Nociceptive?

December 12th, 2020| Topic: RaMbLeS | 0

All kinds of nerve endings on our skin pass specialized information on to our brain. Most have specialized “end-organ structures,” nerve endings shaped and adapted to respond to temperature, chemicals, touch, position, vibration, etc. Then there are also free nerve endings—that just end in the skin without any “end-organ structure”—these are the commonest nerve endings in the skin. For over a century, these free nerve endings had been thought to transmit pain to the brain: nociceptive nerves (i.e., “pain receptive” nerves).

But recent studies indicate that these may not be that “free” after all, and they actually need other non-neural cells to detect pain. So claim scientists from the Karolinska Institute in Stockholm, Sweden, in “Specialized Cutaneous Schwann Cells Initiate Pain Sensation,” published in Science.

Apparently, there are other cells involved in pain sensation—nociceptive Schwann cells. That’s somewhat of an oxymoron since Schwann cells fall in the category of glial cells which, thus far, have been considered merely supportive cells for the more important nerve cells, incapable of sensing, merely second fiddle to neurons’ first violin. They were never considered being “anything-ceptive.” But these actors wrap around those so-called “free” nerve endings in the skin and participate in sensing pain.

Exclaimed Dr. Cheryl Stucky, pain researcher at Medical College of Wisconsin:

It’s a cool idea; they are onto something very important. This finding may change the way we view ‘free nerve endings’—they may not actually be ‘free,’ as has been taught in textbooks.”

All the work was done on mice, but the similarities in skin structure “of mice and men” (and women) indicate that the findings may also represent what happens in humans. When these skin Schwann cells were selectively (and artificially) activated, the animals exhibited every indication of being in pain.

Co-first author Laura Calvo-Enrique said that when she first joined the ongoing work, she found it hard to believe:

The first time I saw the animal withdraw its paw, it was like, Wow! This is really true.”

Apparently the Schwann cell gets activated first, and in some way transmits signals to activate those “free” nerves and—bingo!—you get “Ouch!” And only pain was detected, not heat or cold or any other stimulus.

Said main author, Patrick Ernfors, molecular neurobiologist:

These nociceptive Schwann cells are a highly specialized and mechanosensitive glial cell. For mechanical stimuli, such as pain, the Schwann cell is actually really contributing to nociception.”

So much so, National Geographic titled its report on the findings: “Newly discovered organ may be lurking under your skin.”

All that to say, there is more to pain than meets the eye! Of course this is obvious to those who have undergone loss, affliction, suffering, of any kind. In fact, the commonest word for “pain” in the Old Testament, k’ev (and its cognates), also indicates “suffering” or “sorrows.”

As in:

He was despised and forsaken of men,
A man of sorrows and acquainted with grief;
And like one from whom men hide their face He was despised,
and we did not esteem Him.
Surely our griefs He Himself bore,
And our sorrows He carried;
Yet we ourselves esteemed Him stricken,
Smitten of God, and afflicted.
Isaiah 53:3–4

And this One, the Lord Jesus Christ, who has borne it all and carried it all, will one day finally and fully and forever remove the suffering of his people :

He will wipe away every tear from their eyes;
and there will no longer be any death;
there will no longer be any mourning, or crying, or pain.
Revelation 21:4

Soon … and very soon!

SOURCES:
National Geographic; Science; Pain Research Forum