Understanding the connection between mood disorders & HPA axis
on
In this post I would like to discuss the connection between stress, changes in intestinal permeability & mood disorders especially anxiety and depression.
There are two types of stress, Acute and chronic. Acute stress is connected to the release of cortisone through HPA axis (hypothalamic-pituitary-adrenals) which is related with a potent adaptive immune response including inhibition of the intracellular pathogen immune system, and preservation of the extracellular pathogen immune system). On the other hand, chronic stress is related to maladjustments of the two immune responses mentioned above.
These two types of stress have different impact on intestinal microbiota. In short, acute stress effect on intestinal microbiota is limited. The concern comes with chronic stress.
According to the studies in NCBI-Gut–brain axis and neuroendocrine chronic stress leads to changes in microorganisms in our gut and eventually our mood through HPA axis. Early life stress can increase the cortisone level in plasma and its permeability, and promote bacteria to move to the liver and spleen (9). O’Mahony et al. found that microbiota in the feces of maternal-separate mice changed, in addition cortisone level increased, proinflammatory cytokine tumor necrosis factor alpha (TNF-α), Interferon-γ (IFN-γ) increased and Interluekin-6(IL-6) also had an increasing trend (10). The proinflammatory cytokine, IL-6 is an activator of the HPA axis; consistent activation of this axis can lead to a downregulation of glucocorticoid receptor, which is related with the feedback mechanism of HPA axis, and further leads to HPA axis over-activation making it harder to inhibit inflammatory reaction, this may explain the increased cortisone and proinflammatory cytokine (10). Park et al. found that depression and anxiety model rats show changes in colonic movement and intestinal microbiota, meanwhile motor neuropeptide, intestinal hormone, serotonin (5-HT) also increased which could be a presumptive factor of changes in intestinal movement. In these rats, corticotrophin-releasing hormone (CRH) expression increased in the paraventricular nucleus area of hypothalamus. In contrast, administering CRH to normal rats showed behavioral and intestinal changes similar with the changes induced by stress, strongly suggesting that the depression was the result of changes in intestinal microbiota through HPA axis (5).
Further more, it has been found that microbiota can bring relieve to depression and anxiety. These studies indicate that stress directly impacts HPA axis which leads the increase in cortisone production which increases anxiety levels, changes in intestinal motility and gut micro-ecology . On the other hand, intestinal microbiota can inhibit cortisone production through HPA axis resulting in relieve from anxiety and depression. HPA axis plays a bi-directional role in regulation of the gut-brain axis.
In conclusion, whether you suffer from digestive problems, mood disorders or most commonly both, without addressing chronic stress, healing will be challenging due to the impact of chronic stress on intestinal integrity & HPA axis.
Related posts
May 29, 2023