurotransmitter release. (correct)

    • What is the role of neurotransmitters in synaptic transmission?

    <p>They bind to receptors on the post-synaptic neuron and trigger a response.</p> Signup and view all the answers

    Which of the following statements about electrical synapses is true?

    <p>They allow ions to flow directly between cells.</p> Signup and view all the answers

    What feature allows a neuron to receive inputs from multiple pre-synaptic neurons?

    <p>Multiple branches on a single axon.</p> Signup and view all the answers

    Which statement accurately describes V-SNAREs in the context of synaptic transmission?

    <p>They help with the fusion of vesicles in neurotransmitter release.</p> Signup and view all the answers

    Which type of synapse is characterized by slower communication and modulation of the signal?

    <p>Chemical synapse</p> Signup and view all the answers

    What is the primary role of neurotransmitters at a synapse?

    <p>To transmit signals between neurons or from neurons to target cells</p> Signup and view all the answers

    What is a common characteristic of both chemical and electrical synapses?

    <p>Both facilitate communication between neurons.</p> Signup and view all the answers

    Which neurotransmitter is commonly associated with mood regulation and often targeted in antidepressant medications?

    <p>Serotonin</p> Signup and view all the answers

    What is a potential role of glutamate in the central nervous system (CNS)?

    <p>It is the principal excitatory neurotransmitter.</p> Signup and view all the answers

    What effect do neurotransmitters have on receptors in the post-synaptic neuron?

    <p>They bind and trigger an excitatory or inhibitory response.</p> Signup and view all the answers

    Which of the following neurotransmitters is known for being inhibitory in nature?

    <p>GABA</p> Signup and view all the answers

    What distinguishes an agonist from an antagonist in neurotransmitter activity?

    <p>Agonists enhance neurotransmitter actions, while antagonists diminish them.</p> Signup and view all the answers

    In the context of pharmacological treatment, how can neurotransmitter actions be influenced?

    <p>Through the use of agonists or antagonists.</p> Signup and view all the answers

    Which neurotransmitters are known to be involved in the pathophysiology of anxiety disorders?

    <p>Serotonin and norepinephrine</p> Signup and view all the answers

    Which condition is associated with a deficit in dopamine activity?

    <p>Parkinson's disease</p> Signup and view all the answers

    Which neurotransmitter is NOT classified as a biogenic amine?

    <p>Acetylcholine</p> Signup and view all the answers

    What is the primary function of metabotropic receptors?

    <p>Trigger a signaling pathway</p> Signup and view all the answers

    What is a primary function of neurotoxins such as α-Latrotoxin?

    <p>Promote neurotransmitter release</p> Signup and view all the answers

    What occurs upon neurotransmitter binding to ionotropic receptors?

    <p>Conformational change causing channel opening</p> Signup and view all the answers

    Which of the following effects is caused by botulinum toxin?

    <p>Inhibition of neurotransmitter release</p> Signup and view all the answers

    Which of the following statements about excitatory effects is correct?

    <p>They depend on the type and concentration of ions passing through</p> Signup and view all the answers

    What type of neurotransmitter are neuropeptides generally characterized as?

    <p>Made up of three or more amino acids</p> Signup and view all the answers

    What is the term used to describe neurotransmitters that do not fit into traditional classifications?

    <p>Unconventional neurotransmitters</p> Signup and view all the answers

    What is typically true regarding the removal of neurotransmitters from the synapse?

    <p>It is completed via enzymatic degradation or uptake by glial cells</p> Signup and view all the answers

    How many transmembrane domains are typically found in metabotropic receptors?

    <p>7</p> Signup and view all the answers

    Which substance derived from botulinum toxin is used to treat muscle spasticity and migraines?

    <p>Botox</p> Signup and view all the answers

    In metabotropic receptors, what happens after neurotransmitter binding?

    <p>G-proteins are activated</p> Signup and view all the answers

    What does Batrachotoxin do to neurons?

    <p>Irreversibly binds to Na+ channels</p> Signup and view all the answers

    What characteristic does not define metabotropic receptors?

    <p>They cause immediate ion flow</p> Signup and view all the answers

    Which of the following is a common application of Botox?

    <p>Reduce excessive sweating</p> Signup and view all the answers

    Which neurotransmitter is categorized as an amino acid but is not incorporated into proteins?

    <p>GABA</p> Signup and view all the answers

    What is an effect of ionotropic receptors that is different from metabotropic receptors?

    <p>They typically produce quick physiological responses</p> Signup and view all the answers

    Which part of the metabotropic receptor is located intracellularly?

    <p>C-terminus</p> Signup and view all the answers

    What effect does tetanus toxin have on neurotransmitter release?

    <p>Inhibits release by damaging synaptobrevin</p> Signup and view all the answers

    Which component is NOT involved in the signaling cascade triggered by metabotropic receptors?

