Summary: In order to assess the value of Doppler tissue imaging (DTI) in detecting viable hibernating myocardium, 20 patients with coronary artery disease and chronic left ventricular dysfunction underwent low dose d...Summary: In order to assess the value of Doppler tissue imaging (DTI) in detecting viable hibernating myocardium, 20 patients with coronary artery disease and chronic left ventricular dysfunction underwent low dose dobutamine stress echocardiography and low dose dobutamine stress DTI. The results showed that among the 100 asynergic segments, 35 segments showed improvement after dobutamine infusion (group H) and no changes were observed in the remaining 65 segments (group N). The left ventricular echocardiographic score index decreased from 1.60±0. 35 to 1.44±0.36 ( n =20, P <0.01). During low dose dobutamine stress DTI, there was no difference in the values of velosity of S wave (V s) before dobutamine infusion between two groups. However, after dobutamine infusion, the values of V s and VR in group H were significantly higher than those in group N (V s:10.1±3.0 cm/s vs 7.3±2.2 cm/s, P <0.01; VR: 60 %±41 % vs 25 %±32 %, P <0.001). 95.7 % asynergic myocardial segments with VR≤0 had no viability while 86 % asynergic segments with VR>80 % were viable myocardium. It is concluded that the different reactions to dobutamine stress between hibernating and necrosis myocardium could be showed by DTI and it is more clinically significant when VR≤0 and VR>80 %.展开更多
This study investigates the microclimatic connections between underground systems and the hibernation sites of particular species of bats. The distribution of hibernating bats was analysed in five selected zones desig...This study investigates the microclimatic connections between underground systems and the hibernation sites of particular species of bats. The distribution of hibernating bats was analysed in five selected zones designated Ⅰ-Ⅴ. These zones have a similar relative humidity, diverse temperature ranges inside the system, as well as air flow rates. A multi-year research programme highlighted the relationships between the occurrence of hibernating bats of various species and the microclimate of these particular zones. What is of essential importance are the sites with an air flow in their zones exceeding 0.02 m·s^-1, then is temperature and humidity. The air flow determines more intensive settling of wintering bats （zones Ⅲ, Ⅳand Ⅴ）. The zone Ⅱ-tourist zone with periodic air flows and often visited by humans is the least used by hibernating bats.展开更多
Objective： To investigate in chronic hibernating myocardium in rabbits and the influence and significance of captopril, betaloc, valsartan in angiotensin Ⅱ subtype 1 receptor（AT1R）, angiotensin Ⅱ subtype 2 recep...Objective： To investigate in chronic hibernating myocardium in rabbits and the influence and significance of captopril, betaloc, valsartan in angiotensin Ⅱ subtype 1 receptor（AT1R）, angiotensin Ⅱ subtype 2 receptor（AT2R）, extracellular signal regulated kinase 1/2 （ERK1/2）, c-Jun N-terminal kinase（JNK）. Methods： The model of chronic hibernating myocardium（CHM） was established. The changes of AT1R, AT2R, ERK1/2, JNK in different groups were assessed by western blotting and immunohistochemistry. Results： The amount of AT1R decreased while AT2R increased in the CON group compared with in sham group, and both AT1R and AT2R decreased in drug groups compared with the CON group. The content of ERK had no change in each group, while that of ＂expression＂ p-ERK increased in CON group compared with in sham group, and was lower in drug intervention groups than in CON and sham groups. The contents of JNK and p-JNK decreased in CON and drug intervention groups compared with in sham group. The protein levels of JNK, p-JNK in drug intervention groups were lower than in the CON group. Three drugs can inhibit interstitial fibrosis and reduce apoptotic cells. The expression levels in the groups（with different doses） had statistical difference as well as between groups of captopril and other drugs; however the results between betaloc and valsartan had no significant difference. Conclusion： AT1R, AT2R may be the upper stream receptor of ERK and JNK and may participate in generation and evolution of CHM. Captopril, valsartan and betaloc may preserve CHM by inhibiting ATIR, AT2R and JNK activity.展开更多
