10 replies to this topic

[rodentman]

http://today.reuters...LIFESPAN-DC.XML


Very interesting. The core body temperature was lowered MODESTLY. I'd like to see the results with more extrememe changes in body temperature.

Rodentman

[manofsan]

Others are also writing about this discovery. Here's one quote:

"Scripps Research Institute scientists have found that lowering the body temperature of mice by just 0.5C extends their lifespan by around 15%. Until now the only proven way of increasing longevity has been calorie restriction — but as this also causes a lowering of body temperature the researchers speculate that this cooling may be the underlying mechanism retarding aging. In this study mice with a defect in their lateral hypothalamus, which has the side effect of cooling body temperature, not only lived longer but also ate normal amounts."

So is cooling the ultimate goal here? Well, it's common sense that lower temperature means reduced reaction kinetics. But does that mean the answer lies in altering the body's homeostasis switch to a lower equilibrium temperature?

So does this mean then that Caloric Restriction doesn't produce a limiting reagent effect that slows metabolism, or does CR still have a limiting reagent effect which is just another means to slow metabolism?

[manofsan]

More from The Scientist:

http://www.the-scien.../display/27374/

[rodentman]

The longevitymeme dissmissed this as not truely increasing longevity (in contrast with CR). I'm clueless as to how they came to this conclusion.

[Matt]

People looking at CR seem to want just one reason why it extends lifespan the way it does... it seems as though a lower temperature does contribute to some of the life extension you get from from CR. It will be interesting to see if they can lower temperature much more to see if the effect is bigger.

[Brainbox]

Seems logical since intensity of chemical reactions correlates positively with increase of temperature. But I feel uncomfortable by just thinking about it already

[Matt]

I posted this on the CR list... but might aswell post it here too

I thought that I'd just eat my meal earlier in the evening to increase by over night fasting time. When I did this I woke up with a temperature of 34.85 degrees celsius (94.73 degrees Fahrenheit) and checked it a few times to confirm.

I was wondering how low my temperature would drop, I was suprised just how much it did!

No more very long over night fasts for me... I do want to wake up in the morning

[manofsan]

Well, the announcement says that 36.5C is the most optimal temperature.

http://www.nature.co.../061030-11.html

Gee, I would have thought the lower the better, since the lower the temp the slower the reaction rate.

So the hypothalamus is responsible for regulating core body temperature, huh?

Would there be any way to engineer some kind of artificial mechanism to trick the hypothalamus into lowering our temperature by a half-degreeC?

Well, I mean short of the researchers' use of genetic engineering.

How about a drug that tricks the body into lowering its core temp? How about some electrical pacemaker type of device that stimulates the hypothalamus into lowering the temp?
I dunno, just throwing out ideas...

[lunarsolarpower]

I know my personal body temperature tends to run about 1 Fahrenheit degree below 98.6 whenever it is measured. I wonder if that means that CR would not be of great benefit to me?

[manofsan]

Well, I'm thinking that the Low-Temp benefits and the CR benefits are not somehow mutually exclusive. It seems to me that each can complement the other. So if you're already benefiting from CR, then reducing the body temp would create even further benefit -- and vice-versa.

But I'm still wondering if there's some easier artificial way to lower your body temperature in a precise and healthy way, that doesn't involve the extreme step of genetic engineering. I mean, if we could do it using some macroscopic device employing some conventional mainstream technology, then it could become more feasible/accessible much sooner.

If some kind of precisely-calibrated electronic thermostat could be wired up to your hypothalamus -- maybe a chip -- then it could tell your hypothalamus to turn down the furnace until the temperature is a nice and cool 36.5degC.

Would anyone care to discuss the exact way that the hypothalamus regulates body temperature, so that we can explore the mechanisms on how to influence it? Let me google up some info...

[manofsan]

Check this out:

http://www.pubmedcen...i?artid=1331604

Thermoregulation around a new `set-point' established in the monkey by altering the ratio of sodium to calcium ions within the hypothalamus

R. D. Myers and T. L. Yaksh

Isn't this what we'd like to do?

5. During the calcium-induced hypothermia, the heart rate declined but the electrical activity of the cortex was relatively unchanged. Feeding was also elicited in the hypothermic monkey by noradrenaline microinjected at a site in the hypothalamus at which eating was evoked when the body temperature was normal.

So shifting the chemical equilibrium towards excess calcium ions is the way to lower body temp to a new equilibrium point...

6. The evidence supports the hypothesis that in the primate, the inborn mechanism which establishes the set-point for body temperature at 37° C is the constancy in the intrinsic ratio between sodium and calcium ions within the posterior hypothalamus. If the set-point is elevated or lowered by a disturbance of the balance between these two cations, the monkey nevertheless can thermoregulate normally around the new level of body temperature.

Well, we all certainly want to thermoregulate normally, but we just want to do it while enjoying the benefits of the 20% longer lifespan that comes from hovering around the half-degree lower body temperature.

So what happens when we go below a half-degree? Do we keel over and die, do we become lethargic, catatonic -- what?
Intuition would tell me that when you're asleep, you could probably afford an even bigger drop in body temp than a mere half-degree, since you don't need a whole lot of energy during sleep.
And so it seems to me that if you drop a bit below 36.5C during sleep, then you'd get even more life-extension benefit. Wouldn't that be a good thing?

Hmm, should someone start the Methuselah Popsicle Prize?

Edited by manofsan, 05 November 2006 - 05:21 PM.