RTotM – Histamine Receptors in the Body [Part 2]

After finding out that histamine might be responsible for a lot of my health troubles I wanted to dig deeper into the role of histamine itself – what did the receptors in the body do?

The Four Histamine Receptors (H1-H4)

There are four histamine receptors H1-H4, that perform a number of various function related to immune system response. They are found in lots of different cells within the body. There are also histamine receptors and releasers found throughout other neurons – such as serotonin, dopamine to name a few.

First a diagram to demonstrate what cells they are involved in, and also which functions they seem to perform:

Histamine H1 Receptor

Has a role in:

  • Cytokine and chemokine production [Which is an immune system response]
  • Adhesion molecule production [Also used as an immune system response – to help with clotting (among other things)]
  • Allergy and inflammation [Yes, those annoying parts like skin outbreaks, and swelling are a result of histamine H1 Receptor activity]
  • Vasodilation [The widening of blood cells – usually as an immune system response]
  • Bronchoconstriction [The restriction (tightening) of smooth muscles used for breathing – a core part of asthmatic responses]
  • Platelet aggregation [Part of the immune system response to clot the blood, and to stop you from bleeding further]
  • Hyper mucus secretion [the secretion of mucus in the throat or lungs – a core part of COPD (chronic obstructive pulmonary disease)

As you can see – the H1 receptor is linked to a lot of issues – there is evidence that taking H1 Antagonists (meaning reducing activity) known commonly as anti-histamines can help or even inhibit these responses. Skin conditions and nasal congestion are the two most common expressions of H1 Receptor activity and the main reason that people take antihistamines. An abundance of histamine can cause breathing issues (related to constriction and mucus generation), and can also cause hypersensitivity to skin – resulting in eczema and other atopic dermatitis responses.

Histamine H2 Receptor

Has a role in:

  • Gastric Acid Secretion [Quite a huge role in GERD (Gastroesophageal reflux disease), an over activity of this can produce excess gastric acid which causes a lot of issues with digestion]
  • Increased heart and cardiac response [Very clear that this is something that can influence arrhythmia (irregular heart beat) and tachycardia (fast heart beat) responses.

The H2 Receptor has a lot of roles as a gastric acid and heart rate modulator. An over abundance of histamine can cause a lot of issues with digestion, and can contribute to heart irregularities.

Histamine H3 Receptor

This is probably the one I am most interested in from a cognitive perspective as it appears to show up in a lot of central nervous system cells, and neurons in the brain.

Has a role in:

  • Sleep-wake cycle [The regulation of sleeping and waking – fairly self explanatory]
  • Cognition [Appears to play a role in blood brain barrier permeability which leads to a whole heap of cognitive effects]
  • Homeostatic regulation of energy levels [This seems to play an important role in hunger and might have a significant role in eating disorders]
  • Neurotransmission [One of the ones I am personally most interested in – it seems to inhibit multiple important neurotransmission when there is an excess of histamine in the brain]

So this one is huge, it seems like it controls homeostasis a lot of our bodies, it seems to have a huge role in core systems that maintain our day to day living. H3 Antagonists have had interesting results and are currently “used to treat obesity, myocardial ischemic arrhythmias, cognition disorders, and insomnia”.

Histamine H4 Receptor

This seems to be really important in Mast Cell Activation Syndrome. From my layperson understanding it seems to be the receptor responsible for the release and control of histamine within the body as part of immune response (among other compounds released).

Has a role in (a lot seemed to be shared with the H1 Receptor):

  • Cytokine and chemokine production [Which is an immune system response]
  • Adhesion molecule production [Also used as an immune system response – to help with clotting (among other things)]
  • Allergy and inflammation [Yes, those annoying parts like skin outbreaks, and swelling are a result of histamine H1 Receptor activity]
  • Vasodilation [The widening of blood cells – usually as an immune system response]
  • Bronchoconstriction [The restriction (tightening) of smooth muscles used for breathing – a core part of asthmatic responses]
  • Platelet aggregation [Part of the immune system response to clot the blood, and to stop you from bleeding further
  • Ca++ release from Endoplasmic Reticulum [This is the part of cells in which transportation between parts of the cell takes place]
  • Degranulation [A core part of immune system response to diseases – which releases a number of different compounds of which histamine is one of them from Mast Cells]
  • Chemotaxis [A process whereby Mast Cells accumulate more of these immune system response fighting compounds]
  • Immuno-modulation [As it implies regulation of the immune system response]

As you can see this one may have a huge role in histamine intolerance. Those who have ended up storing more due to activation of chemotaxis (caused sometimes by acute stress) can end up having huge inflammatory responses in response to minor threats – e.g. over active bronchoconstriction resulting in an asthma attack.

In conclusion

Everything that I have mentioned here is explained in the paper I used the diagram from and is available here with way more jargon.

You can see that histamine seems to have a huge role in many systems, and is now becoming more of a research subject. One theory of depression has been around inflammation, and this could very much be the part of this particular type of depression. Recently they have been questioning histamines role and it might seem to explain treatment resistant depression – which is a finding they had last year with mice.

In the next blog I will explain why I tried a low histamine diet and how it seems to have affected me. Suffice to say that in my case I believe a lot of my problems stem from the dysregulation of my histamine system.

Published by roryreckons

I am an ADHD/Autism Coach as well as ADHD/Autism/OCD/CPTSD advocate and independent ADHD/Autism researcher. I am an ADHD/Autism Coach who trained through the ADD Coaching Academy. I write mainly about ADHD/Autism/OCD/Mental health issues, but will also discuss morality, abolition, and current affairs occasionally.

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