Dexmedetomidine's protective mechanism against hyperoxic injury in neonatal rats.

Bronchopulmonary dysplasia (BPD) is a common serious complication of premature babies. No effective means control it. Hyperoxia damage is one of the important mechanisms of BPD. The reaserach confirmed pyroptosis existed in BPD. Dexmedetomidine is a new, high-specific α2 receptor agonist. Previous research foundation found that dexmedetomidine has a protective effect on BPD. To investigate how dexmedetomidine improves hyperoxic lung injury in neonatal mice by regulating pyroptosis. Neonatal rats were randomly divided into four groups: normal control group, hyperoxic injury group, air plus dexmedetomidine group, and hyperoxia plus dexmedetomidine group. After seven days the lungs of rats in each group were extracted, and the wet-to-dry weight ratio of the lung was measured. The lung injury in rats was observed using hematoxylin-eosin staining. Additionally, the expression and localization of nucleotide-binding oligomerization domain-like receptor thermal protein domain associated protein 3 (NLRP3), apoptosis-associated speck-like protein (ASC), and gasdermin D (GSDMD) proteins were examined in the lungs of rats using immunofluorescence staining. The mRNA levels of NLRP3, ASC, caspase-1, and interleukin 18 (IL-18) in the lungs of rats were determined using real-time PCR. Moreover, the protein levels of NLRP3, ASC, caspase-1/cleaved caspase-1, interleukin 1beta (IL-1ß), IL-18, and tunor necrosis factor alpha (TNF-α) were detected in lungs of rats using Western blot. The extent of mitochondrial damage in lung tissues of each group was observed by transmission electron microscopy. The lung tissue injury of the neonatal rats was significantly improved in the hyperoxia plus dexmedetomidine group compared to the hyperoxic injury group. Furthermore, the expressions of pyroptosis-related proteins such as NLRP3, ASC, cleaved-caspase-1, and GSDMD were significantly decreased, along with the expressions of inflammatory factors in lung tissues. By inhibiting the NLRP3/caspase-1/GSDMD pyroptosis pathway, dexmedetomidine reduces the activation and release of inflammatory factors and provides a protective effect against hyperoxic lung injury in neonatal mice.

Retinoic acid reduces kidney injury by regulating oxidative stress, NRF-2, and apoptosis in hyperoxic mice.

Nuclear factor-erythroid-2-related factor-2 (NRF-2) is a cellular resistance protein to oxidants. We investigated the effect of exogenous all-trans retinoic acid (ATRA) on the antioxidant system and NRF-2 in mice kidneys under hyperoxia-induced oxidative stress. Mice were divided into four groups. Daily, two groups were given either peanut-oil/dimethyl sulfoxide (PoDMSO) mixture or 50 mg/kg ATRA. Oxidative stress was induced by hyperoxia in the remaining groups. They were treated with PoDMSO or ATRA as described above, following hyperoxia (100% oxygen) for 72 h. NRF-2 and active-caspase-3 levels, lipid peroxidation (LPO), activities of antioxidant enzymes, xanthine oxidase (XO), paraoxonase1 (PON1), lactate dehydrogenase (LDH), tissue factor (TF), and prolidase were assayed in kidneys. Hyperoxia causes kidney damage induced by oxidative stress and apoptosis. Increased LPO, LDH, TF, and XO activities and decreased PON1 and prolidase activities contributed to kidney damage in hyperoxic mice. After hyperoxia, increases in the activities of antioxidant enzymes and NRF-2 level could not prevent this damage. ATRA attenuated damage via its oxidative stress-lowering effect. The decreased LDH and TF activities increased PON1 and prolidase activities, and normalized antioxidant statuses are indicators of the positive effects of ATRA. We recommend that ATRA can be used as a renoprotective agent against oxidative stress induced-kidney damage.

Quercetin alleviates hyperoxia-induced bronchopulmonary dysplasia by inhibiting ferroptosis through the MAPK/PTGS2 pathway: Insights from network pharmacology, molecular docking, and experimental evaluations.

