Chemical signalling Flashcards
what are the two main amino acid neurotransmitters?
glutamate and GABA
where do glutamate and GABA act?
CNS (brain and spinal cord)
describe the process of glutamate synthesis and storage and reuptake
- synthesized from glutamine
- loaded and stored in vesicles by vesicular glutamate transporters
- removed from synapse by excitatory amino acid transporters
what is glutamate excitotoxicity?
when there is too much glutamate stimulation (not removed from synapse) - damages neurons
what are agonists and antagonists?
agonist - a drug that binds with receptor and produces a reaction
antagonist - a drug that binds with a receptor that reduces or blocks the reaction
what is kinetics?
the rate of transmitter binding and channel gating determines the duration of effects
what are the 2 main glutamate ionotropic receptors?
NMDA and AMPA receptors
describe the NMDA receptor
- glutamate ionotropic receptor
- for calcium channel to open, glutamate and glycine must both bind
- APV blocks glutamate from binding (antagonist)
describe AMPA receptor
- glutamate ionotropic receptor
- controls opening of sodium channels
describe the process of GABA synthesis and storage and reuptake
- synthesized from glutamate
- loaded and stored into vesicles by GABA transporter
- removed from synapse by GABA transporters
what happens when there is too much GABA?
sedation or a coma
describe GABA A receptors
- GABA ionotropic receptors
- controls chloride channels
- muscimol = agonist
- bicuculine = antagonist
what are drugs that reduce GABA activity called? give some examples
anxiolytic e.g benzodiazepines, barbituates
what is neuromodulation?
affecting the response properties of a neuron, but don’t carry primary information themselves. e.g dopamine, serotonin
where are the dopamine neurons located?
in the midbrain: ventral tegmenta area (VTA) & substantia nigra (SN)
what does the nigrostriatal system play a role in?
movement
what system plays a role in reinforcement?
mesolimbic system
what does the mesocortical system play a role in?
functions such as working memory and planning
describe the process of dopamine synthesis
- Dopamine is synthesised from tyrosine by tyrosine hydroxylase(TH)
- this becomes L-Dopa, which becomes dopamine when catalyzed by DOPA decarboxylase
what group of neurotransmitters is dopamine part of?
monoamines
what drug prevents storage of monoamines?
reserpine
describe the process of serotonin synthesis
- made from tryptophan by tryptophan hydroxylase
- this produces 5-HTP
- this produces serotonin when catalyxed by 5-HTP decarbyoxylase
what is fluoxetine?
a drug that blocks serotonin reuptake (anti-depressant)
describe the cholinergic system
- primarily acts in the PNS
- uses the neurotransmitter Acetylcholine
describe acetylcholine synthesis, storage and release
- made from choline
- stored in vesicles
- calcium dependent exocytosis
what drug blocks the breakdown of ACh?
acetylcholinesterase inhibitors
what drug prevents the release of ACh?
botulinum toxin (botox)