chemicals in the brain Flashcards
What is the role of synapsin
Anchors a pool of vesicles to the cytoskeleton
Outline synaptic vesicle release and recycling
after an AP, Voltage-gated Ca2+ channels open and calcium ions flow into the cytoplasm and activates calcium m calmodulin activated kinase 2 (caMKII) which phosphorylates synapsin. p-synapsin can no longer bind to the cytoskeleton, vesicles dock to the active zone.
What is a SNARE complex
They dock vesicles to the plasma membrane
Outline the mechanism of exocytosis
The vesicle docks and calcium is released once the AP arrives, the SNARE complexes are formed which pulls the two membranes together and allows the vesicle ot empty its contents into the synaptic cleft.
What are two important proteins on vesicles that aid in exocytosis
synaptobrevin and synaptotagmin
What are two important proteins on the terminal end of exocytosis
Syntaxin and SNAP-25
What is a property of botox and tetanus
They can prevent neurotransmitter release
What are the categories of neurotransmitters
Amino acids, Monoamines, acetylcholine and neuropeptides.
Where are neuropeptides synthesised, stored and what are they released in response to
They are synthesised in the cell soma and transported to the terminal, stored in secretory granules and released in response to global increase in calcium ions.
Give an example of a fast neurotransmitter
amino acid
give an example of a slow neurotransmitter
neuropeptides
How are fast NM categorised
excitator: glutamate and inhibitory: GABA in the brain and Glycine in the spinal cord and brainstem
How do excitatory NM work
They slightly depolarise the post synaptic cells membrane
How do inhibitory NM work
They slightly hyperpolarise the post synaptic cells membrane
Outline the functions of the seteronergic system
function in: mood, sleep, pain, emotion and appetite
Where is glutamate synthesised
At the presynaptic source either from glucose via the krebs cycle or from glutamine converted to glutaminase into glutamate
Where is glutamate stored
Loaded and stored in vesicles by vesicular glutamate transporters (VGLUT’s)
How is glutamate reuptaked
Reuptake by excitatory amino acid transporters (EAATs) in the plasma membrane of the presynaptic cell and surrounding glial cells.
What is the role of glial cells in the reuptake of glutamine
They convert glu to glutamine and this is transported from the glia back to nerve terminals where it is converted back into glutamate
Where is GABA synthesised
Synthesised from glutamate in a reaction catalysed by glutamic acid decarboxylase (GAD)
Where is GABA stored
loaded and stored into vesicles by vesicular GABA transporter
How is GABA cleared from the synapse
reuptake via transporters on glia and neurons
What is a result of too much GLU with too little GABA
hyper-excitability which can lead to epilepsy
What can too much GABA result in
Sedation/ Coma
What are two types of monoamines
catecholamines and indolamines
give examples of catecholamines
dopamine, adrenaline and noradrenaline
give examples of indolamines
seretonin
Outline catecholamine synthesis 1
tyrosine is converted into dopa and then converted into dopamine
outline catecholamine synthesis 2
dopamine is converted into noradrenaline which is converted into adrenaline
How are catecholamines stored
loaded into vesicles via vesicular monoamine transporters (VMATS)
how are catecholamines released
released in response to increase concentraion of calcium ions
how are catecholamines reuptaked
reloaded back into vesicles, enzymatically degraded by monoamine oxidases (MAOs) or inactivated by catechol-O-methyl-transferase (COMT)b
What is the action of fluoxetine (prozac)
SSRI- blocks reuptake of seretonin
what is the action of fenfluramine
stimulates seretonin release, used as an apetite supressant.
what is the action of MDMA
releases a lot of NT into the synapses.
what is the action of choline acetyl transferase
converts choline and acetyl coA into acetylcholine,
Outline the release and reuptake of acetylcholine
packaged into vesicles by vesicular acetylcholine transporters (VAChT), rapidly degraded in the synaptic cleft via AChE and transported back into the presynaptic terminal
What are neuropeptides
Short polypeptide chains, variable in methods of synthesis and release and they move fairly slowly.
