How do you identify if a neurotransmitter is fast or slow acting?
By the type of channel it activates; (ionotropic = fast, metabotrophic = slow)
Ionotropic receptors are what?
Gated ion channels that are opened by binding of ligand = ions flow; results in a quick effect
Metabotropic receptors are what?
receptors that work through a 2nd messenger system when activated = slow effect; i.e GPCRs
What are the 4 major types of receptor classes?
GPCRs, RTKs, Ligand-gated ICs, NTFRs
How is the signaling of neurotransmitters (NTs) terminated?
- enzymatic degradation
- diffusion away from the synapse
- accumulation in glial cells
What are the possible effects that an NT can have on its target receptor?
stimulator, inhibitor, or modulator
What ion is required for the exocytosis (release) of an NT from a presynaptic neuron?
What are the 5 major biogenic amines?
- norepi (NE)
- Dopa (DA)
- Serotonin (5-HT)
What amino acid are catecholamines (Epi, NE, and Dopa) derived from?
What is the rate-limiting step in catecholamine synthesis?
tyrosine --> L-dopa
Which catecholamine is L-dopa converted into?
Tyrosine --> L-dopa--> Dopa-- >NE
What enzyme is needed to convert NE --> Epi?
phenylethanolamine N-methyltransferase (PNMT)
What are the 2 major enzymes in catecholamine production?
tyrosine hydroxylase and PNMT
That is the sequence of catecholamine synthesis
Where does the conversion of dopamine --> NE occur?
in vesicles called chromaffin granules
Where is NE --> Epi?
What moves Epi from the cytosol into vesicles?
What are COMTs and MAOs?
enzymes that inactive catecholamines convert them into VMA
What products of catecholamine metabolism is used to measure catecholamine production?
Where are NE producing neurons found?
Locus coeruleus = crucial to waking up/awareness; projects to almost all areas of CNS
Where is Epi primarily released?
Where is dopamine made in the CNS?
substantia nigra (black substance) and ventral tegmental area of brain stem
Where does the substantia nigra project to?
striatum (lentiform nuclei & caudate nuclei)
Where does the ventral tegmental area project is DA fibers to?
prefrontal cortex and parts of the limbic system
What are the 4 major systems that use DA?
- substantia nigra = motor
- mesolimbic = VTA --> Nucleus accumbens
- mesocortical = VTA--> frontal cortex
- tuberinfundibular = hypothalamus --> anterior pituitary (prolatin suppression)
where is histamine made in the CNS?
the tuberomammillary nucleus (TMN) of the posterior hypothalamus; project throughout brain
What cognitive state is histamine associated with?
How does histamine down regulate itself?
activation of H3 receptors on presynaptic neuron says there is enough histamine
Diamine oxidase degrades what?
What nuclei make serotonin (5-HT)
raphe nuclei of the brainstem