Effect of Heat Stress, Hypoxia and Hypoxia-hyperoxia on Free Radical Production in mice Mus musculus

Physiological and Proteomic Responses of Dairy Buffalo to Heat Stress Induced by Different Altitudes

Buffalo are mainly distributed in low-altitude (LA), medium-altitude (MA), and high-altitude (HA) regions characterised by different thermal and oxygen environments in Yunnan province, China. Due to black skin, sparse hair, and the low density of skin sweat glands, buffalo are more sensitive to heat stress. Here, we used data-independent acquisition (DIA) proteomics to reveal a broad spectrum of proteins that play roles in adaptation to the heat stress of buffalo raised at low altitude or hypoxia at high altitude. LA buffalo showed higher body temperatures than MA- and HA buffalo, and HA buffalo had higher levels of GSH and SOD and lower levels of ROS compared to LA and MA buffalo. In 33 samples, 8476 peptides corresponding to 666 high-confidence proteins were detected. The levels of circulating complement proteins in the immune pathways were lower in LA and MA buffalo than in HA buffalo. There were higher levels of alpha-1 acid glycoprotein in LA buffalo than in MA and HA buffalo. Relative to MA buffalo, levels of blood oxygen delivery proteins were higher in LA and HA buffalo. A higher abundance of apolipoproteins was detected in LA and MA buffalo than in HA buffalo. In summary, buffalo adopted similar adaptation strategies to oxidative stress induced by heat stress or hypoxia, including immunological enhancement, high efficiency of blood oxygen delivery, and the inhibition of lipid oxidation.

Effects of Hypoxia-Hyperoxia Preconditioning on Indicators of Muscle Damage After Acute Resistance Exercise in Male Athletes

Purpose

The purpose of this study was to investigate the effects of acute repeated hypoxia–hyperoxia preconditioning on resistance exercise (RE)-induced muscle damage in male athletes.

Methods

Eleven young male athletes participated in this randomized double-blind counter-balanced crossover study, and were divided into Normoxia (N) and Hypoxia–Hyperoxia (HH) trials. Subjects of the respective trials were supplied with normoxic (FiO₂ = 0.21), or alternating hypoxic/hyperoxic air (FiO₂ = 0.10/0.99, 5 min each) for 60 min. Thirty minutes after preconditioning, subjects performed acute bouts of RE consisting of bench press, deadlift, and squats. Each exercise included 6 sets of 10 repetitions at 75% one-repetition maximum (1RM) with 2 min rest between sets. After a 2-week washout period, subjects changed trials and completed the same study procedure after the alternate preconditioning. Muscle soreness, maximal voluntary contraction (MVC), and circulating biochemical markers were tested before preconditioning (baseline) and during recovery at 0, 24, and 48 h after exercise.

Results

Acute RE significantly increased levels of muscle soreness, creatine kinase (CK) and myoglobin (Mb), and decreased levels of peak knee extension torque in the N trial. Muscle soreness, CK, and Mb levels of the HH trial were significantly lower than that of the N trial after exercise. Interestingly, interleukin-6 (IL-6) levels of the HH trial increased significantly 0 h after exercise compared to baseline and were significantly higher than that of the N trial 0 and 24 h after exercise. However, no significant differences of thiobarbituric acid reactive substances (TBARS), cortisol, testosterone, peak torque, and average power levels were found between N and HH trials during recovery.

Conclusion

Our data suggest that pre-exercise treatment of alternating hypoxic/hyperoxic air could attenuate muscle damage and pain after acute RE, but has no effect on muscle strength recovery in young male athletes.

Serum proteomics analysis reveals the thermal fitness of crossbred dairy buffalo to chronic heat stress

Chronic heat stress (CHS) reduces the production efficiency of the buffalo dairy industry. Relatively low-abundance proteins with particular functions in biological processes are changed by CHS. The present study aimed to quantify the differences in low-abundance proteins of crossbred dairy buffaloes under CHS and thermal-neutral (TN) conditions. With label-free quantification, 344 low-abundance proteins were identified in serum. Of these, 17 differentially expressed low-abundance proteins with known functions were detected, and six of the differentially expressed proteins related to heat stress were validated with parallel reaction monitoring. Lipase (LPL), glutathione peroxidase 3 (GPX3), cathelicidin-2 (CATHL2), ceruloplasmin (CP), and hemoglobin subunit alpha 1 (HBA1) cooperatively played roles in the thermal fitness of dairy buffalo by decreasing heat production and increasing blood oxygen delivery. Also, dairy buffaloes may adapt to CHS and hypoxia with high levels of RBCs, HBA1 and CP to increase blood oxygen delivery capacity.

