The plateau pika (Ochotona curzoniae) has a strong adaptability to hypoxic plateau environment. We found that the sperm-specific lactate dehydrogenase (LDH-C4) gene Ldh-c expressed in plateau pika cardiac muscle. In order to shed light on the effect of LDH-C4 on the anaerobic glycolysis in plateau pika cardiac muscle, 20 pikas were randomly divided into the inhibitor group and the control group, and the sample size of each group was 10. The pikas of inhibitor group were injected with 1 mL 1 mol/L N-isopropyl oxamate, a specific LDH-C4 inhibitor, in biceps femoris muscle of hind legs, each leg with 500 μL. The pikas of control group were injected with the same volume of normal saline (0.9% NaCl). The mRNA and protein expression levels of Ldh-c gene in plateau pika cardiac muscle were determined by real-time PCR and Western blot. The activities of LDH, and the contents of lactate (LD) and ATP in cardiac muscle were compared between the inhibitor group and the control group. The results showed that 1) the expression levels of Ldh-c mRNA and protein were 0.47 ± 0.06 and 0.68 ± 0.08, respectively; 2) 30 min after injection of 1 mL 1 mol/L N-isopropyl oxamate in biceps femoris muscle, the concentration of N-isopropyl oxamate in blood was 0.08 mmol/L; 3) in cardiac muscle of the inhibitor group and the control group, the LDH activities were (6.18 ± 0.48) U/mg and (9.08 ± 0.58) U/mg, the contents of LD were (0.21 ± 0.03) mmol/g and (0.26 ± 0.04) mmol/g, and the contents of ATP were (4.40 ± 0.69) nmol/mg and (6.18 ± 0.73) nmol/mg (P < 0.01); 5) the inhibition rates of N-isopropyl oxamate to LDH, LD and ATP were 31.98%, 20.90% and 28.70%, respectively. The results suggest that Ldh-c expresses in cardiac muscle of plateau pika, and the pika cardiac muscle may get at least 28% ATP for its activities by LDH-C4 catalyzed anaerobic glycolysis, which reduces the dependence on oxygen and enhances the adaptation to the hypoxic environments.
Acclimatization ; Animals ; Glycolysis ; Hypoxia ; Isoenzymes ; genetics ; metabolism ; L-Lactate Dehydrogenase ; genetics ; metabolism ; Lactic Acid ; analysis ; Lagomorpha ; genetics ; Male ; Myocardium ; enzymology ; Oxamic Acid ; analogs & derivatives ; Oxygen ; RNA, Messenger

Objective To investigate the effect of plateau hypoxia on the blood-brain barrier after subarachnoid hemorrhage (SAH) in rats. Methods Adult male SD rats (n = 78) were randomly divided into 4 groups: sham group (sham), SAH model group (SAH), plateau hypoxia sham group (Hp sham) and plateau hypoxia SAH model group (Hp SAH). The rat model of plateau hypoxia was established through low-pressure simulation chamber (altitude 5000 m), and the SAH model was established by endovascular perforation method. At 24 hours after SAH, neurobehavior score and SAH grade were assessed. The morphological changes of neurons and apoptosis of nerve cells in the CA1 region of hippocampal were observed by the staining of Nissl and TUNEL. The expression of phosphorylated PI3K (p-PI3K), PI3K, phosphorylated Akt (p-Akt), Akt, phosphorylated nuclear factor κB (p-NF-κB), NF-κB, matrix metalloproteinase-9 (MMP-9), occludin and claudin-5 in hippocampal were detected by the method of Western blotting. The expression of occludin and claudin-5 proteins in the CA1 region of hippocampal were observed by immunofluorescent staining. Results At 24 hours after SAH, the neurobehavior score decreased significantly and SAH grade increased significantly in the SAH and Hp SAH group (P< 0.05). Neurobehavior score decreased significantly in the Hp SAH group compared with the SAH group (P < 0.05). In the SAH group, neurons in the CA1 region of hippocampus were atrophied and deformed, the arrangement were disordered, the number of neurons decreased significantly, and the apoptosis of nerve cells increased significantly(P< 0.05). Plateau hypoxia could aggravate the morphological damage of neurons and apoptosis of nerve cells. The expression of p-PI3K/PI3K, p-Akt/Akt, occludin and claudin-5 proteins decreased significantly, while the expression of p-NF-κB/NF-κB and MMP-9 proteins increased significantly in the SAH and Hp SAH group (P< 0.05). The expression of p-PI3K/PI3K and MMP-9 proteins increased significantly in Hp SAH group compared with the SAH group. The expression of claudin-5 protein increased significantly in Hp sham group compared with the sham group (P < 0.05). Immunofluorescent staining showed that the expression of occludin and claudin-5 proteins in the CA1 region of hippocampus decreased in the SAH group. Plateau hypoxia could further decreased the expression of occludin and claudin-5 proteins. Conclusion Plateau hypoxia aggravates blood-brain barrier disruption after subarachnoid hemorrhage in rats through inhibiting PI3K/Akt/NF-κB pathway.

