Hypothalamo-Pituitary-Adrenal axis and Brain during Stress, Yoga and Meditation

A review.

Abstract

Abstract

 Daily challenges of life produce stress. Adaptation to stressful challenges requires maintenance of homeostasis by activation of neural, neuroendocrine and neuroendocrine-immune mechanisms. This has been called “allostasis” or “stability through change”. Allostatic responses alter Hypothalamo-Pituitary-Adrenocortical axis function this causes altered levels of cortisol in the form of continuous high level of cortisol. Cortisol crosses blood brain barrier and change the architecture of brain by action on glucocorticoid and mineralocorticoid receptors present mainly on hippocampus, amygdala, prefrontal cortex, hypothalamus and thus alter the learning, thinking of stressed person. But recent researches showed that yoga and meditation reverse the effect of stress by decreasing the cortisol levels, increasing the blood flow with in brain near ventricles and other places, stimulating the brain and induce neurogenesis and synaptogenesis i.e. increases neural plasticity. Present review discusses Hypothalamo-Pituitary-Adrenal axis (HPA) axis working during stress exposure, brain changes by raised cortisol due to HPA axis activation and also discuss the effect of yoga and meditation on HPA axis and brain to reverse the deleterious effects of stress.