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40 Neurotransmitters and AA products
EVMS biochem ch40
69
Biochemistry
Graduate
04/25/2011

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Term
1. norepinephrine
2. epinephrine
3. dopamine
Definition
3 catecholamines derived from tyrosine
Term
serotonin
Definition
NT derived from tryptophan
Term
GABA
Definition
NT derived from glutamate
Term
choline
Definition
is derived from serine, and produces acetylcholine
Term
neuropeptides
Definition
endorphins and enkephalins
Term
glycine
Definition
secreted at synapses in the spinal cord, inhibitory transmitter
Term
glutamate
Definition
secreted by presynaptic terminals in many of the sensory pathways as well as areas of the cortex, causes excitation
Term
serotonin
Definition
melatonin is derived from
Term
Dopa
Definition
Melanin is derived from
Term
tyrosine
Definition
thyroid hormones are derived from
Term
histidine
Definition
histamine is derived from
Term
arginine
Definition
nitric oxide is derived from
Term
carnitine
Definition
derived from trimethyllysyl residues of protein
Term
dopamine and norepinephrine
Definition
the catecholamines synthesized by neurons
Term
epinephrine
Definition
chatecholamine only synthesized in the adrenal medulla
Term
DOPA
Definition
1st intermediate in the synthesis of catecholamines
Term
catechol
Definition
has an aromatic ring with two hydroxy groups on it
Term
Tyrosine
Definition
is produced from phenylalanine during phenylalanine catabolism, used to produce DOPA, excess is transaminated and degraded
Term
hydroxylase
Definition
catalyzes phenylalanine to tyrosine, or tyrosine to DOPA, requires BH4
Term
biopterin synthesis or dihydrobiopterin reductase
Definition
synthesis of DOPA is impaired by deficits in these 2 paths
Term
DOPA decarboxylase
Definition
utilizes DOPA to form dopamine, utilizes pyridoxal phosphate as a cofactor
Term
substantia nigra
Definition
last step of dopamine synthesis is located in the
Term
parkinson's disease
Definition
loss of dopamine producing neurons, caused by oxidative stress, lipid peroxidation, and cell damage
Term
DOPA analog
Definition
administered to deminish DOPA side affects in the treatment of parkinson's, inhibits DOPA decarboxylase but is unable to cross the blood brain barrier
Term
dopamine hydroxylase
Definition
the reaction that forms norepinephrine from dopamine, utilizes molecular oxygen and requires both copper and ascorbic acid
Term
norepinephrine
Definition
an intermediate in epinephrine synthesis
Term
adrenal medulla
Definition
has high levels of ascorbic acid, biochemical basis of proposed increased need for vitamin C during stress
Term
phenylethanolamine N methyltransferase
Definition
reaction of norepinephrine to epinephrine SAM is methyl doner
Term
adrenal medulla
Definition
has the full pathway to go from tyrosine to epinephrine
Term
inactivation of catecholamines
Definition
these series of reactions can occur in any order and final products are excreted in the urine
Term
Methylation
Definition
type of reaction that is catalyzed by COMT and has SAM as the methyl donor, reaction in inactivation of catecholamines
Term
Oxidation
Definition
reaction of the inactivation of catecholamines, catalized by MAO, causes deamination, froms an aldehyde in which aldehyde oxidases turn it into an acid
Term
vanillylmandelic acid
Definition
inactivated product of norepinephrine, is excreted
Term
homovanillic acid
Definition
inactive compound from dopamine, COMT, MAO, and then aldehyde oxidase
Term
tryptophan hydroxylase
Definition
catalyzes the first step of serotonin synthesis from tryptophan, utilizes O2 and BH4
Term
DOPA decarboxylase
Definition
catalizes serotonin formation in the second step from 5-hydroxytryptophan, same enzyme produces dopamine from DOPA, catalyzed by PLP
Term
Serotonin
Definition
in the CNS inhibits pain in spinal cord, induces calmness and sleep, suggestion that high carb meals increase insulin and stimulates uptake of amino acids into muscle that usually compete with tryptophan entry into the brain
Term
1. MAO - remove NH3
