lecture_10_21

lecture_10_21 - IV.C.2. Neurotransmitters Amino Acids...

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IV.C.2. Neurotransmitters Amino Acids Amines Peptides Other x-mitters Examples Glutamate Serotonin Oxytocin Acetylcholine Glycine Dopamine Endorphines (opiates) Nitric Oxide (NO) GABA Norepinephrine Substance P CO Aspartate Histamine Neurotensin ATP Fast or slow? Fast or slow Fast or slow Slow Where are they made? Present in bouton Made in bouton Made in soma using enzymes How do they get Made there Always there Axoplasmic transport to the bouton? Released by: Vesicles Vesicles Secretory granules Released at: Active Zone Active Zone All Over bouton IV. Neurotransmitters are the chemical substances released by vesicles at chemical synapses. Neurotransmitters tend to be small, charged molecules Neurotransmitters are readily available at the nerve terminal (or bouton). There are 3 main classes of neurotransmitters A. The 3 main classes of neurotransmitters are amino acids, amines and peptides (1) Amino acids (AA) (a) Examples – glutamate, glycine, GABA, aspartate, etc. (b) Amino acid neurotransmitters can mediate fast or slow neural transmission in the brain depending on the receptor. We will talk about this later. (c) Amino acids are present in the bouton (d) Amino acid neurotransmitters are made by synthetic enzymes at the bouton and stored within vesicles near the active zone. (e) It is here, within the active zone, where the neurotransmitter filled vesicles ultimately fuse with the cell membrane and the neurotransmitters are released into the synaptic cleft. (2) Amines - Neurotransmitters are often low molecular weight, nitrogen- containing molecules called amines. (a) Examples – serotonin, dopamine, norepinephrine and histamine (b) Amine neurotransmitters can mediate fast or slow neural transmission in the brain depending on the receptor. We will talk about this later. At neuromuscular junctions, amine release results in very rapid electrical transmission. (c) Amines are synthesized at the bouton (d) Amine neurotransmitters are made by synthetic enzymes at the bouton and stored within vesicles near the active zone. The enzymes required to make the amines must be transported from the soma via axoplasmic transport to the bouton, because the bouton lacks rough ER. It is here, within the active zone, where the neurotransmitter filled vesicles ultimately fuse with the cell membrane and the neurotransmitters are released into the synaptic cleft. (3) Peptides (a) Examples – Oxytocin, endorphins (endogenous opiates), substance P, and neurotensin (b) Peptide neurotransmitters mediate slow neural transmission in the brain. Transmission can take up to 50 msec. longer than seen with the amino acids and amines! (c)
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This note was uploaded on 12/06/2009 for the course NPB 100 taught by Professor Chapman during the Fall '08 term at UC Davis.

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lecture_10_21 - IV.C.2. Neurotransmitters Amino Acids...

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