Quercetin, a bioactive natural compound renowned for its potent anti-inflammatory, antioxidant, and antiviral properties, has exhibited therapeutic potential in various diseases. Given that bronchopulmonary dysplasia (BPD) development is closely linked to inflammation and oxidative stress, and quercetin, a robust antioxidant known to activate NRF2 and influence the ferroptosis pathway, offers promise for a wide range of age groups. Nonetheless, the specific role of quercetin in BPD remains largely unexplored. This study aims to uncover the target role of quercetin in BPD through a combination of network pharmacology, molecular docking, computer analyses, and experimental evaluations.

AMPK/MTOR/TP53 Signaling Pathway Regulation by Calcitonin Gene-Related Peptide Reduces Oxygen-Induced Lung Damage in Neonatal Rats through Autophagy Promotion.

Our previous studies indicated that calcitonin gene-related peptide (CGRP) alleviates hyperoxia-induced lung injury and suggested the possible involvement of autophagy in this process. Herein, we aimed to further explore the potential involvement of tumor protein p53 (TP53) and autophagy in the mode of action of CGRP against hyperoxia-induced lung injury in vitro and in vivo. The study conducted tests on type II alveolar epithelial cells (AECII) and rats that were subjected to hyperoxia treatment or combined treatment of hyperoxia with CGRP, CGRP inhibitor, rapamycin (an autophagy agonist), 3-methyladenine (3-MA, an autophagy inhibitor), TP53 silencing/inhibitor (pifithrin-α), or expression vector/activator (PRIMA-1 (2,2-bis(hydroxymethyl)-3-quinuclidinone)) and their corresponding controls. We found that oxidative stress, apoptosis, and autophagy were all increased by hyperoxia treatment in vitro. However, treating AECII cells with CGRP reversed hyperoxia-induced oxidative stress and apoptosis but further promoted autophagy. In addition, the combined treatment with rapamycin or TP53 silencing with CGRP promoted the effect of CGRP, while contrary results were obtained with combined therapy with 3-MA or TP53 overexpression. In vivo, the number of hyperoxia-induced autophagosomes was promoted in the lung tissue of neonatal rats. Furthermore, hyperoxia increased the expression levels of AMP-activated protein kinase (AMPK) alpha 1 (also known as protein kinase AMP-activated catalytic subunit alpha 1 (PRKAA1)) but inhibited TP53 and mechanistic target of rapamycin (MTOR); these expression trends were regulated by CGRP treatment. In conclusion, we showed that CGRP can attenuate hyperoxia-induced lung injury in neonatal rats by enhancing autophagy and regulating the TP53/AMPK/MTOR crosstalk axis.

Irisin alleviates hyperoxia-induced bronchopulmonary dysplasia through activation of Nrf2/HO-1 pathway.

BACKGROUND: Bronchopulmonary dysplasia (BPD) is a common pulmonary injury among premature infants, which is often caused by hyperoxia exposure. Irisin is a novel hormone-like myokine derived mainly from skeletal muscles as well as adipose tissues. Many studies have indicated that Irisin exert a variety of properties against hyperoxia-induced inflammation and oxidative stress (OS). We aimed to evaluate the effects of irisin on hyperoxia-induced lung injury explore the underlying mechanisms. METHODS: BPD model was established after exposing newborn mouse to 85% oxygen. BPD mouse received continuous intraperitoneal injection of irisin at a dose of 25 µg/kg/day. Lung tissues were collected for histological examination at 7 and 14 days after birth. The alveolarization and alveolar vascularization of each animal was assessed. Levels of oxidative stress indicators, and the expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) in lung tissues were detected at 14 days after birth. RESULTS: Hyperoxia exposure induced a markedly alveolar simplification and a disrupted alveolar angiogenesis, which was ameliorated by irisin treatment. The hyperoxia-induced increase in these oxidative stress indicators was significantly reversed by irisin treatment. The Nrf2/HO-1 pathway is inducted in the hyperoxia-induced BPD mouse model, which is further activated by irisin treatment. CONCLUSION: Our results demonstrated the beneficial effects of irisin in reducing the OS, enhancing alveolarization, and promoting vascular development through activation of Nrf2/HO-1 axis in a hyperoxia-induced experimental model of BPD.

