Lecture 15: chemical brain Flashcards
wat is a chemical signal?
neurotransmitter
what are the two types of signalling with neurotransmitters?
Electrical
Effects on cell metabolism
what happens with a action potential at the synapse?
- action potential reaches pre synaptic terminal
- calcium channels open
- vesicles fuse with membrane and undergo exocytosis
- neurotransmitters are released into the synaptic cleft
- neurotransmitters bind to specific receptors on the postsynaptic neurone
what stem criteria for defining a neurotransmitter?
- substance present in presynaptic cell
- substance must be released upon the arrival of an action potential
- Specific receptors must be present on the postsynaptic cell
- Inactivation of the substance must occur
- substance is applied to the postsynaptic cell directly, it should have the same effect
glutamate is ______ and GABA is ______.
- excitatory
2. inhibitory
Name 3 catecholamines?
Dopamine
Noradrenaline
Adrenaline
monoamines include?
Catecholamines Indoleamines
name a Indoleamine?
Serotonin
ionotropic receptors are also called what?
ligand-gated ion channels
EPSP is ?
Excitatory postsynaptic potential
IPSP is?
inhibitory postsynaptic potential
Ionotropic receptors are _____ acting.
fast
what are glutamate inotropic
receptors?
NMDA, AMPA and kianate
what are glutamate matabotropic receptors?
mGluR group I
mGluR group II
mGluR group III
glutamate causes ___ to come in causing ______.
- sodium
2. depolarisation
glutamate is ______, it can be taken out my a neighbouring ____ cell.
- recycled
2. glia
what would happen if glutamate ermine din the synaptic cleft?
there could be exitotoxicity
where is GABA synthesised?
at the axon terminal by glutamate
what are GABA inotropic
receptors?
GABA(A)
what are GABA Metabotropic receptors?
GABA(B)
what does GABA allow to enter?
negatively charged chloride ions (hyper polarises the cell)
GABA causes a _____ in membrane potential because the cell is ________.
- decrease
2. hyperpolarised
is GABA inhibitory?
yes
Glutamate and GABA are extremely important in the ______ ______.
Basal ganglia
to produce acetylcholine acetate has to become what?
Acetyl coenzyme A
where is Acetyl coenzyme A released from?
mitochondria
Acetyl coenzyme A combines with _____ to form acetylcholine.
1.choline
what does acetylcholine bind too?
Binds to specific ACh receptors on the postsynaptic neuron
what is acetylcholine inotropic receptor?
Nicotinic - fast acting
what also binds to the Nicotinic receptor?
nicotine
what is acetylcholine metabotropic receptor?
Muscarinic – slow acting
acetylcholine is broken down by?
acetylcholinesterase
what happens when acetylcholine is broken down?
choline is transported back.
Glutamate and GABA are very ____ _____ throughout the brain.
1.wide spread
is acetylcholine more localised then glutamate and GABA?
yes
acetylcholine is important for what?
muscle movement and voluntary movement
acetylcholine is found in which parts of the brain?
cortex and hippocampus,
striatum
in what form is acetylcholine found in the striatum?
form of interneurones
acetylcholine can be involved in ____ and _______.
- arousal
2. attention
acetylcholine in the heart slows down what?
herat rate
acetylcholine in muscles ______ muscle movement.
increases
what does a agonist do?
mimics the action of the neurotransmitter
what does a Antagonist do?
blocks the action of the neurotransmitter
Name two agnoists?
Nicotine
Muscarine
Name to Antagonists?
Curare
Atropine
what does Latrotoxin do?
comes from poisonous spiders, increases ACh effects – forms pores in membrane
what does Botulinum toxin (BOTOX) do?
decreases ACh effects – prevents vesicle fusion
Are Noradrenaline and Norepinepherin exactly the same?
yes
what is noradrenaline synthesised from?
dopamine via dopamine beta- hydroxylase
Noradrenaline can become?
adrenaline
Noradrenaline binds to what?
alpha or beta metabotropic receptors
Noradrenaline is ____ acting.
slow
whats an example of what Noradrenaline does?