This study was designed to investigate the role of activation of the ferroptosis pathway in the inhibition of esophageal cancer proliferation and metastasis by realgar, using esophageal cancer Eca109 and KYSE150 cells as the target cells. The rate of inhibition and half-inhibitory concentration (IC₅₀) were measured by the CCK-8 method; clone formation ability was measured by clone formation assay; the changes in reactive oxygen species (ROS) were detected by flow cytometry; the ultrastructure of the cells was observed by transmission electron microscopy; the distribution of intracellular iron particles was observed by Prussian blue staining; the expression of glutathione peroxidase 4 (GPX4) was detected by immunofluorescence staining; the scratch assay was used to detect the cell migration ability; the Transwell assay was used to detect the cell invasion ability; and western blotting was used to detect E-cadherin, Slug and N-cadherin protein expression in the cells. The results show that realgar inhibited the proliferation of Eca109 and KYSE150 cells in a time- and concentration-dependent manner, and the IC₅₀ of Eca109 and KYSE150 cells was 64.297 and 51.337 μmol‧L^-1, respectively. Compared with the control group, many mitochondria in the cytoplasm of Eca109 and KYSE150 cells in the realgar 2IC₅₀ group were swollen and blue-stained particles of different sizes and amounts were found, and ROS fluorescence intensity was significantly increased while GPX4 protein expression was significantly reduced (P < 0.01). Compared with the realgar group, the proliferation, migration, membrane penetration and Slug and N-cadherin protein expression were significantly increased, and the cell inhibition rate and E-cadherin protein expression were significantly decreased in Eca109 and KYSE150 cells in the realgar+ZVAD-FMK group (P < 0.05). The proliferation, migration, membrane penetration and Slug and N-cadherin protein expression were significantly decreased, and the cell inhibition rate and E-cadherin protein expression were significantly increased of Eca109 and KYSE150 cells in the realgar +erastin group (P < 0.05). The above results show that realgar inhibited the proliferation of Eca109 and KYSE150 cells and induced partial ferroptosis in the cells, and the proliferation and metastasis effects of realgar on esophageal cancer cells may work through partial ferroptosis pathway activation.