Changes in protein abundance and reversible protein phosphorylation(RPP)play important roles in regulating hypometabolism but have never been documented in overwintering frogs at high altitudes.To test the hypothesis ...Changes in protein abundance and reversible protein phosphorylation(RPP)play important roles in regulating hypometabolism but have never been documented in overwintering frogs at high altitudes.To test the hypothesis that protein abundance and phosphorylation change in response to winter hibernation,we conducted a comprehensive and quantitative proteomic and phosphoproteomic analysis of the liver of the Xizang plateau frog,Nanorana parkeri,living on the Qinghai-Xizang Plateau.In total,5170 proteins and 5695 phosphorylation sites in 1938 proteins were quantified.Based on proteomic analysis,674 differentially expressed proteins(438 up-regulated,236 down-regulated)were screened in hibernating N.parkeri versus summer individuals.Functional enrichment analysis revealed that higher expressed proteins in winter were significantly enriched in immune-related signaling pathways,whereas lower expressed proteins were mainly involved in metabolic processes.A total of 4251 modified sites(4147 up-regulated,104 down-regulated)belonging to 1638 phosphoproteins(1555 up-regulated,83 down-regulated)were significantly changed in the liver.During hibernation,RPP regulated a diverse array of proteins involved in multiple functions,including metabolic enzymatic activity,ion transport,protein turnover,signal transduction,and alternative splicing.These changes contribute to enhancing protection,suppressing energy-consuming processes,and inducing metabolic depression.Moreover,the activities of phosphofructokinase,glutamate dehydrogenase,and ATPase were all significantly lower in winter compared to summer.In conclusion,our results support the hypothesis and demonstrate the importance of RPP as a regulatory mechanism when animals transition into a hypometabolic state.展开更多
Juvenile three-keeled pond turtles(Chinemys reevesii) were fed diets supplemented with vitamin C(Vc) at doses of 0(basal diet, Vc0), 100(Vc100), 200(Vc200), 500(Vc500) and 2500(Vc2500) mg/kg diets at 28°C for 4 w...Juvenile three-keeled pond turtles(Chinemys reevesii) were fed diets supplemented with vitamin C(Vc) at doses of 0(basal diet, Vc0), 100(Vc100), 200(Vc200), 500(Vc500) and 2500(Vc2500) mg/kg diets at 28°C for 4 weeks, respectively. Then, the water temperature was gradually reduced to 10°C, and the turtles were induced into hibernation. Liver tissue samples were collected at three time points: start of hibernation(T1), 4 and 6 weeks’ hibernation(T2 and T3). A control group fed with the basal diet was set to parallel the whole treatment process, but reared at 28°C constantly. The results showed that hibernation mildly affected the antioxidant system and the influence varied with hibernating time. Hepatic malondialdehyde content of the Vc100 group was significantly lower than that of the other groups at T1. At T2, hepatic MDA in the groups of Vc500 and Vc2500 decreased significantly, while no clear differences were found among all groups at T3. The activities of antioxidant enzymes showed a positive correlation with dietary Vc dose before hibernation. After hibernation, total antioxidant capability was not affected by Vc. Superoxide dismutase activity became similar in different groups at T2, but decreased in higher Vc groups(≥ 200 mg/kg) at T3. Glutathione peroxidase and glutathione-S-transferase activities decreased significantly with dietary Vc supplementation(≥ 100 mg/kg) at T2, but recovered at T3. The result indicates that under normal rearing condition, low dietary Vc supplementation(< 100 mg/kg) might be beneficial to the antioxidant defense system. The effect of dietary Vc on the antioxidant defense system differed during hibernation.展开更多
Muscle wasting is common in mammals during extended periods of immobility. However, many small hibernating mammals manage to avoid muscle atrophy despite remaining stationary for long periods during hibernation. Recen...Muscle wasting is common in mammals during extended periods of immobility. However, many small hibernating mammals manage to avoid muscle atrophy despite remaining stationary for long periods during hibernation. Recent research has highlighted roles for short non-coding microRNAs （miRNAs） in the regulation of stress tolerance. We proposed that they could also play an important role in muscle maintenance during hibernation. To explore this possibility, a group of 10 miRNAs known to be normally expressed in skeletal muscle of non-hibernating mammals were analyzed by RT-PCR in hibernating little brown bats, Myotis lucifugus. We then compared the expression of these miRNAs in euthermic control bats and bats in torpor. Our results showed that compared to euthermic controls, sig- nificant, albeit modest （1.2-1.6 fold）, increases in transcript expression were observed for eight mature miRNAs, including miR-la-1, miR-29b, miR-181b, miR-15a, miR-20a, miR-206 and miR-128-1, in the pectoral muscle of torpid bats. Conversely, expression of miR-21 decreased by 80% during torpor, while expression of miR-107 remained unaffected. Interestingly, these miRNAs have been either validated or predicted to affect multiple muscle-specific factors, including myostatin, FoxO3a, HDAC4 and SMADT, and are likely involved in the preservation of pectoral muscle mass and functionality during bat hibernation.展开更多
