1B CNS : SEROTONIN AND DOPAMINE Flashcards
5HT found in high concentrations in
SELECT ALL THAT APPLY
A. enterochromaffin cells throughout the GI tract
B. storage granules in platelets
C. plexuses of the GI
D. throughout the CNS
A. enterochromaffin cells throughout the GI tract
B. storage granules in platelets
D. throughout the CNS
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DA found in high concentrations in:
plexuses of the GI
Brain
the enteric nervous system
adrenal medulla
plexuses of the GI
Brain
the enteric nervous system
adrenal medulla
Amino acid that is needed for synthesis of serotonin
A. nonessential, tryptophan
B. essential. tryptophan
C. nonessential, tyrosine
D. essential, tyrosine
B. essential. tryptophan
This actively trasports tryptophan into the brain ; a heteromeric carrier protein that transports large neutral and branched-chain amino acids and some drugs across membrane
A. LAT2 (L-type amino acid transporter 2)
B. LAT4 (L-type amino acid transporter 4)
C. LAT3 (L-type amino acid transporter 3)
D. LAT1 (L-type amino acid transporter 1)
D. LAT1 (L-type amino acid transporter 1)
a mixed-function oxidase that requires molecular O2 and a reduced pteridine cofactor for activity, is the rate-limiting enzyme in the synthetic pathway
A. Tyrptophan Hydroxylase
B. Tryptophan Oxidase
C. 5-Hydroxytryptophan decarboxylase
D. 5-monooxygenase tryptophan hydroxylase
A. Tyrptophan Hydroxylase
A brain-specific isoform of tryptophan hydroxylase is entirely responsible for the synthesis of brain 5-HT
A. (TPH1)
B. (TPH2)
C. (TPH3)
D. (TPH4)
B. (TPH2)
SATA about TPH (tryptophan hydroxylase)
a. a mixed-function oxidase that requires molecular O2 and a reduced pteridine cofactor for activity, is the rate-limiting enzyme in the synthetic pathway
b. A brain-specific isoform of tryptophan hydroxylase (TPH2) is entirely responsible for the synthesis of brain 5-HT
c. Accumulated in secretory granules of serotonergic neurons
d. Stored vesicular 5HT
a. a mixed-function oxidase that **requires molecular O2 and a reduced pteridine cofactor for activity, is the rate-limiting enzyme in the synthetic pathway
b. A brain-specific isoform of tryptophan hydroxylase (TPH2) is entirely responsible for the synthesis of brain 5-HT
c. Accumulated in secretory granules **of serotonergic neurons
d. Stored vesicular 5HT
Action of 5HT is terminated via neuronal uptake by:
a. SERT
c. SUN
b. MAO
c. SAT
Action of released 5HT is terminated via neuronal uptake by a specific SERT (Serotonin Transporter),
localized in the membrane of serotonergic axon terminals and in the membranes of platelets
SERT, the 5HT transporter
SERT - serotonin transporter
SERT (Serotonin Transporter), is localized in:
a. membrane of serotonergic axon terminal
b. along plexus GI tract
c. Platelets
d. peripheries
a. membrane of serotonergic axon terminal
c. Platelets
specific and can be inhibited by SSRIs (Selective Serotonin Reuptake Inhibitor) that are used to treat depression and other mood disorders
SERT, the 5HT transporter or reuptake system
5-HIAA from brain and peripheral sites of 5HT storage and metabolism is excreted mainly in the
a. urine
b. stool
c. liver
d. GIT
urine
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5HT is almost entirely synthesized by cells located in the
A.raphe nuclei
B. nuceli regae
C. in the brainstem
D. in the medulla
A.raphe nuclei
C. in the brainstem
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5HT is almost entirely synthesized by cells located in the
A.raphe nuclei
B. nuceli regae
C. in the brainstem
D. in the medulla
A.raphe nuclei
C. in the brainstem
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Subtypes of 5HT1 receptor
A. 5HT1A
B. 5HT1B
C. 5HT1C
D. 5HT1D
A. 5HT1A
B. 5HT1B
D. 5HT1D
Subtype of 5HT1 receptor
Location: CNS Raphe nuclei of brainstem
Function: Neuronal inhibition, behavioural effects: sleep, feeding, thermoregulation, anxiety
Signaling system: G protein (G1/G0), decreased CAMP may modulate Ca channels
**Agonists: Buspirone **
Antaganoist: Ergotamine
5HT1A
Subtype of 5HT1 receptor
Location: CBS (Subiculum) vascular smooth muscle
Main function: Presynaptic inhibition, behavioral effects, pulmonary vasoconstriction
Agonists: Triptans
5HT1B
Subtype of 5HT1 receptor
Location: CNS (cranial blood vessels)
Function: cerebral vasoconstriction
Agonits: Triptans
Antagonists: Ergotamine (PA)
5HT1D
Subtypes of 5HT2 receptor
Location: CNS, PNS, smooth muscle, platelets
