Lecture 12: Neurotransmitters Part I Flashcards
Chemical signaling consists of what 3 parts?
signal
receptor
target molecule/ion channel
Ionotropic receptors are ___________ channels and the _________ is the channel
ligand gated, receptor
Metabotropic receptors contain __________ receptors and the receptor _________ channel.
g-protein coupled, modulates
In Ionotropic receptors, the _______________ forms the ion channel,
Membrane spanning region
comprised of 4-5 subunits
What are the ionotropic glutamate receptors?
NMDA, AMPA/Kainate
Name the cys-loop receptors
nAChR, 5-HT3, GabaA, Glycine, purinergic
Ionotropic receptors contain __ subunits and a complete receptor of _______ subunits
1, 4 or 5
Name 3 main features of the metabotropic receptors.
g protein coupled receptors are here
Monomeric proteins consisting of 7 transmembrane domains
Domains 2,3,6,7 make up NT binding region
nACh receptor is an __________ receptor
ionotropic
nAChR consists of ____ subunits, and its alpha subunits bind _________.
5, ACh
In nAChR, each subunit has 4 __________. The M2 subunit line ______.
transmembrane spanning a-helices, pore
The cytoplasm side of the nAChR receptor has rings of high negative charge that determine the _____________ of the receptor and remove the ___________ of the passing ions.
cation specificity, hydration shell
nAChR is a _________ cation channel
non-selective
Higher driving force for Na+ results in and inward current and an _______.
EPSP
What are the precursors for ACh
acetyl coenzyme A and choline
_______ catalyzes acetylcholine.
ChAT (choline acetyltransferase)
__________ breaks up ACh into acetate and choline
AChE
What takes choline backs up into the presynaptic terminal?
Na+/choline transporter
What condition is characterized by a decrease in EPP?
Myasthenia Gravis
What treats myasthenia gravis?
reversible AChE inhibitors
What causes myasthenia gravis?
antibodies that block AChRs at the post-synaptic NMJ
Insecticides and nerve gases are examples of ____________
Irreversible AChE inhibitors
completely inhibit ACh breakdown
Nerve gases and insecticides cause _________ and _________, particularly resulting in muscle/respiratory failure
overstimulation, neuromuscular paralysis
Classification based on sensitivity for plant alkaloids from tobacco plant and poisonous red mushroom.
Nicotinic and muscarinic AChRs
Give an example of nicotinic agonist.
betel nuts
Give some examples of muscarinic antagonists.
nightshade, belladonna, scopolamine
Muscarinic receptors are _________.
GPCRs
What’s the precursor of glutamate and who releases it?
glutamine, released by glia
Enzyme ________ catalyzes glutamate from glutamine
glutaminase
VgluT is the _______ transporter
glutamate
What is the EAAT?
excitatory amino acid transporter
NMDA-R serves as a ________ detector
coincidence
T/F: voltage-dependent block by Mg2+ ion needs to be relieved by depolarization
True
T/F: Influx of Ca2+ acts as first messenger at intracellular signaling pathways
false, acts as second messenger, relevant to plasticity
T/F: Ca2+ influx through NMDA-Rs results in AMPA-R phosphorylation (early phase)
and eventually gene transcription and protein synthesis (late phase).
True
What’s excitatory, Gq-coupled (PLC ion channels; increase NMDA)
- mostly postsynaptic
Group I, mGLuRs 1 and 5
What’s inhibitory, Gi/Go- coupled ( reduce cAMP), decrease transmitter release; decrease NMDA
- mostly presynaptic, and on glia cells
Group II, mGLuRs 2 and 3
What’s inhibitory, Gi/Go- coupled ( reduce cAMP), decrease transmitter release; decrease NMDA
- mostly presynaptic
Group III, mGLuRs 4,6,7,8
GLutamate decarboxylase catalyzes _______ to _______
glutamate, GABA
What does VIATT stand for?
vesicular inhibitory amino acid transporter
What is the GABA transporter that removes it from synaptic cleft?
GAT
The ionotropic GABA receptors are?
GABAa and GABAc
Effects of GABA agonists?
anxiolytic
anesthetic
sedative
anti-convulsive
Both benzodiazepines and barbiturates (or alcohol) facilitate the ability of GABA to activate the receptor and opening of the _________.
chloride channel (Barbituates increase length of opening, benzodiazepines increase frequency)
What reduces probability of firing of an action potential?
Synaptic inhibition
_____________ open chloride channels, which results in inward flow of negatively charged Cl- ions which causes hyperpolarization.
GABAa/glycine receptors
As long as the ECl- is more hyperpolarized (negative) than the action potential threshold, what can happen?
Depolarizing synaptic potentials can inhibit neurons.
In ________ neurons the intracellular Cl- concentration is controlled by _________, yielding high intracellular level of Cl-
developing, Na/K/Cl co transporter
In _______ cells a ______ co transporter pumps Cl out and lowers internal Cl, making ECl- much more negative
adult, K/Cl
What stimulates opening of K+ channels?
Metabotropic GABA receptors (GABAb), inhibits Ca2+ channels
2 major subtypes of metabotropic GABA receptors are BR1 and BR2, and can assemble as homodimers or __________
heterodimers
Activation of _________ GABAb __________ can inhibit release of GABA from the terminal.
presynaptic, autoreceptors
What can also inhibit release of dopamine, norepinephrine and serotonin?
presynaptic GABAb
What system is a major target for glial modulators?
GABAergic systems