The unit firing activities of neurons in the preoptic area (POA) of ground squirrel hypothalamic tissue slices were recorded and the metabolism of NA in hypothalamus was measured with high performance liquid chromatog...The unit firing activities of neurons in the preoptic area (POA) of ground squirrel hypothalamic tissue slices were recorded and the metabolism of NA in hypothalamus was measured with high performance liquid chromatography (HPLC). Thermosensitivity, proportions, the critical temperature (Tc) and the lowest temperature (TL) of firing activity of the above mentioned neurons, and NA metabolism in hypothalamus were compared in different seasons and hibernating phases. In comparison with that in summer euthermar, it was shown that (i) the percentage and thermosensitivity of the POA neurons varied respectively in the hibernating phases; (ii) TL and Tc of the POA neurons in winter, both euthermar and hibernation, were markedly decreased; (iii) the POA neurons in hibernation became much more sensitive to NA, and the response of cold sensitive neurons to NA changed from inhibiting pattern in summer to exciting one in hibernation; (iv) the contents and metabolism of NA in hypothalamus decreased significantly in the entering phase and deep hibernation phase, while the metabolism of NA increased remarkably in the arousal phase. These changes might explain the regulatory mechanism how ground squirrel actively decreases body temperature (Tb) in entering into hibernation and quickly recovers body temperature in arousal phase.展开更多
Mammalian hibernation is associated with multiple physiological, biochemical, and molecular changes that allow animals to endure colder temperatures. We hypothesize that long non-coding RNAs（lnc RNAs）, a group of no...Mammalian hibernation is associated with multiple physiological, biochemical, and molecular changes that allow animals to endure colder temperatures. We hypothesize that long non-coding RNAs（lnc RNAs）, a group of non-coding transcripts with diverse functions, are differentially expressed during hibernation. In this study, expression levels of lncRNAs H19 and TUG1 were assessed via qRT-PCR in liver, heart, and skeletal muscle tissues of the hibernating thirteen-lined ground squirrels（Ictidomys tridecemlineatus）. TUG1 transcript levels were significantly elevated 1.94-fold in skeletal muscle of hibernating animals when compared with euthermic animals. Furthermore, transcript levels of HSF2 also increased 2.44-fold in the skeletal muscle in hibernating animals. HSF2 encodes a transcription factor that can be negatively regulated by TUG1 levels and that influences heat shock protein expression. Thus, these observations support the differential expression of the TUG1-HSF2 axis during hibernation. To our knowledge, this study provides the first evidence for differential expression of lnc RNAs in torpid ground squirrels, adding lnc RNAs as another group of transcripts modulated in this mammalian species during hibernation.展开更多
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 rh...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.展开更多
In the 19^(th)century,von Frerichs F and Flint A identified a type of acute renal impairment associated with advanced liver disease,characterized by oliguria,absence of proteinuria,and normal renal histology,which was...In the 19^(th)century,von Frerichs F and Flint A identified a type of acute renal impairment associated with advanced liver disease,characterized by oliguria,absence of proteinuria,and normal renal histology,which was later termed hepatorenal syndrome(HRS).HRS primarily affects cirrhotic patients with ascites and often follows severe infections,digestive hemorrhages,or high-volume paracentesis.Pathophysiologically,HRS involves low glomerular filtration rate,hypotension,renin-angiotensin axis activation,water clearance,hyponatremia,and minimal urinary sodium excretion.These conditions mimic those seen in decreased effective circulatory volume(ECV)scenarios such as septic shock or heart failure.HRS represents a specific form of prerenal acute kidney injury(AKI)in patients with baseline renal ischemia,where the kidney attempts to correct decreased ECV by retaining sodium and water.Intense renal vasoconstriction,passive hyperemia from ascites,and acute tubular necrosis(ATN)with specific urinary sediment changes are observed.Persistent oliguria may transition HRS to ATN,although this shift is less straightforward than in other prerenal AKI contexts.Notably,liver grafts from HRS patients can recover function more rapidly than those from other ischemic conditions.Experimental studies,such as those by Duailibe et al,using omega-3 fatty acids in cirrhotic rat models,have shown promising results in reducing oxidative stress and improving kidney function.These findings suggest potential therapeutic strategies and underscore the need for further research to understand the mechanisms of HRS and explore possible treatments.Future research should address the impact of omega-3 on survival and secondary outcomes,as well as consider the balance of therapeutic risks and benefits in severe liver disease.展开更多
