Chemical Sensitivities - Smell, Immunity, and the Brain

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Chemical Sensitivities - Smell, Immunity, and the Brain

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by Dr. Mark Donohoe

ImmuneSupport.com

 

05-26-2008

 

Dr. Mark Donohoe is an Australian GP specialized in Environmental Medicine,

with a special interest in ME/CFS and chemical sensitivities, adverse effects

of medications, and vaccination issues (see _Dr. Mark’s Medical Site_

(http://homepage.mac.com/doctormark/Medical/index.html) ).

This article is excerpted from a book on multiple chemical sensitivities –

Killing Us Softly - that Dr. Donohoe has just offered online for free download

and sharing. He asks only that those who wish to share the book do so by

passing on link to his download page

(_http://web.mac.com/doctormark/DoctorMark/KUS.html _

(http://web.mac.com/doctormark/DoctorMark/KUS.html) ), and impose no

charge.

_________________

OLFACTION AND IMMUNITY

The olfactory nerve, the first cranial nerve, is not a nerve at all. At

least not in the usual sense of a nerve. It is, in my opinion, the strangest

organ one could imagine. It is mysterious, primitive, courageous and an

absurdity

all at once.

In each other link between the inner world and the outer world, the messages

are received through specialized receptors, converted to electrical impulses

of varying frequencies, and the message is passed from neuron to neuron all

the way to that part of the brain designed to interpret and respond to the

message. Along the way, certainly, there are reflex arcs, collateral branches to

eponymous nuclei, and a good deal of eavesdropping by other neurons. But the

basic path is from external stimulus to internal perception - the outer

world to the inner world.

The path is far from direct, however, and there is plenty of room for

magnification, suppression, and misinterpretation along the way. The reason is

that

peripheral nerves, including the cranial nerves, converse only with the

brain through synapses. These are the gaps between nerves, and the message

changes from electrical to chemical transmission momentarily as this gap is

crossed.

The chemical transmitters, known as neurotransmitters, include

acetylcholine, serotonin, dopamine, histamine, and dozens of others. As the

chemical is

ejected from the axon of one nerve to the dendrite of another, the private

message of the nerve becomes, as it were, more public.

Nearby nerves eavesdrop on the message, picking up a fragment here and

there, and spread the gossip to nearby nerves. The nerves seem to then indulge

in

a crude form of democracy, collecting opinions to decide the fate of the

message proffered from below. This indecipherable rabble of activity then

organizes itself, contributes its opinion, sometimes strengthening, sometimes

suppressing, sometimes re-routing the message.

More often than not, the message does not make it to the cortex, where the

brain’s owner may become aware of it. It is lost along the way, extinguished

entirely or passed on to parts of the brain responsible for these types of

messages.

Even when the messages reach the cortex, the likelihood of perception is low

unless the stimulus is novel, alarming, or at least a little unexpected.

The point is that all nerves face the ‘sensorship’ of synapses. All except

one.

The olfactory nerve is less a nerve than it is a misplaced piece of the

brain, dangling almost unprotected in the outside world. Like tubes of pork

through a mincing machine, the brain cells spread through a finely fenestrated

bony plate behind and slightly above the level of the eyes. Within deep clefts

high in the roof of the nose, a square inch of deep yellow tissue on either

side is home to around thirty million olfactory cells. Every last one of them,

a card-carrying member of the central nervous system.

Even more astounding is the fact that these brain cells are “used up,†with

a monthly cycle of regeneration of new cells to replace the old. Somehow,

the “learned†response of those which degenerate is passed backwards to

those

which are to follow, preserving the learned olfactory responses and the

receptor patterns.

It seems, to top it all off, that olfaction has an uncanny resemblance to

another remarkable organ system - the immune system.

And the resemblance is more profound than mere analogy. Both immunity and

olfaction are designed to detect molecules - those that belong to us, and those

that most definitely do not.

The immune response manages admirably with large molecules, typically water

soluble peptides, starches, nucleic acids and glycoproteins. These are

typically swallowed, inhaled, or enter through breaches in our outer coverings.

They become internal threats, and their presence is announced to the body

through antigen presenting cells. These “consume†the foreign molecules,

digest

and splinter them , then sort through the debris to present just a few critical

fragments on their surfaces. Not just any fragments, mind you. Only those

sufficiently available and obvious, and those sufficiently different from our

own molecules to ensure the future attack leaves healthy tissue of the host

alone.

