Characteristics of glucose and lipid metabolism and the interaction between gut microbiota and colonic mucosal immunity in pigs during cold exposure

Background Cold regions have long autumn and winter seasons and low ambient temperatures.When pigs are unable to adjust to the cold,oxidative damage and inflammation may develop.However,the differences between cold and non-cold adaptation regarding glucose and lipid metabolism,gut microbiota and colonic mucosal immunological features in pigs are unknown.This study revealed the glucose and lipid metabolic responses and the dual role of gut microbiota in pigs during cold and non-cold adaptation.Moreover,the regulatory effects of dietary glucose supplements on glucose and lipid metabolism and the colonic mucosal barrier were evaluated in cold-exposed pigs.Results Cold and non-cold-adapted models were established by Min and Yorkshire pigs.Our results exhibited that cold exposure induced glucose overconsumption in non-cold-adapted pig models(Yorkshire pigs),decreasing plasma glucose concentrations.In this case,cold exposure enhanced the ATGL and CPT-1αexpression to promote liver lipolysis and fatty acid oxidation.Meanwhile,the two probiotics(Collinsella and Bifidobacterium)depletion and the enrichment of two pathogens(Sutterella and Escherichia-Shigella)in colonic microbiota are not conducive to colonic mucosal immunity.However,glucagon-mediated hepatic glycogenolysis in cold-adapted pig models(Min pigs)maintained the stability of glucose homeostasis during cold exposure.It contributed to the gut microbiota(including the enrichment of the Rikenellaceae RC9 gut group,[Eubacterium]coprostanoligenes group and WCHB1-41)that favored cold-adapted metabolism.Conclusions The results of both models indicate that the gut microbiota during cold adaptation contributes to the protection of the colonic mucosa.During non-cold adaptation,cold-induced glucose overconsumption promotes thermogenesis through lipolysis,but interferes with the gut microbiome and colonic mucosal immunity.Furthermore,glucagon-mediated hepatic glycogenolysis contributes to glucose homeostasis during cold exposure.

Cold exposure promotes coronavirus infection by altering the gut microbiota and lipid metabolism to reduce host immunity

Objective:Cold exposure has been suggested to be advantageous for the spread and infection of the coronavirus,and the gut microbiota influences the severity of the infection by modulating host inflammatory and immune responses.However,it remains unclear whether the promotion of viral infection through cold exposure is linked to the gut microbiota.Methods:In this study,we performed an unbiased analysis of gut microbiota,serum,and lung tissue metabolome changes in cold-exposed and virus-infected mice,alongside the assessment of immune-inflammatory indicators in serum and lung tissue.Results:The results revealed that both cold exposure and viral infection significantly decreased the percentage of peripheral blood lymphocytes(CD4^(+)T cells,CD8^(+)T cells,and B cell)and increased the expression of inflammatory factors(IL-6,IL-1β,TNF-α,and IFN-γ).Meanwhile,cold exposure disrupted the homeostasis of gut microbiota,elevating the abundance of pathogenic bacteria(Staphylococcus)and diminishing the abundance of beneficial bacteria(Alistipes).Notably,in virus-infected mice exposed to a cold environment,the reduction in the abundance of beneficial bacteria Alistipes was more pronounced than in cases of single virus infection and cold exposure.Analysis of altered serum and lung tissue metabolites highlighted glycerophospholipids,fatty acids,and eicosanoids as the most affected metabolites by cold exposure.These metabolites,closely associated with virus infection,exhibited a significant correlation with immune-inflammatory indicators.Conclusion:These findings establish a mechanistic connection between cold exposure and virus infection,suggesting that cold exposure-induced dysregulation of gut microbiota and lipid metabolism diminishes host immunity,promoting virus infection.