Dear readers:Spring has set in as the Chinese Spring Festival marks the beginning of the charming and life-booming season of the year when the hibernates wake up and the plants come back to life to the summon of the M...Dear readers:Spring has set in as the Chinese Spring Festival marks the beginning of the charming and life-booming season of the year when the hibernates wake up and the plants come back to life to the summon of the Mother Nature,where tree leafs turn green,rivers break the ice to run,the landscape is burgeoning with vigorous fauna and flora,the blessings that we feel very thankful for.But it is not the seasonal warmth that we are now feeling in the economic climate of the troubled world.展开更多
The diversity of rodents in Asian deserts is high.Nevertheless,little is known about their use of daily torpor and hibernation,which are employed by many small mammals worldwide for energy and water conservation to pe...The diversity of rodents in Asian deserts is high.Nevertheless,little is known about their use of daily torpor and hibernation,which are employed by many small mammals worldwide for energy and water conservation to permit survival under adverse environmental conditions.We quantified for the first time,using temperature transponders and data loggers,long-term torpor expression and patterns in sympatric desert hamsters Phodopus roborovskii,striped hamsters Cricetulus barabensis and 3-toed jerboas Dipus sagitta under controlled conditions.Animals were live-trapped in Inner Mongolia in August and held in captivity under short photoperiods and low ambient temperatures(T,s)for about 6 months.Both hamster species(~half of individuals)expressed spontaneous(food available)daily torpor.Daily torpor in desert hamsters was less frequent and shallower than that in striped hamsters,which also had longer torpor bouts during torpor at T 15.8±0.4℃.Only one individual jerboa entered hibernation spontaneously at T,6.2±0.5℃,but all hibernated after food deprivation.The 2 hamster species only slightly changed their body mass during the acclimation,whereas jerboas greatly increased their body mass by 27.9%during the first 2 months of acclimation probably as a preparation for the hibernating season.Our data show that short photoperiod and moderately low T,induces spontaneous daily torpor in the 2 hamster species,suggesting that it is used regularly in the wild.Hibernation in Jerboas occurred at T,6.2±0.5°C especially when food was withheld suggesting limited food availability is the proximate trigger of their hibernation.展开更多
文摘Summary: In order to assess the value of Doppler tissue imaging (DTI) in detecting viable hibernating myocardium, 20 patients with coronary artery disease and chronic left ventricular dysfunction underwent low dose dobutamine stress echocardiography and low dose dobutamine stress DTI. The results showed that among the 100 asynergic segments, 35 segments showed improvement after dobutamine infusion (group H) and no changes were observed in the remaining 65 segments (group N). The left ventricular echocardiographic score index decreased from 1.60±0. 35 to 1.44±0.36 ( n =20, P <0.01). During low dose dobutamine stress DTI, there was no difference in the values of velosity of S wave (V s) before dobutamine infusion between two groups. However, after dobutamine infusion, the values of V s and VR in group H were significantly higher than those in group N (V s:10.1±3.0 cm/s vs 7.3±2.2 cm/s, P <0.01; VR: 60 %±41 % vs 25 %±32 %, P <0.001). 95.7 % asynergic myocardial segments with VR≤0 had no viability while 86 % asynergic segments with VR>80 % were viable myocardium. It is concluded that the different reactions to dobutamine stress between hibernating and necrosis myocardium could be showed by DTI and it is more clinically significant when VR≤0 and VR>80 %.
文摘This study investigates the microclimatic connections between underground systems and the hibernation sites of particular species of bats. The distribution of hibernating bats was analysed in five selected zones designated Ⅰ-Ⅴ. These zones have a similar relative humidity, diverse temperature ranges inside the system, as well as air flow rates. A multi-year research programme highlighted the relationships between the occurrence of hibernating bats of various species and the microclimate of these particular zones. What is of essential importance are the sites with an air flow in their zones exceeding 0.02 m·s^-1, then is temperature and humidity. The air flow determines more intensive settling of wintering bats （zones Ⅲ, Ⅳand Ⅴ）. The zone Ⅱ-tourist zone with periodic air flows and often visited by humans is the least used by hibernating bats.