2. oxidation to carboxyl group
Definition
the steps of inactivation of serotonin, unlike the catecholamines, the hydroxyl on the ring is not methylated
Term
MAO inhibitors
Definition
used to treat depression, block destruction of NE, dopamine, and serotonin in CNS, side effects of high blood pressure and increased HR, interfere with drug detox and detox of ingested amines (displace NE from storage vesicles
Term
Melatonin
Definition
produced in the pineal gland, signals seasonal and circadian rhythms, blood levels increase at night
Term
acetylation fro acetyl CoA
Definition
first step of melatonin synthesis from serotonin
Term
methylation of the ring hydroxyl, uses SAM
Definition
second step of melatonin synthesis from serotonin
Term
GABA
Definition
inhibitory NT secreted by the spinal cord, cerebellun, and cortex
Term
decarboxylation
Definition
reaction to form GABA from glutamate, PLP is a cofactor
Term
a-ketoglutarate
Definition
glutamate uptake in the brain is low, so the primary souce is from.... in astroclial cells
Term
glial cells
Definition
the cells in the brain that inactivate GABA back to glutamate and glutamine
Term
GABA transaminase
Definition
involved in the GABA shunt, regenerates glutamate from GABA using a-ketoglutarate
Term
GABA shunt
Definition
in glial cells produces glutamate, which is converted to glutamine and transported out of the glial cells to neurons where it is converted back to glutamate, glutamine thus serves as a transporter of glutamate between cells in the CNS. Clial cells lack GAD and cannot synthesize GABA
Term
NH4
Definition
astroglial synthesis of glutamine also provides a mechanis for removal of excess amounts of this from the brain
Term
histidine decarboxylase
Definition
catalyzes the formation of histidine from histimine
Term
histamine
Definition
in brain synthesized by mast cells of thalamus, hypothalamus, dura mater, and histaminergic neural fibers. activates presynaptic and postsynaptic receptors
Term
histamine
Definition
in peripheral tissues causes dilation of blood vessels, bronchoconstriction, and increase in HCL secretion in the stomach
Term
1. methylation (histamine methyl transferase nees SAM)
2. MAO B (take off the NH4)
Definition
pathway of histimine inactivation in the brain
Term
1. deamination by deamine oxidase
2. oxidation by NADH
Definition
histamine inactivation in the peripheral tissues 2 steps
Term
MAO-A
Definition
the isozyme that breaks down serotonin, melatonin, norepinephrine, and epinephrine
Term
dopamine
Definition
both forms of MAO break this NT down equally
Term
MAO-A
Definition
isozyme of MAO that is particularly important in the catabolism of monoamines ingested in food
Term
AA decarboxylases
Definition
all use PLP
Term
tyrosinase (Cu dependent tyrosine hydroxylase)
Definition
produces DOPA quinone from tyrosine, increases in melanocytes by UVB light, defect in this enzyme causes albinism
Term
oxidized quinones
Definition
polymerized to form melanins in the skin, eyes, and hair
Term
eumelanin
Definition
black melanin
Term
pheomelanin
Definition
yellow/red melanin
Term
DIT and MIT
Definition
are synthesized by tyrosine peroxidase which generates iodide from iodine and adds it to the tyrosines of thryoglobulin
Term
T3 and T4 thyroid hormones
Definition
synthesized by the MIT and DIT or two DITs. they are then released by lysosomal hydrolysis
Term
choline acetyltransferase
Definition
catalyzes the acetylation of choline which is provided from the diet or derived from phosphatidylcholine to form acetylcholine
Term
Acetylcholinesterase
Definition
inactivates acetylcholine, produces acetic acid and choline, is a serine esterase, is inhibited by the neurotoxin Sarin
Term
citrulline
Definition
when NO is produced from arginine, this urea cycle intermediate is formed
Term
NOS
Definition
mixed function oxidase that utilizes NADPH and O2 to form NO from arginine, several isozymes
Term
NO
Definition
reacts with the Fe-S centers of the ETC thus inhibiting ATP production by nearby parasites and tumor cells
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