Lectures 13: NTs Flashcards
What packs NT into a synaptic vesicle?
Vesicular transport protein
Vesicles bind where on the nerve terminal plasma membrane?
Active zone
Ca2+ triggers…(in nerve terminal)
Fusion
The vesicle is recaptured via endocytosis and protein?
Clathrin
Amino acid NTs (3)
Glutamate, GABA, Glycine
Monoamines (4)
Catecholamines, indoleamines, acetylcholine, histamine
Catecholamines (3)
Dopamine, NE, epi
Indoleamines (2)
Serotonin, melatonin
Other NTs (5 classes)
Nucleosides (adenosine), lipid-derived (anandamine), gases (NO), neurotrophic factors (BDNF), hormones w/ nuclear receptors (steroids)
Ligand-gated channels create a robust…How many transmembrane regions? How many subunits?
Postsynaptic current; 4; 4-5
GPCR has how many transmembrane regions?
7
Two other motifs of neurotransmission in the brain
Protein tyrosine kinases (neurotrophic factors) and nuclear hormone receptors (steroid hormones)
Glutamate acts through…Examples of each and major role.
Ligand-gated channels (rapid neurotransmission, AMPA, NMDA, kainate) and GPCRs (modulatory influences/autoreceptors, mGluR1-8)
What accounts for the vast majority of the brain’s rapid, point-to-point communication?
Glutamate acting on ligand-gated channels
Autoreceptors are…
Gi
Glutamate can be made from which two pathways? And which enzymes? What enzyme turns glutamate into glutamine? What cell expresses this?
Aspartate and alpha-ketoglutarate (transaminase); glutamine (glutaminase); glutamine synthetase; astrocytes
Two glutamate-relevant drugs and their action
Ketamine and phencyclidine; NMDA receptor antagonists
GABA acts through…Examples of each. What ion does the first channel flux? What is the second receptor?
Ligand-gated channels (GABAa) and GPCRs (GABAb); Cl-; autoreceptor
Describe GABA’s synthesis and degradation
GABA is synthesized from glutamate via the enzyme, glutamatic acid decarboxylase (GAD) and degraded by GABA transaminase
How is GABA removed from the synapse?
Returned to the nerve terminal via a plasma membrane GABA transporter
How do anticonvulsant drugs work?
Either increase GABA synthesis or block reuptake
How do sedative-hypnotic drugs work? What are their effects? Two examples?
Promote GABAa receptor function; anticonvulsant/anti-anxiety/pro-sleep; benzos and barbiturates
Where does Glycine primarily serve as a NT? Excitatory or inhibitory? What kind of receptor? Name?
Spinal cord; inhibitory; a ligand-gated Cl- channel; strychnine-sensitive glycine receptor
What is a second function of glycine?
Glycine can bind with relatively low affinity to NMDA glutamate receptors and thereby enhances the ability of glutamate to activate these receptors
How should one think about monoamine NTs?
Play a modulatory roles, by increasing or decreasing the gain on glutamatergic or GABAergic neurotransmission
Describe dopamine synthesis. Denote rate-limiting enzyme
Tyrosine hydroxylase* converts tyrosine to L-DOPA. DOPA decarboxylase converts L-DOPA to dopamine
Describe noradrenergic synthesis
Dopamine is converted into norepinephrine by dopamine β-hydroxylase
Describe adrenergic synthesis
Norepinephrine is converted into epinephrine by phenylethanolamine-N-methytransferase
All catecholamines are degraded by…(2)
Monoamine oxidases (MAOs) and catechol-O-methyltransferase (COMT)
Catecholamines are concentrated into synaptic vesicles via…What other NT uses this?
Vesicular monoamine transporter (VMAT); serotonin