Vascular endothelial growth factor (VEGF) plays an important role in tissues angiogenesis. The adaptation of animals to hypoxic environment is relative to the microvessel density (MVD) in tissues. To further explore the adaptation mechanisms of plateau zokor (Myospalax baileyi) to the hypoxic-hypercapnic burrows, the VEGF mRNA and the MVD in cerebral tissues of the plateau zokor were studied. Total RNA was isolated from liver, and VEGF cDNA was obtained by RT-PCR, then the VEGF cDNA was cloned and sequenced. The coding sequence of plateau pika (Ochotona curzniae), rat (Rattus norvegicus) and mouse (Mus musculus) VEGF cDNA are obtained from GenBank, and the nucleotide and amino acid sequence homology of plateau zokor VEGF cDNA coding sequence with that of plateau pika, rat and mouse were analyzed and compared by using of bioinformatics software. The VEGF mRNA was detected by real-time PCR, and the MVDs in cerebral tissues of the plateau zokor, plateau pika and Sprague-Dawley (SD) rat were measured by immunohistochemical staining. The results showed that the open reading frame of the plateau zokor VEGF was 645 bp, and the coding sequence of the plateau zokor VEGF cDNA shared 92.1%, 93.6% and 93.8% nucleotide sequence homology to that of the plateau pika, rat and mouse, respectively. The deduced amino acid sequence of the plateau zokor VEGF cDNA was composed of 188 amino acids and the amino acids from 1 to 26 were signal peptide sequence. The plateau zokor VEGF188 was 90.2%, 94.9% and 94.4% homologous to that of plateau pika, rat and mouse. The level of VEGF mRNA in brain of the plateau zokor was significantly lower than that of SD rat, but there was no obvious difference in VEGF mRNA level between plateau zokor and plateau pika. The MVD in brain of the plateau zokor was markedly higher than that of plateau pika and SD rat. In conclusion, plateau zokor enhances its adaptation to the hypoxic environment by increasing the MVD. The level of VEGF mRNA in the brain of plateau zokor is lower than that of SD rat, which may be as a result of inhibition by the higher concentration of carbon dioxide in the burrow.
Adaptation, Physiological ; physiology ; Amino Acid Sequence ; Animals ; Arvicolinae ; physiology ; Base Sequence ; Brain ; blood supply ; metabolism ; Hypoxia ; physiopathology ; Microvessels ; anatomy & histology ; Molecular Sequence Data ; RNA, Messenger ; genetics ; metabolism ; Rats ; Rats, Sprague-Dawley ; Species Specificity ; Vascular Endothelial Growth Factor A ; genetics ; metabolism

To investigate the difference between the functions of oxygen uptake in skeletal muscle and living habits of plateau zokor (Myospalax rufescens baileyi) and plateau pika (Ochotona curzoniac), the microvessel densities (MVD) of skeletal muscle of plateau zokor, plateau pika and Sprague-Dawley (SD) rat were measured by immunohistochemical staining; the numerical density on area (N(A)) of mitochondria, and surface density (S(V), external surface area density of mitochondria per unit volume of skeletal muscle fiber) were obtained by stereo microscope technique; mRNA levels of myoglobin (Mb) in skeletal muscle were determined by real-time PCR, and the contents of Mb protein in skeletal muscle were determined by spectro-photometer. The results showed that MVD, N(A) and S(V) of mitochondria in skeletal muscle of plateau pika were significantly lower than those of plateau zokor and SD rat (P<0.05). The mRNA levels of Mb gene in skeletal muscle of plateau zokor and plateau pika were notably higher than that of SD rat (P<0.05). There were significant differences in the contents of Mb among these three species, and plateau zokor and SD rat presented the highest and the lowest value, respectively (P<0.05). The results suggest that even though plateau zokor inhabits in the hypoxia environment, most of its skeletal muscle fiber are red muscle fiber. While most of skeletal muscle fibers of plateau pika are white muscle fibers. This kind of white muscle has low MVD, N(A) and S(V) of mitochondria and less content of Mb compared with the red one, suggesting it obtains most energy from aerobic oxidation. The above-mentioned differences in skeletal muscles may be related to not only the different species, but also the different living habits of these two high altitude species.
Animals ; Hypoxia ; Lagomorpha ; physiology ; Microvessels ; physiology ; Mitochondria, Muscle ; physiology ; Muscle Fibers, Skeletal ; physiology ; Muscle, Skeletal ; blood supply ; physiology ; Myoglobin ; metabolism ; Oxygen ; metabolism ; RNA, Messenger ; Rats ; Rats, Sprague-Dawley ; Rodentia ; physiology

