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Dean Pomerleau

Cold Exposure & Other Mild Stressors for Increased Health & Longevity

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The author of that article,  K.A. Virtanen,  is co-author of the following article on BAT,  with full text available.  Some neat diagrams.   It's a pretty dense article--I'm hoping Mccoy can predigest it for me.

Brown Adipose Tissue Energy Metabolism in Humans

Edited by Sibiriak

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1 hour ago, Sibiriak said:

The author of that article,  K.A. Virtanen,  is co-author of the following article on BAT,  with full text available.  Some neat diagrams.   It's a pretty dense article--I'm hoping Mccoy can predigest it for me.

Brown Adipose Tissue Energy Metabolism in Humans

OK, a demonstration of copy/paste capabilities of the new forum software with some BAT porn:

image.thumb.png.8bd04b25290028f7fbce43d0a36aadf4.png

Figure 1. From: Brown Adipose Tissue Energy Metabolism in Humans.

Uncoupling protein 1 (UCP1)-mediated brown adipose tissue thermogenesis. Upper panel: Brown adipose tissue UCP1-mediated thermogenesis is activated by fatty acids produced via norepinephrine-induced intracellular triglyceride (TG) lipolysis during cold exposure. Middle panel: Acute pharmacological inhibition of intracellular TG lipolysis blunts brown adipose tissue thermogenesis via reduction of intracellular fatty acids availability. Lower panel: Genetic deletion-mediated inhibition of intracellular TG lipolysis in brown adipose tissues leads to increased reliance on circulating nonesterified fatty acids (NEFA) and triglyceride (TG)-rich lipoproteins to sustain UCP1-mediated thermogenesis. The mitochondrion illustration was obtained free of copyright from Pixabay (www.pixabay.com, 2018).

 

Figure 2

 
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The standard definition of brown adipose tissue in vivo in humans. Brown adipose tissue is currently defined in vivo in humans by the combination of two radiological features: (1) 18-fluorodeoxyglucose (18FDG) uptake above a set threshold higher than that usually observed in white adipose tissues using positron emission tomography (left panels); and (2) a radio-density that is compatible with the presence of adipose tissue using computed tomography (right panels). After intravenous (i.v.) injection of 18FDG, whole body (static) positron emission tomography scanning is performed, giving quantitative tissue bio-distribution of the tracer into brown adipose tissues. This tissue tracer uptake is co-registered with tissue radio-density measured using computed tomography. The middle left and right panels show positron emission tomography and computed tomography transverse views, respectively, of supraclavicular brown adipose tissue in a healthy individual during a standardized cooling protocol. Source of illustration: Shutterstock (www.shuterstock.com, 2018, no. 100687138).

 

Figure 3

 
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Whole body glucose uptake into brown adipose tissues and muscles during acute cold exposure. During mild cold exposure, glucose uptake is stimulated in brown adipose tissue, but also in several centrally-located skeletal muscles. Brown adipose tissue glucose uptake is ~8-fold higher than that of skeletal muscles, on average, per gram of tissue during mild cold exposure. However, total mass of brown adipose tissue is about 0.2% of that of skeletal muscles. Therefore, brown adipose tissue and skeletal muscle glucose uptake account for ~1 and 50%, respectively, of systemic glucose disposal. The figures presented were calculated from previously published data in young healthy individuals, before cold acclimation (39). BAT, brown adipose tissue; SUV, standard uptake value. Source of muscle illustration: Shutterstock (www.shuterstock.com, 2018, no. 404668558).

Figure 4

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Organ-specific glucose partitioning during acute cold exposure. The figures presented were calculated from a previously published study in young healthy individuals, before cold acclimation (39), based on calculations that we detailed previously (110). BAT, brown adipose tissue; WATsc, sub-cutaneous white adipose tissues; WATv, visceral white adipose tissue.

Figure 5

 
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Brown adipose tissue uptake of energy substrates. Total brown adipose tissue uptake of energy substrates is calculated from published quantitative, dynamic positron emission tomography or microdialysis experiments in humans, multiplied by a typical total brown adipose tissue mass reported in the literature. Data from (73, 108, 113), (108, 113, 114), (115), and (116) were used to calculate glucose, NEFA, dietary fatty acid, and glutamate BAT uptake, respectively. 18FDG, 18-fluorodeoxyglucose; BAT, brown adipose tissue; NEFA, nonesterified fatty acids; PET/CT, positron emission tomography coupled with computed tomography.

