Effect of cold exposure on browning of white adipose tissues in mice fed with high fat diet / 中国药理学通报

Aim: To observe the effect of cold exposure on browning of white adipose tissues in mice fed with high fat diet. Methods: Male 8-week-old C57BL/6J mice were randomly divided into HFD + 5 °C group and HFD + RT group, after 8 weeks of high-fat diet. Male 8-week-old C57BL/6J mice were randomly divided into normal + 5 °C group and normal + RT group, after 8 weeks of normal diet. Each group of mice were intervened for 2 h at different temperatures in the same time period for 8 weeks. Parameters, including body weight, food intake, inguinal white adipose tissue (iWAT) mass, brown adipose tissue (BAT) mass, blood glucose, blood lipids, leptin, adiponectin, adipose tissue pathology and in situ expression of uncoupling protein 1(UCP1) and prohibitin protein (PHB) in iWAT and BAT. Results: Compared with HFD + RT group, cold exposure not only significantly reduced body weight, blood glucose, iWAT weight/body weight ratio, TC, TG, LDL-C and leptin, but also increased food intake and BAT weight in high-fat diet mice. HE staining showed that iWAT and BAT cells became smaller and had multiple compartments. The iWAT had a browning trend. Immunohistochemistry showed that UCP1 and PHB protein in iWAT and BAT significantly increased. Conclusions: Cold exposure can counteract the weight gain caused by a high-fat diet, which may be related to the activation of brown adipose tissue and the induction of browning of white adipose tissues, increasing heat production and reducing white fat accumulation.

Effect of hypobaric hypoxia and cold exposure on formation of brown adipose tissue in mice / 中国比较医学杂志

Objective To investigate the effect of hypobaric hypoxia and cold exposure on brown adipose tissue in mice. Methods Twenty-four 6-week old SPF C57BL/6 male mice were randomly divided into 4 groups with 6 mice in each group: normal atmospheric pressure and temperature group ( 18~22℃, 20~60 m ) ( NTNP ) , low atmospheric pressure and normal temperature group ( 18~22℃, altitude of 5000 m ) ( NTLP ) , normal atmospheric pressure and cold exposure group(0~6℃, altitude of 20 ~60 m)(LTNP), low atmospheric pressure and cold exposure group(0 ~6℃, altitude of 5,000 m)(LTLP). The experimental period was 4 weeks. The body weight was measured at the beginning and end of the experiment. By the end of the four-week trial, the back and inguinal fat were dissected and observed by histology using HE staining. The expression of UCP-1 as the marker of brown adipose tissue in the back fat was detected by qPCR and western blot. Results The body weight gain of NTNP group was higher ( P< 0. 05 ) than the other three groups. Meanwhile, the color of the back and groin fat tissue of mice of LTNP and LTLP groups were darker, the blood supply in mice of these two groups was richer than the NTLP group. The volume of adipose tissue of NTNP group was higher than others. The histology showed that the back adipose cells of the mice were smaller and darker and full of multilocular lipid droplets, exhibiting a typical morphology of brown fat cells. Compared with the NTNP and NTLP groups, the mRNA and protein levels of UCP-1 were higher under cold exposure, while low atmospheric pressure had a tendency to reduce the mRNA expression of UCP-1. Conclusions The formation of brown fat is affected by the imitated conditions of low atmospheric pressure and cold exposure, and is more closely related to the decresed temperature.

Effect of Lateral Preoptic Area Lesion on Sleep Wakefulness and Thermoregulation In Cold Acclimatized Rats.

Hypothalamic temperature (Thy) alteration is one of the important stimuli that brings about thermoregulatory measures including the changes in wakefulness and muscular activity. The role of the lateral preoptic area (lPOA) in thermoregulation and sleep is well documented. But it is not known whether the integrity of the lPOA is essential for bringing about the changes in sleep-wakefulness (S-W) and thermoregulation in cold ambient temperature (Ta). Neurotoxic lesion of the lPOA resulted in an increase in wake period and core body temperature (Tb) and no change in Thy. Unlike, normal animals, as reported earlier, there was further increase in Tb of the lPOA lesioned rats on acute cold exposure, but the Thy remained unaltered throughout the 28 days of continued cold exposure. The findings demonstrate that the lPOA lesioned rats have lost the ability to reset Thy which may be necessary for thermoregulation during cold exposure. Moreover, increased wake period lasted only 7 days in lesioned, compared to 14 days in normal animals. Less efficient restoration of Tb, and less prolonged wake period during continued cold exposure, are probably the result of the inability of the lPOA lesioned rats to lower Thy, which is necessary to bring about the thermoregulatory measures.

