Heat acclimation affects circulating levels of prostaglandin E2, COX-2 and orexin in humans.

Neurosci Lett. 2013 May 10;542:17-20. doi: 10.1016/j.neulet.2013.03.017. Epub 2013 Mar 21.
Heat acclimation affects circulating levels of prostaglandin E2, COX-2 and orexin in humans.
Shin YO, Lee JB, Min YK, Yang HM.

Department of Healthcare, Global Graduate School, Soonchunhyang University, 646 Asan, Republic of Korea.

We examined serum levels of prostaglandin E2 (PGE2), cyclooxygenase (COX)-2 and orexin before and after heat acclimation (HA) to test the hypothesis that decreased basal body temperature due to HA correlate with circulating levels of these key thermoregulatory molecules. Nine healthy human male volunteers were recruited (age, 21.9±2.7 years). The subjects were exposed to half-body immersion in hot water (42±0.5°C) at the same time of day (2-5p.m.) on alternate days for 3 weeks. The HA protocol included 10 bouts of 30min immersion. All experiments were performed in an automated climate chamber (temperature, 26.0±0.5°C; relative humidity, 60±3.0%; air velocity, <1m/s). Tympanic and skin temperatures were measured, and mean body temperature was calculated. The difference in body weight was used to estimate total sweat loss. Serum levels of PGE2, COX-2 and orexin were analyzed before and after HA. Body temperature decreased significantly (P<0.05) after HA, whereas sweat volume increased significantly (P<0.01). Serum PGE2, COX-2 and orexin concentrations decreased significantly compared to those at pre-acclimation (P<0.001, P<0.01, P<0.01, respectively). Our data suggest that decreased basal body temperature after HA is associated with decreases in thermoregulatory molecules, such as PGE2, COX-2 and orexin.

J Med Food. 2013 Apr;16(4):318-23. doi: 10.1089/jmf.2012.2543.
Oligonol supplementation attenuates body temperature and the circulating levels of prostaglandin E2 and cyclooxygenase-2 after heat stress in humans.
Shin YO, Lee JB, Song YJ, Min YK, Yang HM.

Department of Healthcare, Global Graduate School, Soonchunhyang University, Asan, Korea.

Oligonol, a phenolic production from lychee, has been reported to exhibit anti-oxidative and anti-inflammatory effects. This study investigated the effect of Oligonol supplementation on circulating levels of prostaglandin E2 (PGE2) and cyclooxygenase (COX)-2, as well as body temperature, after heat stress in 17 healthy human male volunteers (age, 21.6±2.1 years). All experiments were performed in an automated climate chamber (26.0°C±0.5°C, relative humidity 60%±3.0%, air velocity less than 1 m/sec) between 2 and 5 p.m. Subjects ingested an Oligonol (100 mg)-containing beverage or placebo beverage before half-body immersion into hot water (42°C±0.5°C for 30 min). Tympanic and skin temperatures were measured and mean body temperatures were calculated. Serum concentrations of PGE2 and COX-2 were analyzed before, immediately after, and 60 min after immersion. Oligonol intake significantly prevented elevation of tympanic (temperature difference: 0.17°C at Post, P<.05; 0.17°C at Re-60, P<.05) and mean body temperatures (temperature difference: 0.18°C at Post, P<.05; 0.15°C at Re-60, P<.05), and lowered concentrations of serum PGE2 (increased by 13.3% vs. 29.6% at Post, P<.05) and COX-2 (increased by 15.6% vs. 21.8% at Post, P<.05), compared to placebo beverage. Our result suggests that Oligonol has the potential to suppress increases in body temperature under heat stress, and this is associated with decreases in serum levels of PGE2 and COX-2.

Both studies are interesting, because they were conducted in humans under very similar circumstances (temperature wise).

Based on this information, Oligonol is worth experimenting with.

So are hot baths, sauna, etc., good idea or bad? A lower basal temperature does not sound like a good idea.

PGE2 is said to control fever response, and also has a role in producing inflammation. There have also been discussions here lately that local elevated temperatures in scalp tissue can't be good for hair (heat shock proteins, inflammations, cellular process slowdown, etc.).

