Corticosteroids Flashcards
Synthesis of corticosteroids?
In adrenal cortex
Corticosteroid Hs?
Cortisol
Aldosterone
Adrenal Deficiency ?
Addison’s Disease
Adrenal Excess?
Cushing’s Disease
Corticosteroids feedback?
Negative Feedback
Corticosteroids Negative Feedback Pathway?
ACTH response to sleep, meals and stress?
ACTH increase after meals, increased steroidogensis in response to meals and are lowest at night and highest at 8AM in the morning
What influences aldosterone levels in body?
- ACTH
- More by renin–angiotensin system and plasma potassium levels
Corticosteroids MOA?
Gene active hormones
* Diffuses into the cell and binds to cytoplasmic
glucocorticosteroid receptors
* Release of chaperone heat shock protein (hsp)
* Activated receptor translocates to the nucleus →
transcription → protein synthesis → steroid response
Why are corticosteroids effects not felt immediately?
Corticosteroids MOA are multi-stepped process there effects are only felt after several hours
Corticosteroids MOA?
- Glucocorticoids are carried via transporter, Glucocorticoid binding protein.
2.Glucocorticoids binds to a receptor complex coupled with two heat-shock proteins, HSP70 and HSP90, located in the cytoplasm.
- Activates receptor and dissociates the two proteins from complex allowing the activated glucocorticoid translocate in the nucleus where it binds to the glucocorticoid response element.
- This activates the complex and alters gene transcription.
- This causes up-regulation of lipocortin and down regulation of COX-2.
Lipocortin Function?
Lipocortin inhibits Phospholipase-A2 and prevents the liberation of arachnoid acid from membrane phospholipids and reduces production of Prostaglandins and Thromboxane-A2.
What is the physiological function of glucocosrticosteriods/cortisol?
BIG FIB
⬆️ Blood pressure
⬆️ Insulin Resistance
⬆️ Glucneogenesis, Glycogen synthesis
⬇️Fibroblast Activity
⬇️Inflammatory Response and ⬇️ Immunosupressant
⬇️Bone formation(osteoblast activitY)
What is the physiological function of mineralcorticosteroids/aldosterone ?
Electrolyte-water balance regulating
Steroid Effects?
6 S’s
Sugar(Hyperglycaemia)
Soggy bones(causes osteoporosis)
Sick(decreased immunity)
Sad(depression)
Salt(water and salt retention)
Sex(decreased libido)
Corticosteroid Metabolic Effects?
- Dose-related
- Carbohydrate, protein and fat metabolism
1.Increases Blood glucose
* formation of glucose from amino acids(gluconeogenesis)
* Glucogenolysis
* Decreased Cellular Uptake
*Glucose release- stimulates insulin release but inhibits peripheral
glucose uptake
* Increased Glucagon(pancreas)
* Promotes glucose storage as glycogen
- Increased Lipolysis
* Increased FFA–release of fatty acids & glycerol into circulation
* Inhibits lipolysis and causes fat depoisition - Decreased Proteins
* Inhibit protein synthesis and stimulate protein catabolism
Why are glucocorticoids vital in fasting?
During fasting, glucocorticoids are vital to prevent (possibly fatal)
hypoglycaemia.
Corticosteroids effect on liver?
Stimulate RNA and protein synthesis in the liver
Corticosteroids effect on muscle?
Degradation of skeletal muscle for gluconeogenesis and therefore causes: muscle wasting and atrophy
Larger amounts - ↓muscle mass,
Corticosteroids effect on children?
- Children – inhibition of growth
Corticosteroids effect on bones?
Bone – osteoporosis, osteonecrosis
Decreased osteoclast activity
Corticosteroids effect on skin?
Decreases Collagen Synthesis and thus:
-easily bruises
-vessel fragility
-stretch marks
-thin skins
-peripheral fat because of fat deposition
Prostaglandins function?
Prostaglandins are hormone-like substances that affect several bodily functions, including inflammation, pain and uterine contractions.
Thromboxane A2?
Thromboxane A2 (TXA2) is a short-lived, lipid mediator synthesized by platelets from arachidonic acid and released from the phospholipid membrane upon platelet activation. Its main role is in amplification of platelet activation and recruitment of additional platelets to the site of injury.
Thromboxanes, a substance produced by platelets, lead to occlusion of blood vessels by fueling blood clots inside the vascular system.
Corticosteroid effects on Phospholipase A2?
Corticosteroids
⬆️synthesis of annexin-1
which inhibits
phospholipase A2
Phospholipase A2 function?
Phospholipase A2 (PLA2) catalyzes the hydrolysis of the sn-2 position of membrane glycerophospholipids to liberate arachidonic acid (AA), a precursor of eicosanoids including prostaglandins (PGs) and leukotrienes (LTs).
Which genes does glucocosteroids suppress?
-Phospholipase A2
-Cyclo-oxygenase-2 (COX-2)
-Interleukin-2 (IL-2) receptor
* These genes are switched on by NFκB.
* synthesis of IκB, which binds to NFκB and inhibits it.
* ↓monocyte/macrophage function
* ↓ circulating T-cells, especially helper T4 lymphocytes
* Prevents lymphocyte proliferation by inhibiting IL-1 and IL-2
* Inhibits transport of lymphocytes to the site of antigenic stimulation
* Inhibits antibody production
* ↓COX-2, inducible nitric oxide synthase (NOS2), and inflammatory cytokines
NFKB function
Switches on PLA2, COX-2 and IL2
Interleukin-2 (IL-2) function?
Interleukin-2 (IL-2) is a pleiotropic cytokine that drives T-cell growth, augments NK cytolytic activity, induces the differentiation of regulatory T cells, and mediates activation-induced cell death.
Glucocorticoid effect on IkB and function on NFKB?
Increases synthesis of IκB, which binds to NFκB and inhibits it.
NFKB is important because it switches on PLA2, COX-2 and IL2
Corticosteroids Function on monocytes/lymphocytes?
Decreases monocyte and macrophage function
Decreases.circulating T-cells, especially helper T4 lymphocytes
* Prevents lymphocyte proliferation by inhibiting IL-1 and IL-2
* Inhibits transport of lymphocytes to the site of antigenic stimulation
* Inhibits antibody production
Corticosteroids effect on COX?
Decreases COX-2, inducible nitric oxide synthase (NOS2), and inflammatory cytokines
Glucorticosteroids CNS effects?
-Adrenal insufficiency – slowing of the alpha rhythm lead to depression
-Glucorticoids cause insomnia and euphoria followed by depression
Glucocorticosteroids CNS effects in large doses?
-intecranial pressure (pseudotumor cerebri)
Glucocorticosteroids ulcer effects?
-Peptic Ulcers by suppressing immune response to H.Pylori
Glucocorticosteroids chronic use effects?
-Chronic use ↓ release of ACTH, growth hormone, TSH, luteinizing
hormone
Glucocorticosteroids blood calcium effects?
-Fat redistribution
-Decrease Vitamin D and calcium absorption
Glucocorticosteroids renal function effects?
Renal function: Cortisol deficiency – impaired renal function,
⬆️vasopressin secretion & ⬇️water secretion
Vasopressin Function?
Vasopressin down regulates blood pressure and plasma osmolarity
Glucocorticosteroids fetal lung development effects?
Glucocorticorticoids stimulates the production of pulmonary
surfactant – lungs – breathing
Glucocorticosteroids epigenetic regulation effects?
- Alter activity of DNA methyltransferases, other enzymes involved
epigenesis - Consequences – pregnant mums, young infants and children-
predispose to behavioural/somatic disorders e.g. depression,
obesity, metabolic syndrome