New mechanism of pain control revealed

[helvella]

I noticed a new paper today. Which set me thinking.

It is heavy going reading these things. Don't feel in the least surprised if it all goes above your head - by far the majority is miles above mine!

And it is very largely me speculating and joining ideas I have read. Quite possibly entirely wrongly.

But if it does makes any sense, could we be getting somewhere towards understanding pain - possibly such as in CFS/ME and even myofascial trigger points? As well as the many pains reported by so many even without any of those diagnoses.

New mechanism of pain control revealed

Date:

November 25, 2020

Source:

Kyushu University

Summary:

Researchers have identified a unique population of astrocytes in the dorsal horn of the spinal cord of mice that produces pain hypersensitivity when activated by neurons carrying signals down from the brain. The findings indicate that the role of descending neurons in controlling spinal pain transmission is not limited to suppression and point to this group of astrocytes as a new target for enhancing the effect of chronic pain treatments.

Later, in the main paper, it says:

It was previously assumed that certain sensory neurons only transmit pleasant tactile sensations, while other specializes to transmit pain. During chronic nerve pain, normal touch can cause pain, but how this happens has remained a mystery. Scientists at Karolinska Institutet have now discovered that a small RNA molecule (microRNA) in sensory neurons regulates how touch is perceived. Upon nerve damage, levels of this molecule drop in the sensory neurons, which results in raised levels of a specific ion channel that makes the nerve cells sensitive to pain.

sciencedaily.com/releases/2...

The idea that normal touch can cause pain sounds as if it is, potentially, a (or even "the") mechanism behind the still unexplained allodynia. Where the slightest brush (literally with a soft brush or a feather), which should hardly be noticeable at all, ends up causes significant pain.

The other thing that struck me was that thyroid hormone is one of the factors deeply involved with microRNA.

(One example paper: ncbi.nlm.nih.gov/pmc/articl... )

Now, just think, some astrocytes are specifically involved in T4 to T3 conversion within the brain. Is it possible the newly discovered dorsal horn astrocytes convert T4?

Thyroid hormone and astrocyte morphogenesis

Andréa Gonçalves Trentin 1

Affiliations

• PMID: 16648287

• DOI: 10.1677/joe.1.06680

Abstract

Astrocyte cells clearly play a role in neural development, but nowadays their total action is seen as a far wider one. Recent findings consider them as stem cells, involved in the control of most facets of functional neural networks. Astrocytes play a central role in thyroid hormone metabolism in the brain, being the principal transporters of thyroxine from the blood, responsible for its conversion to 3,5,3'-triiodothyronine and hence supplying the neural tissues with the biologically active form of the hormone. Specific thyroid hormone transporters play an essential role in this regulatory system. The presence of thyroid hormone receptors has been demonstrated in cultured astrocytes. Furthermore, thyroid hormone regulates several aspects of astrocyte differentiation and maturation, including the production of extracellular matrix proteins and growth factors, and thus controls neuronal growth and neuritogenesis. Therefore, astrocytes are currently suggested as important mediators of thyroid hormone in neuronal development.

pubmed.ncbi.nlm.nih.gov/166...

Please feel free to point out how wrong-headed I have been.

[tattybogle]

Please feel free to point out how wrong-headed I have been.

i'd love to oblige..... but i may be some time.

Will need to start at 'Astrocytes' in dictionary

I do like the sound of Dorsal Horned Astrocytes converting T4.... but at the moment i can't get past picturing them as sort of dinasour/ space creature

🐉 👽 🐙

[LindaC]

Thank you!

[jimh111]

This paper is rather long, I've saved a copy but don't think I will get around to studying it.

A simpler mechanism is magnesium deficiency (intracellular) which occurs in hypothyroidism. MD lowers the threshold for NMDA receptors which leads to allodynia or hyperalgesia relating to visceral or chronic pain as experienced in IBS and fibromylagia. These receptors also regulate the powerful slow wave contractions in the gut which are abnormal in IBS. I describe this in my website and one day I plan to get around to putting up the fibromyalgia topic which will also detail the MD effects.

[Hillwoman]

Nothing intelligent to add, but all very interesting.

[Sandra600]

Maybe this discovery will lead to better treatment for chronic pain? We live in hope🙂

[jimh111]

It's going to take quite some time. It's over a decade since I researched it but I want to put my conclusions down but I will need to find all the studies (in lots of boxes) and make sense of them again. I will also need to check if there are more recent studies that confimr or disprove what I have concluded so far!

[TSH110 in reply to jimh111]

A true labour of love ☺️

[thyr01d]

Very cheering Helvella, even though I don't completely understand it all, at least it's moving in what looks like the right direction. Can't bear to think about how the poor mice suffer though.