Brown Adipose Tissue as a Therapeutic Target for Obesity: From Mice to Humans

Brown adipose tissue (BAT) is a site of sympathetically activated non-shivering thermognenesis during cold exposure and after spontaneous hyperphagia, thereby involving in the autonomic regulation of energy balance and body fatness. Recent radionuclide studies have demonstrated the existence of metabolically active BAT in adult humans. Human BAT is activated by acute cold exposure, particularly in winter, and contributes to cold-induced increase in whole-body energy expenditure. The metabolic activity of BAT is lower in older and obese individuals. The inverse relationship between the BAT activity and body fatness suggests that BAT, because of its energy dissipating activity, is protective against body fat accumulation. In fact, either repeated cold exposure or daily ingestion of some food ingredients acting on transient receptor potential channels recruited BAT in association with increased energy expenditure and decreased body fatness. Thus, BAT is a promising target for combating obesity and related metabolic disorders in humans.

Brown Adipose Tissue as a Regulator of Energy Expenditure and Body Fat in Humans

Brown adipose tissue (BAT) is recognized as the major site of sympathetically activated nonshivering thermogenesis during cold exposure and after spontaneous hyperphagia, thereby controling whole-body energy expenditure and body fat. In adult humans, BAT has long been believed to be absent or negligible, but recent studies using fluorodeoxyglucose-positron emission tomography, in combination with computed tomography, demonstrated the existence of metabolically active BAT in healthy adult humans. Human BAT is activated by acute cold exposure, being positively correlated to cold-induced increases in energy expenditure. The metabolic activity of BAT differs among individuals, being lower in older and obese individuals. Thus, BAT is recognized as a regulator of whole-body energy expenditure and body fat in humans as in small rodents, and a hopeful target combating obesity and related disorders. In fact, there are some food ingredients such as capsaicin and capsinoids, which have potential to activate and recruit BAT via activity on the specific receptor, transient receptor potential channels, thereby increasing energy expenditure and decreasing body fat modestly and consistently.

Hypothalamic temperature: A key regulator in homeostatic restoration of sleep during chronic cold exposure in rats.

Exposure to cold ambient temperature (Ta) affects sleep-wake (S-W) state. The vigilance states on the other hand influence thermal status of the animals. Simultaneous recording of body temperature (Tb) with S-W is crucial to understand the homeostatic relationship between the two. In the present study we recorded both Tb and hypothalamic temperature (Thy) along with S-W, during acute and chronic exposure to mild cold (Ta). Electrooculogram (EOG), electroencephalogram (EEG) and electromyogram (EMG) electrodes were chronically implanted in rats to assess S-W. A thermocouple, near the preoptic area, and radio transmitter in the peritoneum, were implanted, to record Thy and Tb respectively. After three days of baseline recordings of S-W, Thy and Tb at Ta of 26°C, the rats were exposed to mild cold Ta (18°C) for 28 days. All the parameters were recorded during cold exposure and also for five days after the termination of cold exposure. On the first day of cold exposure there was a decrease in slow wave sleep and paradoxical sleep, but they were restored by the 21st day of continued exposure. The Thy remained decreased throughout the cold exposure. Though the Tb showed a slight decrease on the first day of cold exposure, there was no appreciable change during the subsequent days. The Thy came back to near pre exposure level on termination of cod exposure. The decrease in Thy during mild cold exposure would have triggered cold defense mechanisms. Increase in wakefulness during acute cold exposure and non-shivering thermogenesis during chronic cold exposure are probably responsible for the maintenance of Tb. Decrease in Thy is probably the key trigger for initiating thermoregulatory measures to maintain Tb and homeostatic restoration of sleep.

Cytokine Response to Exercise during Exposure to Cold / 日本補完代替医療学会誌

This study examined cytokine responses to cold exposure together with the effects of exercise and thermal adaptation. Ten male short-track skaters who had adapted to a cold environment, and ten male inline skaters who had not, were each assigned to two experimental conditions. For the cold condition, subjects sat for 60 min at 5–8°C, then exercised on a cycle ergometer for 60 min at 65% maximal oxygen uptake (at 5–8°C), and finally sat again for 120 min at room temperature (20–25°C). In the control condition, subjects participated in the same protocol as the above but at room temperature (20–25°C). Blood samples were collected at pre-cold exposure, post-cold exposure (pre-exercise), post-exercise, post-30 min, post-60 min, and post-120 min, and analyzed for plasma concentrations of interleukin (IL)-1 receptor antagonist (IL-1ra), IL-8, IL-10, IL-12p40, soluble tumor necrosis factor receptor I (sTNFR-I), cortisol, and myoglobin by using enzyme-linked immunosorbent assay (ELISA). 60-min cycle ergometer exercise induced significant increases in plasma IL-1ra, IL-10 and IL-12p40 at room temperature in short-track skaters adapted to the cold, but significant decreases in these cytokines were observed with exposure to cold. These results indicate that acute cold exposure has a suppressive effect on cytokine response during exercise, suggesting the possibility of preventive effects on immunosuppression, heat stroke and allergy induced by exercise.<br>

