Amino Acid Neurotransmitters

Glutamate

GABA

Glycine

Both glutamate and glycine are synthesized from glucose and other pre-cursor molecules in all cells

Vesicular glutamate transporters (EAAT's or excitatory amino acid transporters) move glutamate into synaptic vesicles which are expressed differentially:

VGLUT 1, 2, 3

These vesicles are found only in glutamatergic neurons and are therefore good markers

After release into synaptic cleft, is rapidly removed by other glutamate transporters in cell membranes in both neurons and astrocytes

Glutamate is its pre-cursor

Glutamic acid decarboxylase (GAD) is the key enzyme in GABA synthesis - good marker for GABAergic neurons

Packed into vesicles by VGATs

Re-uptake and membrane transport is mediated by GAT 1, 2, and 3

Metabolized by GABA-T

3 Types of Ionotropic Receptors

AMPA

Kainate

NMDA

Permeable to sodium and potassium

Permeable to sodium, potassium, calcium

Coincidence detectors - will not open immediately in response to glutamate - a build-up intracellularly must cause this --- meaning this is both voltage and ligand-gated

Glutamate must be bound and at resting membrane potential the channel is blocked by magnesium

Both pre and post-synaptic elements must be active

Long-Term Potentiation: the strengthening of a synapse, sometimes activated by cascades which are responses to NMDA