Glucocorticoid signaling is fundamental in healthy stress coping and in the pathophysiology of stress-related diseases, such as
post-traumatic stress disorder (
PTSD).
Glucocorticoids are metabolized by
cytochrome P450 (CYP) as well as 11-β-hydroxysteroid
dehydrogenase type 1 (11βHSD1) and 2 (11βHSD2). Acute stress-induced increase in
glucocorticoid concentrations stimulates the expression of several CYP sub-types. CYP is primarily responsible for
glucocorticoid metabolism and its increased activity can result in decreased circulating
glucocorticoids in response to repeated stress stimuli. In addition, repeated stress-induced
glucocorticoid release can promote 11βHSD1 activation and 11βHSD2 inhibition, and the 11βHSD2 suppression can lead to apparent
mineralocorticoid excess. The activation of CYP and 11βHSD1 and the suppression of 11βHSD2 may at least partly contribute to development of the blunted
glucocorticoid response to stressors characteristic in high trait anxiety,
PTSD, and other stress-related disorders.
Glucocorticoids and
glucocorticoid-metabolizing
enzymes interact closely with other biomolecules such as inflammatory
cytokines, monoamines, and some monoamine-metabolizing
enzymes, namely the
monoamine oxidase type A (
MAO-A) and B (
MAO-B).
Glucocorticoids boost
MAO activity and this decreases monoamine levels and induces oxidative tissue damage which then activates inflammatory
cytokines. The inflammatory
cytokines suppress CYP expression and activity. This dynamic cross-talk between
glucocorticoids, monoamines, and their metabolizing
enzymes could be a critical factor in the pathophysiology of stress-related disorders.Lay summaryGlucocorticoids, which are produced and released under the control by brain regulatory centers, are fundamental in the stress response. This review emphasizes the importance of
glucocorticoid metabolism and particularly the interaction between the brain and the liver as the major metabolic organ in the body. The activity of
enzymes involved in
glucocorticoid metabolism is proposed to play not only an important role in positive, healthy
glucocorticoid effects, but also to contribute to the development and course of stress-related diseases.