Aberrant Upregulation of Compensatory Redox Molecular Machines May Contribute to Sperm Dysfunction in Infertile Men with Unilateral Varicocele: A Proteomic Insight

Aims: To understand the molecular pathways involved in oxidative stress (OS)-mediated sperm dysfunction against a hypoxic and hyperthermic microenvironment backdrop of varicocele through a proteomic approach. Results: Protein selection (261) based on their role in redox homeostasis and/or oxidative/hyperthermic/hypoxic stress response from the sperm proteome data set of unilateral varicocele (UV) in comparison with fertile control displayed 85 to be differentially expressed. Upregulation of cellular oxidant detoxification and glutathione and reduced nicotinamide adenine dinucleotide (NADH) metabolism accompanied with downregulation of protein folding, energy metabolism, and heat stress responses were observed in the UV group. Ingenuity pathway analysis (IPA) predicted suppression of oxidative phosphorylation (OXPHOS) (validated by Western blotting [WB]) along with augmentation in OS and mitochondrial dysfunction in UV. The top affected networks indicated by IPA involved heat shock proteins (HSPs: HSPA2 and HSP90B1). Their expression profile was corroborated by immunocytochemistry and WB. Hypoxia-inducible factor 1A as an upstream regulator of HSPs was predicted by MetaCore. Occurrence of reductive stress in UV spermatozoa was corroborated by thiol redox status. Innovation: This is the first evidence of a novel pathway showing aberrant redox homeostasis against chronic hypoxic insult in varicocele leading to sperm dysfunction. Conclusions: Upregulation of antioxidant system and dysfunctional OXPHOS would have shifted the redox balance of biological redox couples (GSH/GSSG, NAD⁺/NADH, and NADP⁺/NADPH) to a more reducing state leading to reductive stress. Chronic reductive stress-induced OS may be involved in sperm dysfunction in infertile men with UV, where the role of HSPs cannot be ignored. Intervention with antioxidant therapy warrants proper prior investigation.

Effects of hyperoxia periodic training on free radicals production, biological antioxidants potential and lactate dehydrogenase activity in the lungs of rats, Rattus norvigicus

Oxygen therapy has been widely used in lung injury (Li), adult respiraotory syndrome (ARDS) and inflammatory lung diseases as well as in mechanical ventilation in intensive care units. Exposure to hyperoxia is known to induct the production of reactive oxygen species (ROS) by mitochondria. Despite decades of research, the role of hyperoxia training in oxidative stress and ROS formation in the lungs is not known. The purpose of this study was to examine the effects of periodic-hyperoxia training on biological antioxidants (BAP) and lactate dehydrogenase (LDH) activities and free radicals (FR) production. Thirty adult male rats, matched with age and body weigh, were randomly assigned to three groups. The first group served as control (C) and the second (HP) was exposed to hyperoxia for 48. Animals in the third group (HP-T) were trained on hyperoxia for 1.5 h daily for three weeks. Following the exposure period for each group animals were sacrificed and lungs tissues were homogenized for BAP, LDH and FR determinations. LDH activity was determined by Randox protocol (Randox - UK). BAP and FR were determined using dROM method (H&D - Italy). Results showed that mean (±SD) BAP activity increased significantly (p < 0.05) from the baseline control of 7105.88 ± 2021.49 to 8611.20 ± 1245.26 (U/L) after hyperoxia training; then dropped to 6784.00 ± 1879.50 during hyperoxia exposure for 48 h. Whereas mean (±SD) FR production increased significantly (p < 0.05) from the baseline control of 262.50 ± 67.52 to 339.90 ± 64.84 during HP exposure for 48 h, then dropped to 211.13 ± 52.05 (Carr), during HP training. Similarly, LDH activity increased significantly (p < 0.05) from the baseline control of 210.31 ± 70.93 to 339.90 ± 64.84 during HP exposure for 48 h, then dropped to 159.30 ± 20.61(U/L), following HP-periodic training. Furthermore, the correlation (r = 0.67×) of LDH on FR was significant (p < 0.05), implying that reduction in ROS generation induced by HP-periodic training is related to reduced rate of cell apoptosis caused oxidative stress. Based on the results of the present study HP-periodic training is recommended in order to resist oxidative damage in the lungs.

