Junctional transmission & Principles of receptor function Flashcards
(23 cards)
What is the role of calcium at the synapse?
Calcium influx triggers the release of neurotransmitters from the presynaptic terminal by activating the SNARE complex, which facilitates vesicle docking and exocytosis.
What is the SNARE complex, and what is its function?
The SNARE complex consists of vesicular and presynaptic membrane proteins that interact to enable vesicle docking, fusion, and neurotransmitter exocytosis in response to calcium influx.
How is the size of the post-synaptic response determined?
It is determined by three quantal parameters:
The number of release sites (N)
The release probability (P)
The quantal size (Q)
Formula: Mean EPSC = N × P × Q
What neurological disorders are linked to SNARE complex impairments?
Neurodegenerative diseases (Alzheimer’s, Parkinson’s)
Neurodevelopmental disorders (autism)
Psychiatric disorders (schizophrenia, depression, bipolar disorder)
How does SNAP-25 deficiency or overexpression affect the brain?
Deficiency: Linked to schizophrenia, autism, and learning/memory impairments.
Overexpression (SNAP-25B isoform): Associated with early-onset bipolar disorder.
What are the key functions of dopaminergic neurons?
They regulate reward, motivation, pleasure, motor function, compulsion, and preservation. Located in the frontal cortex, hippocampus, and nucleus accumbens.
What happens in dopaminergic deficits?
Deficits are observed in Parkinson’s disease (motor dysfunction) and depression (mood dysregulation).
Name six signal transduction proteins and their roles.
Kinases: Add phosphate groups.
Phosphatases: Remove phosphate groups.
Phospholipases: Hydrolyze membrane phospholipids.
Ubiquitin-ligases: Tag proteins with ubiquitin for degradation.
Proteases: Break peptide bonds.
GTPases: Hydrolyze GTP to GDP.
What is synaptic plasticity?
The ability of synapses to change structurally or functionally in response to experience. A key form is long-term potentiation (LTP), which underlies learning.
What is the formula for mean excitatory post-synaptic current (EPSC)?
Mean EPSC = N × P × Q
(Number of release sites × Release probability × Quantal size).
How do drugs affect dopamine levels?
Drugs can alter dopamine levels by blocking reuptake (e.g., via DAT inhibition), enhancing release, or inhibiting breakdown (e.g., MAO inhibitors).
What is the significance of the dorsal cochlear nucleus in plasticity?
It exhibits synaptic plasticity (structural/functional changes), as studied by Oertel (2004), contributing to adaptive auditory processing
What is the primary role of calcium in neurotransmitter release?
Calcium influx triggers vesicle fusion via SNARE complex activation, enabling exocytosis of neurotransmitters.
Which neurological disorders are linked to SNAP-25 abnormalities?
Deficiency: Schizophrenia, autism, learning/memory deficits.
Overexpression (SNAP-25B): Early-onset bipolar disorder.
A patient presents with tremors and bradykinesia. Which dopaminergic pathway is impaired?
Degeneration of dopaminergic neurons in the substantia nigra, leading to reduced dopamine in the striatum (motor dysfunction).
How do MAO inhibitors increase synaptic dopamine?
They block monoamine oxidase (MAO), slowing dopamine breakdown and prolonging its effects.
A patient with learning deficits shows reduced hippocampal synaptobrevin 2. Why?
Synaptobrevin 2 is critical for vesicle fusion; its deficiency impairs neurotransmitter release and synaptic plasticity.
Overexpression of which SNARE protein is linked to high-functioning autism?
Syntaxin 1A overexpression disrupts synaptic vesicle docking.
Which brain region exhibits plasticity tied to auditory adaptation?
Dorsal cochlear nucleus (Oertel, 2004).
What is the precursor molecule for dopamine synthesis?
Tyrosine → converted to L-DOPA → dopamine.
How do ubiquitin-ligases contribute to Alzheimer’s disease?
They tag misfolded proteins (e.g., tau) for degradation; dysfunction leads to toxic protein accumulation
A patient with euphoria and hyperactivity uses cocaine. How does it affect dopamine?
Cocaine blocks dopamine transporters (DAT), increasing synaptic dopamine by preventing reuptake.
What synaptic change underlies learning and memory?
Strengthened synaptic connections via increased AMPA receptor insertion (structural/functional plasticity).