    <p>Receptor antagonists</p> Signup and view all the answers

    What is one characteristic that differentiates metabotropic receptors from ionotropic receptors?

    <p>They activate G-proteins after neurotransmitter binding.</p> Signup and view all the answers

    What is the typical speed of response for ionotropic receptors?

    <p>Rapid, within milliseconds.</p> Signup and view all the answers

    Which of the following effects is associated with metabotropic receptors?

    <p>Longer-lasting effects due to complex signaling pathways.</p> Signup and view all the answers

    What role do metabotropic receptors play in learning and memory?

    <p>They are crucial for synaptic plasticity.</p> Signup and view all the answers

    What is synaptic plasticity?

    <p>The capacity of synapses to strengthen or weaken over time.</p> Signup and view all the answers

    How can metabotropic receptors influence ionotropic receptors?

    <p>By influencing their trafficking and expression.</p> Signup and view all the answers

    What is considered a primary function of metabotropic receptors in the brain?

    <p>To filter out unimportant information.</p> Signup and view all the answers

    What physiological processes are influenced by metabotropic receptors?

    <p>Gene transcription and protein synthesis.</p> Signup and view all the answers

    Where is a high density of metabotropic receptors found?

    <p>Hippocampus.</p> Signup and view all the answers

    What is one outcome of the activation of metabotropic receptors?

    <p>Changes in gene expression and enzyme activity.</p> Signup and view all the answers

    What does a signal to noise ratio in the context of metabotropic receptors refer to?

    <p>The balance between important and unimportant signals.</p> Signup and view all the answers

    Why are metabotropic receptors targeted for drug development?

    <p>They are involved in gene transcription and protein synthesis.</p> Signup and view all the answers

    What kind of effect does metabotropic receptor activation produce in terms of duration?

    <p>Short to long-lasting depending on the pathway.</p> Signup and view all the answers

    What role do syntaxin and SNAP-25 play in neuronal communication?

    <p>They mediate docking and exocytosis of synaptic vesicles.</p> Signup and view all the answers

    Which protein unwinds SNARE proteins to disassemble the SNARE complex?

    <p>NSF</p> Signup and view all the answers

    What is the effect of excitatory post-synaptic potential (EPSP) on the membrane potential?

    <p>It makes the inside of the cell more positive.</p> Signup and view all the answers

    Which ions are primarily involved in inhibitory post-synaptic responses?

    <p>Cl- entering and K+ exiting</p> Signup and view all the answers

    What occurs during hyperpolarization of the post-synaptic membrane?

    <p>The inside becomes more negative.</p> Signup and view all the answers

    What happens when small EPSPs or IPSPs summate?

    <p>They create a localized change in membrane potential.</p> Signup and view all the answers

    Which of the following best describes the flexibility of synaptic signaling?

    <p>It allows for adjustments in neurotransmitter release and receptor numbers.</p> Signup and view all the answers

    What is the main function of synaptic plasticity?

    <p>To strengthen or weaken synaptic transmission.</p> Signup and view all the answers

    What type of neurotransmitters are classified as small molecules?

    <p>Simple amino acids and other small compounds</p> Signup and view all the answers

    Which effect would a decrease in neurotransmitter release typically have?

    <p>Decrease in postsynaptic receptor activation.</p> Signup and view all the answers

    The all-or-nothing response in action potentials refers to what phenomenon?

    <p>A threshold being reached or not, leading to action potential or none.</p> Signup and view all the answers

    Which role do SNAPs (Soluble NSF Attachment Proteins) play?

    <p>They bind to the SNARE complex and aid in recruiting NSF.</p> Signup and view all the answers

    How does an excitatory synapse affect an action potential?

    <p>It increases the chance of firing an action potential.</p> Signup and view all the answers

    Study Notes

    Biochemistry of Neurotransmitters

    • The lecture covers neurotransmitters, their functions, receptors, agonists, antagonists, and their roles in various diseases.

    Course Objectives

    • Describe the structures and functions of neurotransmitters like acetylcholine, adrenaline, noradrenaline, serotonin, dopamine, histamine, glutamate, GABA, aspartate, and glycine.
    • List examples of agonists and antagonists for the mentioned neurotransmitters.
    • Give an account of neurotransmitter receptor structures and their mechanisms.
    • Discuss the roles of neurotransmitters and their receptors in conditions like anxiety, dementia, depression, schizophrenia, Parkinson's disease, and migraine.
    • Explain how neurotransmitter actions in the central nervous system (CNS) can be pharmacologically modified to treat disorders.

