NEUROENDOCRINE RESPONSE TO STRESS
NEUROENDOCRINE RESPONSE TO STRESS
- Sudden exposure to any stress initially produces sympathetic alarm reaction.
- Reaction includes,
- Generalized & profuse sympathetic neural discharge.
- Increased adrenal medullary secretion.
On persistence of stressful stimulus:
- Short-lived alarm reaction.
- Response lasting hours, days or even weeks.
- Eg: Seen typically in patients undergoing major abdominal surgery – “Surgical Stress”.
- Person with multiple fractures.
- Person with extensive burns.
EVENTS:
- Neuroendocrine response & consequent metabolic disturbances are,
1. Hypothalamus mediated neuro-endocrine response:
1a) Increased hormonal secretion –
- ACTH
- Glucocorticoid – Cortisol
- Growth hormone
- Adrenal medullary catecholamines (epinephrine)
- Thyroxine
- Antidiuretic hormone
1b) Decreased hormonal secretion:
- Pituitary gonadotropin (LH, FSH).
2. Sympathetic reaction:
2a) On Kidney:
- Increased sympathetic discharge to renal vessels
- Coupled with hypovolemia (due to blood loss etc.)
2b) On Pancreas:
- Increased pancreatic sympathetic discharge depressing insulin secretion
- Promotes glucagon secretion.
3. Renal reaction to stress:
- Renin-angiotensin system activation.
- Increased renin, angiotensin II & aldosterone secretion.
METABOLIC EFFECTS DURING STRESS
- Neuroendocrine secretions cause following metabolic disturbances during stress –
1. On protein metabolism:
- Causes “Catabolism“
- Most important metabolic change in stress.
Other effects –
- Anemia
- Hypoproteinemia
- Loss of lean body mass (mainly muscle proteins).
- Most important hormone is Cortisol.
2. On Carbohydrate metabolism:
Causes Hyperglycemia due to,
- Insulin suppression.
Coupled with increased hormone secretion of,
- Glucagon.
- Growth hormone.
- Glucocorticoids (cortisol).
- Catecholamines (epinephrine & norepinephrine).
3. On Lipid metabolism:
- Increased Plasma FFA level
- Result of suppressed insulin secretion &
- Increased cortisol, GH & catecholamines secretion.
Steps:
- (under hormonal influence)
- Increased lipolysis → Leading to elevated plasma FFA level
4. On electrolytic balance:
4a) On Salt & Water:
- Promotes salt & water retention.
- Renin-angiotensin-aldosterone system activation.
- Due to elevated ADH & aldosterone secretion.
4b) On Potassium:
- Loss of Potassium.
- Due to elevated aldosterone secretion.
Exam Important
NEUROENDOCRINE RESPONSE TO STRESS
- Sudden exposure to any type of stress initially produces sympathetic alarm reaction.
- Eg: Seen typically in patients undergoing major abdominal surgery – “Surgical Stress”
EVENTS:
1a) Leads to increased hormonal secretion –
- ACTH
- Glucocorticoid – Cortisol
- Growth hormone
- Adrenal medullary catecholamines (epinephrine)
- Thyroxine
- Antidiuretic hormone
1b) Decreased hormonal secretion seen with –
- Pituitary gonadotropin (LH, FSH).
2. Sympathetic reaction:
2b) On Pancreas:
- Increased pancreatic sympathetic discharge depressing insulin secretion.
- Promotes glucagon secretion.
3. Renal reaction to stress:
- Activation of Renin-angiotensin system
- Increases secretion of renin, angiotensin II & aldosterone.
METABOLIC EFFECTS DURING STRESS
1. On protein metabolism:
- Most important metabolic change in stress.
- Causes “Catabolism”.
- Loss of lean body mass (mainly muscle proteins).
- Due to Cortisol.
2. On Carbohydrate metabolism:
- Causes Hyperglycemia due to,
- Suppression of insulin secretion.
Coupled with increased secretion of hormones like –
- Glucagon.
- Growth hormone.
- Glucocorticoids (cortisol).
- Catecholamines (epinephrine & norepinephrine).
