Moulton Lava

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Sunday, May 27, 2007

Substance P

There is a neuropeptide called Substance P which I learned about last week. It's a tachykinin that's implicated in a lot of stuff, including fibromyalgia pain, vomiting, anxiety, and various other stress responses. Environmental stressors seem to stimulate release of Substance P.
Substance P is involved in the transmission of pain impulses from peripheral receptors to the central nervous system. It has been theorized that it plays a part in fibromyalgia. Capsaicin has been shown to reduce the levels of Substance P probably by reducing the number of C-fibre nerves or causing these nerves to be more tolerant. Capsaicin is a Substance P antagonist. It acts to reduce the level of Substance P. In the central nervous system, Substance P has been associated with the regulation of mood disorders, anxiety, stress, reinforcement, neurogenesis, respiratory rhythm, neurotoxicity, nausea, emesis (vomiting), and pain.
Tachykinins tend to speed up the neural firing rate, to improve the response time in the face of danger. The psychological effect is that things appear to happen in slow motion. You feel you have more time — more clock cycles — to figure out what to do. Capsaicin is the hot stuff in chili peppers and Mongolian Fire Oil.

One of the more interesting beneficial effects of Substance P is neurogenesis. Evidently, Substance P causes the brain to generate brand new neurons, perhaps to enable the brain to host new adaptations to cope with persistent stressful and problematic situations.

4 Comments:

Blogger the thistle said...

That wikipedia article is ambiguously worded. Substance P is involved in the regulation of neurogenesis. In fact, it has been shown to be involved in decreased neurogenesis in the hippocampus (seat of learning, autobiographical memory).

This write-up argues substance p isn't even a pain-signaling molecule, and that, rather, it's involved in the formation of pain-avoidance behaviors.

If you put these two ideas together, you get the same conclusion that you had in your blog entry ("Pain is healthy for your brain..."), but with a different biochemical explanation ("...because avoiding pain suppresses neurogenesis").

12:49 PM  
Blogger Moulton said...

Many thanks for chiming in here.

I am not surprised to learn of diminished capacity for storing episodic memory. I happen to be uncommonly strong on storing semantic memory (general scientific knowledge) and remarkably weak on storing episodic memory (personal biographical anecdotes).

It occurs to me that if one is good at problem-solving, then one need not store up a diary of unsolved problems. But if one is weak at problem-solving, then one is better served by recording painful memories for later hand-off to someone who is good at devising novel solutions.

Judging from the 'absent-minded professor' comment in your bio page, I take it that you are somewhere on the Asperger's spectrum.

On the Simon Baron-Cohen instrument, I fall exactly midway between the means for Asperger's Syndrome and the NeuroTypical population.

Also, I happen to be a redhead, which (if other speculative theories hold) means I have diminished stores of Adrenaline, Dopamine, and Oxytocin relative to the general population with more typical Eumelanin/Pheomelanin ratios.

In any event, I've increased my consumption of Hot 'n' Spicy foods, on the theory that a little more Capsaicin can't hurt.

2:21 PM  
Blogger the thistle said...

Whether I fall into the Asperger's spectrum I can only speculate. Once, many years ago, I was diagnosed with depression, but I have not had consistent subsequent health care or consistent relationship with any psychiatric professional such that somebody would have made any conclusions about my particular condition.

But I do frequently misplace my keys. Or forget to eat. Or leave the house without the things I need at the place where I'm leaving to go to.

Thanks for the tip on capsaicin. I'm going to have to do a little research on it now. (Does it pass the blood-brain barrier?) I was fishing around for information on SP antagonists when I found your entry.

5:33 PM  
Blogger Moulton said...

AS is sometimes characterized as the "Absent-Minded Professor Syndrome."

Here's more...

How well can you read the expression in someone's eyes?

You can take Simon Baron-Cohen's Adult Eye Test to find out.

It will take you about half an hour, plus you have to open multiple windows, especially if you want to carefully score your results.

Take both Parts 1 and 2 of the test, but first download or view the
next-to-last page of the Instructions which will give you the Score Sheet (and afterwards you can score using the last page of the Instructions, which is the Answer Sheet).

Out of 36 sets of eyes, I got 24 right and 12 wrong, where each set of eyes offered a multiple-choice of 4 possible answers. I found the female eyes harder to judge than the male eyes, and my score reflects that: I got 5 male eyes wrong and 7 female eyes wrong.

The third reference at the bottom of the link above (the 2001 paper) gives an analysis of results for normal populations and subjects with Autism Spectrum disorders and Aspergers Syndrome (High-Functioning
Autism).

The mean correct score for the general population is 26. The mean correct score for subjects with AS/HFA is 22. At 24, I fall midway
between the two populations, making me borderline normal, borderline AS/HFA.

Incidentally, Simon Baron-Cohen, the British academic and researcher who developed that test, is a first-cousin of Sacha Baron Cohen, the comedic actor who plays Borat.

As to Capsaicin, I only know what I read in that Wikipedia article — that it's reported to be a Substance P antagonist. The article suggests the means of interference, which does not sound like it passes the blood-brain barrier, but rather works by exciting the pain-signaling nerves until they become depleted of Substance P at the receptor sites in the brain. You can Google up Capsaicin+Substance+P to find more material.

4:01 AM  

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