Silicon dioxide nanoparticles inhibit the effects of cold exposure on metabolism and inflammatory responses in brown adipocytes

Objective:Nanoparticles(NPs)in haze are potentially hazardous to health,which is more severe in the winter.Brown adipose tissue(BAT)plays important roles in obesity,insulin resistance,and diabetes.Though the toxicology of NPs has been intensively studied,few studies have been reported on the antagonistic effects between Silicon dioxide(SiO_(2))NPs and cold exposure in brown adipocytes.Materials and methods:We evaluated changes by quantitative real-time reverse-transcriptase polymerase chain reaction(qRT-PCR)on metabolism genes,plasticity genes and the inflammatory responses genes in brown adipocytes in vitro.Results:The expression of adipogenic genes PRDM16,Dio2,PGC-1αand UCP1 was upregulated upon cold exposure(P<0.05),but downregulated by SiO_(2) NPs(P<0.05).The results demonstrated that there was antagonistic effect between SiO_(2) NPs and cold exposure on the plasticity genes and metabolism genes in brown adipocytes,where the main effects of SiO_(2) NPs or cold exposure on the plasticity genes and metabolism genes were significant(P<0.05).Moreover,the levels of interleukin(IL)-1β,IL-6 and tumor necrosis factor(TNF)-αwere upregulated by SiO_(2) NPs or cold exposure(P<0.05).The factorial analysis indicated that there was also antagonistic effect between SiO_(2) NPs and cold exposure on the toxic effects in brown adipocytes,in which the main effects of cold exposure and/or SiO_(2) NPs on the toxic effects were significant(P<0.05).Conclusion:SiO_(2) NPs inhibit the effect of cold exposure on metabolic genes and inflammatory responses genes in brown adipocytes.

Cold exposure alters proteomic profiles of the hypothalamus and pituitary in female rats

Objective:Studies have shown that both short-term and long-term cold exposures disturb the biological process.The aim of the present study is to investigate the effects of intermittent cold exposure on proteomic profiles in the hypothalamus and pituitary of female Sprague-Dawley(SD)rats.Materials and methods:The rats were exposed to-10°C in a cabin for 4 h per day,and the treatment lasted for 14 days.The comparative label-free LC-MS/MS analysis was performed to investigate the changes of proteomic profiles in the hypothalamus and pituitary.ELISA analysis was used to validate the expression of differential proteins.Results:22 differential proteins in the hypothalamus and 75 differential proteins in the pituitary were identified by the label-free proteomic analysis.Gene ontology annotation and enrichment analysis indicated that cold exposure disrupted protein phosphorylation,filopodium assembly,intracellular protein transport,peripheral nervous system neuron axonogenesis,spinal cord development,Golgi organization,positive regulation of pseudopodium assembly,and cell-cell adhesion.Three proteins(Cdc42,Ptprs,and Setd7)were down-regulated in the cold exposure group.Conclusion:The results indicate that intermittent cold exposure alters the proteomic profiles of hypothalamus and pituitary in female rats.

Artificial cold exposure induced stroke in renovascular hypertensive rats and its association with cold-inducible RNA binding protein mRNA expression in brain tissue and blood pressure