These often overlooked macrophages really are the brightest of the body’s

cells, combining the skills of a computer, a librarian, and an entire judicial

system in a single cell. Many may say (and I am not one of them, mind you)

that this last added quality adds nothing to the total of its wonders.

A novel virus appears, say, on the nasopharynx, along with many of its

friends. This is surely a splendid place to take up residence, they think among

themselves. All facilities laid on - moisture, darkness, sugars, mucus - heaven

on a stick in virus terms. Before long, however, in the normal course of

business, a scene reminiscent of a third rate 1960s Japanese movie emerges. A

monstrous, formless blob, the size of a whole building, flows into an

outstretched tentacle of its own making, and consumes dozens of the viruses

sitting

smugly in the soggy warmth of their newfound home.

Within minutes, the verdict is in. “Guilty - Not welcomeâ€, and the message

along with a molecular snapshot of the offender is hoisted on wanted notices

all over the surface of the macrophage.

The jig is up. The vacation for the intruder is about to come to an end, and

the story is finished apart from the mopping up operation. Within minutes

this is carried out by lymphocytes blaring their own chemical sirens. These

sidle up alongside the macrophage, take a photocopy of the offender’s image,

and

then clone themselves, each with an image of the intruder in mind. The virus

has little chance at this point, and must surely consider the whole deal a

little like a seaside holiday in a hurricane. The only escape is into the

cells surrounding them, where the whole process starts again.

The olfactory receptors, on the other hand, are well designed to detect

smaller molecules, almost exclusively fat soluble.

The greasy surface of the receptor area is almost impervious to water

soluble molecules, and the design of the roof of the nose is such that proteins

and

dust are rarely encountered. They are just too heavy, too sticky and too big

for this. They become trapped in the mucous and hairs of the nasal cavity,

and are most often swept back out in that act of almost orgasmic delight and

relief, the sneeze.

Each of us has around three hundred or so distinct odors, and the unique

combination goes to make up our own “smell signature.†Just as with the

immune

system, which learns the “immune signature†of its owner in the thymus

gland

in infancy, we are “blind†to our own signatures most of the time. Were it

not so, we would be attacking our own tissue unmercifully (as is the case in

autoimmune disease), or drown in our own redolent aromas, losing all

possibility of distinguishing the faint scents upon which we depend.

The structure of our noses is less amenable to showering of the receptors

than it is for many of our mammalian relatives. Sheep dogs and Alsatians not

only have around forty times more olfactory receptors, they have an air pathway

through the nose which guarantees molecular intermingling with the deep

reddish-brown mucosal surfaces. We humans need to flare our nostrils, squint

our

noses, and draw breath in a most unusual fashion to really get those aromatic

molecules into the folds of our upper noses.

We usually need to “sniff†to really get a grip on these ephemeral

messengers. A single molecule is sufficient to cause a response in a single

nerve,

but this will still be lost in the noise of the other, more abundant molecules

trapped in the sniff. We seem to need about forty or so nerves firing before

the cascade of magnification in the “smell brain†occurs.

One can imagine that the increase in “olfactory noise†which has occurred

as a result of our chemicalized century would be making this process more

difficult and tenuous all the time. It is my own opinion that we really do

smell

less these days than when I was a child, and there is some evidence for this.

That, however, is a different story.

What happens between reception and recognition is something of a divine

mystery, one we are only beginning to unravel using tools from chaos theory,

functional brain imaging, and animal studies.

There is no easy way to understand what occurs in the olfactory bulb, and

how that message is disseminated for use from that point.

Those familiar with the concept of chaos and “attractors†have a better

chance than most, but it is still a wonderfully mysterious process, deserving

of

our urgent attention.

As the molecules in question bind to the nerves with the matching molecular “

receptors,†the nerve not only gives an electrical “quiver,†it seems

that

the molecule itself is transported into the cell itself, in an event

reminiscent of the poor viruses and the macrophage.

Why would we want these molecules inside our cells? More specifically, why

would we want them in our brain? In medicine, we learned of a mythical

creature known as the “blood-brain barrier,†the purpose of which was to

prevent

foreign molecules from entering the territory of thought and consciousness. So

why would there be such a shoddy back door to such an elaborate system of

protection?

To understand the purpose, we may need to understand the brain.

WHAT IS A BRAIN?

The answer seems obvious. It is a thinking machine, an exquisite and

infinitely complex computer. Some may even say that the brain is the seat of

consciousness, the thing that makes us who we are.

