Synaptic Trans SDL1 Flashcards
Where synaptic vesicles aggregate before release
presynaptic density, active site
Where receptor aggregate
postsynaptic density
electrical junctions
gap junctions, bidirectional, fast
chemical transmission
chemical synapse, unidirectional, slow, better controlled
Criteria for NT
localization, release, mimicry, inactivation
Tyrosine Derivatives?
Epinephrine, Dopamine, Norepinephrine
NT synthesis and packaging
step- by-step from readily available precursors
Enzymatic Control of Synthesis
enzyme molecule concentration, rate limiting step, phosphorylation, specificity
where are peptide neurotransmitters made?
soma –> nerve terminal
where are small molecules made?
ACh, Epi made in nerve terminal
What do autoreceptors do?
bind NT and modulate release of transmitter
AP sequence?
Depolarization –> Ca2+ influx at terminal –> exocytosis of vesicle
Binding of NT to postsynaptic receptor (3)
- single transmitter can bind multiple times
- usually reversible
- effect is concentration dependent
High concentration of NT may cause…
binding to specific and non-specific receptors –> undesirable side effects if non-specific activate
Termination of NT action (4)
- extracellular degradation enzymes
- specific reuptake proteins
- diffusion of NT away
- internalization of ligand-receptor complex
What are the two classes of postsynaptic receptors?
ionotropic and metabotropic
What is an ionotropic receptor?
ligand-gated, fast ex: ACh nicotinic
What is a metabotropic receptor?
G-protein coupled, slow ex: ACh muscarinic receptor
Characteristics of Ionotropic
fast onset, short duration, direct effect on channel, no second messenger or amplification
Characteristics of Metabotropic
slow onset, long duration, no ion channel, no direct effect on channel, second messenger and amplification
What determines excitation or inhibition?
receptor
Excitation
Depolarization, excitatory
Inhibition
Hyperpolarization, Inhibitory
Pre-synaptic inhibition
axo-axonic synapses
too much excitation
epilepsey
too much inhibition
anesthesia, coma
4 types of NT
amines, amino acids, neuropeptides, gases
Unique about Peptides
- synthesis directed by mRNA
- exist as inactive precursor
- made in cell body–>terminal
- cut into small pieces–> active
Amines
Serotonin, Histamine, ACh, Dopamine, Epi, NE
SHADE N
Amino Acids
Glutamate, GABA, Glycine
Types of GABA
GABAa: ionotropic
GABAb: Metabotropic
Neuropeptides
opioids, CCK, Oxytocin, Vasopressin
Gases
NO, CO
Opioid peptides
Beta-endorphin, enkephalin, dynorphin
Catecholamines
- dopamine, nor, epi
- tyrosine derivatives
- catechol nucleus
- tyrosine hydroxylase is rate limiting
Catecholamines and Cold medicine
mimic activation of sympathetic nervous system, reverse low BP
Serotonin
- Tyrptophan precursor
- Zoloft, SSRI
- allow serotonin to be active longer
Histamine
- histidine precursor
- cold medicines
ACh
- choline precursor
- RL: uptake of choline
- biosyn enzyme: CAT
- muscarinic: metabotropic
- degradative: AChE
Glutamate
- glutamine precursor
- after, taken up by axon terminals
- ionotropic: NMDA, non-NMDA
- metabotropic: IP3, DAG
What is glutamate considered as?
excitatory NT, too much release in stroke can lead to excitotoxicity
GABA
- glutamate precursor
- iono: GABAa, Ca2+ influx
- metab: GABAb, K+ efflux
Glycine
considered inhibitory
NO
gas, retrograde messenger, smooth muscle dilation
α-bungarotoxin
- snake venom
- blocks binding of ACh to nicotinic receptor in NM junction
Benzodiazepine
tranqulizer, increases frequency of GABAa Cl- opening
Zoloft
SSRI, block re-uptake
Botox
prevents release of ACh from nerve terminal
Organophosphates
irreversibly inactivates acetylcholinesterase
atropine
muscarnic receptor blocker, block postganglionic PS
Baclofen
- GABAb agonist
- epilepsy
Barbituate
sedative, increase duration of GABAa Cl- opening
Cocaine
blocks monoamine re-uptake at synapse, prolong NT
Curare
- plant toxin
- blocks binding ACh to nicotinic on skeletal muscle
Morphine
mimics opioid peptide binding
Neostigmine
- inhibit acetylcholinesterase, prolong ACh
- treats MS
PCP
NMDA glutamate receptor blocker
Strychnine
- glycine receptor blocker
- rat poison
tricyclic antidepressants
blocks monoamine reuptake