BACKGROUND： High incidence of stroke at interchange period of autumn and winter was demonstrated by epidemiological survey, and the specific causes should be further investigated. OBJECTIVE： To investigate the influence of artificial cold exposure on the incidence of stroke in renovascular hypertensive rats （RHR）, and analyze the association with blood pressure and cold-inducible RNA binding protein （CIRP） mRNA expression in brain tissue. DESIGN： A completely randomized grouping design, a randomized control animal trial. SETTINGS： Lab of Neurology, the First Affiliated Hospital of Sun Yat-sen University; Department of Chemistry, Open laboratory of Chemical Biology, Institute of Molecular Technology for Drug Discovery and Synthesis, University of Hong Kong. MATERIALS： Male SD rats （n=460）, weighing 80 - 100 g were obtained from Guangdong Province Health Animal Unit. A modified RXZ-300A intelligent artificial climate cabinet （Ningbo Jiangnan Instrument Co. ,Ltd., China）. METHODS： The experiment were processed in the Lab of Neurology, the First Affiliated Hospital of Sun Yat-sen University and the Open Laboratory of Chemical Biology, Institute of Molecular Technology for Drug Discovery and Synthesis, University of Hong Kong from October 2004 to November 2005. Rats （n = 400） were operated to establish 2-kidney 2-clip RHR model as described previously. The sham-operated rats （n =60） served as normotensive controls. Eight weeks later, 300 of RHR were randomly selected according to their systolic blood pressure （SBP） and divided into 3 sub-groups （n =100 per group）： mild hypertensive group （SBP of 160 - 200 mm Hg）, moderate hypertensive group （SBP of 200 - 220 mm Hg） and severe hypertensive group （SBP 〉 220 mm Hg）. Each group was further divided into two groups （n =50） under ACE and non-ACE. Normal sham-operated SD rats （n =60）, SBP 〈 140 mm Hg, were randomly divided into two groups： Sham-operated control group （n =30） under ACE and non-ACE. To establish the ACE and non-ACE treatment, rats were housed individually in artificial climate cabinet, and ACE was designed as three cycles of 12-hour light of 22℃ （7 ： 00 - 19 ： 00） and 12-hour dark of 4℃（19 ： 00 - 7 ： 00）. The non-ACE group was kept at 22℃ throughout the experiment. MAIN OUTCOME MEASURES： Blood Pressure changes were measured and stroke symptom were observed; Expression of the CIRP were examined by reverse transcription-polymerase chain reaction. RESULTS： Finally 360 rats were involved in the analysis of results. ①Incidence of stroke： The incidence of stroke in 2k2c RHR was significantly higher after a three-day intermittent （12-hour） ACE （29.3%） as compared with that in non-ACE （17.3%） （P 〈 0.05）. Furthermore, the severe hypertensive 2k2c RHR （BP 〉 220 mm Hg） was found to have much higher incidence of stroke （66%, 33/50） than the mild （8%, 4/50） and moderate （18%） hypertensive 2k2c RHR. ②CIRP mRNA in brain tissue： ACE treatment stimulated the mRNA expression of CIRP in non-stroke 2k2c RHR but not in stroke 2k2c RHR （P 〈 0.05）. CONCLUSION： High blood pressure and low expression of CIRP are associated with ACE induced stroke.

Stress injuries and autophagy in mouse hippocampus after chronic cold exposure

Cold exposure is an external stress factor that causes skin frostbite as well as a variety of diseases.Estrogen might participate in neuroprotection after cold exposure,but its precise mechanism remains unclear.In this study,mice were exposed to 10°C for 7 days and 0–4°C for 30 days to induce a model of chronic cold exposure.Results showed that oxidative stress-related c-fos and cyclooxygenase 2 expressions,MAP1LC3-labeled autophagic cells,Iba1-labeled activated microglia,and interleukin-1β-positive pyramidal cells were increased in the hippocampal CA1 area.Chronic cold exposure markedly elevated the levels of estrogen in the blood and the estrogen receptor,G protein-coupled receptor 30.These results indicate that neuroimmunoreactivity is involved in chronic cold exposure-induced pathological alterations,including oxidative stress,neuronal autophagy,and neuroimmunoreactivity.Moreover,estrogen exerts a neuroprotective effect on cold exposure.

Cold exposure and capsaicin promote 1,2-dimethylhyrazine-induced colon carcinogenesis in rats correlates with extracellular matrix remodeling

BACKGROUND Extracellular matrix(ECM)remodeling and stiffening,which are correlated with tumor malignancy,drives tumor development.However,the relationship between ECM remodeling and rat experimental model of 1,2-dimethylhyrazine(DMH)-induced colorectal cancer(CRC)imposed by cold and capsaicin exposure remains unclear.AIM To explore the effects of cold exposure and capsaicin on ECM remodeling and ECM enzymes in DMH-induced CRC.METHODS For histopathological analysis,the sections of colon tissues were stained with hematoxylin and eosin,Masson’s trichrome,Picrosirius red,and Weigert’s Resorcin-Fuchsin to observe the remodeling of collagen and elastin.Additionally,the protein expression level of type I collagen(COL I),type 3 collagen(COL III0,elastin,matrix metalloproteinase(MMP)1,MMP2,MMP9,and tissue-specific matrix metalloproteinase 1(TIMP1)was assessed by immunohistochemistry.The messenger RNA(mRNA)levels of COL I,COL III,elastin,and lysyl oxidase-like-2(LOXL2)in the colon tissues of rats was measured by reverse-transcriptase quantitative polymerase chain reaction.RESULTS Although no differences were observed in the proportion of adenomas,a trend towards the increase of invasive tumors was observed in the cold and capsaicin group.The cold exposure group had a metastasis rate compared with the other groups.Additionally,abnormal accumulation of both collagen and elastin was observed in the cold exposure and capsaicin group.Specifically,collagen quantitative analysis showed increased length,width,angle,and straightness compared with the DMH group.Collagen deposition and straightness were significantly increased in the cold exposure group compared with the capsaicin group.Cold exposure and capsaicin significantly increased the protein levels of COL I,elastin,and LOXL2 along with increases in their mRNA levels in the colon tissues compared with the DMH group,while COL III did not show a significant difference.Furthermore,in immunohistochemical evaluations,MMP1,MMP2,MMP9,and TIMP1 staining increased in the cold exposure and capsaicin group compared with the DMH group.CONCLUSION These results suggest that chronic cold and capsaicin exposure further increased the deposition of collagen and elastin in the colonic tissue.Increased COL I and elastin mRNA and protein levels expression may account for the enhanced ECM remodel and stiffness variations of colon tissue.The upregulated expression of the LOXL2 and physiological imbalance between MMP/TIMP activation and deactivation could contribute to the progression of the CRC resulting from cold and capsaicin exposure.

