PSYC 455 Lecture Notes - Lecture 12: Butyric Acid, Axon Hillock, Carboxy-Lyases
26 Apr 2018
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PSYC 455
Lecture 12 – Inhibitory Amino Acids
• Inhibitory Amino Acids
1. Glycine
2. GABA (y-Amino Butyric Acid):
a. Role:
- Quiets down the neuron system (i.e. regulates neuronal firing everywhere in
the brain):
i. Either by:
Stopping the neuron from firing by hyperpolarizing the membrane
via GABAA receptors
Preventing the neuron from releasing its neurotransmitters via
GABAB receptors by inhibiting the Voltage-Gated Calcium
Channels
b. Synthesis:
- Production:
i. Synthesized from glutamate:
GAD (Glutamic Acid Decarboxylase) changes glutamate to GABA.
- Transportation:
i. After the GABA is synthesized in the terminal it is stored in vesicles by
the Vesicular GABA Transporter (GAT):
All GABA transporters rely on a sodium gradient to work (i.e. as
the sodium flows in, so does the GABA)
- Release and Termination:
i. Once GABA is released into the synapse, there are two ways to
terminate the signal:
GABA transaminase breaks down GABA
GABA can be reuptaken into the pre-synaptic terminal by the GAT
GABA being reuptaken into nearby glia (which also has a
theoretical GAT)
c. GABA Receptors:
- GABAA (LGIC):
i. Ionotropic (found on the Post synaptic terminal).
ii. 5 subunits (19 possible conformations):
Permeable to Cl-:
Because of diffusional forces chloride will flow in, making the
membrane more negative (i.e. the chloride ions hyperpolarize
the membrane):
1) When the membrane is more negative, it is harder to
reach the firing threshold at the axon hillock (i.e. this is
Mother Nature’s way of inhibiting the neuron from firing
too much)
Binding sites:
GABA binding site
Allosteric binding sites:
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Inhibitory amino acids: glycine, gaba (y-amino butyric acid), role: Quiets down the neuron system (i. e. regulates neuronal firing everywhere in the brain): Stopping the neuron from firing by hyperpolarizing the membrane via gabaa receptors. Preventing the neuron from releasing its neurotransmitters via. Gad (glutamic acid decarboxylase) changes glutamate to gaba. After the gaba is synthesized in the terminal it is stored in vesicles by the vesicular gaba transporter (gat): All gaba transporters rely on a sodium gradient to work (i. e. as the sodium flows in, so does the gaba) Once gaba is released into the synapse, there are two ways to terminate the signal: Gaba can be reuptaken into the pre-synaptic terminal by the gat. Gaba being reuptaken into nearby glia (which also has a theoretical gat: gaba receptors: Mother nature"s way of inhibiting the neuron from firing too much)