    Neurotransmission

    • The synapse is the junction between two neurons or a neuron and a target cell (e.g., muscle or gland).
    • The pre-synaptic neuron sends the signal.
    • The post-synaptic neuron receives the signal.
    • Action potentials stimulate release of neurotransmitters.
    • Neurotransmitters bind with receptors on the post-synaptic neuron, causing various effects.

    Chemical and Electrical Synapses

    • Chemical synapses are the most common type, utilizing neurotransmitters for communication.
    • They involve the release of neurotransmitters from a pre-synaptic neuron that bind to receptors on a post-synaptic neuron.
    • Communication is unidirectional.
    • Electrical synapses allow direct electrical communication through gap junctions.
    • Ions flow directly between cells, causing faster and bidirectional signal transmission.

    Chemical Synaptic Transmission

    • Neurotransmitters are synthesized and stored in vesicles.
    • Action potential arrival at the terminal triggers calcium influx.
    • Calcium causes vesicle fusion with the membrane, releasing neurotransmitters.
    • Neurotransmitters bind to receptors, inducing various effects.
    • Neurotransmitters can be removed via reuptake, enzymatic degradation, or diffusion.

    SNARES

    • Soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) are crucial for vesicle fusion and neurotransmitter release.
    • Vesicle membrane: synaptobrevin.
    • Target membrane: syntaxin, SNAP-25.
    • Other molecules aid in the disassembly and recycling of SNARE proteins, assisting in future neurotransmitter release.

    Exocytosis of Neurotransmitters

    • The arrival of an action potential at the presynaptic terminal stimulates calcium entry.
    • Vesicular membranes fuse with the presynaptic membrane.
    • Neurotransmitters are released into the synaptic cleft.

    Excitatory vs Inhibitory post-synaptic responses

    • Neurotransmitters can evoke excitatory or inhibitory responses depending on the receptors they act on and the resulting ion flow.
    • Excitatory postsynaptic potentials (EPSPs) increase the likelihood of action potential generation, often by depolarizing the postsynaptic membrane.
    • Inhibitory postsynaptic potentials (IPSPs) reduce the likelihood of action potential generation, often by hyperpolarizing the postsynaptic membrane.

    Chemical Synapses are Flexible

    • Synaptic strength can change due to modifications in neurotransmitter release and receptor numbers.
    • These plasticity changes are essential for learning and memory processes (including addiction).

    Classification of Neurotransmitters

    • Amino acids: glutamate, aspartate, GABA, glycine, etc.
    • Biogenic amines: dopamine, norepinephrine, serotonin, histamine, etc.
    • Neuropeptides: endorphins, etc.
    • Acetylcholine

    Neurotoxins

    • Some toxins can promote neurotransmitter release (e.g., black widow spider venom).
    • Others inhibit release (e.g., botulinum toxin, tetanus toxin, batrachotoxin).

    Botox

    • Botox is derived from botulinum toxin.
    • It inhibits acetylcholine release, weakening muscles.
    • Medical uses include reducing wrinkles, treating muscle spasms, and migraines.

    Unconventional Neurotransmitters

    • Endocannabinoids, gasotransmitters (e.g., nitric oxide), purinergic signaling molecules (ATP), and adenosine.
    • These molecules often act as modulators of classic neurotransmitter systems.
    • They are less commonly stored in synaptic vesicles than other neurotransmitters.

    Ionotropic and Metabotropic Receptors

    • Neuroreceptors categorized as ionotropic or metabotropic based on signaling mechanisms.
    • Ionotropic receptors are ligand-gated ion channels.
    • Metabotropic receptors are G protein-coupled receptors.
    • Both function to change ion flow and affect post-synaptic potential, but ionotropic processes are faster.

    Ionotropic Receptors

    • Direct activation of ion channels by neurotransmitters.
    • Fast, short-acting responses.
    • Receptor changes shape in response to neurotransmitter binding, causing ion channels to open or close.

    Metabotropic Receptors

    • Signal transduction pathways are involved, causing slower, but often longer-lasting responses.
    • Usually involve intracellular signaling cascades.
    • Receptors are G-protein coupled. Changes in ion channel activity or other cellular responses like gene expression.

    Metabotropic Receptors in Memory and Learning

    • Synaptic plasticity is key for learning and memory.
    • Metabotropic receptors play a crucial role in changing the strength of synapses.
    • They significantly affect the process of neurotransmission in the hippocampus.

    Neurotransmitter Receptor Summary

    • A summary table outlining the types of receptors for various neurotransmitters (ionotropic and metabotropic) including function and properties (e.g., excitatory or inhibitory effects).

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    Description

    This quiz delves into the biochemistry of neurotransmitters, highlighting their structures, functions, and the various receptors involved. It covers key neurotransmitters such as dopamine and serotonin, their agonists and antagonists, and their implications in diseases like anxiety and Parkinson's. Gain insights into how these neurotransmitters can be pharmacologically modified for treatment.

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