Glucose supplementation improves intestinal amino acid transport and muscle amino acid pool in pigs during chronic cold exposure

Mammals in northern regions chronically suffer from low temperatures during autumn-winter seasons.The aim of this study was to investigate the response of intestinal amino acid transport and the amino acid pool in muscle to chronic cold exposure via Min pig models(cold adaptation)and Yorkshire pig models(non-cold adaptation).Furthermore,this study explored the beneficial effects of glucose supplementation on small intestinal amino acid transport and amino acid pool in muscle of cold-exposed Yorkshire pigs.Min pigs(Exp.1)and Yorkshire pigs(Exp.2)were divided into a control group(17℃,n=6)and chronic cold exposure group(7℃,n=6),respectively.Twelve Yorkshire pigs(Exp.3)were divided into a cold control group and cold glucose supplementation group(8℃).The results showed that chronic cold exposure inhibited peptide transporter protein 1(PepT1)and excitatory amino acid transporter 3(EAAT3)expression in ileal mucosa and cationic amino acid transporter-1(CAT-1)in the jejunal mucosa of Yorkshire pigs(P<0.05).In contrast,CAT-1,PepT1 and EAAT3 expression was enhanced in the duodenal mucosa of Min pigs(P<0.05).Branched amino acids(BCAA)in the muscle of Yorkshire pigs were consumed by chronic cold exposure,accompanied by increased muscle RING-finger protein-1(MuRF1)and muscle atrophy F-box(atrogin-1)expression(P<0.05).More importantly,reduced concentrations of dystrophin were detected in the muscle of Yorkshire pigs(P<0.05).However,glycine concentration in the muscle of Min pigs was raised(P<0.05).In the absence of interaction between chronic cold exposure and glucose supplementation,glucose supplementation improved CAT-1 expression in the jejunal mucosa and PepT1 expression in the ileal mucosa of cold-exposed Yorkshire pigs(P<0.05).It also improved BCAA and inhibited MuRF1 and atrogin-1 expression in muscle(P<0.05).Moreover,dystrophin concentration was improved by glucose supplementation(P<0.05).In summary,chronic cold exposure inhibits amino acid absorption in the small intestine,depletes BCAA and promotes protein degradation in muscle.Glucose supplementation ameliorates the negative effects of chronic cold exposure on amino acid transport and the amino acid pool in muscle.

PITPNC1 promotes the thermogenesis of brown adipose tissue under acute cold exposure

Brown adipose tissue (BAT) plays an essential role in non-shivering thermogenesis. The phosphatidylinositol transfer protein, cytoplasmic 1 (PITPNC1) is identified as a lipid transporter that reciprocally transfers phospholipids between intracellular membrane structures. However, the physiological significance of PITPNC1 and its regulatory mechanism remain unclear. Here, we demonstrate that PITPNC1 is a key player in thermogenesis of BAT. While Pitpnc1^(−/−) mice do not differ with wildtype mice in body weight and insulin sensitivity on either chow or high-fat diet, they develop hypothermia when subjected to acute cold exposure at 4℃. The Pitpnc1^(−/−) brown adipocytes exhibit defective β-oxidation and abnormal thermogenesis-related metabolism pathways in mitochondria. The deficiency of lipid mobilization in Pitpnc1^(−/−) brown adipocytes might be the result of excessive accumulation of phosphatidylcholine and a reduction of phosphatidic acid. Our findings have uncovered significant roles of PITPNC1 in mitochondrial phospholipid homeostasis and BAT thermogenesis.

