Neurotransmitters
Review:
Metabotropic
Does not let ions in
second messenger system, (g-proteins)
Life Cycle Of Neurotransmitters
Reuptake: drawn back to the presynaptic cell & reused
Needs energy (atp)
Enzyme Degradation: Special enzymes in extracellular fluid break it down
Glia Cell removal: astrocytes remove neurotransmitters into the bloodstream
Neurotransmitters: General Comments
There are >100 types of neurotransmitters
Many fit into more than 1 type of receptor
Way more than 100 receptors
Not inherently inhibitory or excitatory, but depend on the receptor that they fit
into
Small neurotransmitters (misc) & big neurotransmitters (peptides)
Many neurotransmitters are considered hormones when in the bloodstream
Neurotransmitter criteria
1. Needs to be present in the presynaptic cell
2. Neurons must be able to make or accumulate the chemical
3. Must be a way to inactivate or stop the signal
Neurotransmitters 1
, 4. Should be released when the presynaptic neuron is stimulated
5. If it is applied exogenously it should mimic the effects (if it is taken from cell
and given to another the effects should be the same)
Groups & types of Neurotransmitters
Amino Acids
Glutamate
Very Abundant in the brain (90% of all synapses)
Typically excitatory
Synthesized from glutamine
Perception, memory, learning
Get glutamate from food & we produce it
Binds to GPCR (Gq & Gi) & ionotropic receptors
Often opens Na+ channels
Removed by Glia & reuptake
EAATs= excitatory amino acid transporters
3 Ionotropic receptors
Kainate receptors (allows sodium into the cell)
AMPA
Very straightforward cation channels, letting sodium in
(depolarization)
NMDA
Co-localized with AMPA
Ligen gated, cation channel
Has a magnesium block in it (Mg2+ ion)
When a depolarization occurs, magnesium ion leaves
Neurotransmitters 2
Review:
Metabotropic
Does not let ions in
second messenger system, (g-proteins)
Life Cycle Of Neurotransmitters
Reuptake: drawn back to the presynaptic cell & reused
Needs energy (atp)
Enzyme Degradation: Special enzymes in extracellular fluid break it down
Glia Cell removal: astrocytes remove neurotransmitters into the bloodstream
Neurotransmitters: General Comments
There are >100 types of neurotransmitters
Many fit into more than 1 type of receptor
Way more than 100 receptors
Not inherently inhibitory or excitatory, but depend on the receptor that they fit
into
Small neurotransmitters (misc) & big neurotransmitters (peptides)
Many neurotransmitters are considered hormones when in the bloodstream
Neurotransmitter criteria
1. Needs to be present in the presynaptic cell
2. Neurons must be able to make or accumulate the chemical
3. Must be a way to inactivate or stop the signal
Neurotransmitters 1
, 4. Should be released when the presynaptic neuron is stimulated
5. If it is applied exogenously it should mimic the effects (if it is taken from cell
and given to another the effects should be the same)
Groups & types of Neurotransmitters
Amino Acids
Glutamate
Very Abundant in the brain (90% of all synapses)
Typically excitatory
Synthesized from glutamine
Perception, memory, learning
Get glutamate from food & we produce it
Binds to GPCR (Gq & Gi) & ionotropic receptors
Often opens Na+ channels
Removed by Glia & reuptake
EAATs= excitatory amino acid transporters
3 Ionotropic receptors
Kainate receptors (allows sodium into the cell)
AMPA
Very straightforward cation channels, letting sodium in
(depolarization)
NMDA
Co-localized with AMPA
Ligen gated, cation channel
Has a magnesium block in it (Mg2+ ion)
When a depolarization occurs, magnesium ion leaves
Neurotransmitters 2