The Relationship between Cold-Exposure and Hypertension / 대한산업의학회지

OBJECTIVES: This study was carried out to suggest preventive methods for hypertension in cold-exposed workers. METHODS: In 11 refrigeration industries, 68 workers working in refrigerated areas more than one time per day were selected as the exposed group, and 68 workers not exposed to cold were selected as the control group. We interviewed the subjects with a questionnaire covering occupational history, and conducted clinical and laboratory tests including measurements of blood pressure and core temperature. RESULTS: The systolic blood pressure in the exposed group(130.0+/-13.3 mmHg) was significantly higher than that recorded in the control group(118.3+/-12.1 mmHg), as was the diastolic blood pressure in the exposed group(82.7+/-8.5 mmHg) versus the control group(77.4 +/-8.7 mmHg). The core temperature in the exposed group(36.1+/-0 . 7degrees C) was significantly lower than that experienced in the control group(36.4+/-0 . 5degrees C). In logistic regression analysis, age, cold exposure severity and milk intake were significant variables, with odds ratios of 5.204(95 % CI 1.440~18.812), 2.674(95 % CI 1.080~6.618), and 0.364(95 % CI 0.141~0.942), respectively. CONCLUSIONS: Our study suggests that cold-exposed workers have higher a higher risk of hypertension, and that their core temperature is lower. Risk factors affecting hypertension of cold-exposed workers include age, cold exposure severity and milk intake. For the prevention of hypertension, cold-exposed workers should minimize cold-exposure time as much as possible.

Effects of propylthiouracil on body temperature in rats during cold exposure / 中国病理生理杂志

AIM: To investigate the effect of cold exposure on the thermoregulatory function in hypothyroid rats. METHODS: Hypothyroid model was established by administration of antithyroid drug propylthiouracil(PTU) in rats. Colonic temperature was measured using digital thermometer. Plasma T_3 and T_4 concentrations were determined by radioimmunoassay. The effect of cold exposure on body temperature was observed after 2 weeks of PTU treatment. RESULTS: Plasma T_3 and T_4 concentrations were reduced markedly 2 weeks after PTU treatment, and colonic temperature was also decreased markedly; Hyperthermic response was not different between PTU group and control group during cold exposure. CONCLUSION: This study suggests that PTU-induced hypothyroid rat possesses a robust thermogenic response to short bouts of cold exposure.

Relationship between thermoregulation and cold-induced vasodilation during cold exposure with regard to maximal oxygen intake / 体力科学

Based on the maximal oxygen intake (VO<SUB>2</SUB>max), 24 male students were classified into high (H-G), middle (M-G) and low (L-G) groups of the VO<SUB>2</SUB>max level. In each VO<SUB>2</SUB>max level group, thermoregulation characteristic values during cold exposure at an ambient temperature (Ta) of 12°C were compared with several parameters of cold-induced vasodilation (CIVD) measured at 28°C (observation 1) and the parameters measured after 30 min from the start of 60-min cold exposure (observation 2) . The relationship between CIVD as a peripheral vasomotor regulation response, and autonomic thermoregulatory response was examined. The results are as follows:<BR>A . H-G showed the smallest decreases in the rectal temperature (Tre) and in mean skin temperature (Tsk), and these parameters decreased as VO<SUB>2</SUB>max decreased. Enhancement of metabolic heat production (M) was highest in H-G and lowest in L-G.<BR>B . In the observations 1 and 2 of the CIVD tests, mean skin temperature (MST), temperature at first rise (TFR) and resistance index (RI) increased with rise in VO<SUB>2</SUB>max, while time of temperature rise (TTR) decreased. In the observation 2, TFR remained low by decreased temperature before water immersion (TBI) and, with TBI taken into consideration, no significant change in RI was observed except only in L-G.<BR>C. MST, TTR and RI in the CIVD measurements (observation 1 and 2) were significantly correlated with the mean thermoregulation characteristic value during 30-60 min after the start of cold exposure (the second half period) .<BR>D. During the second half period of cold exposure, significant negative correlations were observed between Tsk and body fat% (BF%) and between M and BF %. VO<SUB>2</SUB>max was significantly correlated with RI, Tre, Tsk and M.<BR>These results indicate that difference in physical fitness for endurance is clearly reflected in the values of cold-induced vasodilation in thermoneutral zone and during cold exposure. The peripheral vascular resistance of finger increased during cold exposure from that in thermoneutral zone causing decrease of finger skin temperature. After that, due to hunting reaction, the peripheral vascular resistance decreased, and a correspondance was observed between effectiveness in raising finger skin temperature through increase in skin blood flow and physical fitness for endurance. An interrelation was observed between the local cold resistance of peripheral vasomoter during exposure of finger to ice water and the whole cold resistance of autonomic temperature regulation during cold exposure of the whole body. It may be inferred that the subjects with high physical fitness for endurance have low insulative of body fat but have good cold tolerance by enhancement of heat production and preservation of skin temperature.