Plateau zokor (Myospalax baileyi) and plateau pika (Ochotona curzniae) are native to the Qinghai-Tibet plateau. To study their adaptive mechanisms, the ratios of heart weight to body weight (HW/BW) and right to left ventricular plus septum weights [RV/(LV+S)] were determined; the microvessel density (MVD) of cardiac muscle were measured by immunohistochemical staining; the numerical density on area (N(A)), volume density (V(V)), specific surface (δ), and surface density (S(V)) of mitochondria were obtained by microscopy and stereology; the contents of myoglobin (Mb) and lactic acid (LD), and the activity of lactate dehydrogenase (LDH) in cardiac muscle were analyzed by spectrophotometer. The results showed that the HW/BW of plateau zokor [(4.55±0.26)%] and plateau pika [(4.41±0.38)%] was significantly greater than that of Sprague-Dawley (SD) rat [(3.44±0.41)%] (P<0.05), but the RV/(LV+S) [(22.04±1.98)%, (25.53±3.41)%] was smaller than that of SD rats [(44.23±3.87)%] (P<0.05). The MVD and N(A) of cardiac muscle were 1688.631±250.253 and 0.768±0.123 in SD rat, 2002.888±367.466 and 0.868±0.159 in plateau pika and 2 990.643±389.888 and 1.012±0.133 in plateau zokor. The V(V) of mitochondria in plateau zokor (0.272±0.045) was significantly lower than that in plateau pika (0.343±0.039) and SD rat (0.321±0.048) (P<0.05), while the δ of mitochondria in plateau zokor (9.409±1.238) was higher than that in plateau pika (6.772±0.892) and SD rat (7.287±1.373) (P<0.05). The S(V) of mitochondria in plateau pika (2.322±0.347) was not obviously different from that in plateau zokor (2.468±0.380) and SD rat (2.227±0.377), but that in plateau zokor was significantly higher than that in SD rat (P<0.05). The contents of Mb in cardiac muscle of plateau zokor [(763.33±88.73) nmol/g] and plateau pika [(765.96±28.47) nmol/g] were significantly higher than that of SD rat [(492.38±72.14) nmol/g] (P<0.05), the content of LD in plateau zokor [(0.57±0.06) mmol/L] was obviously higher than that in plateau pika [(0.45±0.06) mmol/L] and SD rat [(0.48±0.02) mmol/L] (P<0.05), and the activity of LDH in plateau zokor [(16.90±2.00) U/mL] and plateau pika [(20.55±2.46) U/mL] were significantly lower than that in SD rat [(38.26±6.78) U/mL] (P<0.05). The percentage of LDH-H in cardiac muscle decreased in order in plateau zokor, plateau pika and SD rat. In conclusion, plateau zokor and plateau pika adapt better to hypoxia than SD rat by increasing the SV of mitochondria, MVD and content of Mb in the cardiac muscle. However, the parameters of mitochondria in the two high-altitude animals are different possibly because of the differences of habitats and habits.
Adaptation, Physiological ; Animals ; Heart ; physiology ; Hypoxia ; metabolism ; Isoenzymes ; metabolism ; L-Lactate Dehydrogenase ; metabolism ; Lagomorpha ; physiology ; Rats ; Rats, Sprague-Dawley ; Tibet

