Exam 3: Glutamate and GABA Flashcards
glutamate is stored and presumably release as a ___
co-transmitter
glutamate is synthesized from _____ by ______ which requires _____
glutamine by glutaminase
needs ATP for energy
3 vesicular glutamate transporters
VGLUT1, VGLUT2, VGLUT3
move glutamate into synaptic vesicles
glutamate as a co-transmitter
can store in separate vesicles or the same one - may be released at diff sites
DA-glutamate neusons of VTA release DA from varicosites and glutamate from terminals
- reinforcing properties of drug use
astrocytes
take up glutamate from extracellular space, express glutamate receptors, and respond to activation of those receptors
gliotransmission
astrocytes release glutamate
after glutamate is released into synaptic cleft, it is rapidly removed by
excitatory amino acid transporters (EAAT1-EAAT5) on cll membranes
also take up aspartate
how do astrocytes convert glutamate to glutamine
glutamine synthetase
3 types of ionotropic receptors
NMDA, AMPA, Kainate
excitatory - depolarize postsynaptic cell
types of metabotropic receptors
mGluR - 3 classes
AMPA and Kainate receptors are depolarized by
flow of sodium ions
NMDA receptors allow what ion/ions to flow through
Ca and Na
Ca activates a second messenger
NMDA receptors - how the work
when at resting potential Mg blocks channel pore, when depolarized Mg ions dissociate
to open channel: BOTH glutamate and glycine or D-serine must bind at the SAME time
glutamate system in brain
cortico-cortical pathway - between thalamus and cortex
cortico-striatal pathway- movement, basal ganglia
implicated in learning and memory, facilitated movement
AMPA and NMDA receptors implicated in
learning and memory
ampakines
enhance action of AMPA receptors by reducing rate of deactivation or desensitization
influx of Ca through NMDA activates protein kinases leading to more
AMPA receptors being inserted in ost synaptic membran
inc sensitivity of postsynaptic neuron to glutamate
facilitates learning and memory
high levels of glutamate can be
toxic to nerve cells
- prolonged depolarization leads to eventual damage or death
major inhibitory AA transmitters
GABA
glycine
can GABA be a co-transmitter like glutamate?
yes
GABA is made from ____ and catalyzed by____
made form glutamate
catalyzed by glutamic acid decarboxylase (GAD)
what moves GABA and glycine into vesicles
VGAT / VIAAT
GABA is removed from synapse by
GAT-1, GAT-2, GAT-3
what is GABA metabolized to
glutamate and succinate by GABA aminotransferase (GABA-T)
GABA A receptor
ionotropic
each receptor has 5 sub units in various combinations
GABA B receptor
metabotropic
GABA A receptor channels allow what ion to move into cell, what happens
chloride
causes hyperpolarization and inhibition of postsynaptic cell
what are GABA A receptors sensitive to
CNS-depressant drugs with antianxiety, sedativem and anticonvulsant properties
- subunit composition of the receptor in important
benzodiazepines (BDZs) on GABA A receptors
sensitivity requires presence of gamma subunit (y)
sedating effects of BDZs require a1 subunits
anxiolytic actions require a2 subunits
ethanol has similar properties to GABA A receptor
GABA B receptor effect in postsynaptic cells
inhibit cAMP formation and K+ channel opening
role of GABA B receptors
learning and memory
anxiety
depression - like behaviors
responses to drugs of abouse
