Synaptic Transmission and Neurotransmitters

What is a connexin

Two neurons connected by a gap junction

What do connextions allow for?

Cell-to-cell communication

What do Pannexins do?

Form membrane channels that release ATP and mediate paracrine signaling

What do connexins form into?

Connexons

What are connexons also known as?

Hemichannels

What do two connexons from adjacent cells do?

Dock together to form gap junctions

What is the function of connexin channels?

Allow for direct cell-to-cell communication

What can pass through connexin channels

Ions, small molecules

What are connexins closed as when not docked

hemichannels

Where are connexin channels typically present?

Astrocytes, schwann cells, smooth muscles

What do pannexin channels form?

Single-membrane channels only

What do pannexin channels not form?

Gap junction

Main function of pannexin channels

Release molecules from the cell to the extracellular space

When do pannexin channels open?

Mechanical sress, high intracellular Ca2+, high extracellular K+

Where are key features found

Neurons/gilial cells, immune cells, many other tissues

What connexin is in the PNS

Connexin 32

What do Cx32 gap junctions do

connect layers of myelin sheath

What is the functional importance of Connexin32

Maintains myelin integrity, supports normal nerve conduction, faciliatates metabolic support across myelin

What gene is Cx32 in?

GJB2 gene

What disease is caused by mutations in Cx32

X-link charcot marie tooth diease

What does CMTX cause?

Peripheral neuropathy, demyelination, slowed nerve conduction

Where are neurotransmitter released from

presynaptic membrane

Where do chemical synapses bind to their receptors?

Postsynaptic or presynaptic membrane

What is quantal release

triggers EPSP or IPSP

What do SNARE proteins do

help dock vesicles and then zip together to force membranes to fuse

What does calcium bind to

Synaptotagmin

What does the binding of calcium to synaptotagmin do?

triggers fusion and exocytosis

What does botulinum toxin do?

Prevents the release of ACh

How does botulinum toxin hurt the body

cleaves SNARE proteins at the presynaptic terminal of neuromuscular junctions

what kind of paralysis does botulinum cause?

Flaccid

Where are small NTs made

terminal

Where are peptides made

cell body

What does ACh do?

Muscle contraction, autonomic nervous system signaling, and cognitive processes

What does Glutamate do?

major excitatory neurotransmitter in the CNS, and used in communication

What kind of receptors does glu act on?

Ionotropic and metabotropic receptors

What is glutamate essential for?

synaptic transmission, plasticity, learning, and memory

What does GABA do

inhibitory neurotransmitter in the CNS

What receptors does GABA use

GABAa and GABAb

Where is glycine found

spinal cord and brainstem

What does glycine regulate

Spinal cord and brainstem

How does glycine act

Opens chloride channels

What does glycine result in

Hyperpolarization of neurons

What are the Amines

serotonin, dopamine, norepinephrine, epinephrine, histamine

Epinephrine pathway

tyrosine → Dopamine → Norepinephrine → epinephrine

What are catecholamines derived from

Tyrosine

What are indolamines derived from

tryptophan

What is an Indolamine

Serotonin

What does dopamine do

Reward, motor control, cognition

what does norepinephrine do

Attention, arousal, stress responses

What does epinephrine do?

Peripheral, also CNS

What does Serotonin do

mood, sleep, appetite, cognition

What does histamine do

Sleep/wake regulation, appetite, alertness

What disorders are dopamine imbalances associaed with

Parkinsons and schizophrenia

What does norepinephrine act through

Adrengergic receptors, and plays a key role in the sympahtetic nervous system

What does epinephrine do

Fight-or-flight

What does histamine do outside of neurotransmitter

Immune response

Hypothalamus releases

TRH, LHRH, somatostatin

What in released by the pituitary

ACTH, prolactin, lutenixing hormine, tyrotropin, growht hormone, vasopressin, oxytocin

Examples of endorphons

Enkephalins, opiods

Other NTs

Substance P, Bradykinin, angiotensin II

What makes NO different

diffuses freely

What does NO do

Synaptic plasticity, learning, memory, and regulation of blood flow

What makes CO

Heme oxygenase

What does CO do?

Neural signaling, synaptic modulation, regulation of blood vessel tone

What describes NO

aster-acting and more widely studied

What decribes CO

slower, more sustained effects in neural signaling.

What are eCBs

Lipid based neurotransmitters

Where are eCBs made

brain

Most well known eCB

Anandamide, 2-archidonoylglycerol

What do eCBs act as

Retrograde messengers

What do eCBs bind to

presynaptic CB1 receptors

What is the result of eCBs

Decreased release of neutrotransmitter

What are eCBs involved in

Mood, memory, pain reg, appetite, and stress response

What does the VTA do

Key brain region that regulates reward, motivation, and reinforcement learning by releasing dopamine

What integrates dopaminerguc signals from VYA

Nucleus accumbens

What kind of receptors are on ligand-gated

ionotropic receptors

What kind of receptor is kn g-coupled

metabotropic receptor

What kind of receptors on enzyme linked

Tyrosine kinase

How does ACh on nicotinic ACh work

Na triggers release of acetylcholine and Na

How does metabotropic work?

Choline goes through transporter to trigger acetylcholine movement

What kind of receptor is used for nicotinic

ion

What kind of receptor is used for muscarinic aCH

G protein

What uses muscarinic ACh

Brain, peripheral

What uses ionotropic ACh receptor

Skeletal muscle, brain

What are glutamate ion channels called

iGluRs

What does glutamate protein coupled called

mGluRs

What is a GAB agonist

Isoflurane

What does isoflurance trigger

Channel opening

How does propofol work

Increases gaba mediated inhibitory tone in the CNS

What does Propofol cause

Increases the duration of gaba, causing hyperpolarization

What does ethanol do

Increases presynaptic GABA

What does Ethanol do?

Allosterically modulates GABAa, increasing inhibitory effect

What kind of receptor is long term

G protein

What does Lidocaine do

Blocks Na+ channel inside

What does curare do

binds to nAChR

What does Amphetamine do

Causes neurons to release dopamine, norepinephrine, serotonin by reversing transporter

What does amphetamine increase the release of more

Dopamine and norepinephrine

What does tetrodoxin do

Blacks Na channels on the outside

What does Nerve gas do

Binds to AChE and disables it

What does MDMA do

Increases serotonin, dopamine, and norepinphrine through transporter reversal