基金the Natural Science Fundfor Colleges and Universities in Jiangsu Province(03KJB320145)the Science and Technology projects fund of Xuzhou city(X2002036)
文摘Objective： To investigate in chronic hibernating myocardium in rabbits and the influence and significance of captopril, betaloc, valsartan in angiotensin Ⅱ subtype 1 receptor（AT1R）, angiotensin Ⅱ subtype 2 receptor（AT2R）, extracellular signal regulated kinase 1/2 （ERK1/2）, c-Jun N-terminal kinase（JNK）. Methods： The model of chronic hibernating myocardium（CHM） was established. The changes of AT1R, AT2R, ERK1/2, JNK in different groups were assessed by western blotting and immunohistochemistry. Results： The amount of AT1R decreased while AT2R increased in the CON group compared with in sham group, and both AT1R and AT2R decreased in drug groups compared with the CON group. The content of ERK had no change in each group, while that of ＂expression＂ p-ERK increased in CON group compared with in sham group, and was lower in drug intervention groups than in CON and sham groups. The contents of JNK and p-JNK decreased in CON and drug intervention groups compared with in sham group. The protein levels of JNK, p-JNK in drug intervention groups were lower than in the CON group. Three drugs can inhibit interstitial fibrosis and reduce apoptotic cells. The expression levels in the groups（with different doses） had statistical difference as well as between groups of captopril and other drugs; however the results between betaloc and valsartan had no significant difference. Conclusion： AT1R, AT2R may be the upper stream receptor of ERK and JNK and may participate in generation and evolution of CHM. Captopril, valsartan and betaloc may preserve CHM by inhibiting ATIR, AT2R and JNK activity.
基金supported by the National Natural Science Foundation of China(32001110)Training Program for Cultivating Highlevel Talents by the China Scholarship Council(2021lxjjw01)Open Project of State Key Laboratory of Plateau Ecology and Agriculture,Qinghai University(2021-KF-004)。
文摘Changes in protein abundance and reversible protein phosphorylation(RPP)play important roles in regulating hypometabolism but have never been documented in overwintering frogs at high altitudes.To test the hypothesis that protein abundance and phosphorylation change in response to winter hibernation,we conducted a comprehensive and quantitative proteomic and phosphoproteomic analysis of the liver of the Xizang plateau frog,Nanorana parkeri,living on the Qinghai-Xizang Plateau.In total,5170 proteins and 5695 phosphorylation sites in 1938 proteins were quantified.Based on proteomic analysis,674 differentially expressed proteins(438 up-regulated,236 down-regulated)were screened in hibernating N.parkeri versus summer individuals.Functional enrichment analysis revealed that higher expressed proteins in winter were significantly enriched in immune-related signaling pathways,whereas lower expressed proteins were mainly involved in metabolic processes.A total of 4251 modified sites(4147 up-regulated,104 down-regulated)belonging to 1638 phosphoproteins(1555 up-regulated,83 down-regulated)were significantly changed in the liver.During hibernation,RPP regulated a diverse array of proteins involved in multiple functions,including metabolic enzymatic activity,ion transport,protein turnover,signal transduction,and alternative splicing.These changes contribute to enhancing protection,suppressing energy-consuming processes,and inducing metabolic depression.Moreover,the activities of phosphofructokinase,glutamate dehydrogenase,and ATPase were all significantly lower in winter compared to summer.In conclusion,our results support the hypothesis and demonstrate the importance of RPP as a regulatory mechanism when animals transition into a hypometabolic state.