Closer inspection is less than supportive of this cerebro-centric view of

the human brain. In fact, when you really get down to the basics, this view

seems more and more like the view of the ancients, that the earth is the center

of the universe, and all revolves around it.

The brain is a gland. Or rather, it is a part of a glandular complex called

the endocrine system.

Most of the brain conducts boring, slow hormonal business, gaining input

from its distant receptors throughout the body, and sending molecules forth to

ensure that the internal environment remains a fit place to live. This

miracle, known as homeostasis, allows past sea dwellers to live in the dry and

inhospitable atmosphere.

We carry our private seas within, and our hormones are bottled messages,

adrift on the waves and tides which bathe our every cell. They drift in their

billions. Some, like thyroid stimulating hormone, usually carry fairly simple

messages; “Doing fine, maintain courseâ€; “Temperature dropping, step it

up a

littleâ€; and the like.

Some, such as adrenaline, fire off more complex and urgent missives, such as

“Predator chasing - breathe faster, open airways, open vascular floodgates

to muscles, pump stronger, cease digestion, and run for your life.â€

They are certainly amazing molecules, hormones. They are the language

within, the phonemes, utterances and gossip of the body. Each has its own

factory

and chain of command, each has a shape which seems to actively seek out

receptors on the cells designed to receive its message, each has specific and

powerful effects at astonishingly low concentrations, and each participates in

a

most extraordinary and exquisite feedback system.

The hormones have ghosts, you see. The molecule is made in the gland, the

receptor is made in the cells which listen for, even yearn for the message. One

would think that that was that. Message sent. Message received. Over and

out.

The truth is far from that. Firstly, hormones need a feedback mechanism, a

way of asking for more and communicating their satisfaction. This is where the

brain comes in handy. It is a good organizer and is able to sort through

conflicting and complex messages as if designed for the task. The foot hits the

appropriate accelerator or brake, and the stimulus is reset.

There are a couple of levels to this. Usually, the organs which produce

hormones - the pancreas, gonads, adrenals, thyroid and many more - are dotted

around the body for no particularly good reason. Far flung outposts, they seem

on the end of a tenuous and indirect communications system.

When compared to the nervous system, these remind me of smoke signals

compared to telephones. It may be the reason that doctors have long overlooked

the

importance of the endocrine system – it is too old, indirect and messy to

have too much relevance for “modern man.â€....

What is the value of such an indirect system? It seems that the answer lies

in the almost effortless ability of the system to sort itself out, to manage

the amazingly complex task of running all the trillions of cells in the body,

all without a pilot. That is it. The endocrine system is our body’s

autopilot, good enough to manage most day to day tasks which would otherwise

require

our entire focus and attention. The brain invests in an automated solution.

We are on autopilot, yet like a kid in the cockpit, we are given a wheel to

let us pretend that we are driving. Then, like the child, we turn the wheel

whichever way the jet goes, feigning control.

…So what happens when the “olfactory noise†increases? Hundreds of

thousands of new molecules, all with no evolutionary history and no appropriate

response, bombard the olfactory epithelia and the vomeronasal organ with every

breath. What happens? It is hard to say, as truly novel molecules were a rather

rare occurrence until this century. Nature usually edited old and successful

molecules, and recycled the general structure of the important ones….

If one had to guess, it is likely that the “default†response to a new

molecule would be to interpret it as bad news, a threat or a poison.…The

biologically successful response [to chemicals] would be one which could

identify and

minimize such exposure. One which could induce a sufficiently strong

aversion response to prevent ongoing risk and damage. MCS.

 

….MCS may, in short, be an adaptation to a lousy environment by developing

the skills to avoid such environmental exposure. Those with MCS may, in fact,

be the most normal people in the world. One could even suggest they are

advanced compared to the rest of us, with a heightened sense able to detect and

minimize risk for survival.

 

* * * *

But there's much more to it. Download _Killing Us Softly_

(http://web.mac.com/doctormark/DoctorMark/KUS.html)

_http://web.mac.com/doctormark/DoctorMark/KUS.html_

(http://web.mac.com/doctormark/DoctorMark/KUS.html) to read the

rest of Dr. Donohoe’s MCS detective story – for example, why he believes:

* “The people we call ‘multiple chemical sensitivities’ are not

suffering a hypersensitivity response at all. They are suffering neurotoxic

injuries, and are susceptible individuals in the normal population.â€

* MCS and Chronic Fatigue Syndrome “are different aspects of a single

group of illnesses.â€

* " We sleep, it seems, because our bacteria force us to! "