Neurotransmitters And Their Receptors Flashcards
What is caused by excess glutamate?
Excitotoxicity (ischemia, epilepsy, hypoglycaemia or trauma)
What is the main excitatory neurotransmitter in the brain?
Glutamate (0.5 synapses)
Which neurotransmitter produces inhibitory postsynaptic potentials (IPSP)?
GABA
What defines a neurotransmitter as a bionic amine?
Possessing an amine side chain
Name the 4 main catecholamines and what they were derived from.
L-DOPA, dopamine, noradrenaline and adrenaline all from tyrosine
Which 2 neurotransmitters are involved in reward pathways?
Dopamine and serotonin
What are the main functions of peptide hormones?
Modulate pain, emotions, stress levels and appetite
What is the main peptide neurotransmitter involved in pain and how is this pain reduced?
Substance P, release is inhibited by opiods
How is acetylcholine removed from the synapse?
Via the enzyme, acetylcholinesterase
Which neurotransmitters are reuptaken, either the glia or the neurone?
GABA, glutamate and serotonin
What is the mechanism for the removal of peptide hormones from the synapse?
They diffuse away from the synapse
What are the two main neuroreceptors?
Metabotropic (GPCR) and ionotropic (LGIC)
There are two types of LGIC, what are they?
Cationic allowing positive ion influx and anionic allowing negative ion influx
GPCR are characterised by what structural aspect?
Their single polypeptide, 7 transmembrane helices
The activation of a G protein by the binding of a neurotransmitter leads to what?
A signalling cascade of amplification
Which ionotropic receptors are pentamers?
GABA, glycine and acetylcholine
What is the structure of nicotinic acetylcholine receptors?
Must have at least 2 alpha subunits. Usually 3 alpha and 2 beta
Why is it less common for LGIC to allow passage of calcium?
Because calcium is large, the receptor much posses the alpha-7 domain
How many transmembrane helices does a subunit have if it’s C terminal in intracellular?
3 helices, the 2nd being a pore loop
If a subunit has 4 transmembrane helices, where are the N and C terminals situated?
Both outside if the cell
LGIC subunits have transmembrane helices, which helix is most important and why?
2nd as it controls ion entry
What are the different types if glutamate receptors?
AMPA, NMDA and kainate
How many subunits do glutamate ionotropic receptors have?
4, tetrameric
How is AMPA formed?
2 gluR1 subunits and 2 gluR2 subunits
What change is made to an AMPA receptor to allow calcium movement?
One gluR2 is replaced by a gluR1
Why does the glutamate NMDA receptor require a high frequency stimulant?
Because it is ordinarily block by magnesium
How does glycine enhance glutamate effects?
Binds to NMDA receptors and acts as a co agonist
What must the ionotropic GABAa receptors posses to work?
At least 2 beta subunits
The binding of GABA to GABAa allows what ion to flow? What does this cause?
Chlorine, causing hyperpolarisation
What affect does picrotoxin have on GABAa receptors?
Binds and prevents the movement of choline, reducing the inhibitory effects
What drug can be used to prevent GABA binding to GABAa receptors?
Benzodiazepines
In meta preppie receptors, where is the G protein situated?
Between helices 5 and 6 and near the C terminal
There are metabotropic receptors for which neurotransmitters?
Dopamine, NA, adrenaline, histamine, serotonin, glutamate, GABAb and muscarinic
There are many metabotropic receptor subtypes for each neurotransmitter, why?
Because of the specific G protein bound
What G protein is bound the the beta-adrenergic receptor that binds NA?
Gs
Which G protein is bound to the mGluR metabotropic receptor for glutamate?
Gq
Which G protein is bound the the D2 metabotropic dopamine receptor?
Gi