文摘Juvenile three-keeled pond turtles(Chinemys reevesii) were fed diets supplemented with vitamin C(Vc) at doses of 0(basal diet, Vc0), 100(Vc100), 200(Vc200), 500(Vc500) and 2500(Vc2500) mg/kg diets at 28°C for 4 weeks, respectively. Then, the water temperature was gradually reduced to 10°C, and the turtles were induced into hibernation. Liver tissue samples were collected at three time points: start of hibernation(T1), 4 and 6 weeks’ hibernation(T2 and T3). A control group fed with the basal diet was set to parallel the whole treatment process, but reared at 28°C constantly. The results showed that hibernation mildly affected the antioxidant system and the influence varied with hibernating time. Hepatic malondialdehyde content of the Vc100 group was significantly lower than that of the other groups at T1. At T2, hepatic MDA in the groups of Vc500 and Vc2500 decreased significantly, while no clear differences were found among all groups at T3. The activities of antioxidant enzymes showed a positive correlation with dietary Vc dose before hibernation. After hibernation, total antioxidant capability was not affected by Vc. Superoxide dismutase activity became similar in different groups at T2, but decreased in higher Vc groups(≥ 200 mg/kg) at T3. Glutathione peroxidase and glutathione-S-transferase activities decreased significantly with dietary Vc supplementation(≥ 100 mg/kg) at T2, but recovered at T3. The result indicates that under normal rearing condition, low dietary Vc supplementation(< 100 mg/kg) might be beneficial to the antioxidant defense system. The effect of dietary Vc on the antioxidant defense system differed during hibernation.
基金supported by a Discovery grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada (Grant No. 6793)
文摘Muscle wasting is common in mammals during extended periods of immobility. However, many small hibernating mammals manage to avoid muscle atrophy despite remaining stationary for long periods during hibernation. Recent research has highlighted roles for short non-coding microRNAs （miRNAs） in the regulation of stress tolerance. We proposed that they could also play an important role in muscle maintenance during hibernation. To explore this possibility, a group of 10 miRNAs known to be normally expressed in skeletal muscle of non-hibernating mammals were analyzed by RT-PCR in hibernating little brown bats, Myotis lucifugus. We then compared the expression of these miRNAs in euthermic control bats and bats in torpor. Our results showed that compared to euthermic controls, sig- nificant, albeit modest （1.2-1.6 fold）, increases in transcript expression were observed for eight mature miRNAs, including miR-la-1, miR-29b, miR-181b, miR-15a, miR-20a, miR-206 and miR-128-1, in the pectoral muscle of torpid bats. Conversely, expression of miR-21 decreased by 80% during torpor, while expression of miR-107 remained unaffected. Interestingly, these miRNAs have been either validated or predicted to affect multiple muscle-specific factors, including myostatin, FoxO3a, HDAC4 and SMADT, and are likely involved in the preservation of pectoral muscle mass and functionality during bat hibernation.
文摘The unit firing activities of neurons in the preoptic area (POA) of ground squirrel hypothalamic tissue slices were recorded and the metabolism of NA in hypothalamus was measured with high performance liquid chromatography (HPLC). Thermosensitivity, proportions, the critical temperature (Tc) and the lowest temperature (TL) of firing activity of the above mentioned neurons, and NA metabolism in hypothalamus were compared in different seasons and hibernating phases. In comparison with that in summer euthermar, it was shown that (i) the percentage and thermosensitivity of the POA neurons varied respectively in the hibernating phases; (ii) TL and Tc of the POA neurons in winter, both euthermar and hibernation, were markedly decreased; (iii) the POA neurons in hibernation became much more sensitive to NA, and the response of cold sensitive neurons to NA changed from inhibiting pattern in summer to exciting one in hibernation; (iv) the contents and metabolism of NA in hypothalamus decreased significantly in the entering phase and deep hibernation phase, while the metabolism of NA increased remarkably in the arousal phase. These changes might explain the regulatory mechanism how ground squirrel actively decreases body temperature (Tb) in entering into hibernation and quickly recovers body temperature in arousal phase.
基金supported by a Discovery Grant from the Natural Sciences and Engineering Research Council of Canada (Grant No. RGPIN/402222-2012) awarded to PJM
文摘Mammalian hibernation is associated with multiple physiological, biochemical, and molecular changes that allow animals to endure colder temperatures. We hypothesize that long non-coding RNAs（lnc RNAs）, a group of non-coding transcripts with diverse functions, are differentially expressed during hibernation. In this study, expression levels of lncRNAs H19 and TUG1 were assessed via qRT-PCR in liver, heart, and skeletal muscle tissues of the hibernating thirteen-lined ground squirrels（Ictidomys tridecemlineatus）. TUG1 transcript levels were significantly elevated 1.94-fold in skeletal muscle of hibernating animals when compared with euthermic animals. Furthermore, transcript levels of HSF2 also increased 2.44-fold in the skeletal muscle in hibernating animals. HSF2 encodes a transcription factor that can be negatively regulated by TUG1 levels and that influences heat shock protein expression. Thus, these observations support the differential expression of the TUG1-HSF2 axis during hibernation. To our knowledge, this study provides the first evidence for differential expression of lnc RNAs in torpid ground squirrels, adding lnc RNAs as another group of transcripts modulated in this mammalian species during hibernation.