Figure 6

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Glucose metabolism in brown adipose tissue. Most of the glucose taken up by brown adipose tissue during cold exposure does not contribute to thermogenesis. Experimental data show that approximately half of the glucose molecules are excreted from brown adipose tissue as lactate. Most of the remaining glucose likely contributes to glycerol production (glyceroneogenesis) and/or fatty acid synthesis (de novolipogenesis) for intracellular triglyceride synthesis. The mitochondrion illustration was obtained free of copyright from Pixabay (www.pixabay.com, 2018).

Figure 7

 
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Intracellular triglyceride (TG) mobilization in brown adipose tissue during cold exposure. Left panel: Brown adipose tissue (BAT), white adipose tissue (WAT) and trapezius muscle change in radio-density during standardized acute cold exposure from previously published studies of our group (39, 73, 108, 109). Right panel: During cold-induced brown adipose tissue metabolic activation, up to 8 g of intracellular triglycerides can be mobilized within 2 h. The metabolic fate of the fatty acids that are mobilized is currently unknown. Although these fatty acids likely constitute most of the energy substrates driving brown adipose tissue thermogenesis, a fraction of them may also be released in circulation to be utilized by other tissues. NEFA, nonesterified fatty acids; UCP1, uncoupling protein 1. The mitochondrion illustration was obtained free of copyright from Pixabay (www.pixabay.com, 2018).

Figure 8

 
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Brown adipose tissue (BAT) oxidative metabolism and contribution to total body energy expenditure. Brown adipose tissue oxygen consumptions are from U Din et al. (143) and brown adipose tissue-containing adipose tissue (AT) mass range is from Leitner et al. (61). Calculations were made assuming energy expenditure of 4.801 kcal per liter of oxygen consumed (201) and an adipose tissue density of 0.925 g.ml−1 (202). AT, adipose tissue.

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3 hours ago, Sibiriak said:

.... It's a pretty dense article--I'm hoping Mccoy can predigest it for me.

I'm feeling pretty queasy in the stomach now, LOL

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J Therm Biol. 2018 Oct;77:137-144. doi: 10.1016/j.jtherbio.2018.08.016. Epub 2018 Aug 23.

Sex difference in cold perception and shivering onset upon gradual cold exposure.

Abstract

To maintain a thermal balance when experiencing cold, humans reduce heat loss and enhance heat production. A potent and rapid mechanism for heat generation is shivering. Research has shown that women prefer a warmer environment and feel less comfortable than men in the same thermal condition. Using the Blanketrol® III, a temperature management device commonly used to study brown adipose tissue activity, we tested whether the experimental temperature (TE) at which men and women start to shiver differs. Twenty male and 23 female volunteers underwent a cooling protocol, starting at 24 °C and gradually decreasing by 1-2 °C every 5 min until an electromyogram detected the shivering or the temperature reached 9 °C. Women started shivering at a higher TE than men (11.3 ± 1.8 °C for women vs 9.6 ± 1.8 °C for men, P = 0.003). In addition, women felt cool, scored by a visual analogue scale, at a higher TE than men (18.3 ± 3.0 °C for women vs 14.6 ± 2.6 °C for men, P < 0.001). This study demonstrates a sex difference in response to cold exposure: women require shivering as a source of heat production earlier than men. This difference could be important and sex should be considered when using cooling protocols in physiological studies.

KEYWORDS:

Cold temperature; Sex characteristics; Shivering; Skin temperature; Thermogenesis; Thermosensing

PMID:
 
30196892
 
DOI:
 
10.1016/j.jtherbio.2018.08.016
 
____________________________________________________________
FYI: I noticed there are quite a few used Blanketrol machines on eBay (sort by distance) some are quite cheap.  It would be fun to have one of those!

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An interesting look at cold induced cognitive impairment (and how to prevent it).  Unclear what type of cinnamon was used, but they also used green tea extract which performed better than either pepper or cinnamon when it comes to markers of BAT activation:

 

Int J Hyperthermia. 2018 Sep 13:1-10. doi: 10.1080/02656736.2018.1511835. [Epub ahead of print]

Pepper and cinnamon improve cold induced cognitive impairment via increasing non-shivering thermogenesis; a study.

