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Author Topic: Does hypoxia trigger neurogenesis?  (Read 4102 times)

Offline Caleb

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Does hypoxia trigger neurogenesis?
« on: 22/02/2015 20:32:22 »
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3652689/ leads to a 2013 PUBMED article: "Post ischemia intermittent hypoxia induces hippocampal neurogenesis and synaptic alterations and alleviates long-term memory impairment"

The above study was done on rats, but there are a variety of studies showing that intermittent hypoxia can lead to the growth of new neurons, etc.

My primary exercise is 20 minutes going up and down my single set of stairs, with my knees bent,  lifting up and down a 12 pound weight in the hand not near the bannister, and focusing on holding my breath. I had thought that this was very, very difficult. However, today I tried doing this while taking a breath every three seconds, this after downloading a breath beeper app for my Iphone. Now THAT was very, very demanding and my sweat level was very high.

Sure slowed down my speed on the stairs -- but with bent knees, I don't go too fast anyway. However, after 20 minutes of this, I had a deep tiredness that I haven't had in a long time.

If I had access to a treadmill, I sure would try the same thing, breathing every three minutes or so on an incline, maybe with knees bent.

If I take our grandson on my shoulders and then sing, I get out of breath very, very quickly and it seems the same principle.

Any reactions?

Caleb

« Last Edit: 28/02/2015 11:23:34 by chris »


 

Offline alancalverd

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Probably explains why old aviators sit around in the clubhouse reminiscing.

Loud music and marijuana smoke have a similar effect but probably induce false memories. As rock musicians say "the older we get, the better we were". How do I know they are false memories? 'Cos I'm like really, really old but no gold disc, so I can't have been that good!
 

Offline Caleb

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Oops! Sorry, I thought this subject was about "Re: Hypoxia and Neurogenesis -- Seems the research supports this in rats" and not about false memories, etc.

But that does give me a chance, now that I think of it, to mention this very, very interesting article on preventing stroke damage to rats by putting them in a hypoxic (low oxygen environment) for a while. See: http://www.ncbi.nlm.nih.gov/pubmed/23028788

The following is from Plosone and Pubmed and is very, very interesting, I mean, if you are interested in preserving brain function, etc.

Yours,

Caleb

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

Training the brain to survive stroke.
Dunn JF1, Wu Y, Zhao Z, Srinivasan S, Natah SS.
Author information
Abstract
BACKGROUND:
Presently, little can be done to repair brain tissue after stroke damage. We hypothesized that the mammalian brain has an intrinsic capacity to adapt to low oxygen which would improve outcome from a reversible hypoxic/ischemic episode. Acclimation to chronic hypoxia causes increased capillarity and tissue oxygen levels which may improve the capacity to survive ischemia. Identification of these adaptations will lead to protocols which high risk groups could use to improve recovery and reduce costs.
METHODS AND FINDINGS:
Rats were exposed to hypoxia (3 weeks living at an atmosphere). After acclimation, capillary density was measured morphometrically and was increased by 30% in the cortex. Novel implantable oxygen sensors showed that partial pressure of oxygen in the brain was increased by 40% in the normal cortex. Infarcts were induced in brain with 1 h reversible middle cerebral artery occlusions. After ischemia (48 h) behavioural scores were improved and T2 weighted MRI lesion volumes were reduced by 52% in acclimated groups. There was a reduction in inflammation indicated by reduced lymphocytes (by 27-33%), and ED1 positive cells (by 35-45%).
CONCLUSIONS:
It is possible to stimulate a natural adaptive mechanism in the brain which will reduce damage and improve outcome for a given ischemic event. Since these adaptations occur after factors such as HIF-1α have returned to baseline, protection is likely related more to morphological changes such as angiogenesis. Such pre-conditioning, perhaps with exercise or pharmaceuticals, would not necessarily reduce the incidence of stroke, but the severity of damage could be reduced by 50%.
 

Offline alancalverd

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The first line of my reply did address the true memory aspect. But the underlying hypothesis should be borne out by epidemiology as there are significant and fairly normal human populations living above 6000 ft altitude - hypoxia is evident in non-adapted people above this altitude.

So the question is whether the residents of Denver or Mexico City experience less longterm memory impairment than average, and how this compares with professional aircrew (cabin pressure is usually 6000 ft). But from what I know of Denver and Mexico City, you may have a problem to disentangle the effect of marijuana!
 

Online Colin2B

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...But from what I know of Denver and Mexico City, you may have a problem to disentangle the effect of marijuana!
Ah, give me confounding factors anyday  :)
 

Offline Caleb

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The point researchers made about "exercise-induced hypoxia" is that it is quite minor, certainly as compared with high altitude, etc.

Sprinters may experience it many times a day.

My focus is on whether this intermittent "getting out of breath during exercise" has actual health benefits, and I think it probably does have some important benefits.

Caleb
 

Online Colin2B

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Interesting. The adaptive factors are very similar to aerobic exercise which increases vascular density in heart tissue and hence improve the ability of the heart survive a heart attack. There are also studies which suggest exercise is a good protector from dementia.

The point researchers made about "exercise-induced hypoxia" is that it is quite minor, certainly as compared with high altitude, etc.
Must have missed this bit. This preconditioning is much longer than exercise would give, but less practical unless the patient is bed bound or uses a respirator.

But the underlying hypothesis should be borne out by epidemiology as there are significant and fairly normal human populations living above 6000 ft altitude - hypoxia is evident in non-adapted people above this altitude.