The plateau pika (Ochotona curzoniae) and plateau zokor (Myospalax baileyi) are specialized native species of the Qinghai-Tibetan plateau. The goal of this study was to examine physiological differences in skeletal muscle glycolysis and hepatic lactate metabolism between these two species. The partial sequence of pyruvate carboxylase (PC) gene was cloned and sequenced. The mRNA expression levels of PC and lactate dehydrogenases (LDH-A, LDH-B) were determined by real-time PCR. The enzymatic activity of PC was measured using malic acid coupling method. The concentration of lactic acid (LD) and the specific activities of LDH in liver and skeletal muscle of two species were measured. The different isoenzymes of LDH were determined by native polyacrylamide gel electrophoresis (PAGE). The results showed that, (1) LDH-B mRNA level in skeletal muscle of plateau zokor was significantly higher than that of plateau pika (P < 0.01), but no differences was found at LDH-A mRNA levels between them (P > 0.05); (2) PC, LDH-A and LDH-B mRNA levels in liver of plateau pika were significantly higher than those of plateau zokor (P < 0.01); (3) The LDH activity and concentration of LD in skeletal muscle and liver, as well as the PC activity in liver of plateau pika were significantly higher than those of plateau zokor (P < 0.01); (4) The isoenzymatic spectrum of lactate dehydrogenase showed that the main LDH isoenzymes were LDH-A4, LDH-A3B and LDH-A2B2 in skeletal muscle of plateau pika, while the main LDH isoenzymes were LDH-AB3 and LDH-B4 in skeletal muscle of plateau zokor; the main isoenzymes were LDH-A3B, LDH-A2B2, LDH-AB3 and LDH-B4 in liver of plateau pika, while LDH-A4 was the only isoenzyme in liver of plateau zokor. These results indicate that the plateau pika gets most of its energy for sprint running through enhancing anaerobic glycolysis, producing more lactate in their skeletal muscle, and converting lactate into glucose and glycogen in the liver by enhancing gluconeogenesis. As a result, the plateau pika has a reduced dependence on oxygen in its hypoxic environment. In contrast, plateau zokor derives most of its energy used for digging activity by enhancing aerobic oxidation in their skeletal muscle, although they inhabit hypoxic underground burrows.
Animals ; Glycolysis ; Hypoxia ; metabolism ; Isoenzymes ; metabolism ; L-Lactate Dehydrogenase ; metabolism ; Lactic Acid ; metabolism ; Lagomorpha ; physiology ; Liver ; enzymology ; Muscle, Skeletal ; enzymology ; Oxygen ; metabolism ; RNA, Messenger

Plateau zokor (Myospalax baileyi) is a subterranean mammal. Plateau zokor has high learning and memory ability, and can determine the location of blocking obstacles in their tunnels. Forkhead box p2 (FOXP2) is a transcription factor implicated in the neural control of orofacial coordination and sensory-motor integration, particularly with respect to learning, memory and vocalization. To explore the association of foxP2 with the high learning and memory ability of plateau zokor, the cDNA of foxP2 of plateau zokor was sequenced; by using plateau pika as control, the expression levels of foxP2 mRNA and FOXP2 protein in brain of plateau zokor were determined by real-time PCR and Western blot, respectively; and the location of FOXP2 protein in the brain of plateau zokor was determined by immunohistochemistry. The result showed that the cDNA sequence of plateau zokor foxP2 was similar to that of other mammals and the amino acid sequences showed a relatively high degree of conservation, with the exception of two particular amino acid substitutions [a Gln (Q)-to-His (H) change at position 231 and a Ser (S)-to-Ile (I) change at position 235]. Higher expression levels of foxP2 mRNA (3-fold higher) and FOXP2 protein (>2-fold higher) were detected in plateau zokor brain relative to plateau pika brain. In plateau zokor brain, FOXP2 protein was highly expressed in the cerebral cortex, thalamus and the striatum (a basal ganglia brain region). The results suggest that the high learning and memory ability of plateau zokor is related to the high expression levels of foxP2 in the brain.
Amino Acid Sequence ; Amino Acid Substitution ; Animals ; Brain ; metabolism ; Forkhead Transcription Factors ; metabolism ; Lagomorpha ; physiology ; Learning ; Memory ; RNA, Messenger