Effects of acute cold exposure on oxidative balance and total antioxidant capacity in juvenile Chinese soft-shelled turtle,Pelodiscus sinensis

Acute cold exposure may disturb the physiological homeostasis of the body in ectotherms.To date,there has been no information on the effects of cold exposure on homeostasis of reactive oxygen species(ROS)or antioxidant defense response in the Chinese soft-shelled turtle,Pelodiscus sinensis.In this study,P.sinensis juveniles were acclimated at 28℃,transferred to 8℃ as cold exposure for 12 h,then moved back to 28℃ rewarming for 24 h.We measured the ROS level and total antioxidant capacity(TAC)in the brain,liver,kidney and spleen at 2 and 12 h cold exposure,and at the end of the rewarming period.Malonaldehyde(MDA)and carbonyl protein were used as markers of oxidative damage.Turtles being maintained simultaneously at 28℃ were used as the control group.Cold exposure did not disturb the ROS balance in all 4 tissues,while rewarming raised the ROS level in the brain and kidney of P.sinensis.Cold exposure and rewarming decreased the TAC in the brain,liver and spleen but did not change the TAC in the kidney.MDA and carbonyl protein levels did not increase during the treatment,indicating no oxidative damage in all 4 tissues of P.sinensis.Our results indicated that extreme cold exposure did not impact the inner oxidative balance of P.sinensis,but more ROS was produced during rewarming.P.sinensis showed good tolerance to the harsh temperature change through effective protection of its antioxidant defense system to oxidative damage.This study provides basic data on the stress biology of P.sinensis.

Effects of intermittent cold-exposure on culprit plaque morphology in ST-segment elevation myocardial infarction patients: a retrospective study based on optical coherence tomography

Objective:Present study aimed to explore the effects of intermittent cold-exposure(ICE)on culprit plaque morphology in patients with ST-segment elevation myocardial infarction(STEMI)in frigid zone.Methods:Totally 848 STEMI patients with plaque rupture(N=637)or plaque erosion(N=211)were enrolled consecutively according to optical coherence tomography imaging.Data on the changes of outdoor air temperature corresponding to 24 solar terms were collected.Patients were divided into different groups according to 24 solar terms and the number of days with indoor central heating.Imaging data were measured and analyzed qualitatively and quantitatively.Statistical analysis was conducted to elucidate the possible association of the STEMI patients of different groups with plaque morphology of culprit vessel with alterations of ambient temperature.Results:The incidence of both plaque rupture and plaque erosion presented trough in summer.The incidence of plaque rupture reached a peak value in early winter when outdoor air temperature dropped below 0℃and declined with supply of central heating.Persistent cold exposure in early winter was positively and significantly associated with plaque rupture.The incidence of plaque erosion presented a peak in severe winter with outdoor air temperature dropping below-20℃and steady supply of central heating.ICE in severe winter was positively and significantly associated with plaque with intact intima,especially in aged male or current smoking patients.The positive correlation of cold exposure with lipid size in culprit plaque in winter weakened with central heating.Conclusion:ICE resulted from switching staying in between outdoor cold environment and indoor warm temperature with central heating in severe winter changed culprit plaque morphology in STEMI.Plaque rupture decreased whereas plaque erosion increased impacted by ICE.The effect of ICE on the transformation of plaque morphology might be explained by reduced lipid deposition.

