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Pharmacology > Histamine > Flashcards

Histamine Flashcards

1
Q

What is a tissue hormone

A

A hormone that can be produced basically everywhere in the body

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2
Q

Name 5 different tissue hormones - or autacoids

A

Histamine
Serotonin
Bradykinin
Prostaglandins
Anaphylatoxins

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3
Q

How is histamine derived in an organism?

A

From the decarboxylation of the amino acid histidine

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4
Q

Where is histamine most prevalent in?

A

Ehrlich’s mast cells
Basophils
Histaminocytes

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5
Q

Where is histamine concentration highest in

A

Organs with good blood supply
-> Skin, mucous membranes, lungs, GI tract

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6
Q

Which species have a higher histamine blood content?

A

Goats and rabbits

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7
Q

High number of what in the blood indicate allergy?

A

Eosinophils

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8
Q

What causes the physiological effect of histamine?

A

Low levels of endogenous histamine circulating in blood in free form

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9
Q

What causes histamine release?

A

Insecticides
Plant and animal based toxins
Medicinal products
Anaphylatoxins
etc

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10
Q

What occurrence in body may cause the release of histamine

A

Inflammation
Allergy
and anaphylactic shock

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11
Q

What kind of stressors may cause release of histamine?

A

Trauma
Hot, cold, UV radiation,
Antigen-antibody reaction (allergies

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12
Q

What kind of drugs and chemicals may produce direct degranulation of mast cells with release of histamine independently from development of allergy?

A

Morphine
Codeine
Vancomycin
Polymyxin

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13
Q

Name some biological roles that histamine is involved in

A
  1. Sleep-wake mechanism
  2. Energy metabolism
  3. Behavioural regulation (feeding, drinking, sexual)
  4. Function of endocrine glands
  5. Regulation of autonomous functions
  6. Vestibular function, analgesic mechanism
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14
Q

What is the biological role of histamine in behavioural regulation

A

It inhibits the feeding behaviour of animals,
Stimulates motor activity, drinking, sexual behaviour

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15
Q

What is the biological role of histamine in the function of endocrine glands?

A

It increases the release of adrenocorticotropic hormone, luteinizing hormone, prolactin and vasopressin

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16
Q

What is the biological role of histamine in the regulation of autonomous functions?

A

I.e., Increase in blood pressure, decrease in body temperature, increase in the blood glucose content

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17
Q

How is histamine involved in vestibular system

A

It is involved in the emetic response to vestibular stimulation -> Motion sickness

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18
Q

What kind of drugs have been used to treat vomiting from vestibular stimuli?

A

Histamineblocking drugs (H2 blockers)

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19
Q

In which animals does histamine cause a substantial decrease in blood pressure?

A

In cats and dogs

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20
Q

In which animals does histamine cause an increase in blood pressure?

A

In the hare and Guinea pig

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21
Q

What is the mechanism of blood pressure decrease caused by histamine

A

Dilatation of peripheral capillaries (-> redness of skin)

22
Q

Effects of histamine on smooth muscle?

A

Contraction (uterine muscle, bronchi, GI tract)
(Mainly H1)

23
Q

What kind of tissue and organs are most affected by histamine?

A

Skin and respiratory tract

24
Q

What does histamine do in GI tract?

A

It is a potent stimulant of hydrochloric acid secretion by gastric mucosa (H2)
Also
Final common mediator of gastric secretion

25
Q

What is anaphylaxis?

A

Hypersensitivity phenomena associated with antigen-antibody reactions, which evoke active release of histamine from the mast cell pool

26
Q

What cause the physiological and tissue responses in anaphylaxis?

A

Free histamine and other autacoids

27
Q

What happens in allergy and anaphylactic shock?

A

Dilated peripheral blood vessels
Increased blood flow
Increased permeability of blood vessels
Reduced blood volume
Large arteries and veins are empty of blood
Peripherial blood vessels have excess blood
Smooth muscle is contracted

28
Q

What are signs of allergy and anaphylactic shock in skin?

