Neurobiology - Week 4 - Neurotransmitters Flashcards
What are the key anatomical elements of the neurotransmitter process?
- Neurotransmitter synthesising enzymes
- Synaptic vesicles/transporters
- Reuptake transporters
- Degradative enzymes
- Transmitter gated-ion channels
- G-protein-coupled receptors
- G-proteins
- G-protein-gated ion channels
- Second messenger cascades
Where are G-protiens found?
Intracellular regions of the membrane
What are the 3 classes of neurotransmitters?
Amino acids, amines and peptides
What was the first identified neurotransmitter?
acetylcholine
What are the 3 criteria to be a neurotransmitter?
- Synthesis and storage in the presynaptic neuron
- Released by the presynaptic axon terminal
- When applied, mimics post-synaptic cell response produced by the release of neurotransmitters from the presynaptic neuron
How does immunohistochemistry help to identify neurotransmitters?
We’re using the immune system to create antibodies against a particular sequence of amino acids, to identify peptides,
Explain the process of utilising immunohistochemistry to identify neurotransmitters
- Inject neurotransmitter into candidate (e.g. rabbit/mouse)
- Withdraw specific antibodies from ear vein
- Purify antibodies
- Get a brain tissue section and slice
- Apply antibody to the tissue for 48 hours
- Antibody binds to neurotransmitters in the brain tissue slices
- Ability to identify neurotransmitters
What are acetylcholine (ACh) receptors?
- Nicotinic
- Muscarinic
What are 3 glutamate agonist receptors?
- AMPA
- NMDA
- Kainate receptor
What is an ionotropic receptor?
- Ligand-gated ion channels
- Has confirmational change
- Selective ion channels open
- Fast response
What is a metabotropic receptor?
- G-protein coupled receptors
- Slow response
What 3 neurotransmitters are derived from tyrosine?
Catecholamines (norepinephrine & epinephrine)
Dopamine
What amino acid is serotonin derived from?
tryptophan
What does GABA stand for?
Gamma-amino-butyric-acid
Is GABA an inhibitory or excitatory neurotransmitter?
Major inhibitory neurotransmitter in CNS
How many subunits form a pore in the transmitter-gated ion channels?
5
(Pentamers)
Describe an NMDA receptor and it’s function
Discuss GABA receptors
What are 3 steps in g-protein-coupled receptor transmissions?
- Binding of the neurotransmitter to the receptor protein
- Activation of G-proteins
- Activation of effector systems
Describe the basic structure of a g-protein-coupled receptor
A single polypeptide with 7 membrane-alpha-helices
What are the 5 steps in a G-protein operations
Describe divergence and convergence
G protein signal amplification
Who was the person to discover the first neurotransmitter acetylcholine?
Otto Loewi - 1920’s
What neurotransmitter doe glutamatergic neurons use?
Glutamate
What is In Situ Hybridization?
Strands of mRNA consist of nucleotides arranged in a specific sequence.
Each nucleotide will stick to one other complementary nucleotide.
a synthetic probe is constructed containing a sequence of complementary nucleotides that will allow it to stick to the mRNA.
If the probe is labelled, the location of cells containing the mRNA will
be revealed.
What is fluorescence in situ hybridization also known as?
FISH
What is microiontophoresis?
a process for observing or recording the effect of an ionized substance on nerve cells that involves inserting a double micropipette into the brain close to a nerve cell,
injecting an ionized fluid through one barrel of the pipette,
and using a concentrated saline solution in the other tube as an electrical conductor to pick up and transmit back to an oscilloscope any change in neural activity
What is Dale’s principle?
The idea that a neuron has only one neurotransmitter
Many peptide-containing neurons violate Dale’s principle because these cells usually release more than one neurotransmitter: an amino acid or amine and a peptide.
What is the enzyme that converts Acetyl CoA + Choline to Acetylcholine?
Choline acetyletransferase (ChAT)
What is the 4 step catecholamine synthesis from tyrosine to epinephrine
What is the enzyme that converts tyrosine to L-dopa?
Tyrosine hydroxylase (TH)
What is the enzyme that converts L-dopa to Dopamine?
Dopa decarboxylase
What enzyme converts dopamine (DA) to norepinephrine (NE)?
Dopamine beta-hydroxylase (DBH)
What enzyme converts norepinephrine (NE) to Epinephrine?
Phentolamine N-methyltransferase (PNMT)
What is the 2 step enzymatic sequence synthesising serotonin from tryptophan?
What enzyme converts tryptophan to 5-hydroxytryptophan?
Tryptophan hydroxylase
What enzyme converts 5-HTP to serotonin?
5-HTP decarboxylase
What is the chemical compound name for serotonin?
5-hydroxytryptamine
What are the 3 amino acid neurotransmitters?
- Glycine
- GABA
- Glutamate
What is The basic mode of operation of G-proteins
(a) In its inactive state, the subunit of the G-protein binds GDP.
(b) When activated by a G-protein-coupled receptor, the GDP is exchanged for GTP.
(c) The activated G-protein splits, and both the G (GTP) subunit and the G subunit become available to activate effector proteins.
(d) The G subunit slowly removes phosphate (PO4) from GTP, con- verting GTP to GDP and terminating its own activity.
What to protein kinases do?
transfer phosphate from ATP to proteins
called phosphorylation.
What enzymes remove phosphate groups within second messenger groups?
Protein phosphatases
What is the most excitatory neutransmitter in the brain?
Glutamate
What is the most inhibitory neurotransmitter in the brain?
GABA
What is neurotransmitter divegerence?
when the neuron fires, the signal is sent to many other neurons (divergence).
What is convergence?
where one neuron is influenced by many others (convergence)
