From receptor balance to rational glucocorticoid therapy

Area of Science:

• Neuroendocrinology
• Stress Physiology
• Behavioral Neuroscience

Background:

• Corticosteroids, the end product of the hypothalamic-pituitary-adrenal axis, play a dual role in brain function.
• They are crucial for appraising stressful experiences, decision-making, and cognitive performance during stress adaptation.
• Their actions are mediated by mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs), which are abundant in limbic brain neurons.

Observation:

• Phasic glucocorticoid receptor (GR) occupancy during ultradian rhythm is essential for maintaining corticosteroid responsiveness.
• Mineralocorticoid receptor (MR) activation initially enhances limbic network excitability for appraisal and emotion regulation during stress.
• Rising corticosteroid levels occupy GR, shifting resources to limbic-cortical circuits for behavioral adaptation and memory.

Findings:

• An imbalance between MR and GR activation disrupts the hypothalamic-pituitary-adrenal axis, increasing vulnerability to stress.
• This MR:GR imbalance is linked to chronic stress, depression, and exposure to synthetic glucocorticoids.
• Glucocorticoid psychopathology may arise from suppressed ultradian/circadian rhythms and depleted brain MR by endogenous corticosterone.

Implications:

• Understanding the MR:GR balance is key to managing stress-related disorders.
• This knowledge can inform the development of rational glucocorticoid therapies.
• Targeting corticosteroid receptor systems may offer novel treatments for depression and stress-related psychopathology.