Neurotransmitters & Receptors Flashcards
What are the steps of the NT release?
- Arrival of AP & terminal depolarization
- Opening of voltage-gated Ca channels
- Ca2+ enter synaptic terminal
- Docking & fusion of vesicles to presynaptic membrane
- Exocytosis: NT release into synaptic gap
What are the ways to stop the action of a NT?
Reuptake, Degradation, Diffusion
What is the criteria to be a NT?
- Found in presynaptic terminal
- Enzymes for synthesis
- Release upon stimulation of the presynaptic neuron
- Acts on a postsynaptic receptor and produces a biological effect
- Can be inactivated
- Predictable pharmacological action
What are the major classes of NT?
Amino acids, amines, peptides, retrograde messengers
What are the excitatory amino acids?
Glutamate and aspartate
What does VGlut do?
Packages glutamate into vesicles
What are the inhibitory amino acids?
GABA & Glycine
What are the enzymes needed for GABA?
GAD transforms glutamate into GABA; VGAT fills vesicles
What are the properties of glycine?
converted from serine; responsible for IPSPs in spinal cord; VIAAT
What are the types of amines?
Acetylcholine, catecholamine, indoleamine
What are the catecholamine NT?
dopamine, norepinephrine, epinephrine
What does dopamine do? What is it made from?
Movement, learning, attention, emotion; Tyrosine –> DOPA –> Dopamine
What is the Idoleamine NT?
Serotonin
What does serotonin do?
Regulates mood, emotional behavior, sleep and arousal; Target system of hallucinogenic & antidepressant drugs
What is Purine (ATP)?
Often packaged in synaptic vesicles with other NT an co-released during neurotransmission
What are peptides?
Short chains of amino acids; synthesized in cell bodies, packaged in the Golgi, and transported to synaptic terminal via microtubles
What are types of Retrograde messengers?
Endocannabinoids and soluable gases
What is the role of endocannabinoids?
Widespread inhibitory function in CNS
What is Dale’s principle?
The hypothesis that neuron releases the same NT at all its synapses
What are the categories of NT receptors?
Ionotropic & Metabotrophic
What are the properties of Ionotrophic receptors (transmitter-gated ion channels)?
- fast synaptic transmission
- sensitive detectors of chemicals
- directly regulate flow of ionic currents
- selective
What are the steps of G protein-coupled receptors?
- Binding of the NT to the receptor protein
- Activation of G-proteins
- Exchange of GDP to GTP
- Activation of affecter systems
What is the difference between ionotrophic and metabotrophic receptors? How many transmembrane domains does each have?
Metabotrophic are much slower, last for longer, and are extensively amplified.
Metabotrophic= 7 transmembrane
Ionotrophic = 4 transmembrane
What are heteroreceptors?
Respond to NT other than the ones contained in its synaptic vesicle
What are autoreceptors?
Respond to NT that are released from its own synaptic vesicle
What are the essential components of signaling systems?
- A molecular signal
- A receptor molecule
- A target effector molecule (response)
What are the types of Molecular signals?
Cell impermeant; cell permeant; cell-associated
What are cell-impermeant molecules?
Includes NT (do not readily cross membranes)
What are cell-permeant molecules?
Includes steroid-based molecules, thyroid hormone and retinoids
What are cell-associated molecules?
Cell membrane potentials to cell membrane receptor interactions of closely apposed cells
What is exogenous?
Produced outside of the body
What is an endogenous?
Produced within the body
What is the cyclic nucleotide stimulatory pathway? What is an example of a NT?
I go to AC for Crap & Poker”; NT binds to receptor which changes the GPCR and GDP is exchanged to GTP. The Gs Alpha subunit stimulates adenyl cyclase. With the addition of ATP, cAMP releases PKA.; EX: norepinephrine
What is the cyclic nucleotide inhibatory pathway? What is an example of a NT?
G4; NT binds to receptor and changes the GPCR. GDP is exchanged forGTP. Alpha subunit Gi stimulates guanyly cyclase. With the addition of ATP, cGMP stimulates PKG.; EX: Dopamine
What is the lipid cascade pathway? What is an example of a NT?
G-CPID; NT binds to receptor and changes the GPCR. GDP is exchanged for GTP and the Alpha subunit Gq stimulates Phospholipase C. With PIP2, IP3 and DAG are formed. IP3 releases Ca2+, calmodlin, and camK2. DAG stimulates PKC; EX: Glutamate