Exhaled breath condensate profiles of U.S. Navy divers following prolonged hyperbaric oxygen (HBO) and nitrogen-oxygen (Nitrox) chamber exposures.

Prolonged exposure to hyperbaric hyperoxia can lead to pulmonary oxygen toxicity (PO2tox). PO2tox is a mission limiting factor for special operations forces divers using closed-circuit rebreathing apparatus and a potential side effect for patients undergoing hyperbaric oxygen (HBO) treatment. In this study, we aim to determine if there is a specific breath profile of compounds in exhaled breath condensate (EBC) that is indicative of the early stages of pulmonary hyperoxic stress/PO2tox. Using a double-blind, randomized 'sham' controlled, cross-over design 14 U.S. Navy trained diver volunteers breathed two different gas mixtures at an ambient pressure of 2 ATA (33 fsw, 10 msw) for 6.5 h. One test gas consisted of 100% O2(HBO) and the other was a gas mixture containing 30.6% O2with the balance N2(Nitrox). The high O2stress dive (HBO) and low O2stress dive (Nitrox) were separated by at least seven days and were conducted dry and at rest inside a hyperbaric chamber. EBC samples were taken immediately before and after each dive and subsequently underwent a targeted and untargeted metabolomics analysis using liquid chromatography coupled to mass spectrometry (LC-MS). Following the HBO dive, 10 out of 14 subjects reported symptoms of the early stages of PO2tox and one subject terminated the dive early due to severe symptoms of PO2tox. No symptoms of PO2tox were reported following the nitrox dive. A partial least-squares discriminant analysis of the normalized (relative to pre-dive) untargeted data gave good classification abilities between the HBO and nitrox EBC with an AUC of 0.99 (±2%) and sensitivity and specificity of 0.93 (±10%) and 0.94 (±10%), respectively. The resulting classifications identified specific biomarkers that included human metabolites and lipids and their derivatives from different metabolic pathways that may explain metabolomic changes resulting from prolonged HBO exposure.

Dexmedetomidine Protects Cerebellar Neurons against Hyperoxia-Induced Oxidative Stress and Apoptosis in the Juvenile Rat.

The risk of oxidative stress is unavoidable in preterm infants and increases the risk of neonatal morbidities. Premature infants often require sedation and analgesia, and the commonly used opioids and benzodiazepines are associated with adverse effects. Impairment of cerebellar functions during cognitive development could be a crucial factor in neurodevelopmental disorders of prematurity. Recent studies have focused on dexmedetomidine (DEX), which has been associated with potential neuroprotective properties and is used as an off-label application in neonatal units. Wistar rats (P6) were exposed to 80% hyperoxia for 24 h and received as pretreatment a single dose of DEX (5µg/kg, i.p.). Analyses in the immature rat cerebellum immediately after hyperoxia (P7) and after recovery to room air (P9, P11, and P14) included examinations for cell death and inflammatory and oxidative responses. Acute exposure to high oxygen concentrations caused a significant oxidative stress response, with a return to normal levels by P14. A marked reduction of hyperoxia-mediated damage was demonstrated after DEX pretreatment. DEX produced a much earlier recovery than in controls, confirming a neuroprotective effect of DEX on alterations elicited by oxygen stress on the developing cerebellum.

Nocturnal normobaric hyperoxia treatment in a case of chronic diabetic macular edema.

