Anatomy
Neurotransmitter
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Neurotransmitter
, Neurotransmitter Physiology
See Also
Neuron
Serotonin
Definitions
Neurotransmitter
Endogenous signaling molecules affecting
Neuron
behavior by acting at nerve
Synapse
,
Muscle Cell
s and glands
Neurotransmitters are synthesized and released by
Neuron
s
Physiology
Neurotransmitters in
Gene
ral
More than 500 Neurotransmitters have been identified in humans
Chemical Structures
Amino acids (e.g. glutamate,
Aspart
ate, gamma-Aminobutyric acid or GABA, glycine)
Monoamines (e.g.
Dopamine
,
Norepinephrine
,
Epinephrine
, histamine,
Serotonin
)
Peptides (
Oxytocin
,
Somatostatin
, substance P)
Purines (
Adenosine Triphosphate
or ATP,
Adenosine
)
Miscellaneous (acetylcholine or ACh)
Function
Excitatory Neurotransmitters
Acetylcholine
Norepinephrine
Glutamate
Inhibitory Neurotransmitters
Dopamine
Produced in
Substantia Nigra
and released into
Basal Ganglia
Gamma-Aminobutyric acid (GABA)
Broad distribution (see below)
Glycine
Produced in spinal cord
Serotonin
Produced in median raphe and
Hypothalamus
Neurotransmitters with
Sedative
and
Analgesic
properties (
Opioid
-like)
Endorphins
Enkephalins
Neuroendocrine Brain Regions (Pigmented Regions)
Locus Ceruleus
Norepinephrine
Secretin
g nucleus in pons
Important in wakefulness and attention
Substantia Nigra
Dopamine
Secretin
g region in
Midbrain
Substantia Nigra
degeneration results in
Dopamine
deficiency and
Parkinsonism
Physiology
GABA and
NMDA
N-methyl-D-
Aspart
ate (
NMDA
) receptor
Glutamate binds
NMDA
receptors and results in excitation
NMDA
receptors are up regulated in chronic
Alcohol Abuse
NMDA
Antagoists include
Ketamine
Gamma-aminobutyric acid (GABA) receptor
GABA Agonists bind GABA receptors and result in inhibition
GABA Receptors are down regulated in chronic
Alcohol Abuse
Physiology
Neurotransmitter at
Synapse
Medications affecting Precursor Uptake
L-Phenylalanine
L-Tyrosine
L-Dopa
Dopamine
(DA)
Norepinephrine
(NE)
Epinephrine
(E)
L-Tryptophan
5-Hydroxytryptophan,
5-Hydroxytryptamine
(
5-HT
) =
Serotonin
Choline/lecithin + AcetylCoA => Acetylcholine (Ach)
Medications affecting Synthetic Enzymes
Metyrosine (Demser) blocks Tyrosine hydroxylase
Decrease DA, NE, E, 5HT
Methyldopa
(
Aldomet
) blocks decarboxylation
Decrease DA, NE, E, 5HT
Medications affecting Transfer into
Vesicle
No clinically available drugs
Medications affecting
Vesicle
storage
Reserpine
(
Serpasil
) depletes storage
Decreases DA, NE, E, 5HT
Medications affecting
Vesicle
mobilization
Affects
Nerve Impulse
Conduction
Vesicle
release
Electroconvulsive Therapy
decreases DA, NE, E, 5HT
Medications affecting Post-synaptic receptors
Reversible receptor blockade by
Neuroleptic
s (
Haldol
)
Medications affecting Neurotransmitter reuptake
Reuptake inhibition by all
Antidepressant
s (
Prozac
)
Medications affecting Neurotransmitter breakdown
No drugs available
Medications affecting Neurotransmitter dilution
No drugs available
Medications affecting Neurotransmitter breakdown
Monamine oxidase inhibitor (MOAi) (
Parnate
,
Nardil
)
Tacrine
Inhibits Acetylcholinesterase
Increases Acetylcholine
Physiology
Neurotransmitter Theory applied to Psychiatric Medication
Neuroleptic
s
Deplete Neurotransmitter Stores
Rauwolfia alkaloids (e.g.
Reserpine
)
Phenothiazine: Chlorpromazine (Thorazine)
Thioxanthenes: thiothixene (Navane)
Butyrophenones:
Haloperidol
(
Haldol
)
Receptor blockade
Lithium Carbonate
Interferes with Neurotransmitter storage Na-K Pump
Stimulants
Mimic Neurotransmitter at storage or Receptor sites
Amphetamine
s:
Methamphetamine
(Methedrine)
Benzyl-piperidines:
Methylphenidate
(
Ritalin
)
Antidepressant
s:
MAO inhibitor
s
Monoamine Oxidase (MAO) is a naturally in-vivo enzyme that metabolizes
Serotonin
and
Norepinephrine
Inactivation or inhibition of MAO results in increased levels of
Serotonin
and
Norepinephrine
Tranylcypromine
(
Parnate
)
Inactivate MAO
Polycyclic:
Imipramine
HCl (
Tofranil
)
Inhibit MAO reuptake
Antidepressant
s:
SSRI
and
SNRI
Decreased
Serotonin
and norephinephrine are associated with
Major Depression
Reuptake inhibitors increase these Neurotransmitters in the
Synapse
by blocking reuptake
Selective Serotonin Reuptake Inhibitor
s (
SSRI
)
Serotonin Norepinephrine Reuptake Inhibitor
s (
SNRI
)
Resources
Neurotransmitters (Wikipedia)
https://en.wikipedia.org/wiki/Neurotransmitter
References
Goldberg (2014) Clinical Physiology, MedMaster, p. 88
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