A

Itching, redness, mottled skin (hyperemia), hives

29
Q

Manifestation of the action of histamine in dogs and cats

A

Vomiting
Diarrhea
Hypersalivation
Dilatation of blood vessels
Strong contraction of uterus

30
Q

Manifestation of the action of histamine in horses

A

Salivation,
Lacrimation
Dyspnea
Colic
Diarrhea

31
Q

Manifestation of action of histamine in guinea pigs

A

Bronchospasm and respiratory arrest

32
Q

Manifestation of action of histamine in humans

A

Smooth muscle contractions (bronchial constriction + laryngeal edema)
Increase in secretion of glands
Decrease in bp
Increase in permeability of blood vessels and allergic skin reactions

33
Q

What are the therapeutic uses of histamine

A

None. But it can be used for diagnostic purposes

34
Q

Where are the 4 histamine receptors mainly located in?

A

H1: Mainly in smooth muscle
H2: Mainly in glands
H3: Presynaptic (auto)receptor, modulates neurotransmitter release from neurons
H4: Mainly in immune system cells and GI tract (participates in inflammation)

35
Q

What are the clinically relevant Histamine receptors

A

Mainly H1 and H2. But also H4

36
Q

Manifestations of stimulation of H1 receptors

A

Intestinal contraction
Contraction of uterus
Bronchial contraction
Constriction of arteries and veins
Increase in permeability of blood vessels
Release of adrenaline and NO
Activation of CNS

37
Q

Manifestations of stimulations of H2

A

Secretion of gastric glands
Secretion of bronchial glands
Relaxation of uterus ?
Relaxation of bronchi ?
Tachycardia, inotropic effect on the heart
Dilation of the small blood vessels
Suppression of histamine release from basophils and mast cells
Activation of the CNS

38
Q

Manifestations of stimulation of H3 receptors

A

Suppression of histamine release (autoreceptor of histaminergic neurons)

39
Q

What do antihistamine substances do?

A

Block the H (1 or 2) receptors and the pharmacodynamic interactions that arise from them

40
Q

What are the physiological antagonists of histamine, and what do they do?

A

Adrenaline and noradrenaline
-> Reduce swelling and cause constriction of blood vessels
-> involved in inhibition of release of histamine

41
Q

What kind of side effect do first-generation antihistamines have? and name an example?

A

Sedative side effect
-> Chlorpheniramine

42
Q

Name some second-generation antihistamines

A

Cetirizine, loratadine

43
Q

Clinical use of H1 blockers

A

Supportive therapy in case of
Asthma, inflammatory processes, gangrenous processes

44
Q

What are some clinical signs of allergy in animals

A

Restlessness
Anorexia
Salivation
Coughing
Edema
Urticaria, pruritus, eczema
Inflammation of mucous membranes and eyes
Contraction of smooth muscle

45
Q

What are some effects of H2 blockers

A

Reduce secretion of gastric and bronchial glands and eliminate the vomiting-inducing effect of histamine

46
Q

Where are H2 blockers used?

A

I.E., for treatment of ulcers in the stomach or duodenum
-> Reduce secretion of pepsin & Hydrochloric acid in gastric glands

47
Q

What is serotonin involved in?

A

Thermoregulation
Sleep-wake mechanism
Stimulates the motility
Influences behavior

48
Q

What does a deficit of serotonin lead to

A

Lack of sleep
Emotional stress
Aggressiveness

49
Q

Serotonin antagonsists

A

Lysergic acid diethylamide (LSD)
Cyproheptadine (treatment of allergies)
Tropisetron & Ondansetron (strong anti-vomiting effect)

50
Q

What are cytokines and what do they do

A

Cell signaling molecules that aid cell to cell communication in immune responses.
Stimulate the movement of cells toward the sites of inflammation, infection and trauma

51
Q
A

Pharmacology (18 decks)

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