This Is MS Multiple Sclerosis Knowledge & Support Community

Ok...........the following pertains to Huntington's disease, but it also provides a short explanation with regard to apoptosis (which as we all know, we want to inhibit apoptosis in MS). And we all know how integral that Ca2 influx plays in axonal degeneration in MS, also.

Read the highlighted portions below and you will see how what they are saying also relates to apoptosis in MS.

(Hey...........blame Robin for getting me started here today. )

Deb

*************************

Proc Natl Acad Sci U S A. 2005 Feb 15;102(7):2602-7. Epub 2005 Feb 3. Related Articles, Links


Disturbed Ca2+ signaling and apoptosis of medium spiny neurons in Huntington's disease.

Tang TS, Slow E, Lupu V, Stavrovskaya IG, Sugimori M, Llinas R, Kristal BS, Hayden MR, Bezprozvanny I.

Department of Physiology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.

Huntington's disease (HD) is caused by polyglutamine expansion (exp) in huntingtin. Here, we used a yeast artificial chromosome (YAC) transgenic mouse model of HD to investigate the connection between disturbed calcium (Ca2+) signaling and apoptosis of HD medium spiny neurons (MSN). Repetitive application of glutamate elevates cytosolic Ca2+ levels in MSN from the YAC128 mouse but not in MSN from the wild-type or control YAC18 mouse. Application of glutamate results in apoptosis of YAC128 MSN but not wild-type or YAC18 MSN. Analysis of glutamate-induced apoptosis of the YAC128 MSN revealed that (i) actions of glutamate are mediated by mGluR1/5 and NR2B glutamate receptors; (ii) membrane-permeable inositol 1,4,5-trisphosphate receptor blockers 2-APB and Enoxaparin (Lovenox) are neuroprotective; (iii) apoptosis involves the intrinsic pathway mediated by release of mitochondrial cytochrome c and activation of caspases 9 and 3; (iv) apoptosis requires mitochondrial Ca2+ overload and can be prevented by the mitochondrial Ca2+ uniporter blocker Ruthenium 360; and (v) apoptosis involves opening of mitochondrial permeability transition pore (MPTP) and can be prevented by MPTP blockers such as bongkrekic acid, Nortriptyline, Desipramine, Trifluoperazine, and Maprotiline. These findings describe a pathway directly linking disturbed Ca2+ signaling and degeneration of MSN in the caudate nucleus in HD. These findings also suggest that Ca2+ and MPTP blockers may have a therapeutic potential for treatment of HD.

PMID: 15695335 [PubMed - indexed for MEDLINE]

Ok..........here is a recent study regarding what I mentioned above, i.e. CA2 influx and axonal degeneration in MS.

Deb
****************

Ann Neurol. 2006 Jan 3; [Epub ahead of print] Links

Mitochondrial dysfunction as a cause of axonal degeneration in multiple sclerosis patients.

Dutta R, McDonough J, Yin X, Peterson J, Chang A, Torres T, Gudz T, Macklin WB, Lewis DA, Fox RJ, Rudick R, Mirnics K, Trapp BD.

Department of Neurosciences, Lerner Research Institute.

OBJECTIVE: Degeneration of chronically demyelinated axons is a major cause of irreversible neurological disability in multiple sclerosis (MS) patients. Development of neuroprotective therapies will require elucidation of the molecular mechanisms by which neurons and axons degenerate. METHODS: We report ultrastructural changes that support Ca2+-mediated destruction of chronically demyelinated axons in MS patients. We compared expression levels of 33,000 characterized genes in postmortem motor cortex from six control and six MS brains matched for age, sex, and postmortem interval. As reduced energy production is a major contributor to Ca2+-mediated axonal degeneration, we focused on changes in oxidative phosphorylation and inhibitory neurotransmission. RESULTS: Compared with controls, 488 transcripts were decreased and 67 were increased (p < 0.05, 1.5-fold) in the MS cortex. Twenty-six nuclear-encoded mitochondrial genes and the functional activities of mitochondrial respiratory chain complexes I and III were decreased in the MS motor cortex. Reduced mitochondrial gene expression was specific for neurons. In addition, pre-synaptic and postsynaptic components of GABAergic neurotransmission and the density of inhibitory interneuron processes also were decreased in the MS cortex. INTERPRETATION: Our data supports a mechanism whereby reduced ATP production in demyelinated segments of upper motor neuron axons impacts ion homeostasis, induces Ca2+-mediated axonal degeneration, and contributes to progressive neurological disability in MS patients. Ann Neurol 2006.