- binds to beta receptor
- activates G protein
- increases effector adenyl cyclase
- increases cAMP
- increases protein kinase
- increases protein phosphorylation
Noradrenaline can mainly be found in the?
locus coeruleus
locus coeruleus projects noradrenaline to which other parts of the brain?
cortex and hippocampus
noradrenaline is involved in ….
- Attention and memory during cognitive tasks
- arousal
- sleep-wake cycle
noradrenaline modulates ___ __ ______ via the ______ nervous system
- fight or flight
2. sympathetic
where does dopamine reside and where does it project too?
resides in the substantial nigra
projects to the striatum
dopamine pathway is involved in functions such as?
- reward
- pleasure,euphoria
- motor function
- compulsion
- preservation
serotonin pathway is involved in functions such as?
mood
memory processing
sleep
cognition
Nigrostriatal pathway is a critical pathway in the ___ _____.
basal ganglia
what neurone does the striatum contain?
medium spiny neurons
what type of medium spiny neurons are excited by dopamine?
those expressing dopamine D1 receptors
MSNs expressing dopamine D2 receptors are what by dopamine?
inhibited by dopamine
what happens when dopamine minds to dopamine D2 receptors ?
- binds to dopamine D2
- activates Gi protein
- decreases effector adenyl cyclase
- decreases cAMP
- decreasesprotein kinase
- decreases protein phosphorylation
Parkinson’s Disease is a ______ _______.
- hypokinetic
2. disorder
Parkinson’s is what kind of condition?
neurodegenerative condition
what happens to dopamine during Parkinson’s Disease?
- Dopamine-producing cells in the substantia nigra undergo cell death
- disorder of basal ganglia causing less movement
what are symptoms of pakinsons disease?
• Bradykinesia – Slowness of movement – Shuffling gait • Akinesia – Difficulty initiating movements • Rigidity due to increased muscle tone • Resting tremor • Depression
what are treatments for Parkinson’s disease?
- L-DOPA
- Deep brain stimulation
- Anticholinergic drugs
(Not used much nowadays) - Cell transplantation
where is the Ventral tegmental area located?
in the midbrain
Ventral tegmental area is known as the _____ leaning centre.
1.reward
Dopaminergic cell bodies reside in the ___
VTA
Tonic firing of dopamine neurones causes what?
small spikes, not sufficient to evoke response
what are the two types of firing in the VTA?
tonic and phasic
Phasic firing of dopamine neurones causes what?
large spikes, leading to dopamine being released at presynaptic neurone and receptors being activated.
what did Schultz do?
- recorded from the VTA of monkeys
- trained to link visual cue with reward
what is the nucleus accumbens known as?
motivational centre
what experiment shows how dopamine is linked to motivation?
Healthy rat would travel more to get more food.
rats with no dopamine would take the easy route with little food.
what does cocaine do (linked to dopamine)?
blocks dopamine transporter
why does someone get addicted to cocaine?
nucleus accumbens gets more and more dopamine, become addicted.
what are the pleasure peptides in the brain?
Opioids
what do opioids bind too?
bind to opioid G-protein coupled receptors
Name 4 opioid drugs?
Morphine
Opium
Heroin
Fentanyl
Name 4 Endogenous opioids?
ß-Endorphin
Enkephalin
Dynorphin
Nociceptin
How is serotonin made?
form Tryptophan
where do we get Tryptophan from?
diet
which serotonin receptor is inotropic ?
5HT3 is ionotropic
majority metabotropic
serotonin is also known as?
5-HT
whats the main region for serotonin?
raphe nuclei
serotonin is projected to the?
forebrain
serotonin is removed form the synaptic cleft via?
SERT
what do SSRI’s do?
keep serotonin in the synaptic cleft (used to treat depression)
which neuropeptides increase apetite?
Orexigenic neuropeptide:
NPY
AgRP
which neuropeptides decrease apetite?
Anorexigenic neuropeptides:
pomC
CART
what is leptin involved in?
Leptin is a key hormone involved in the regulation of food uptake and energy expenditure
where is leptin synthesised from?
adipose tissue
leptin ____ appetite?
decreases
