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Chapter 6: Neurotransmitter Systems (Exam II) (Neurotransmitter Receptors,…
Chapter 6: Neurotransmitter Systems (Exam II)
Serotonin- Once synthesized, transported into vesicles by VMAT2
SERT is involved in reuptake
In cytosol, metabolized by MAO
Amino Acid NTs
Glycine
GABA
Glutamate is precursor; vGATs package into vesicles
Glutamic Acid Decarboxylase (GAD)- Key enzyme in synthesis- GOOD MARKER FOR GABA
membrane transported by GAT
metabolized by GABA-T
Glutamate
VGLUT1, VGLUT2, VGLUT3 move Glutamate into vesicles- GOOD MARKERS FOR GLUTAMATE
Glutamate and Glycine: synthesized from glucose and other precursors in all cells
Endocannabinoids- Anandamide and 2-AG
Retrograde Messengers
Bind to CB1 receptors (brain) and CB2 (immune system)
GPCRs
Gaseous NTs
Nitric Oxide
Synthesized by arginine
Retrograde Transmitter
Neurotransmitter Receptors
Ionotropic
4 or 5 subunits
Fast response
Metabotropic
1 subunit
Receptor subtypes: receptors with different characteristics in different tissues
Acetylcholine
Nicotinic- IONOTROPIC- Nicotine agonist, curare antagonist
Muscarinic- METABOTROPIC- Muscarine agonist, atropine antagonist
Glutamate Receptors (Ionotropic)
Kainate
NMDA
Coincidence detectors- both a ligand- and voltage-gated ion channel
Ligand gate: glutamate must be bound
Voltage gate: at resting Vm channel is blocked by Mg2+
Long-Term Potentiation- learning and memory
Ca2+ influx activates kinases like CaMKII
Ca2+ phosphorylates existing AMPA receptors, enhancing their sensitivity to glutamate
More AMPA receptors in postsynaptic membrane
AMPA
Coexistence of NMDA (Na+, K+) and AMPA (Na+, K+, Ca2+) receptors in the postsynaptic membrane
GABA Receptor- GABAa receptor gates a Cl- channel
Receptor subtypes: receptors with different characteristics in different tissues
Protein Kinases phosphorylate ion channels
Divergence & Convergence: 1 Transmitter activates multiple receptor subtypes & Multiple transmitters activate multiple effector systems, respectively