Yet, it is said that a higher PGE2/PGD2 is good for hair.

What's your take on PGE2, CS?

Edit: PGE2 has a role in bone resorption too. Could this have any implication for hair health? I'm recalling skull expansion theory.

I'm convinced after looking into all of the research I could find based on Xenon's theory, and I think it totally adds up.

I think any worry about reducing PGE2 is nothing, because PGE2 is synonymous with COX-2 and PGD2...so, it's not a concern at all.

The above studies were conducted in temperature elevation of 42 Celsius (107 F), and post that temperature increase, saw a drop in those markers, which is natural...Intriguing is how Oligonol suppressed increases in body temperature under heat stress.  Having a drop in COX-2 is something very desirable.

To add further weight, there is another study on this supplement:

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2895700/

To summarize the benefits.The cortisol concentration and serum levels of IL-1beta and IL-6 after Oligonol intake were significantly decreased compared to before treatment

Thanks, CS.

Nice information CS. Very interesting.

A lower basal temperature does not sound like a good idea.

Not so much lower basal temperature, but rather balanced. When the scalp severely overheats, it is difficult for it to be brought back to core temperature, hence the inflammation I commonly experience if I carry out intensive exercise everyday. By intensive exercise I mean increased cardio / neuromuscular, such as sprinting or lifting very heavy weights. This really causes a sharp increase in scalp temperature.

I don't want to scare people off doing exercise or using hot saunas, as they are beneficial for sweating out toxins and maintaining good health, I'm just reporting my observations on the detrimental effects of increased and, more importantly, prolonged scalp temperature.  

I can do a work out everyday, just so long as I allow my scalp to cool down to it's core temperature afterwards. My methods in doing so, are drinking plenty of cool drinks before and after, then just wearing a pair of shorts, so that body heat can easily escape from sweat pores located all over the body. I'll also go outside in the open air, as this really helps with thermoregulation. Also, if a detect any early signs of inflammation, I'll dab the affected area with a little cool water.

I don't know if everyone's scalps are as thermosensitive as mine, I guess you will just have to observe for any signs of inflammation after a heavy work out or anything that causes the scalp to overheat. I generally don't shed any hair if I'm just relaxed; the only time I have ever lost hair is when my scalp has severely overheated. Had I have not made this connection some years ago, I'd have been completely bald now. That I have no doubt.

P.S. Another thing I have noticed in regards to hair thinning through heat; when my temples overheat, I also notice that the outer areas of my eyebrows also overheat, consequently this hair has thinned in these areas over the years.

ETA: I think that sleeping on the areas susceptible to hairloss, may cause compression of sweat tubules within the crown and temples, I think that when this happens, the scalp finds it difficult to release heat. This problem, as I have also found, seems to be exacerbated by a build up of sebum, which can also cover sweat pores.

Xenon, the "A lower basal temperature does not sound like a good idea." quote was in reference to the study posted in the OP. As you may read, the heat acclimation lowered the subjects' basal temperature, probably by decreasing their PGE2, etc.

My (frontal, where I have thinned hair) scalp does not have good thermoregulation either. In winter months, only this part goes cold- a few years ago this was not the case. In summer and other months, some days the frontal scalp is okay, at other times it goes hot. When it goes hotter or colder than the rest of the body, I know that spells trouble for the hair.

^^I do feel scalp inflammation from extremes of cold, yet not in the temples. Instead I felt it in the formerly tight areas of the upper crown and vertex (where the skull bone protrudes a little moreso).

I've not really bothered studying that much about the effects of cold on my scalp, as it is quite rare that it drops below core temperature. I read a study that histamines degranulate from mast cells when tissue is very cold, yet I am more inclined to think that this inflammation is induced by vasoconstriction within already tightened tissues. I think someone posted a study on here about how leukocytes increase in tissue suffering from hypoxia. This may be what happens when cold air causes the skin to enter a state of contraction for too long.

It seems to me, that many people suffer from an all over tight scalp, and likely is this the reason for their baldness, whereas I only used to have slight tightness in the upper crown / vertex areas.

Anyways, I'm just going to lurk here and there from now on. If I regrow anymore hair over the next few months, I'll be sure to inform you of my progress.