To explore the adaptive mechanisms of plateau zokor (Myospalax baileyi) to the enduring digging activity in the hypoxic environment and of plateau pika (Ochotona curzoniae) to the sprint running activity, the functional differences of malate-aspartate shuttle system (MA) in liver of plateau zokor and plateau pika were studied. The ratio of liver weight to body weight, the parameters of mitochondria in hepatocyte and the contents of lactic acid in serum were measured; the open reading frame of cytoplasmic malate dehydrogenase (MDH1), mitochondrial malate dehydrogenase (MDH2), and the partial sequence of aspartate glutamate carrier (AGC) and oxoglutarate malate carrier (OMC) genes were cloned and sequenced; MDH1, MDH2, AGC and OMC mRNA levels were determined by real-time PCR; the specific activities of MDH1 and MDH2 in liver of plateau zokor and plateau pika were measured using enzymatic methods. The results showed that, (1) the ratio of liver weight to body weight, the number and the specific surface of mitochondria in hepatocyte of plateau zokor were markedly higher than those of plateau pika (P < 0.01 or P < 0.05), but the content of lactic acid in serum of plateau pika was significantly higher than that of plateau zokor (P < 0.01); (2) MDH1 and MDH2 mRNA levels as well as their enzymatic activities in liver of plateau zokor were significantly higher than those of plateau pika (P < 0.01 or 0.05), AGC mRNA level of the zokor was significantly higher than that of the pika (P < 0.01), while no difference was found at OMC mRNA level between them (P > 0.05); (3) mRNA level and enzymatic activity of MDH1 was significantly lower than those of MDH2 in the pika liver (P < 0.01), MDH1 mRNA level of plateau zokor was markedly higher than that of MDH2 (P < 0.01), but the activities had no difference between MDH1 and MDH2 in liver of the zokor (P > 0.05). These results indicate that the plateau zokor obtains ATP in the enduring digging activity by enhancing the function of MA, while plateau pika gets glycogen for their sprint running activity by increasing the process of gluconeogenesis. As a result, plateau pika converts the lactic acid quickly produced in their skeletal muscle by anaerobic glycolysis and reduces dependence on the oxygen.
Adaptation, Physiological ; physiology ; Adenosine Triphosphate ; metabolism ; Altitude ; Animals ; Aspartic Acid ; metabolism ; Cloning, Molecular ; L-Lactate Dehydrogenase ; analysis ; metabolism ; Lactic Acid ; blood ; Lagomorpha ; classification ; physiology ; Liver ; anatomy & histology ; physiology ; Malate Dehydrogenase ; genetics ; metabolism ; Malates ; metabolism ; Membrane Transport Proteins ; genetics ; metabolism ; RNA, Messenger ; genetics ; metabolism

AIMTo explore the adapting metabolic mechanisms of the plateau zokors to the hypoxic-hypercapnic environment.

METHODSThe activities of lactate dehydrogenase in serum and tissues, and the content of lactate in serum of plateau zokors in spring, summer and autumn were determined by using method of enzyme analysis. The spectrums of lactate dehydrogenase isoenzymes in serum and tissues of plateau zokors in spring, summer and autumn were analyzed by using method of the discontinuous systemic poly-acrylamide perpendicular plank gel electrophoresis.

RESULTSThe activities of lactate dehydrogenase in serum had obvious seasonally difference that were higher in spring and lower in autumn, and the content of lactate in serum showed same changing pattern. The spectrums of lactate dehydrogenase isoenzymes in serum showed five bands that were LDH1, LDH2, LDH3, LDH4 and LDH5 from positive pole to negative pole respectively, it showed clearly two bands in serum of summer that were LDH4 and LDH5 and one band in serum of autumn that was LDH5. The activities of LDH in tissues of skeleton muscle, cardiac muscle and brain were higher compared with the other tissues, it decreased markedly from spring to summer to autumn. In tissues of liver, kidney and lungs, activities of LDH were lower. Activities of LDH in livers, were significantly higher in spring compared that in summer and autumn, which had no obvious difference between summer and autumn. Activities of LDH in kidneys and lungs, showed no obviously difference between spring and summer, which decreased markedly in autumn. The spectrums of lactate dehydrogenase isoenzymes in tissues of cardiac muscle, liver, lungs, kidney, brain and skeleton muscle showed five bands, the spectrums were obvious different in different tissues, and the content of LDH isoenzymes showed seasonal changes in different tissues.

CONCLUSIONGlycolysis levels in plateau zokors had obvious seasonally change which increased in spring and decreased in autumn significantly. It related to the activity of plateau zokors in different seasons and seasonal fluctuation of oxygen and carbon dioxide in burrows of plateau zokors.

Animals ; Carbon Dioxide ; metabolism ; Isoenzymes ; analysis ; metabolism ; L-Lactate Dehydrogenase ; analysis ; metabolism ; Rodentia ; metabolism ; Seasons