PURPOSE: To study the long-term anatomic and physiologic effects of nocturnal normobaric hyperoxia (NNBH) in a patient with treatment-resistant diabetic macular edema (DME). METHODS: A 64-year-old diabetic man with bilateral DME requiring regular anti-VEGF treatments in both eyes was started on 5 LPM (40% FiO2) NNBH treatment 6-h per night. Visual acuity, OCT measurements of retinal thickness and volume, as well as the number of injections given in each eye were retrospectively examined one year prior and prospectively after initiation of NNBH, as well as before and after a planned 1-month discontinuation of NNBH. RESULTS: The patient received 12 anti-VEGF injections in the year prior to beginning NNBH treatment (4 OD; 8 OS) and did not require any injections after commencing NNBH treatment. Visual acuity improved and stabilized to 20/20 and macular edema rapidly resolved in both eyes following initiation of NNBH. After a planned 1-month NNBH vacation, DME recurred but quickly resolved once NNBH treatment was restarted. CONCLUSION: This model case demonstrates that a 6-h NNBH regimen can be successful in treating DME and improving vision, without the need for intravitreal injections. NNBH is a more acceptable treatment regimen compared to 24-h continuous oxygen delivery and may provide a less invasive alternate method for treating DME in patients with diabetes. Further study is warranted.

Oxygen-supplying syringe to create hyperoxia-inducible hydrogels for in situ tissue regeneration.

Recent trends in the design of regenerative materials include the development of bioactive matrices to harness the innate healing ability of the body using various biophysicochemical stimuli (defined as in situ tissue regeneration). Among these, hyperoxia (>21% pO2) is a well-known therapeutic factor for promoting tissue regeneration, such as immune cell recruitment, cell proliferation, angiogenesis, and fibroblast differentiation into myofibroblast. Although various strategies to induce hyperoxia are reported, developing advanced hyperoxia-inducing biomaterials for tissue regeneration is still challenging. In this study, a catalase-immobilized syringe (defined as an Oxyringe) via calcium peroxide-mediated surface modification is developed as a new type of oxygen-supplying system. Hyperoxia-inducible hydrogels are fabricated utilizing Oxyringe. This hydrogel plays a role as a physical barrier for hemostasis. In addition, hyperoxic matrices induce transient hyperoxia in vivo (up to 46.0% pO2). Interestingly, the hydrogel-induced hyperoxia boost the initial macrophage recruitment and rapid inflammation resolution. Furthermore, hyperoxic oxygen release of hydrogels facilitates neovascularization and cell proliferation involved in the proliferation phase, expediting tissue maturation related to the remodeling phase in wound healing. In summary, Oxyringe has excellent potential as an advanced oxygen-supplying platform to create hyperoxia-inducing hydrogels for in situ tissue regeneration.

Caffeine reduces oxidative stress to protect against hyperoxia-induced lung injury via the adenosine A2A receptor/cAMP/PKA/Src/ERK1/2/p38MAPK pathway.

Objectives: Caffeine has been shown to reduce the incidence of bronchopulmonary dysplasia (BPD). To investigate the protective mechanism of caffeine in a hyperoxia-based cell model of BPD in vitro.Methods: Type II alveolar epithelial cells (AECs II) were isolated and randomly divided into 6 groups: the normal, hyperoxia, caffeine (50 µM caffeine), antagonist (5 µM ZM241385), agonist (5 µM CGS21680), and DMSO groups. Transfection with siRNA against adenosine A2A receptor (siA2AR) was performed in AECs II.Results: Caffeine alone or in combination with adenosine A2A receptor (A2AR) antagonist inhibited apoptosis, promoted proliferation and reduced oxidative stress (OS). The cyclic adenosine monophosphate (cAMP), protein kinase A (PKA) mRNA, A2AR mRNA and the protein levels of A2AR, phospho-Src, phospho-ERK1/2, phospho-P38 and cleaved caspase-3 were decreased in the caffeine and antagonist groups compared with that in the hyperoxia group. However, the effects of caffeine above were weakened by the A2AR agonist. Knockdown of A2AR showed similar results to caffeine.Discussion: Caffeine can reduce apoptosis, promote proliferation, and alleviate OS in hyperoxia-induced AECs II injury by inhibiting the A2AR/cAMP/PKA/Src/ERK1/2/p38MAPK signaling pathway. Caffeine and A2AR may serve as a promising therapeutic target for BPD in prematurity.