PMID: 16392116 [PubMed - as supplied by publisher]

So..............if the mechanism(s) of degeneration are so similar between HD and MS, and desipramine is helpful in HD, is it not possible that the same MOAs of desipramine may indeed be beneficial in MS?

Levetiracetam also inhibits CA2 influx.

Once again, I just reiterate this as an indication that there are some neuroprotective, preventative and regenerative strategies out there.

And they are oral medications and fairly cheap.

My gut feeling? That there probably is some study going on out there (just not "formal" or known as of yet) with regard to all this and MS.

As I said.........in recent months, I have been taken much more seriously.

And if I am taken more seriously, then that means that at least some of the MS researchers and treating physicians are beginning to think outside the box a little more than before. (If anybody thinks outside the box, I'm sure many would say it's ME!)

Or else why waste their time in listening or talking to ME for so long now??

Deb

****************************

Deb—It’s nice to see you and Robin out of the shadows.

Your post about mitchondrial dysfunction, Ca2+ influx and axonal degeneration in people with MS presents an opportunity I can’t miss. You guessed it too, hormones could theoretically have something to do with it IMO.

A while ago I noted that estrogen and progesterone exhibit the potential to protect against glutamate excitotoxicity and intracellular Ca2+. DHEA protects against glutamate excitotoxicity too but maybe via a different mechanism than beta-estradiol (a form of estrogen).

Per this study beta-estradiol, DHEA, and DHEAs protect against NMDA-induced neurotoxicity in rat hippocampal neurons by different non-genomic mechanisms

With respect to mitochondrial dysfunction and calcium overload, DHEA and other neurosteroids preserve neuronal mitochondria from calcium overload

Thus, in the present work we provide evidence that DHEA with several other neurosteroids protect the mitochondria against intracellular Ca(2+) overload by inhibiting Ca(2+) influx into the mitochondrial matrix.

Another study found there may be a dysfunction in DHEA secretion in people with MS

Lastly, it also seems that people with MS tend to have lower DHEA(s) levels than healthy controls. Per this study

Mean DHEAS levels were lower in MS patients compared with healthy controls (P = 0.049), but there were no significant differences between the clinical subgroups of MS.

That finding is consistent with other studies I’ve been able to read that measured DHEA levels in people with MS. It’s all very interesting, that’s what the non scientist thinks. Hormones could be a factor in MS. At the very least it seems to me they may be important in general neuroprotection.

Take care all.

Sharon

Hi, Sharon! It's great to see you, too!

Yep...............I knew that would bring you out! And I agree with you.

I think there are several "markers" they can and should be testing in MSers, you know? And they don't. Such as hormone levels, cortisol, glutamate.................no matter how you turn it, it all keeps coming down to the same things, doesn't it? The total HPA axis is highly involved.

And yet, to get the neuros to think out of the box is like pulling teeth!

Deb

Deb,

Glutamate is something I see again and again in research papers but I'm still not sure what it means (I thought it was an ingredient in chinese take-aways). I also see references to sodium channels / calcium channels. HPA Axis is another term that I do not understand. If you have a spare 10 minutes I would appreciate a short idiots guide on what these things are.

Ian

bromley,

There is no easy way to describe all this. One of our previous discussions with regard to the HPA was at:

http://www.thisisms.com/modules.php?nam ... hlight=hpa

A short discussion on sodium and calcium channels is at:

http://www.thisisms.com/modules.php?nam ... hlight=ca2

As Robin so aptly described ion channels in the above discussion: "...the interaction between sodium / potassium ions and the axon create the electrical impulse or action potential that is the nerve signal."

