The Vagus Nerve and Vasopressin

So the vagus nerve works really well at reducing the severity of so many things… but we don’t know why that is exactly. I am going to propose a hypothesis – welcome to my brain.

Here’s a study on vagus nerve stimulation

Vagus Nerve Stimulation (VNS) has been proven to be a useful treatment across a number of domains and has been used effectively to treat epilepsy and depression in adults. There is accumulating evidence to suggest that it can be used to help quell inflammation in a number of other autonomic or inflammatory disorders, which would make it useful for a wider range of pediatric patients as well. Preliminary studies have shown promise for VNS being used for stroke, autoimmune diseases, heart and lung failure, obesity, and pain management, but further studies are needed to fully elucidate the mechanistic actions that explain VNS’s potential role in treating these disorders. Many of these studies are not mechanistic in nature, and further pathway analysis and studies focused on the mechanisms by which VNS alters autonomic tone are key to further our understanding of vagus nerve modification. VNS interacts with the body’s immune system to modify inflammatory tone by altering the release of pro- and anti-inflammatory cytokines. We have summarized some of these key inflammatory markers in Figure 3. There is an overwhelming evidence to suggest that vagus nerve is an important component of the immune response and manipulating vagal tone is a way to modulate the immune system. Using VNS to manipulate vagal tone provides an exciting new opportunity for minimally invasive therapeutic intervention in adult and pediatric patients.

A review of vagus nerve stimulation as a therapeutic intervention

The vagus nerve represents the main component of the parasympathetic nervous system, which oversees a vast array of crucial bodily functions, including control of mood, immune response, digestion, and heart rate. It establishes one of the connections between the brain and the gastrointestinal tract and sends information about the state of the inner organs to the brain via afferent fibers. In this review article, we discuss various functions of the vagus nerve which make it an attractive target in treating psychiatric and gastrointestinal disorders. There is preliminary evidence that vagus nerve stimulation is a promising add-on treatment for treatment-refractory depression, posttraumatic stress disorder, and inflammatory bowel disease. Treatments that target the vagus nerve increase the vagal tone and inhibit cytokine production. Both are important mechanism of resiliency. The stimulation of vagal afferent fibers in the gut influences monoaminergic brain systems in the brain stem that play crucial roles in major psychiatric conditions, such as mood and anxiety disorders. In line, there is preliminary evidence for gut bacteria to have beneficial effect on mood and anxiety, partly by affecting the activity of the vagus nerve. Since, the vagal tone is correlated with capacity to regulate stress responses and can be influenced by breathing, its increase through meditation and yoga likely contribute to resilience and the mitigation of mood and anxiety symptoms.

Vagus Nerve as Modulator of the Brain–Gut Axis in Psychiatric and Inflammatory Disorders

It seems that it’s tied to inflammation. I have been wondering about blood flow – I did a whole blog on blood.

But more importantly I wanted to know why it made you happy and what might be a reason for it seeming to make it so that you can socialise more easily – which is apparently another one of it’s effects – because it reduces anxiety.

Then I came to something no one really talks about that much.

Vassopressin

Vasopressin, also called antidiuretic hormone (ADH), arginine vasopressin (AVP) or argipressin.

Literally this is it’s current function according to science:

Vasopressin regulates the tonicity of body fluids. It is released from the posterior pituitary in response to hypertonicity and causes the kidneys to reabsorb solute-free water and return it to the circulation from the tubules of the nephron, thus returning the tonicity of the body fluids toward normal. An incidental consequence of this renal reabsorption of water is concentrated urine and reduced urine volume. AVP released in high concentrations may also raise blood pressure by inducing moderate vasoconstriction.

Basically according to theories now all this one thing does is control the amount of water.

It does stop you from urinating if you lose too much water. Ever noticed that when you don’t drink that you don’t need to pee despite maybe having a lot of water still – that is vasopressin doing it’s job. When you lose as little as 2% of your body water it can double the content of vasopressin in the blood.

Why do I care?

Vasopressin and Oxytocin appear to have complicated transmitter interactions – it’s been hypothesised that these are the behaviours:

Literally the interaction between Oxytocin and Vasopressin appear to modulate the love-fear reaction in humans. The above article covers it in more detail.

Hang on I thought stress was related to cortisol – and only cortisol…

Yeah it is – it definitely seems to play a role in a lot of things. But do you know the most common way of getting rid of cortisol? – Excreting it. This is done by drinking water – which will in turn allow your body to release cortisol through urination. You can also exercise – there are many ways of excreting water from the body.

Ok so what’s the connection with the vagus nerve then?

When Vagus Nerve Stimulation (VNS) was put into rats to test fluid consumption they found something interesting – they drank the same amount, but they didn’t drink as often. Not only that – the amount of arginine vasopressin (AVP) was lower in the blood.

These results suggest that VNS may activate vagal afferent components which related to inhibition of AVP secretion and then suppressed the augmentation of thirst. Frequent drinking small volume may benefit for homeostasis in CHF.

Chronic vagal nerve stimulation suppress thirst through decreasing vasopressin secretion in the rats with chronic heart failure

Wait a second – if VNS seems to work, and it also seems to supress vasopressin does that mean vasopressin might have a role in inflammation?

Vasopressin is a small neuropeptide initially identified as the physiologically essential antidiuretic hormone more than 50 years ago. Since then, it has increasingly become apparent that vasopressin is an important hormonal component of the response to stress. In fact, it appears that the antidiuretic effect is only one of several biologically significant actions of vasopressin exerted during the response to stress. This review highlights the main features of vasopressin as a stress hormone produced by relatively simple hypothalamic neurons that release their neurotransmitters into the blood stream and also send axonal projections to key parts of the brain that control the response to stressful environmental challenges. Special focus is on the role of vasopressin in (1) setting the efficacy of adrenal corticosteroid feedback inhibition; (2) the stress of pain; and (3) supporting the response to inflammation.

Vasopressin as a Stress Hormone

My point is this:

I think Vasopressin might be the single most important neurochemical for understanding anxiety, depression, inflammation – it seems to control blood flow. When it was injected into the guts of rats it inhibited gastric motility, it could be the thing that’s causing all the issues with inflammation throughout the body – and especially in the brain.

If VNS works by reducing the amount of vasopressin, and causes a decrease in inflammation then it stands to reason that we should DEFINITELY look into the function of vasopressin outside of it’s current small understanding.

DRINK WATER.

Published by roryreckons

I am an ADHD/Autism/OCD advocate and independent ADHD/Autism researcher. I am training in 2021 to become an ICF Accredited ADHD coach. I write mainly about ADHD/Autism/OCD/Mental health issues, but will also discuss morality, abolition, and current affairs occasionally.

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