Increased Antioxidant Potential and Decreased Free Radical Production in Response to Mild Injection of Crude Venom, Cerastes cerastes gasperetti

ABSTRACT The purpose of this study was to examine the effects of Cerastes cerastes gasperetti crude venom (CCV) on free radical (FR) production and biological antioxidant potential (BAP). Thirty male rats, matched with age and weight, were divided randomly into three groups: control (C), negative control (NC), and experimental (E). Animals in the control group served as control for needlestick and venom injection. Animals in the negative control group, which served as control for venom-induced effects, were injected intraperitoneally (IP) with saline for 8 days, whereas animals of the experimental group were injected IP with crude CCV, at a dose of 1/4 LD(50), for the same period. All animals of the three groups remained under normal laboratory and dietary conditions. Blood samples were collected by heart puncture technique and were analyzed immediately for FRs and BAP. ANOVA analysis indicated a significant difference (p < 0.05) among group means. Tukey-Kramer multiple comparisons showed that FRs increased significantly (p < 0.05) in the NC group, implying that needlestick during injection of saline for 8 days caused internal organ injury sufficient enough to induce reactive oxygen species (ROS) generation. Surprisingly, there were no significant (p > 0.05) changes in FRs in the E group as compared with the C group, which indicates that CCV counteracted the effects induced by ROS. BAP increased significantly (p < 0.05) in the E group as compared with the NC group, reflecting the activation of some antioxidant enzymes. Linear regression of FRs on BAP was significant (p < 0.05) in both the C and E groups. Based on the results of this study, it can be concluded that the CCV contains biochemical factors that activate antioxidant enzymes, as evident by elevation in the BAP that depresses ROS formation.

Oxidative stress in preretinopathic diabetes subjects and antioxidants

BACKGROUND

This study assessed the effect of a systemic oral treatment with antioxidants (AOs) in preretinopathic diabetes (PRD) patients, through the evaluation of oxidative stress in plasma and changes in the full-field electroretinogram (ERG).

METHODS

Thirty-two PRD subjects with good metabolic control were recruited. Patients were randomized in two groups, one of which received oral AO treatment with α-lipoic acid at 400 mg/day in association with genistein and vitamins, whereas the other group received a placebo. Free radicals and the AO barrier were evaluated in plasma with the Free Radical Analytical System 4 instrument (H&D srl, Parma, Italy), and the same day the electrophysiological response was measured by ERG. These analyses were performed at enrollment and after 30 days of treatment.

RESULTS

Statistically significant increases of plasma AO levels and ERG oscillatory potential values were observed in the group treated with AO, but not in the control group.

CONCLUSIONS

Results of this preliminary study suggest that an oral treatment with AOs in PRD subjects may have a protective effect on retinal cells, as detected by ERG analysis, through the strengthening of the plasma AO barrier.

Effects of exposure of rats to periodic versus continuous hyperoxia on antioxidant potentials and free radical production in relation to ultrastructural changes in myocardial cells

The purpose of the present study was to examine the effects of periodic hyperoxia training (PHT) and/or continuous exposure to hyperoxia (HP) on free radical (FR) levels and biological antioxidant potentials (BAPs) in relation to ultrastructural pathological changes in myocytes. Thirty adult male rats were randomly assigned to three groups: control (C), HP, or PHT. HP rats were continuously subjected to atmospheres containing 100% O2 for 48 h, whereas PHT animals breathed 100% O2 for 30-min periods three times daily over a 3-week period. Ultrastructural examination of isolated myocytes from the HP rats showed that swelled mitochondria with constricted and proliferated cristae of the inner membrane were associated with disarrangement of myofibrils as well as the loss of I-banding. Heart tissue supernatant analyses also provided evidence of significantly higher FR levels in samples from the HP rats as compared with values noted with materials from control and PHT rats. In contrast, BAP was significantly higher in the samples from rats in the PHT group as compared levels associated with the control or the HP hosts. As HP resulted in mitochondrial pathological alterations in the cristae, this implied the induction of a myocardium oxidative stress (MOS). As PHT enhanced BAP, it may be concluded that PHT likely enhances an apparent antioxidant response that did not permit FR to build up. Because PHT elevations would be expected to help lower FR levels, it would seem that periodic hyperoxia training might induce an adaptive resistance in the heart against the formation of potentially toxicologically deleterious reactive metabolite species.