Ion channels:

http://en.wikipedia.org/wiki/Ion_channel

Glutamate:

http://www.annalsnyas.org/cgi/content/a ... /1018/1/35

It has been shown over and over again that one of the ways axons are damaged and/or degenerated is by an influx of Ca2+. If cellular sodium density can be maintained and calcium influx inhibited, it is surmised that degeneration of the axons can be stopped.

We've discussed these things on here many times in the past and it's hard now for me to reinvent the wheel, as they say. If you do a search, you'll probably find many other conversations here that we've had many times in the past that covers all of these things.

Deb

Deb,

Thanks .

Sort of connected is Dignan's post today about HP 184 (a sodium and potassium channel blocker). I'm not sure how calcium and glutamate fit into this. But hopefully, one day, there will be better drugs to limit the damage caused by the immune system, and drugs to protect the nerve fibres.


Ian

Calcium is another ion protein, along with potassium and sodium. If too much calcium (Ca2+) gets into the axon, it degenerates it. Calcium influx also is part of what causes neuropathic pain, and has a direct correlation with the immune system. It has been shown that dysfunction and dysregulation of these ion channels is an integral part of MS.

I'm sorry, Ian. It's hard to explain simply.

Here's a press release that sort of explains a little more. I'll highlight the best description(s):

Scientists Propose New Method For Studying Ion Channel Kinetics
LOS ALAMOS, N.M., April 18, 2005 -- Scientists working at Los Alamos National Laboratory have developed a new method for the study of ion channel gating kinetics. An ion channel is a protein pore that lets ions (charged atoms such as calcium) pass through a cell's membrane. The method fits data to a new class of models, called manifest interconductance rank (MIR) models, which will give researchers a better understanding of the mechanisms by which ion channels open and close.

In research published in the current issue of the prestigious Proceedings of the National Academy of Sciences, Laboratory theorists William Bruno and John Pearson, and postdoctoral researcher Jin Yang describe their work using independent open-to-closed transitions to simplify the models of ion channel gating kinetics that are used to represent undetectable changes between different open and closed states.

Ion channels gating functions are critical to biological function. In humans, for example, nerves and muscles could not function without ion channels and you would not be able to think or move. Faulty ion channels in humans have been shown to cause severe diseases like cystic fibrosis and diabetes and more subtle, but still dangerous physiological effects, like over-responses to general anesthetics. According to Bruno, "we found a new way of simplifying the models that reflects the fact that one's knowledge is incomplete about what transitions can happen between states of a channel. For example, in the case of one open state, (O), and two closed (C) states, it is impossible to tell whether transitions connect the O to both C's (C-O-C), or to only one (C-C-O). We have found a set of simple models that can fit any data uniquely, so that data can always distinguish models in our set (it contains C-C-O but not C-O-C). This should allow molecular biologists to come up with better, simpler models for what is happening in ion channels, even when the complete picture remains hidden."

John Pearson added, "Ions such as calcium, sodium and potassium play a fundamental role in nearly all biological processes. Calcium, for example, is important in fertilization, cell death, cell division, human hearing, memory, vision, and the immune system. It also plays a factor in cancer, Alzheimer's, alcohol caused neuronal damage, migraine headaches, cardiomyopathy (heart failure), hypertension and a host of other normal and abnormal physiological functions. Other ions and ion channels are important for processes such as muscle contraction and nerve conduction."
Researchers have long been able to isolate a single channel and detect the flow of ions and to electrically observe whether the channel open and closed. By looking at how long the channel stays open or closed, they also could infer that there are several different open and closed states. Using models called Aggregated Markov Processes, the researchers are able to represent the undetectable changes between different open states, and between different closed states. However, there are an enormous number of ways to connect even a small number of states. For example, only four open and four closed states connect in more than 2 million possible ways.

Using a data set of patch clamp recordings, the Los Alamos researchers can apply the MIR method to mathematically reduce the level of redundancy among the millions of possible ion channel topologies. Patch clamps are instruments using in studying ion channel kinetics. The overall goal of the research is to provide tools and strategies for understanding the topologies of ion channels that allow researchers to focus on smaller, more manageable data sets.

