Corticosteroids and stress response

Question 1

stressor

Answer 1

a stimulus that disrupts homeostasis and causes the stress response:

• a predator running towards you
• a difficult and important exam

Question 2

what is the stress response:

Answer 2

a suite of physiological and behavioural responses to a stressor that help to restore homeostasis

Question 3

what is the two step physiological stress response

Answer 3

1. sympathetic nervous system
   - quick response system, within seconds
   - release of epinephrine
2. HPA Axis (hypothalamic-pituitary-adrenal axis)
   - slower response system, minutes to hours
   - release of cortisol

Question 4

what does the hypothalamus release that acts on the pituitary gland to produce ACTH

Answer 4

CRH (corticotrophin-releasing hormone)

Question 5

Consequences of the stress response

Answer 5

• increased heart rate
• increased oxygen intake
• increased blood glucose levels
• increased blood flow to muscles
• increased alertness
• inhibition of digestion and the immune system
• release of endorphins
• dilation of the pupils

Question 6

Chronic stress related to several health problems:

Answer 6

– Heart disease
– Diabetes
– Ulcers
– Growth problems
– Compromised immune system

Question 7

what percentage of depressed patients have elevated cortisol

Answer 7

50%

Question 8

tell me about rhythmic cortisol release

Answer 8

high in the morning 7-9am and low 11-4am

this may be the reason for sleep disturbances in depression

Question 9

Dexamethasone Suppression Test

Answer 9

• People usually have high cortisol in the morning
• If given Dex HPA negative feedback turns this off, so no cortisol surge
• Not true of depressed patients

Question 10

what disease is often associated with depression

Answer 10

cushings disease

• increased ACTH
• high cortisol

Question 11

Addisons disease

Answer 11

• low cortisol

- adrenal insufficiency

Question 12

Stress response and the immune system timeline

Answer 12

• 1st few minutes – immune system is enhanced
• After about an hour of stress – immune system returns to normal
• Chronic stress suppresses immune system functioning

Question 13

what is the role of cortisol as an anti-stress hormone

Answer 13

• helps reduce inflammation during stress, but it also acts as an immunosuppressant

Question 14

exam stress study what was the conclusion

Answer 14

Lowered levels of Interferon gamma (IFN-g), which is normally released by T lymphocytes and natural killer (NK) cells.

There was a significant decrease in the number of macrophages, interferons, lymphocytes and natural killer (NK) cells.

Question 15

what are the physical stressors of space flight

Answer 15

• G-force acceleration

* Cosmic radiation •Pressure variations

Question 16

what are the emotional stresses of space flight

Answer 16

• flight tasks
• Public events
• Being strapped to a rocket!!

Question 17

conclusion of astronauts and EBV virus study

Answer 17

• There was a decrease in the virus specific antibodies in all the astronauts.

Question 18

most commonly prescribed steroid

Answer 18

prednisolone

- low potency and a short half life

Question 19

dexamethasone

Answer 19

• high potency

- long half life

Question 20

glucocorticoids suppress cell-mediated immunity… give my a couple examples of what they inhibit the production of

Answer 20

IL-1,IL-2,IL-3,IL-4,IL-5,
IL-6, IL-8, TNF-a

• Suppress humoral immunity - B cells express less
IL-2R and secrete less IL-2
• Downregulation of Fc receptors on macrophages- reduced phagocytosis of opsonised cells and bacteria

Question 21

Side-effects of steroids

Answer 21

• Immunosuppression
• Hyperglycemia due to gluconeogenesis, insulin resistance, impaired glucose tolerance
• Skin fragility, bruising
• Osteoporosis
• Weight gain
• Adrenal insufficiency
• Muscle breakdown
• Irregular menstruation
• CNS
• Cushing syndrome

Question 22

why’d o you have to be careful when withdrawing steroids

Answer 22

• excess use suppress CRH and ACTH and prolonged use leads to adrenal atrophy
• less than one week = abruptly is ok
• 6-10 days = taper for 4 days
• 11-30 days = twice replacement, then by 25% every 4 days then there will be a three month recovery
• > 30 days = reduce to twice replacement, then by 25% per week, then 0800h check with cortisone. Recovery may take 1 year.

Question 23

what are the two stages of autoimmunity in diabetes

Answer 23

• 1st stage: insulitis - lymphocyte invasion of pancreatic islets.
• 2nd stage: overt diabetes, massive death of islet B cells - loss of glucose homeostasis

Question 24

link between pancreas and the GI system

Answer 24

PLN sample self-antigens from pancreas and also gut. Non-specific gut pertubations influence b-reactive
T cells. Potential explanation for relationship between diseases Like coeliac and type 1 diabetes. Link between neonatal immune system development and gut development.