Study Link

 

Abstract

Despite an understanding that a major effect of cold exposure is a fall in core body temperature which is responsible for the observed decrements in the performance, it is surprising that thermogenic supplements are seldom evaluated to verify if they can aid in improving the performance during cold exposure. Following evidence from our previous study indicating the ability of pepper and cinnamon to improve coldendurance, we investigated further here if the improved endurance had advantages in real time where they could positively affect cognitive performance (assessed by Novel object test) when exposed to cold in albino wistar rats. In order to delineate if the observed improvement if any, was due to their cognitive enhancing ability or thermogenic potential, distinctive room temperature (RT) and cold temperature (CT) groups were used. Cold exposure impaired cognitive performance which improved following treatment with both the spices. We noted an increased rate of cold adaptive thermogenesis in CT treated group as evidenced by an elevated norepinephrine, free fatty acid levels in blood, increased expression of UCP1 in brown adipose tissue, the net effect being a decreased fall in the core body temperature. Absence of any notable effect in these parameters in the RT treated group ascertained that at least in the current experimental set up the observed improvement in performance in CT treated group is due to the thermogenic potential of the spices alone. In conclusion, our results demonstrate that the cognitive impairment caused by exposure to cold can be effectively countered by agents with thermogenic potential.

KEYWORDS:

Spices; cold stress; learning and memory; non-shivering thermogenesis; novel object test

PMID:
 
30208750
 
DOI:
 
10.1080/02656736.2018.1511835
 
 

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This wasn't the focus of the study, but these researchers discovered a synergy in mice between calorie restriction and BAT stimulation for beneficial health outcomes.  I guess this is not surprising since we know BAT activation is hampered by obesity.

Lab Invest. 2018 Sep 26. doi: 10.1038/s41374-018-0120-x. [Epub ahead of print]

Activation of brown adipose tissue enhances the efficacy of caloric restriction for treatment of nonalcoholic steatohepatitis.

Abstract

Nonalcoholic steatohepatitis (NASH) is the form of nonalcoholic fatty liver disease that can evolve into cirrhosis. Lifestyle modifications achieving 10% weight loss reverse NASH, but there are no effective approved drug treatments. We previously identified defective adaptive thermogenesis as a factor contributing to metabolic syndrome and hepatic steatosis. We have now tested whether increasing nonshivering thermogenesis can improve preexisting NASH in mice. In high-fat diet-fed foz/foz mice with established NASH, treatment with β3AR agonist restored brown adipose tissue (BAT) function, decreased body weight, improved glucose tolerance, and reduced hepatic lipid content compared to untreated counterparts, but had no impact on liver inflammation or on nonalcoholic fatty liver disease activity score (NAS). Similarly, β3AR agonist did not alter liver pathology in other steatohepatitis models, including MCD diet-fed diabetic obese db/db mice. Caloric restriction alone alleviated the hepatic inflammatory signature in foz/foz mice. Addition of a β3AR agonist to mice subjected to caloric restriction enhanced weight loss and glucose tolerance, and improved liver steatosis, hepatocellular injury, and further reduced liver inflammation. These changes contributed to a significantly lower NAS score such as no (0/9) animals in this group fulfilled the criteria for NASH pathology compared to eight out of ten mice under caloric restriction alone. In conclusion, β3AR agonist counteracts features of the metabolic syndrome and alleviates steatosis, but does not reverse NASH. However, when coupled with weight loss therapy, BAT stimulation provides additional therapeutic advantages and reverses NASH.

PMID:
 
30258096
 
DOI:
 
10.1038/s41374-018-0120-x
Edited by Gordo

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https://www.cell.com/cell/fulltext/S0092-8674(18)31500-9?fbclid=IwAR1xelMsqAYbATAbpdvgS1IwqtRGMSmdHrFvZmWF-d8b9nOJZO8vs3AEZmk

Secretin: An Old Hormone with a Burning Secret

Most theories of meal-induced thermogenesis involve a gut-brain-brown adipose tissue axis driving sympathetic nervous system-mediated thermogenesis. Li et al. demonstrate that secretin released by the gut after a meal binds to abundant receptors in brown adipose tissue to stimulate thermogenesis, inhibiting food intake and thereby suggesting a novel role for secretin regulating satiety.

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