Function: Neuronal excitation, behavioral effects, smooth muscle contraction (gut, bronchi, etc.), platelet aggregation, vasodilation/vasoconstriction
Signaling system: G protein (Gq/G11) increase IP3, Ca
Agonists: LSD, a methyl 5HT
Antagonist: Ketanserin, Ritanserin, Cyproheptadine, Methysergide
5HT 2A
Subtypes of 5HT2 receptor
Location: CNS (choroid plexus, hypothalamus)
Function: CSF production, neuronal excitation
Agonist: LSD, a methyl 5HT
Antagonist: Methysergide
5HT 2C
Subtypes of 5HT2 receptor
Location: Gastric Fundus
Function: Contraction
Agonists: LSD, a methyl 5HT
5HT 2B
Serotonin Receptor:
Location: PNS, CNS
Function: Neuronal excitation, emesis, behavioural effects, anxiety
Signaling system: Ligand-gated cation channel
Agonist: 2-methyl 5HT
Antagonist: Dolesatron, Granisetron, Ondansetron, Palonosetron, Tropisetron
A. 5HT 3
B. 5HT6
C. 5HT 4
D. 5HT 7
5HT 3
Serotonin Receptor:
Location: CNS
Function: **Modulation of exploratory behavior
**
A. 5HT 3
B. 5HT6
C. 5HT 5
D. 5HT 7
C. 5HT 5
Serotonin Receptor:
Location: GI tract, CNS
Function: Neuronal excitation, GI motility
Signaling system: G protein, increased CAMP
Agonist: Metoclopramide, cisapride
Antagonist: GR-113808
A. 5HT 3
B. 5HT 4
C. 5HT 5
D. 5HT 6
B. 5HT 4
Location: CNS, leukocytes
Function: Learning and memory
A. 5HT 3
B. 5HT 4
C. 5HT 5
D. 5HT 6
D. 5HT 6
Location: CNS, GI tract, blood vessels
Function: thermoregulation, circadian rhythm
A. 5HT 5
B. 5HT 4
C. 5HT 7
D. 5HT 3
C. 5HT 7
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RECEPTORS THAT ARE INHIBITORY
a. 5HT1
b. 5HT3
c. 5HT5
d. 5HT7
a. 5HT1
c. 5HT5
RECEPTORS THAT ARE EXCITATORY
a. 5HT2
b. 5HT3
c. 5HT4
d. 5HT6
e. 5HT7
a. 5HT2
b. 5HT3
c. 5HT4
d. 5HT6
e. 5HT7
serotonin that uses** ligand gated Na and K cation channel**
5ht1
5ht2
5ht3
5ht4
5ht3
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serotonin receptors mechanism:
Decreasing cellular levels of CAMP
a. 5ht1
b. 5ht4
c. 5ht5
d. 5ht7
a. 5ht1
c. 5ht5
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serotonin receptors mechanism:
Increasing cellular levels of CAMP
a. 5ht4
b. 5ht6
c. 5ht7
d. 5ht1
a. 5ht4
b. 5ht6
c. 5ht7
serotonin receptor that has mechanism which **depolarizing plasma membrane **
5ht3
serotonin receptor that has mechanism which increasing cellular levels of IP3 and DAG
5ht2
true or false
Neither selective serotonin receptor agonists nor antagonists are completely selective, thus may exhibit other effects on any of the other types of serotonin receptors
true
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actions of 5ht on PLATELETS
- With injured endothelium platelets release substances that promote platelet aggregation
- 5HT binds to platelet 5HT1 receptors and elicits a weak aggregation response that is markedly augmented by the presence of collagen
- 5HT exerts a direct vasoconstrictor effect hemostasis → enhanced by locally released autocoids (thromboxane A2, kinins, and vasoactive peptides)
- With injured endothelium platelets release substances that promote platelet aggregation
- 5HT exerts a direct vasoconstrictor effect hemostasis → enhanced by locally released autocoids (thromboxane A2, kinins, and vasoactive peptides)
5HT binds to platelet 5HT1 SHOULD BE 5HT2A receptors and elicits a weak aggregation response that is markedly augmented by the presence of collagen
which is incorrect 5HT:
- The classical response of blood vessels to 5HT is dilation on splanchnic, renal, pulmonary, and cerebral vasculatures
- 5HT has** positive inotropic and chronotropic actions** on the heart
- Activation of **5HT3 **receptors on vagus nerve endings elicits the Bezold-Jarisch reflex → extreme bradycardia and hypotension
- The classical response of blood vessels to 5HT is CONTRACTION
SATA on effects of serotonin on blood pressure
a. early sharp fall
b. brief rise
c. brief fall
d. prolonged fall
e. prolonged rise
a. early sharp fall
b. brief rise
d.prolonged fall
match:
vasodilation
vasocontriction
thombus formation
5HT2A
5HT1
5HT3
5ht1 - vasodilation
5ht2a - vasoconstriction, thrombus formation
effect of serotonin on heart
a. positive inotropic, negative chronotropic
b. negative inotropic, positive chronotropic
c. positive inotropic, positive chronotropic
d. negative inotropic, negative chronotropic
c. positive inotropic, positive chronotropic
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Effects of serotonin on visceral smooth muscle
a. GIT: increased peristalsis, increased secretions
b. Bronchi: bronchoconstriction
c. Inhibits gastric secretion (acid and pepsin) but increases mucus production