Studies show increased risk of stroke at altitude even among resident populations. Climbers can suffer from oedema thought to be due to hypoxia. Blood pressure is also affected by hypoxia, afro mountaineers tend to have reduced systolic BP whereas Caucasian have increased.

My focus is on whether this intermittent "getting out of breath during exercise" has actual health benefits, and I think it probably does have some important benefits.

Most research indicates yes, but this is not necessarily true of holding breath during exercise.
Holding breath during exercise increases BP and could trigger a stroke. I do light weight training to keep muscle tone and all the advice is to breath out during the exertion, and breath as normally as possible.
The biggest single indicator of ability to survive a heart attack is VO2 Max. This is best improved by aerobic exercise which gets you out of breath.
As a recreational diver, I have trained to improve my breath holding and ability to work with low oxygen, but I would not use this as day to day exercise as I believe the dangers are too great.
 

Offline Caleb

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Let's take it to specifics:

You say: "Most research indicates yes, but this is not necessarily true of holding breath during exercise.
Holding breath during exercise increases BP and could trigger a stroke. I do light weight training to keep muscle tone and all the advice is to breath out during the exertion, and breath as normally as possible.
The biggest single indicator of ability to survive a heart attack is VO2 Max. This is best improved by aerobic exercise which gets you out of breath.
As a recreational diver, I have trained to improve my breath holding and ability to work with low oxygen, but I would not use this as day to day exercise as I believe the dangers are too great."

But let's go to the example I give of military recruits jogging/running and chanting in cadence back to their leader as they do so.

Do you think this is dangerous? If so, maybe military trainers are doing it wrong? I doubt it.

About you're being a recreational diver -- holding one's breath for a long period of time may well be dangerous -- but if one engages in exercise that repeatedly (not grabbing, e.g., a large stone and dropping 200 feet down, and surfacing 2 minutes later) moderately leaves you out of breath, isn't this not better than an exercise that NEVER makes you out of breath? That steadfastly avoids leaving you out of breath?

Speak, if you will, to the situation of jogging/running with a group of people and chanting/singing back to the leader. Don't you think that this is a reasonably effective way of increasing cardio fitness, this by combining exercise with breathing restriction? If not, then why not?

Yours,

Caleb
 

Online Colin2B

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My focus is on whether this intermittent "getting out of breath during exercise" has actual health benefits, and I think it probably does have some important benefits.

Most research indicates yes, but this is not necessarily true of holding breath during exercise.
Holding breath during exercise increases BP and could trigger a stroke

As you can see, I was addressing the question of breath holding

I did mention the benefit of exercise which gets you out of breath, in fact this is the generally recommended marker of moderate aerobic exercise.
For some levels of aerobic exercise it is recommended that you should be able to carry on a conversation, or even sing, but this is used as a pace marker - also by the army.

This is best improved by aerobic exercise which gets you out of breath.

Can I just mention one other item before I leave this thread:

...... However, after 20 minutes of this, I had a deep tiredness that I haven't had in a long time.

Deep tiredness after exercise is a warning sign for all forms of exercise, particularly after only 20min. It is possible your brain/heart are reaching very low oxygen levels, deeper than that used in the papers you quoted.
Putting you grandchild on shoulders and singing is very different and I see no problem with that as long as you feel no ill effects.

 

Offline Caleb

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"Deep tiredness" I felt was certainly no greater than going up a hill with a backpack and plugging away for a while. But I sure was interested in how quickly that outcome was caused by stair climbing and breathing only every three seconds.

Thanks for your thoughts on this!

Yours,

Caleb
 

Offline Caleb

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Re: Does hypoxia trigger neurogenesis?
« Reply #10 on: 28/02/2015 19:35:32 »
This is a very interesting study about how three half-hour bouts of exercise induced hypoxia in obese males led to a significant increase in carbohydrate oxidation across 7.5 hours as compared to subjects who were not in the hypoxic condition. Perhaps this is what I thought I felt after my little 20 minute bouts of exercised induced hypoxia -- the apparent deep tiredness that I speculated I felt more after hours of back-packing. Hmm...

The following article is at: http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0108629

"Impact of Exercise and Moderate Hypoxia on Glycemic Regulation and Substrate Oxidation Pattern
Takuma Morishima, Ayaka Mori, Hiroto Sasaki, Kazushige Goto
Published: October 16, 2014DOI: 10.1371/journal.pone.0108629"

"We understand that some limitations should be carefully considered for interpretation of the present study. First, subjects in the present study were overweight men, but they did not have any metabolic disorder, which may affect the present results. Further studies using severely obese people or people with type 2 diabetes are necessary to extend our understanding. Second, substrate levels in blood do not correspond correctly to substrate utilization because substrate levels such as glucose, lactate or FFA are influenced by the rates of appearance and disappearance. This will partly explain for lack of attenuations of glucose and insulin responses in hypoxia, in despite of augmented carbohydrate oxidation.

"Conclusion

"Neither rest alone nor rest and exercise under moderately hypoxic conditions attenuated postprandial glucose responses. Additionally, rest alone under moderately hypoxic condition did not affect the substrate oxidation pattern markedly. However, carbohydrate oxidation was enhanced significantly over 7.5 h when three bouts of submaximal exercise were incorporated under moderately hypoxic conditions."


This is an interesting factor, I think --  exercise-induced hypoxia. Might be particularly useful for those with diabetes, by clearing the system of carbohydrate, as well as, perhaps, helping one be resistant to stroke, etc.

Yours,

Caleb
 

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Re: Does hypoxia trigger neurogenesis?
« Reply #10 on: 28/02/2015 19:35:32 »

 

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