Lecture 4 Flashcards
Neurohormones
blood transport
Neuromodulators
a chemical messenger that communicates with target cells more distant than the synapse by diffusing away from the point of release.
What is required for a chemical to be a neurotransmitter?
Specific synthetic machinery.
Packaged into vesicles.
Release is coupled to excitation in the presynaptic nerve terminal.
Specific and selective post-synaptic receptors.
Mechanism for inactivation.
Classical neurotransmitter
- Monoamines (dopamine, norepinephrine, serotonin).
- Acetylcholine
- Amino acids.
Non-Classical
- Neuropeptides
- Lipids
- Gases
Catecholamines
Include: dopamine & norepinephrine, epinephrine.
Structure & synthesis.
Storage.
Release.
Inactivation.
How are catecholamines synthesized?
tyrosine → dopa → dopamine → norepinephrine → epinephrine.
What is the enzyme needed to catalyze tyrosine to DOPA?
Tyrosine hydroxylase
What is the enzyme needed to catalyze DOPA to Dopamine
AADC
What is the enzyme needed to catalyze Dopamine to Norepinephrine?
DBH.
Tyrosine hydroxylase
- Rate-limiting enzyme.
- Neural stimulation regulates production.
- Phosphorylation activates.
- Trans-synaptic induction.
L-DOPA
- If you wanted to produce more dopamine in the brain you could skip a step by just pricing brain to dopa.
- L-DOPA can get through BBB.
- A common medication for parkinson’s disease.
Vesicular monoamine transporter (VMAT2)
transport monoamine into vesicles.
Reserpine
drug that blocks vesicular transport meaning that DA and NE are no longer protected from breakdown within the nerve terminal.
alpha-2 autoreceptor
- are receptive to norepinephrine
- are pre-synaptic
- hyperpolarize post-synaptic membranes
- function similarly to dopamine D2 receptors.
Amptheamitimes
fools transporter into getting in and spits dopamine out, once it gets in it stimulates vesicular release and make more dopamine release.
MAO
- breaks down monoamines.
- active in synapse (and beyond) vs within cell.
COMT
- metabolism
- non-neuronal
D1 receptor
- Metabotropic
- Family → D1 & D5.
D2 receptor
- metabotropic
- Family → D2, 3, & 4.
- Gates K+ channels.
Tonic DA
- Dopamine is released in tonic fashion, some continuous/slow and sustained release that helping to keep systems active.
- Modulatory role (sets a tone, focus attention).
Phasic DA
- Comes in phases, bigger sudden release when something important/attention grabbing happens.
- Reactive (alerts to potentially salient info)
DA on Cognition & Behaviour
- Motor activity.
- Internal anticipatory reward signal.
- Higher level cognition (attention & working memory.
Adrenergic Receptors
are metabotropic
