Behavioral Neuroscience, Lecture on October 17 th
Amino acids are the most common class of neurotransmitter found in the brain.
Glutamate - major excitatory amino acid.
GABA - major inhibitory amino acid.
almost all forebrain synaptic communications are accomplished by one of
Glycine - major inhibitory neurotransmitter in the spinal cord and hindbrain.
Glutamatergic transmission uses these ionotropic receptors:
AMPA: ligand-gated Na+ channel
Kainate: Na+ and K+ channel
NMDA: Ca++ channel
*Named after the drugs that are specific agonists to each receptor.
Excitotoxicity: neural injury such as stroke may cause excess release of
glutamate, which is toxic to neurons.
GABA(A) is ionotropic, producing fast, inhibitory effects.
GABA(B) is metabotropic, slow inhibitory effects.
*GABA will always give you an inhibitory effect.
Often co-released with "classical" neurotransmitters.
released in all parts of axon terminal, not just active zone.
destroyed by enzymes after release.
Most peptide receptors are metabotropic.
Endorphins: endogenous opioid peptides.
(Same as what heroin and opines bind to)
analgesia and reward.
The gas nitric oxide (NO), differs from other neurotransmitters.
does not follow the rules needed to be a neurotransmitter; special case. Produced in locations other than the axon terminal- mainly in dendrites, and
diffuses as soon as it is produced, rather than released.
Serves as a retrograde transmitter because it works backwards by diffusing back
into the presynaptic neuron.
Drugs - mechanisms of action,
Drugs can be classified by the way that they influence specific functional
mechanisms of the neurons.
Competitive ligand, drugs that bind to the same receptor site as the
Non competitive ligand, binds instead to a modulatory site on the receptor.
Agonist - increase neurotransmitter action
Antagonist - decrease neurotransmitter action
*Drugs can affect any of the steps of synaptic transmission to achieve
1) increase neurotransmitter precursors AGONIST
2) destroy synthesizing enzymes ANTAGONIST
3) prevent storage of neurotransmitter in vesicles ANTAGONIST
4) stimulate release of neurotransmitter AGONIST
5) decrease neurotransmitter release ANTAGONIST