Neurotransmitters Flashcards
What is the primary excitatory neurotransmitter?
Glutamate
What enzyme catalyzes the reaction of α-ketoglutarate to glutamate?
glutamate dehydrogenase
How is glutamate synthesized?
α-ketoglutarate (NADPH as a cofactor)
glutamine via glutaminase enzymes
Glutamate release is a ____________ dependent process
Calcium
What is an autoreceptor? What autoreceptors are specific to glutamate?
A receptor for the neurotransmitter released by that neuron;
mGluR2 & mGluR3
Where are VGluTs found?
In the membrane of vesicles of glutamatergic neurons
In what type of cell would you most likely find plasma membrane glutamate transporters?
astrocytes
What do plasma membrane glutamate transporters co-transport along with glutamate?
Sodium
The primary cell that mediates uptake of glutamate is the __________, via the _______________.
astroglia; glutamine-glutamate shuttle
What are the steps of the glutamine-glutamate shuttle?
a) glutamate accumulated by astroglia is converted to glutamine via the enzyme glutamate synthase
b) glutamine is then released and taken up by neurons
c) glutamine within neurons is converted back to glutamate and packaged into vesicles
What are two basic glutamate receptors?
Ionotropic
Metabotropic
What are the two types of ionotropic receptors?
non-NMDA
NMDA
What is the function of non-NMDA receptors? What are the two subtypes?
conduct mostly sodium and potassium
AMPA and kainite
What is the function of NDMA receptors?
conduct calcium, sodium and potassium
What are the properties of NDMA receptors?
(1) high conductance (big pipe)
(2) requires glycine as a cofactor
(3) requires membrane depolarization AND ligand binding to the receptor to open
(4) channel opens and closes slowly
In NDMA receptors, membrane depolarization relieves the ______________.
Magnesium plug
What is an example of a neuroactive lipid?
2-AG
Where are the highest amounts of 2-AG found?
striatum
limbic cortex
hippocampus
cerebellum
What also activates the same receptor as THC?
2-AG
How does 2-AG synthesis differ from glutamate synthesis?
Synthesized and released simultaneously
not stored in vesicles
2-AG is not formed unless _____ is also present and activated.
DGL (diacylglycerol lipase)
How does MGL inactivate 2-AG?
hydrolyzes 2-AG into glycerol and arachidonic acid
What are the physiological roles of 2-AG?
Functions to modulate many fundamental brain processes: feeding sleep blood pressure balance & posture memory mood
What are the properties of the Cannabinoid receptor (CB1)?
a) G protein coupled
b) almost always presynaptic
c) inhibits the opening of calcium channels, therefore inhibits neurotransmitter release