The MIR research fits into a broader area of expertise that Los Alamos National Laboratory maintains in the field of complex systems modeling in general, and modeling in theoretical biology and biophysics in particular.

Los Alamos National Laboratory is operated by the University of California for the National Nuclear Security Administration of the U.S. Department of Energy and works in partnership with NNSA's Sandia and Lawrence Livermore national laboratories to support NNSA in its mission. Los Alamos enhances global security by ensuring the safety and reliability of the U.S. nuclear deterrent, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to defense, energy, environment, infrastructure, health and national security concerns.

Glutamate binds to ion (proteins) and affects ion channel gating. It is shown that too much glutamate is what can cause the most detrimental effects in MS ion channel dysfunction (and particularly in ALS):

"Glu is the most abundant excitatory neurotransmitter in the nervous system. In the synaptic cleft Glu binds to two type of receptors ionotropic and metabotropic Glu receptors. The ionotropic receptors are non-NMDA (AMPA and kainate) and NMDA receptors. Because of its role in synaptic plasticity, it is believed that Glu is involved in cognitive functions like learning and memory in the brain. Both the pre- and post-synaptic neurons at Glu synapse have Glu-reuptake systems which quickly lower Glu concentration.

In excess, Glu triggers a process called excitotoxicity, causing neuronal damage and eventual cell death, particularly when NMDA receptors are activated. This may be due to:

High intracellular Ca2+ exceeding storage capacity [1] and damaging mitochondria, leading to release of cytochrome C and apoptosis.
Glu/Ca2+-mediated promotion of transcription factors for pro-apoptotic genes, or downregulation of transcription factors for anti-apoptotic genes. ...

... Excitotoxicity is due to the opening of the calcium channels which results in an increase in free calcium. ...."

Oh.........and bromley (and Sharon can attest to this also)........there are plenty of drugs out there (levetiracetam for one) that are proven to be highly neuroprotective by either decreasing glutamate or inhibiting Ca2+ influx, or both.

Deb,

This is all a bit mind-boggling to someone who steered well away from sciences at school - but there is also a sense of hope. As the mechanisms causing axonal damage are identified there appear to be drugs that can slow down / stop the mechanisms. The UK MS Society is undertaking trials of such drugs (which offer little to the drugs companies) and you have suggested other drugs which are already available. Maybe the sorts of neuro-protective drugs being trialled by the New Zealand company Neuren might also assist. I can see a future where we have one of those pill boxes with a dozen different pills to addrees the different aspects of this disease. It will hopefully become a manageable disease like diabetes.


Ian

Deb,

By coincidence the follwoing research was posted today.

http://www.msif.org/go.rm?id=13138

It might as well be in Japanese but I understood neuro-protection.

Ian

Bromley,

It is Greek to me too. Maybe someone that understands the article will explain it to the rest of us.

Hi, Folks!

Yes, the article you posted is saying what I was above and in previous posts. That article links you to this one (posted above):

Ann Neurol. 2006 Jan 3; [Epub ahead of print] Related Articles, Links


Mitochondrial dysfunction as a cause of axonal degeneration in multiple sclerosis patients.

Dutta R, McDonough J, Yin X, Peterson J, Chang A, Torres T, Gudz T, Macklin WB, Lewis DA, Fox RJ, Rudick R, Mirnics K, Trapp BD.

Department of Neurosciences, Lerner Research Institute.

