What is the key physiological effect of cortisol?

Key Physiological Effects of Cortisol

Cortisol plays a crucial role in regulating metabolism, stress response, and inflammation in the body, with its primary function being the mobilization of energy reserves to prepare the body for metabolic demands. 1

Primary Physiological Effects

• Metabolic regulation:

  • Increases blood glucose levels by stimulating gluconeogenesis
  • During physical and psychological stress, cortisol production can increase up to five times the normal amount 1
  • Promotes catabolism of proteins and lipids to provide substrates for glucose production
  • Decreases glucose oxidation and increases lipid oxidation 2

• Stress response:

  • Central to the "fight or flight" response
  • Released from the adrenal glands following hypothalamic-pituitary-adrenal (HPA) axis activation
  • Allows threats to be addressed through physiological changes including increased heart rate and blood pressure 3

• Anti-inflammatory effects:

  • Suppresses immune and inflammatory responses
  • Helps regulate the body's defense mechanisms 1

Secondary Physiological Effects

• Cardiovascular regulation:

  • Maintains basal and dynamic vascular tone through effects on the endothelium
  • Helps regulate blood pressure by increasing blood vessel sensitivity to constrictive materials 1

• Fat distribution:

  • Affects body fat distribution, particularly in the abdominal area
  • High levels are associated with central obesity and metabolic syndrome 1
  • Individuals with high cortisol responsiveness have greater propensity to weight gain and obesity 4

• Brain function:

  • Acts on brain structures including the amygdala, hippocampus, and prefrontal cortex
  • Chronic elevation can lead to altered brain connectivity 3

Physiological Consequences of Cortisol Dysregulation

Excess Cortisol

• Promotes visceral obesity, insulin resistance, hypertension, and dyslipidemia 1
• Can lead to metabolic syndrome components
• Associated with type 2 diabetes, cardiovascular events, vertebral fractures, and increased mortality 1

Cortisol Deficiency

• Decreases basal energy expenditure by approximately 10%
• Increases insulin sensitivity, which may induce hypoglycemia
• Reduces urinary urea excretion 5

Clinical Relevance

The normal circadian rhythm of cortisol includes a marked increase upon awakening (awakening cortisol response), which helps prepare the body for daily metabolic demands 6. This pattern is distinct from the cortisol response to acute stress, as evidenced by different relationships with blood glucose levels.

Understanding cortisol's physiological effects is essential for managing stress-related disorders, as effective stress management interventions can positively influence cortisol levels 7, potentially improving both mental and physical health outcomes.