block 6 lecture 4 CNS biochemistry Flashcards
what are some examples of types of neurotransmitterS?
amino acids
gasses
example of small molecule neurotransmitter?
acetylecholine, glutamate
feature of small molecule neurotransmitter?
rapid
what are larger neurotransmitetrs called?
neuropeptides
features of neuropeptides?
neuromodulators and slower crossing the synapse
what protein does the microtubule system use to transport the enzyme to the axon nerve terminal?
kinesthin
what are the major classes of neurotransmitter?
biogenic amines, amine acids, gasses, neuropeptides
what do co-transmitters give rise to?
versatility to neurotransmission
what does low frequency stimulation of neurons produce?
release of small vesicles
what does high frequency stimulation of neurons produce?
release of small and large vesicles
what are in small clear core vesicles?
low molecular weight neurotransmitters
what are in dense core vesicles?
bioamines and neuropeptides
what are the criteria for a neurotransmitter?
must be in neuron, must produce response in target cell, same response must be produced when chemicals are experimented with, must be a mechanism of removal, specific receptore must be present on post synaptic cell
how can you identify neurotransmitters?
immunocytochemistry, in situ hybridisation, microiontophanesis, radio-ligand binding, alpha bungaro toxin, atrope belladonna
what are the types of receptors?
ionotropic receptors and metapotropic receptors
what are ionotropic recptors?
must encorporate an ion channel
whata re metabotropic receptors?
act via receptor coupled to an intrecellular intermediate
structure of acetylecholine involves?
amine
where would you find acetylecholine?
PNS
neuromuscular junction
autonomic ganglia
in the CNS what is acetlycholine involved in?
learning, memory, sleep, arousal, aggression, biorhythms, thermo regulation and sexual behaviour
in the parasympathetic and sympathetic nervous system where is acetylecholine used?
pre ganglionic neurons
what is altzhiemers because of?
loss of cholinergic fibers
where do projections go from the pons?
basal forbrian, thalamus and neocortex
what neurons is acetylecholine found in?
hippo campus and cerebral cortex
what are cholinergic neurons also important for?
keeping us awake
where do you get choline from?
diet
how is acetylcholine produced?
choline and acetyl CoA are combined to form acetylecholine
what is the enzyme called in the formation of acetylecholine?
choline acetate transferase
what is the mainbreak down enzyme of acetylecholine?
acetylecholine esterase
what is the other breakdown enzyme of acetylecholine?
pseudocholine esterase
what does acetylecholine esterase do?
hydrolyses acetylecholine into choline and acetic acid in the synaptic cleft
how can choline be removed from the synaptic cleft?
taken up by presynaptic neuron by transporter mechanisms using sodium
how does neostigmine, physiostigmine and donepizil work?
inhibits acetylecholine esterase
what can neostigmine, physiostigmine and donepizil be used for?
myasthenia gravis, glaucoma and smooth muscle dysfunction
what are the two types of nicotinic receptors?
nicotonim Nn
nicotinic Nm
where do you find nicotinic Nn?
post ganglionic neurons
where do you find nicotinic Nm?
skeletal muscle end plates
where are muscarinic receptors found?
in peripheral tissues
what is glutamate?
excitatory neurotransmitter, amino acid
what forms glutamate?
glutamine is converted to glutamate
what is the enzyme involved in glutamate synthesis?
glutaminase
how is glutamate removed?
transporters on the presynaptic membrane
nearby glial cells
what do glial cells do to glutamate?
convert it to glutamine by glutamine synthase
what are the three types of glutamine receptor?
AMDA
NMDO
kainate
which glutamate receptor is related to epilepsy?
NMDA
what are most inhibitory neurons in the CNS?
GABA
glycine
what is involved in the production of GABA?
glutamate is converted to GABA by glutamic acid decarboxylase
what are the two types of GABA receptors?
GABAa and GABAb
what are GABAa receptors?
ionotropic
what are GABAb receptors?
metaprotropic
what is the structure of GABAa structure?
5 subunits
how does diazapam work?
interacts with GABA receptor to increase the influx of chloride ions into the neuron
how does GABA work at GABAa receptors?
binds and opens the channel, allowing an influx of chloride ions which hyperpolarises the membrane potential making it more negative and so neurons are inhibited
what type of drug is diazapam?
anxiolytic
what is stiff persons syndrome?
antibodies to glutamic acid decarboxylase resulting in a state of rigidity
what happens in epilepsy?
uncontrolled stimulation of the brain
