Chapter 8 - Gaba Synthesis, Release, and Inactivation

GABA

GABA only functions as a NT, and is only manufactured by GABAergic neurons

Mainly inhibitory

Glutamic Acid Decarboxylase (GAD)

Synthesizes GABA from Glutamate in one step

Vesicular Inhibitory Amino Acid Transporters (VIAAT)

OR Vesicular GABA Transporters (VGAT)

moves GABA and gylcine into vesicles

GAT 1

found in neurons/astrocytes 

found in nerve terminals, utilized in GABA reuptake

A selective inhibitor is available for pharacological study

GAT 2

found in neurons/astrocytes

GAT 3

only found in astrocytes

Gaba Aminotransferase (GABA-T)

found in neurons and astrocytes

metabolizes GABA into glutamate

1 glut for every GABA

Vigabatrin

Irreversible inhibitor of GABA-T

leads to build up of GABA levels in the brain (infantile spasms)

GABA Co-released w/ NT

Glycine, ACh, DA, Glutamate

ACh and GABA

Found in the Basal Forebrain neurons on hippocampus: posses separate populations of vesicles with ACh or GABA using VAChT or VGAT

DA and GABA

Released from the Midbrain (substantia nigra and VTA)

Neurons lack GAD expression, so they take up GABA from extracellular fluid from GAT-1 or synthesized transmitter in an unusal way

Both transported in VMAT2

Glut and GABA

Unsure if they are packaged in the same vesicles

They are used together to finetune the release of the brain