ELM10: Neurotransmitters Flashcards
What are monoamines?
Derived from aromatic amine acids and are aromatic
What are neuropeptides?
Small peptides derived from larger precursor proteins cut up by proteases
What are the 5 different groups of neurotransmitter classification?
Monoamines
Amines
Neuropeptides
Amino acids
Others
What is Dale’s Principle?
A neuron only releases one type of neurotransmitter
What is the revised version of Dale’s principle?
A neuron only releases one combination of neurotransmitter
What is the criteria for the identification of neurotransmitters?
Synthesised by neuron
Present in synaptic terminal at right concentration
Released on presynaptic stimulation
Exogenous application to post synaptic cell evokes response
Mechanism for removal from synapse
What are the two ways glutamate is removed from the synapse?
Taken into presynaptic neuron by excitatory amino acid transporter
Diffuse out of synapse
How is excess glutamate removed once is diffuses out of the synapse?
- Astrocytes have EAAT in membrane to take in glutamate
- Metabolises glutamate into glutamine by glutamine synthase
- Transporter sends glutamine out to be taken up by glutamine transporter and into presynaptic nerve terminal again
- Turned into glutamate by glutaminase
What are the two types of acetylcholine receptors?
Nicotinic and muscarinic
What are the characteristics of a nicotinic acetylcholine receptor?
Ionotropic
Pentameric
16 subunits in humans
Many receptor types
2ACh sites
Built in cation channel
Excitatory
Fast responses
What are some characteristics of muscarinic acetylcholine receptors?
Metabotropic
Monomeric
M1-5 subtypes
5 receptor types
Binding site for G protein
1 ACh site
Influences K+ permeability
Excitatory or inhibitory
Slow responses
What are the two types of glutamate receptors?
Ionotropic
Metabotropic
What are the characteristics of an ionotropic glutamate receptor?
Ligand gated ion channels
Fast
iGluR A
What are the characteristics of metabotropic glutamate receptors?
Family C GPCRs
Slower
mGlyR
What are some characteristics of NMDA receptors?
Highly permeable to Ca2+
Blocked by Mg2+ at RMP
Need glycine as a coagonist
2 glutamate to bind 2 glycine to bind
What is the process of normal transmission at the glutaminergic nerve terminal?
- Current flow induced by AMPA activation causes depolarisation
- Transmits to soma
- Deplarisation deactivates NMDA
- Increased depolarisation and influx of calcium causes more depolarisation
- Transmits to soma
- mGluR1 activation
What are the two types of GABA receptors?
GABA A
GABAB
What are the characteristics of GABA A receptors?
Ligand gated chloride channels
Fast
Pentamers
Many different subunits
What are the characteristics of GABAB receptors?
Family C GPCRs
Slower
What occurs when GABA binds?
Chlorine entry to cell which causes inhibition
Hyperpolarisation
What are the two subunits of GABA B?
GABA B1 and GABA B2
What is the mechanism of GABA B?
- Inhibit voltage gated calcium channels
- Inhibit transmitter release
- Open potassium channels and reduce post synaptic excitability
- Inhibit adenylyl cyclase
What are autoreceptors?
Regulate neurotransmitter release
Presynaptic
Receive NTs for the nerve terminal they’re in
What is an example of autoreceptors?
Controlling noradrenaline release from cardiac sympathetic neurons
What are heteroreceptors?
Responds to a neurotransmitter different to the neuron its embedded in
What is an example of heteroreceptors?
Acetylcholine regulating dopamine release in the striatum