c. GIT: increased peristalsis, decreased secretion
d. Bronchi: bronchodilation
a. GIT: increased peristalsis, increased secretions
b. Bronchi: bronchoconstriction
c. Inhibits gastric secretion (acid and pepsin) but increases mucus production
SATA effect of serotonin on nerve endings
a. activation of afferent nerve endings
b. tingling and pricking sensation
c. pain
d. activation of efferent nerve endings
a. activation of afferent nerve endings
b. tingling and pricking sensation
c. pain
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effects of serotonin in respiration
a. brief stimulation of respiration
b. hyperventilation
c. transient apnea
d. coronary chemoreflex
a. brief stimulation of respiration
b. hyperventilation
c. transient apnea (large doses)
d. coronary chemoreflex
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effects of serotonin in respiration
a. brief stimulation of respiration
b. hyperventilation
c. transient apnea
d. coronary chemoreflex
a. brief stimulation of respiration
b. hyperventilation
c. transient apnea (large doses)
d. coronary chemoreflex
effects on platelets (5ht2a)
a. causes changes in shape
b. weak aggregator
c. potent fibrinolysis
d. vasodilation
a. causes changes in shape
b. weak aggregator
effects of direct injection on CNS
a. sleepiness
b. change in body temperature
c. hunger
d. behavioral effects
a. sleepiness
b. change in body temperature
c. hunger
d. behavioral effects
effects of serotonin on inflammation
a. pro-inflammatory influence in acute inflammatory states
b. acting via the 5HT2A recepto
c. airway inflammation
d. asthma
a. pro-inflammatory influence in acute inflammatory states
b. acting via the 5HT2A recepto
c. airway inflammation
d. asthma
Depletion of 5HT elicits
narcoplesy
insomnia
hyperactivity
Depletion of 5HT with* p-chlorophenylalanine*, a tryptophan hydroxylase inhibitor, elicits insomnia that is
reversed by the** 5HT precursor, 5-hydroxytryptophan
**
treatment with l-tryptophan or with nonselective 5HT agonists
accelerates sleep onset and prolongs total sleep time
which are true?
a. Serotonin serves a critical role in aggression and impulsivity
b. Human studies reveal a correlation between high CSF 5-HIAA and violent impulsivity
c. Human studies reveal a correlation between low CSF 5-HIAA and violent impulsivity and aggression
a. Serotonin serves a critical role in aggression and impulsivity
c. Human studies reveal a correlation between low CSF 5-HIAA and** violent impulsivity and aggression**
a 5HT2C receptor agonist approved for weight loss
Lorcaserin
mechanism for lorcaserin
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- Decrease food consumption and promote satiety
- selectively activating 5HT2C receptors on anorexigenic proopiomelanocortin neurons in the arcuate nucleus of the hypothalamus
- selectively activating 5HT6 receptors
- inhibiting 5HT2C
- Decrease food consumption and promote satiety
- selectively activating 5HT2C receptors on anorexigenic proopiomelanocortin neurons in the arcuate nucleus of the hypothalamus
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TRUE:
a. serotonin involved in sleep, temperature regulation, thought, cognitive function, behavior, mood, appetite, vomiting and pain perception
b. **precursor of melatonin in pineal gland that regulates biological clock and maintain circadian rhythm
c. neuro-endocrine function which regulates hypothalamic neurons that control release of anterior pituitary hormones **
d. initiate vasocontrictor phase of migraine and participates in neurogenic inflammation of cranial blood vessels.
ALL ARE TRUE
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TRUE:**
a.** nausea and vomiting evoked by cytotoxic drug/radiotherapy is mediated by release of 5ht
b. causes platelet agrregation** and** clot formation** at site of injury to blood vessel
c. promotes retraction of injured vessel
d. 5ht release from platelets may trigger acute vasospastic episodes of larger arteries
all are true
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TRUE:
a. increased responsiveness to 5ht and decreased uptake and clearance by platelets seen in hypertensives
b. enterochromaffincells and 5ht containing neurons regulate peristalsis and local reflexes in gut (activated by intestinal distention)
c. carcinoid tumors-produce massive amounts of 5ht leading to bowel hypermotility and bronchoconstriction
d. pleaagra duetp diversion of tryptophan for synthesizing 5ht
all are true