OBJECTIVE: Degeneration of chronically demyelinated axons is a major cause of irreversible neurological disability in multiple sclerosis (MS) patients. Development of neuroprotective therapies will require elucidation of the molecular mechanisms by which neurons and axons degenerate. METHODS: We report ultrastructural changes that support Ca2+-mediated destruction of chronically demyelinated axons in MS patients. We compared expression levels of 33,000 characterized genes in postmortem motor cortex from six control and six MS brains matched for age, sex, and postmortem interval. As reduced energy production is a major contributor to Ca2+-mediated axonal degeneration, we focused on changes in oxidative phosphorylation and inhibitory neurotransmission. RESULTS: Compared with controls, 488 transcripts were decreased and 67 were increased (p < 0.05, 1.5-fold) in the MS cortex. Twenty-six nuclear-encoded mitochondrial genes and the functional activities of mitochondrial respiratory chain complexes I and III were decreased in the MS motor cortex. Reduced mitochondrial gene expression was specific for neurons. In addition, pre-synaptic and postsynaptic components of GABAergic neurotransmission and the density of inhibitory interneuron processes also were decreased in the MS cortex. INTERPRETATION: Our data supports a mechanism whereby reduced ATP production in demyelinated segments of upper motor neuron axons impacts ion homeostasis, induces Ca2+-mediated axonal degeneration, and contributes to progressive neurological disability in MS patients. Ann Neurol 2006.

PMID: 16392116 [PubMed - as supplied by publisher]

I wish that it was easier to explain in layman's terms, but the other links I posted above and Robin's explanation are about the best that I can do.

Mitochondria is what feeds a cell energy:

"Mitochondria are sometimes described as "cellular power plants", because their primary function is to convert organic materials into energy in the form of ATP..."

ATP is what stores and transfers the energy within the cell itself:

"Adenosine 5'-triphosphate (ATP) is the nucleotide known in biochemistry as the "molecular currency" of intracellular energy transfer; that is, ATP is able to store and transport chemical energy within cells. "

The ions and the functioning of the ion channels is what moves that energy out of one cell to another (thereby transferring the messages from the brain to other parts of the body).

The CNS is sort of like a huge electrical wiring harness in a car. All of these terms relate to how the cellular "electricity" in the body is produced, transfered, converted, and then utilized (via ion channels) to and from the rest of the body via the axons (from one axon to the next). And it is a very precise balance between the three ions to open and close the "gates" between cells and axons that allows the energy to "move" throughout the body.

Just like a car that has a "short circuit" somewhere, when any part of this process is interrupted or becomes dysfunctional for any reason, then cells and neurons die (apoptosis), axons degenerate, etc.

Anyway, as has been found in research, the axonal degeneration and eventual progression of disability in MS is caused by the dysfunction of the exchange of nerve signals through the axon. It's like an electrical wire has been cut. Even if an axon has been demyelinated, it can still work just fine (transfering nerve signals from the brain to other parts of the body), as long as it does not get bombarded with too much Ca2+ (ionic calcium influx), which is what causes the axon's eventual demise in MS.

Neuroprotection will basically involve protecting the axon from the influx of Ca2+. The influx of Ca2+ can also be affected via the manipulation of the potassium and sodium channels.

Does this help any?

Sorry I can't do better.

Deb

EDIT: Oh, and what they are saying in the above article is that they are finding additional and various physiological mechanisms that end up causing the Ca2+ influx.

Which then may lead to several methods or medications that work to prevent that.

SECOND EDIT: And you know, I just noticed this statement from the above abstract: "In addition, pre-synaptic and postsynaptic components of GABAergic neurotransmission and the density of inhibitory interneuron processes also were decreased in the MS cortex."

If anyone recalls the narrative I posted back in June, 2004 (which you can still find on this website), I questioned in it whether affecting GABA and the synapses wouldn't be beneficial in MS! I just realized that! Well, I'll be darned!

Ok..........I had to go look myself as to what I had speculated on in my very first attempt at research. In my June, 2004 article, I proposed:

...."The survival of oligodendrocytes is crucial to sustain or repair myelin in MS. Oligodendrocytes contain GABA. Levetiracetam exhibits effects and regulation of GABAa. Desipramine shows affects (secondary message) on GABAb. Might this combination not prove HIGHLY beneficial in MS, as it not only may affect the survival to maturity of oligodendrocytes, but this combination of medications appears to regulate ion channels -
maintains sodium density and reduces potassium? (Also see Dr. Peter Calabresi's recent theory on potassium channels and MS.) There is also evidence of desipramine’s beneficial effects on sulfatide, thereby exhibiting further indication of the drug’s assistance with the survival of oligodendrocytes." ....

Good heavens! I think I sometimes freak myself out!!