Steroids Flashcards

1
Q

What physiological roles do steroids Play in the body

A

Cell membranes and cell signalling

Anti inflammatory agents

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2
Q

Steroid structure

A

4 cycloalkane structure - 3 cyclohexane rings and 1 cyclopentane ring

Variation obtained by different functional groups attached to the 4-ring core and oxidation states of the rings

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3
Q

Biological role of cholesterol

A

Facilitates membrane fluidity
Controls membrane permeability

Synthetic precursor - important for the biosynthesis of many cellular constituents - Vitamin D and steroid hormones

Steroidgenesis

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4
Q

What is steroidgenesis

A

Biological process whereby steroid hormones are generated from cholesterol

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5
Q

Where are corticosteroids produced

A

Adrenal cortex

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6
Q

Where are sex steroids produced

A

Ovaries, testes, adrenal gland

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7
Q

What do corticosteroids do

A

Regulate immune function , stress response and metabolism

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8
Q

Examples of corticosteroid

A

GlucocorticoidS and mineralcorticoids

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9
Q

What do sex hormones do

A

Interact with estrogen or androgen receptors

Differentiate sex and support reproduction

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10
Q

Examples of sex hormones

A

Androgens (testosterone)
Oestrogens (estradiol)
Progestogens (progesterone)

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11
Q

What inflammatory mediator does steroids reduce the production of

A

Cytokines

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12
Q

What does dexamethasone treat

A
Asthma 
Allergies 
Cancer 
Colitis 
Arthritis
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13
Q

What does dexamethasone do

A

Anti inflammatory mechanism of action

Reduces vasodilation and permeability of vessels
Regulates gene expression
Dampens activation of immune cells

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14
Q

How does dexamethasone treat covid 19

A

Mechanical ventilation and stress up regulates ACE2 expression
Enables virus entry into cells

Dexamethasone and other steroids block this pathway , preventing increase in ACE2 expression

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15
Q

Steroid mechanism of action ( up to entering nucleus )

A

Steroid crosses plasma membrane and interacts with steroid receptor
Steroid binding to receptor displaces chaperone eg HSP90
Steroid receptor complexes can then form a dimer and enter the nucleus

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16
Q

What can the steroid receptor complex do once in nucleus

A

Cause transcription / translation of proteins such as IkB by binding to DNA and functioning as a transcription factor

Directly interact with NFkB (p50:p65) to suppress cytokine synthesis

17
Q

What does iKb inhibit

A

NF-kB

18
Q

What does NF-kB produce

A

Pro inflammatory proteins

19
Q

What is a cytokine

A

Any of A number of substances such as interferons , interleukin and growth factors which are secreted by a certain no of cells of the immune system and have effects on other cells

20
Q

Others ways steroids can have a anti inflammatory effect

A

Directly affect cells of the immune system to suppress or inflammatory responses

Inhibit the production of pro inflammatory cytokines
Promote production of anti inflammatory cytokines

Promote the apoptosis of T cells , macrophage and dendritic cells ,wading to a reduced immune response
Reduce Nk cell cytotoxicity
Recipe Bcell antibody production
Reduce expression of cell surface molecules responsible for T cell activation

Also implicated in regulating arachidonic acid metabolism
Increase transcription and translation of lipocortins
Suppress phospholipid A2 activity and suppress COX enzymes
Reduced production of inflammatory mediators

21
Q

Beclomethasone diproprionate

A

Prodrug of beclometasone
Administered by inhalation
Half life -2,8 hrs

22
Q

Prednisolone

A

Approved for treatment of wide range of inflammatory disease
Oral administration
Readily absorbed by GI tract
Half life 2-3 hours

23
Q

Hydrocortisone

A

Main glucocorticoid secreted by adrenal cortex
Synthetic derivative administered by IV
used in emergencies
Half life 6-8 hrs