Advancements in understanding inflammatory responses and the development of cardiovascular diseases under cold stimulation

Cold stimulation has been linked to acute myocardial infarction and other cardiovascular diseases.Residents in the frigid zones,such Heilongjiang Province,experience a higher incidence of adverse cardiovascular events during winter,posing a significant health threat and increasing the overall medical burden.Cold stimulation serves as an detrimental stressor,inducing inflammation in the body.Therefore,understanding the role of inflammatory responses induced by cold stimulation in the occurrence and development of cardiovascular diseases is of paramount importance.Given the impact of cold on inflammation in cardiovascular diseases and the expanding array of anti-inflammatory methods for the treatment of cardiovascular diseases,delving into the inflammatory responses mediated by can significantly complement cardiovascular disease management.This review explorest the synergistic relationship between cold stimulation and inflammation induction,elucidating how this interplay influences the occurrence and progression of cardiovascular diseases.

The effects of cold stimulation and exercise on human health

Cold stimulation and exercise are two independent stimulus variables,each yielding unique impacts on human health.However,in many cases,individuals often encounter both factors simultaneously,particularly in colder regions where outdoor physical activity is prevalent.Despite numerous studies exploring the effects of cold exposure and exercise independently,only a limited number of comprehensive reviews have evaluated their combined influence on health.This review aims to bridge this gap by meticulously examining the potential benefits and detriments of both cold stimulation and exercise on human health.Specifically,the review focuses on their impacts on cardiovascular,respiratory,and immune function,as well as the favorable effects of moderate exercise on the human body.While evidence suggests that cold exposure can enhance health outcomes in certain disease contexts,it also poses risks,particularly for vulnerable populations.Furthermore,while moderate exercise is generally beneficial,engaging in physical activity in cold weather conditions can increase the risk of hypothermia,frostbite,and other cold-related injuries.Consequently,there is an urgent need to develop safe and effective guidelines for exercising in cold weather,particularly for individuals living in colder regions.This review emphasizes the necessity for further research on the combined effects of cold stimulation and exercise,with the goal of informing public health policies and guidelines for physical activity in cold weather conditions.

Multiple inducible thermogenic mechanisms in the development of cold acclimatization

Extreme cold environment can threaten human health and life through increasing the risk of myocardial infarction,stroke,frostbite,and hypothermia.Insufficient heat production to maintain core body temperature is a major cause of cold injury.To cope with cold stress,human and other mammals have developed the capacity of cold acclimatization to adapt to such a harsh environment.Adaptive non-shivering thermogenesis is a ubiquitous form of cold acclimatization.This review article systematically summarizes the role of three inducible thermogenic forms,including food intake,circadian rhythms,and cold exposure in mediating non-shivering thermogenesis under cold exposure and presents the potential interventions for minimizing the adverse health consequences of cold temperature.

Research progress on adaptive modifications of the gut microflora and regulation of host glucose and lipid metabolism by cold stimulation

The gut microflora is a combination of all microbes in intestine and their microenvironment,and its change can sensitively reflect the relevant response of the body to external environment and remarkably affect body's metabolism as well.Recent studies have found that cold exposure affects the body's gut microflora,which can lead to changes in the body's metabolism of glucose and lipid.This review summarizes recent research on the effects of cold exposure on gut microbes and metabolism of glucose and lipid,aiming to provide some new ideas on the approaches and measures for the prevention and treatment of diabetes and obesity.

Tranilast treats cold-related hypertension by reducing the expression of NLRP3 inflammasome

Objective:Cold exposure is associated with increased prevalence of hypertension and the related severe cardiovascular events.Aberrant activation of the nucleotide-binding oligomerization domain-like receptor protein 3(NLRP3)inflammasome plays an important role in the development of hypertension.Tranilast(TR),an inhibitor of NLRP3,provides a useful pharmacological probe for exploring the role of NLRP3 in pathogenesis associated with inflammation and its potential application as a therapeutic agent.This study was designed to examine the effects of TR on NLRP3 and hypertension in rats exposed to cold environment to simulate the frigid-zone conditions.Methods and results:Sprague Dawley(SD)rats were exposed to moderate cold temperature(4±1℃),and then were randomized to receive TR or vehicle for 3 weeks,while the control group was raised under rat room temperature(RT,23±1℃).We found that cold exposure substantially increased blood pressure,NLRP3 inflammasome level,and fibrosis in aorta,which were reversed by TR.Conclusion:TR has an anti-hypertensive property in cold environment,and this beneficial action is likely conferred by its inhibitory effects on inflammation and fibrosis.These findings suggest TR as a potential drug for the treatment of cold-induced hypertension.

