Chronic stress increases level of a protein that decreases availability of mood-regulating chemical
on 14 June 2017
Chronic stress, when the cracks appear

As a general rule, I always look for the potential for stress and/ or anxiety in any presenting issue when I see clients. The rationale being, that stress and anxiety are known to limit or debilitate normal brain function. It is always going to be more difficult to help anyone when their brain isn't firing on all four cylinders! The research below adds a little weight to my treatment philosophy, as well as a clearer picture of the WHY factor . . . . . .

The main component that seems to be running amok here is transglutaminase 2 (TG2), which leads to a lack of BDNF (Brain-derived neurotrophic factor). BDNF is found in several places in the brain but perhaps, for me, the most interesting is the hippocampus, cortex and basal forebrain. These areas are crucially involved in memory, learning and higher thinking (our executive function). It seems obvious to me, that if something is impeding memory formation, storage and retrieval, then this will affect the way we experience life; daily and long term. When it comes to depression, the absence of normal function in these areas of the brain is a major factor in the negative feeling towards life and living. Whilst science will predominantly point towards the advancement of pharmaceutical intervention, albeit with the occasional reference to therapeutic ones, my focus is on how can we use the mind.

Hypnosis is essentially akin to mind engineering, the only thing that changes, is, perspective, perception and the chemical architecture of specific networks. Consequential to that, we start to think, behave and react differently and that changes lives! Anyway, the take away from this is, do all you can to limit unnecessary stress and anxiety. We actually need a certain amount of stress and anxiety to keep us safe, so the objective is never to eliminate it but rather, learn to use it to our advantage.

The Research:

Scientists have found elevated levels of transglutaminase 2, or TG2, in the brains of mice experiencing chronic stress -- an animal model of depression -- as well as the prefrontal cortex of depressed people who committed suicide. High TG2 levels in the mouse translated to atrophy of neurons, depression-like symptoms and reduced levels of TrkB, the receptor for brain-derived neurotrophic factor, a brain-nourishing molecule that also aids connectivity, said Dr Anilkumar Pillai, a neuroscientist in the Department of Psychiatry and Health Behaviour at the Medical College of Georgia at Augusta University.

When scientists overexpressed TrkB, it relieved the depression-like symptoms in their animal model. "If you don't have enough BDNF, then all the serotonin in the world won't help," said Pillai, corresponding author of the study in the Nature journal Molecular Psychiatry. Likewise, when they directly reduced TG2 levels using a drug or a viral vector, more BDNF signalling occurred and depressive symptoms abated, said Pillai, who suspects that the protein may be a powerful new target in the fight against depression. They found TG2 levels increased in their animal model following administration of stress hormones and after several weeks of actual stress that mimics the lives of chronically stressed individuals. Both produced classic depressive behaviour and increased TG2 levels in the prefrontal cortex, a region involved in complex thoughts, decision-making as well as mood and personality expression.

Serotonin is a major neurotransmitter in the brain involved in many functions, including mood regulation. Serotonin levels in a depressed patient's blood should be high because serotonin signalling in the brain is low, Pillai said. Blood levels can be used to help diagnose the condition that affects about 350 million people worldwide and is the leading cause of disability, according to the World Health Organization. Many cell types make serotonin. Interestingly, the vast majority of serotonin is made in the gut, but neurons do make some of their own, Pillai said. Astrocytes make BDNF, whose levels are also low in depression. Although just how the two work together is an unfolding mystery. In this study, Pillai and his team further linked them by showing that treatment that increases serotonin availability -- as most antidepressants do -- also increased levels of the BDNF receptor thru the action of RAC1. TG2 converts serotonin to RAC1, a protein that helps rejuvenate the BDNF receptor, TrkB.

Now the MCG scientists have shown that in depression a healthy balance of all these is upset, as elevated TG2 makes less serotonin available, leaving insufficient levels to enable proper communication between neurons. The brain also is more vulnerable as the increased level of activated RAC1 is inexplicably degraded, which leads to less instead of more BDNF signalling. "Increased amounts of TG2 will eventually lead to decreased levels of RAC1, and BDNF signalling is just not happening," Pillai said. Next steps include looking for other drugs that lower TG2 levels. For the study, researchers used cysteamine, whose clinical uses today include treatment of a rare genetic condition in which a buildup of crystals can cause kidney failure. Unfortunately, the drug creates an odour that has patients bathing multiple times daily. They also want to directly measure serotonin levels following treatment, although Pillai notes that increased BNDF signalling should be significant to alleviate symptoms.

Story Source:
The above post is reprinted from materials provided by Medical College of Georgia at Augusta University. Note: Content may be edited for style and length.

Journal Reference:
1. C D Pandya, N Hoda, A Crider, D Peter, A Kutiyanawalla, S Kumar, A O Ahmed, G Turecki, C M Hernandez, A V Terry, A Pillai. Transglutaminase 2 overexpression induces depressive-like behaviour and impaired TrkB signalling in mice. Molecular Psychiatry, 2016; DOI: 10.1038/mp.2016.145