Effect of dobutamine and hyperoxia on free radicals production in relation to the ultrastructural alterations in the endothelial of myocardial capillary in rats, Rattus norvigicus

Hyperoxia has been widely used as model for oxidative stress. Free radicals (FR), suproxide anion (*O(-)(2)) and nitric oxide anion (*NO(-)), are highly toxic and have detrimental effects on nitroso-redox balance in the myocyte. Myocardium is rich with beta-adrenergic receptors and endothelial is the site of NO production. The authors hypothesized that graded doses of dobutamine result in hyperkinetic state, which shifts the nitroso-redox balance toward the buildup of reactive species in dose-dependent excess. The purpose of the present study was to investigate free radicals production and coronary endothelial cell pathological changes following increasing length of breathing oxygen (100% O(2)) and progressive doses of dobutamine. Thirty-five adult male rats, matched with age and body weight, were randomly assigned to 7 groups. The first group served as control (C) and the 2nd, 3rd, and 4th groups were exposed to hyperoxia (100% O(2) breathing) for 24,48, and 72 h, whereas the 5th, 6th, and 7th groups were injected dobutamine 10,20, and 30 microg kg(-1), respectively. Following the treatment condition for each group, animals were sacrificed and heart tissues were divided randomly into two parts. The first part was processed for the ultrastructure, using transmission electron microscope (TEM), and the second was homogenized for FR determination. TEM examination showed that O2 breathing for 24 h resulted in hypertrophy and proliferation of endothelial cells lining the coronary capillary, which was lodged by lymphoid cells. Distended and irregular contour of endothelium, enlarged nucleus, protrusion membrane, as well as pinocytotic vesicles were also observed. Free radicals (FR) production at all levels of hyperoxia exposures and dobutamine injections were significantly (p < .05) higher than control group. In addition, dobutamine induced higher relative FR production, as compared with hyperoxia, implying more severe myocyte injury. Based on the results of the present study, it can be concluded that O2 breathing for 24 h or higher resulted in variety of pathological changes of the endothelium of coronary capillary that were induced by the buildup of oxidants by-products. Because dobutamine caused relative higher in FR production levels, as compared with hyperoxia levels, throughout this implied it aggravated the myocyte capillaries' endothelium more heavily, which could have resulted in more intense ultrastructural deteriorations.

Effect of hyperoxia on the ultrastructural pathology of alveolar epithelium in relation to glutathione peroxidase, lactate dehydrogenase activities, and free radical production in rats, Rattus norvigicus

Hyperoxia (HP) exposure inducts reactive oxygen species (ROS) in the lungs that may result in lung injury, including alveolar epithelial and endothelial cells. Lactate dehydrogenase (LDH) activity relates to glycolysis, whereas glutathione peroxidase (Gpx) activity relies on the pentose phosphate pathway (PPP). The purpose of this study was to examine early ROS-induced alveolar pathological changes in relation to the activity of glutathione peroxidase (GPx) and lactate dehydrogenase (LDH) activity. Twenty adult male rats, matched with age and body weight, were randomly assigned to two groups, control and experimental. The experimental group was exposed to hyperoxia for 24 h. Ultrastructure examination showed degenerated pneumocyte type I, containing swollen mitochondria associated with dilated rough endoplasmic reticulum, and was projecting into the alveolar lumen. Pneumocyte II showed mitochondria swelling and hyperplasia and was desquamated in structure, depleted in surfactant, and falling into the alveolar lumen. Pulmonary capillary showed distention without observed damage in the endothelial layer. Following HP, the average (+/-) free radical (FR) production increased significantly (p<.05) from the baseline control of 181.20+/-30.06 to 260.30+/-68.10 (Carr U) and average (+/-SD) GPx activity also increased significantly (p<.05) from the baseline control of 8178.30+/-2402.62 to 19,589.50+/-2392.44 (U/L), whereas average (+/-SD) LDH activity decreased significantly (p<.05) from baseline control of 194.11+/-75.52 to 42.68+/-11.41 (U/L), which demonstrated slowing down of glycolysis. Based on these results it can be concluded that exposure to high inspired oxygen inducted the buildup of mitochondria-driven ROS that was related to early injury in the alveolar epithelium without obvious endothelium injury.