Mild Decrease in Skin Temperature Reduces the Heart Rate during Moderate Exercise

The purpose of this study was to investigate the effects of a mild decrease in skin temperature on the heart rate, substrate oxidation, and hormonal responses during exercise. Ten young men performed treadmill exercises approximately 65% of their maximal oxygen uptake for 60 min under two trials： （1） mild body cooling trial, and （2） control trial. Rectal and skin temperatures were recorded during and after exercise. Heart rate and oxygen uptake were monitored during exercise. Blood samples for catecholamine, cortisol, free fatty acid, insulin, and glucose concentrations were collected before, immediately after, and 1 h after exercise. In the mild body cooling trial, mean skin temperature decreased by 1.7 ＋ 0.7~C in the last minutes of exercise, compared with before exercise. No differences in rectal temperature were seen between the two trials. Although oxygen uptake during exercise and blood parameters did not differ between the trials, heart rate and subjective fatigue during exercise was lower in the mild body cooling trial than in the control trial. This study suggests that mild body cooling reduces the heart rate and subjective fatigue during moderate exercise, but does not affect substrate oxidation or hormonal responses to exercise.

Effect of Temperature on Emergency Ambulance Call-Outs for Cardiovascular Causes:A Scoping Review

Climate change has increased interest in the effects of the thermal environment on cardiovascular health.Most studies have focused on mortality data.However,pre-hospital care data are better able to evaluate these effects,as they can register the full spectrum of the disease in real time.This scoping review aims to synthesize the epidemiological evidence regarding the effects of the thermal environment on cardiovascular morbidity in the pre-hospital setting,evaluated through ambulance calls.A staged literature search was performed using the PubMed database for the period between 1st January 2000 and 30th March 2023,using the MeSH terms“Weather”AND“Emergency Medical Services”.A total of 987 publications were identified that examined the correlation between the thermal environment and ambulance call-outs for cardiovascular causes.The studies were mostly ecological time series,with significant variability in the methodological aspects employed.An increase in the number of ambulance call-outs has been observed in association with low temperatures,both for overall cardiovascular pathologies and for certain pathological subtypes.For high temperatures,no effect has been observed in overall call-outs,although an increase has been observed during heat waves.The demand for ambulances for cardiac arrests is increased by both low and high temperatures and during heat waves.Ambulance call-outs for cardiovascular causes increase with low temperatures and heat waves,with no significant increase in the overall demand associated with high temperatures.Ambulance call-outs for cardiac arrests are the only subtype that is increased by high temperatures.

Hibernation with rhythmicity:the circadian clock and hormonal adaptations of the hibernating Asiatic toads(Bufo gargarizans)

Hibernation is one of the fundamental strategies in response to cold environmental temperatures.During hibernation,the endocrine and circadian systems ensure minimal expenditure of energy for survival.The circadian rhythms of key hormones,melatonin(MT),corticosterone(CORT),triiodothyronine(T3),and thyroxine(T4),and the underlying molecular regulatory mechanisms of hibernation have been well determined in mammals but not in ectotherms.Here,a terrestrial hibernating species,Asiatic toad(Bufo gargarizans),was employed to investigate the plasma CORT,MT,T3,and T4;and the retina,brain,and liver mRNA expression of the core clock genes,including circadian locomotor output cycles kaput(Clock),brain and muscle ARNT-like 1(Bmal1),cryptochrome(Cry)1 and 2,and period(Per)1 and 2,at 7-time points over a 24-h period under acute cold(1 day at 4℃),and hibernation(45 days at 4℃).Our results showed that the circadian rhythms of the core clock genes were rather unaffected by acute cold exposure in the retina,unlike the brain and liver.In contrast,during hibernation,the liver clock genes displayed significant circadian oscillations,while those in the retina and brain stopped ticking.Furthermore,plasma CORT expressed circadian oscillations in both groups,and T3 in acute cold exposure group,whereas T4 and MT did not.Our results reveal that the plasma CORT and the liver sustain rhythmicity when the brain was not,indicating that the liver clock along with the adrenal clock synergistically maintains the metabolic requirements to ensure basic survival in hibernating Asiatic toads.