Study of cold-induced vasodilation due to cold exposure / 体力科学

This study was carried out to examine the following. 1) For 20 adult males in summer, cold-induced vasodilation (CIVD) immersed in ice water (ice water CIVD) and CIVD exposed to cold air of 0°C, -5°C and -10°C (cold air CIVD) were compared. The blood pressure was measured and examined during the course of measuring ice water CIVD and -10°C cold air CIVD. 2) -10°C cold air CIVD was measured in summer and in winter for 40 males.<BR>The results for 1) and 2) are summarized as follows.<BR>1. Definite effects of the difference in thermal transmission rate was observed between cold air CIVD and ice water CIVD. Finger skin temperature fell as the temperature at cold air CIVD dropped to 0, -5 and -10°C. At -10°C cold air CIVD where the drop of skin temperature was greatest, the temperature at first rise (TFR) was higher, time of temperature rise (TTR) was longer and amplitude of temperature (AT) was greater, compared with the respective values at ice water CIVD. However, no difference was observed in mean skin temperature (MST) during the exposure. Individual difference in values at cold air CIVD was greater than that at ice water CIVD.<BR>2. The time of maximum rise of blood pressure response after cold exposure was 5 minutes at ice water CIVD and 20 minutes at -10°C cold air CIVD. The rate of blood pressure rise at -10°C cold air CIVD was significantly greater. The time when the rise of blood pres-sure reached the maximum was identical with the time when the skin temperature became lowest.<BR>3. At -10°C cold air CIVD, MST and TFR were higher and TTR shorter in winter than those in summer. At ice water CIVD, the values in summer were higher for MST and TFR and shorter for TTR as mentioned previously.<BR>4. The temperature before -10°C cold air CIVD (TB) showed a significant correlation with MST and TFR, though not with TTR.<BR>5. A comparison of these results with Watanuki et al.'s report reveal some differences.

The effect of exposure to low temperature on the metabolism of carbohydrates, lipids and protein in the larvae of Philosamia ricini.

Exposure of the silkworm (Philosamia ricini) larvae to cold temperature (2°C) and subsequent exposure to room temperature (29° C) resulted in the mortality of the larvae. Cold exposure brought about significant decrease in enzymic activity of proteases, aminotransferases, diacylglycerol lipase and in the amounts of some haemolymph sugars and polyols. However, glycerol increased sharply in response to severe cold exposure. There was also a marked increase in the levels of protein, pyruvate, total free amino acids, total lipid, phospholipid and triacylglycerols. In the colder environment, carbohydrates served as the energy source. Glycerol appears to have conferred cryoprotection to the cold-stressed Philosamia ricini larvae.

THE EFFECT OF VITAMIN E ON GPT, GOT AND LDH ACTIVITY OF COLD EXPOSED RATS / 营养学报

To evaluate the effect of vitamin E on GPT, GOT and LDH activity of cold exposed rats, young male rats (70-100g body weight) were randomly divided into Ⅰ-Ⅲ groups. All the animals were fed on basic ration. The group I was given vitamin E 5mg (5mg/ml) intraperitoneally once every other day for 10 days. After the vitamin E treatment, group Ⅰ and Ⅲ were kept in a cold chamber (-1?1℃) and group Ⅱ at room temperature (20?1℃) for 48 hours. At the end of experimental period, serum GPT, GOT and LDH activity of all animals were analyzed. According to the data, the GPT, GOT and LDH activity were increased significantly in group I than in groups Ⅰ and Ⅱ. These results suggested that the vitamin E may have the efficiency of maintaining the structural integrity of the cells of cold exposed animals.

EFFECTS OF VITAMIN E ON URINARY CYCLIC NUCLEOTIDE EXCRETION OF COLD-EXPOSED RATS / 营养学报

The paper was designed to consider the effect of vitamin E on metabolism of cyclic nucleotide in cold exposed male rats. The urinary excretion of cyclic nucleotide was investigated by radioimmunoassay after male rats treated with vitamin E in 4℃ exposure. The results showed that urinary excretion of cyclic nucleotide had been increasing and cAMP/cGMP ratio had been not changing in cold exposed male rats. When one week of the experiment vitmin E could increase urinary cAMP excretion more in its treated group than cold exposed group alone (P