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Inflammation > Histamine and Serotonin > Flashcards

Histamine and Serotonin Flashcards

1
Q

Serotonin other name

A

5-H (5-Hydroxytryptamine)

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2
Q

How does histamine cause effect

A

Via H1,2,3&4 rec
Subtypes account for effect variability
H2 is responsible for controlling gastric acid secretion

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3
Q

Histamine effects

A

Smooth m contraction of bronchi, gut and large vessels
Smooth m relaxation of small arterioles - cause drop in BP
Incr vasc perm (immediate)
Incr gastric acid secretion

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4
Q

Histamine distribution

A 
Widely distributed
(High level goats and rabbits
Lower level cats dogs humans horses)
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5
Q

Histamine production pathway

A

Histidine - histamine by action of L-histidine decarboxylase enz

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6
Q

Histamine production sites

A

Mast cell has slow synthesis then stores due to slow turnover depletion can occur
Faster synth rate at gastric mucosa parietal cells
CNS neurons and lymphocytes also synth it

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7
Q

Histamine storage

A 
Mast cells (main)
Basophil in the blood
High histamine con in skin and intestinal and bronchial mucosa due to high mast cell level
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8
Q

Histamine release in carnivores cause

A

Hypotension

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9
Q

Histamine release in rabbits cause

A

Bronchoconstriction and R heart dilation

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10
Q

Histamine release in guinea pigs cause

A

Bronchiconstriction and asphyxiation

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11
Q

Anaphylaxis and allergy histamine release pathway

A

Antigen-IgE interaction on mast cell surface
Cause incr IC Ca2+ level (effect TFs and trigger cytokine release)
Complex histamine released
Histamine released from storage granules

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12
Q

Drugs and chemicals that can cause direct mast cell degran and hist release

A 
Morphine
Codeine
Pp antibiotics
Neuromuscular blocking agents
(Also endogenous molecules like bradykinin)
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13
Q

Effect of physical injury eg scratch to skin surface

A

Redness and urtication due to histamine release locally

Triple response of redness, swelling, flare

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14
Q

CV syst effects of Hist

A

Originally H1 assoc but at high dose also H2
Constrict large vessels generally, and dilate arterioles and microcirc
Species variation as to dom (eg rabbit pressor effect dom, carnivore vasodil of microcirc dom)

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15
Q

Resp system effects of hist

A 
Bronchoconstriction (esp GP)
Bronchial relaxation (sheep H2)
Tracheal relaxation (cats)
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16
Q

Intestinal smooth muscle effects of histamine

A

Gen contracted

17
Q

Uterine smooth muscle effect of histamine

A

Gen contracted

18
Q

Exocrine gland effects of histamine

A

Gastric acid secretion incr mediated by H2

19
Q

H1 rec pathway sognalling

A

GPCR

Coupled to PLC which converts PiP2 to DAG and IP3 which incr IC Ca 2+ levels

20
Q

H2 rec pathway signallinc

A

GPCR
Linked to adenylyl cyclase act which converts ATP to cAMP so incr cAMP level which act on Pro Kinase A which opens ca2+ chamnels

21
Q

Incr cA and GMP levels promote

A

Vascular relaxation

22
Q

2nd messenger from rec dep on

A

Cell type
Rec type
Alpha subunit type that will act when bound to GTP and then convert it to GDP

23
Q

How hist cause incr vasc permeability

A

Phosphorylate IC adhesion molecule cadherin causes gaps between endo cells to appear

24
Q

Hist effects of leucocytes

A

Can trigger cytokine release and other inflamm mediators

25
Q

Hist Effect on chronic inflamm

A

Affect macroph B and T lymphocyte fx, cytokine prod, MHC c2 antigens expression on cell surface

26
Q

H1 antihistamines

A

Block H1 rec
Distinct from physiological antagonism
Well absorbed after oral administration by monogastrics, not ruminants
More pronounced side effects with IV administration

27
Q

Antihistamine effects

A

Counteract effects of allergic reactions and anaphylactic type reactions

28
Q

Specific antihistamines

A 
Diphenhydramine
Cyproheptadine
Chlorphenamine
Levobastine
Iodoxamine
29
Q

Specific a-h uses

A

Cns effects (travel anxiety)
Allergy conjunctivitis
Feline asthma
Skin? (Eg excessive grooming in cats)

30
Q

Serotonin synth

A

Trytophan (in diet) to 5-hydroxytryptophan to 5-hydroxytrptamind

31
Q

Serotonin metabolism

A

5-hydroxytryptamine to 5-HIAA catabolised by MAO

32
Q

Receptor subgroups and structures

A

5HT1,2,3,4

Most GPCR only 3 is ion gated

33
Q

Role in inflam

A

Incr platelet aggregation and vasc permeab
Play role in autoimm disease eg RA
Incr COX-2 level which incr inflam mediator production
May be mediated by spec sub types of rec?

34
Q

5HT1 agonist

A

Sumatriptan

Used in migraine management

35
Q

5HT3 antagonist

A

Ondansetron

Used in management of chemo induced emesis

36
Q

SSRIs

A

Serotonin reuptake inhibitors

Used in depression management eg fluoxetine and sertraline

37
Q

GIT relation to 5HT

A

Produces and stores 5HT locally in enterochromaffin cells (main source)
Helps control GI fx
Can be excitatory or inhibitory dep on location and sub type

38
Q

Platelet relation to 5HT

A

Store but dont synth

Release promotes platelet aggregation and local vasoconstriction

39
Q

CNS relation to 5HT

A

Multiple effects, affects wake/sleep cycle, behaviour, anxiety

Inflammation (6 decks)

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