基金This work was supported by the National Natural Science Foundation of China(NSFC,31270457,30800129 to Z.X.),NSFC(31971413)the Natural Science Foundation of Hebei Province(NSFHB,C2020205038 to D.L).
文摘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.
文摘In the 19^(th)century,von Frerichs F and Flint A identified a type of acute renal impairment associated with advanced liver disease,characterized by oliguria,absence of proteinuria,and normal renal histology,which was later termed hepatorenal syndrome(HRS).HRS primarily affects cirrhotic patients with ascites and often follows severe infections,digestive hemorrhages,or high-volume paracentesis.Pathophysiologically,HRS involves low glomerular filtration rate,hypotension,renin-angiotensin axis activation,water clearance,hyponatremia,and minimal urinary sodium excretion.These conditions mimic those seen in decreased effective circulatory volume(ECV)scenarios such as septic shock or heart failure.HRS represents a specific form of prerenal acute kidney injury(AKI)in patients with baseline renal ischemia,where the kidney attempts to correct decreased ECV by retaining sodium and water.Intense renal vasoconstriction,passive hyperemia from ascites,and acute tubular necrosis(ATN)with specific urinary sediment changes are observed.Persistent oliguria may transition HRS to ATN,although this shift is less straightforward than in other prerenal AKI contexts.Notably,liver grafts from HRS patients can recover function more rapidly than those from other ischemic conditions.Experimental studies,such as those by Duailibe et al,using omega-3 fatty acids in cirrhotic rat models,have shown promising results in reducing oxidative stress and improving kidney function.These findings suggest potential therapeutic strategies and underscore the need for further research to understand the mechanisms of HRS and explore possible treatments.Future research should address the impact of omega-3 on survival and secondary outcomes,as well as consider the balance of therapeutic risks and benefits in severe liver disease.
文摘Dear readers:Spring has set in as the Chinese Spring Festival marks the beginning of the charming and life-booming season of the year when the hibernates wake up and the plants come back to life to the summon of the Mother Nature,where tree leafs turn green,rivers break the ice to run,the landscape is burgeoning with vigorous fauna and flora,the blessings that we feel very thankful for.But it is not the seasonal warmth that we are now feeling in the economic climate of the troubled world.
基金supported by grants from the National Natural Science Foundation of China to QSC(31470473 and 32260261)a Chinese Academy of Sciences Visiting Scientists Fellowship to FG.
文摘The diversity of rodents in Asian deserts is high.Nevertheless,little is known about their use of daily torpor and hibernation,which are employed by many small mammals worldwide for energy and water conservation to permit survival under adverse environmental conditions.We quantified for the first time,using temperature transponders and data loggers,long-term torpor expression and patterns in sympatric desert hamsters Phodopus roborovskii,striped hamsters Cricetulus barabensis and 3-toed jerboas Dipus sagitta under controlled conditions.Animals were live-trapped in Inner Mongolia in August and held in captivity under short photoperiods and low ambient temperatures(T,s)for about 6 months.Both hamster species(~half of individuals)expressed spontaneous(food available)daily torpor.Daily torpor in desert hamsters was less frequent and shallower than that in striped hamsters,which also had longer torpor bouts during torpor at T 15.8±0.4℃.Only one individual jerboa entered hibernation spontaneously at T,6.2±0.5℃,but all hibernated after food deprivation.The 2 hamster species only slightly changed their body mass during the acclimation,whereas jerboas greatly increased their body mass by 27.9%during the first 2 months of acclimation probably as a preparation for the hibernating season.Our data show that short photoperiod and moderately low T,induces spontaneous daily torpor in the 2 hamster species,suggesting that it is used regularly in the wild.Hibernation in Jerboas occurred at T,6.2±0.5°C especially when food was withheld suggesting limited food availability is the proximate trigger of their hibernation.