Naturally Acquired Kelch13 Mutations in Plasmodium falciparum Strains Modulate In Vitro Ring-Stage Artemisinin-Based Drug Tolerance and Parasite Survival in Response to Hyperoxia.

The ring-stage survival assay was utilized to assess the impact of physiological hyperoxic stress on dihydroartemisinin (DHA) tolerance for a panel of Plasmodium falciparum strains with and without Kelch13 mutations. Strains without naturally acquired Kelch13 mutations or the postulated genetic background associated with delayed parasite clearance time demonstrated reduced proliferation under hyperoxic conditions in the subsequent proliferation cycle. Dihydroartemisinin tolerance in three isolates with naturally acquired Kelch13 mutations but not two genetically manipulated laboratory strains was modulated by in vitro hyperoxic stress exposure of early-ring-stage parasites in the cycle before drug exposure. Reduced parasite tolerance to additional derivatives, including artemisinin, artesunate, and OZ277, was observed within the second proliferation cycle. OZ439 and epoxomicin completely prevented parasite survival under both hyperoxia and normoxic in vitro culture conditions, highlighting the unique relationship between DHA tolerance and Kelch13 mutation-associated genetic background. IMPORTANCE Artemisinin-based combination therapy (ACT) for treating malaria is under intense scrutiny following treatment failures in the Greater Mekong subregion of Asia. This is further compounded by the potential for extensive loss of life if treatment failures extend to the African continent. Although Plasmodium falciparum has become resistant to all antimalarial drugs, artemisinin "resistance" does not present in the same way as resistance to other antimalarial drugs. Instead, a partial resistance or tolerance is demonstrated, associated with the parasite's genetic profile and linked to a molecular marker referred to as K13. It is suggested that parasites may have adapted to drug treatment, as well as the presence of underlying population health issues such as hemoglobinopathies, and/or environmental pressures, resulting in parasite tolerance to ACT. Understanding parasite evolution and control of artemisinin tolerance will provide innovative approaches to mitigate the development of artemisinin tolerance and thereby artemisinin-based drug treatment failure and loss of life globally to malaria infections.

Insulin-like growth factor-1 reduces hyperoxia-induced lung inflammation and oxidative stress and inhibits cell apoptosis through PERK/eIF2α/ATF4/CHOP signaling.

Background: Insulin-like growth factor-1 (IGF-1), a member of the insulin family, has a high degree of homology with insulin and exhibits anti-inflammatory and anti-oxidative stress properties. However, the potential protective effect of IGF-1 on hyperoxia-induced lung injury remains unknown. In this study, we aimed to explore the effects and mechanism of action of IGF-1 in hyperoxia-induced lung injury in neonatal rats. Materials and Methods: Hematoxylin-eosin staining was used to observe pathological changes in lung tissue; transmission electron microscopy was used to examine the ultrastructure, and ELISA was used to detect the level of pro-inflammatory cytokines in bronchoalveolar lavage fluid. Further, malondialdehyde, glutathione, and superoxide dismutase activities in lung tissue were evaluated. TUNEL staining was used to detect cell apoptosis, and western blot analysis was used to detect the expression of Bax, Bcl-2, Caspase-3, p-PERK, p-eIF2α, ATF4, and CHOP in the lung tissue. Moreover, the wet/dry weight ratio of lung tissue was determined. Results: Intraperitoneal injection of IGF-1 effectively reduced lung tissue damage induced by hyperoxia; production of inflammatory cells and release of pro-inflammatory cytokines, oxidative stress, and cell apoptosis. Further, IGF-1 down-regulated the expression of ATF4, CHOP, and Bax/Bcl-2, and inhibited the phosphorylation of PERK and eIF2α. Conclusion: The results suggest that IGF-1 reduces hyperoxia-induced lung inflammation and oxidative stress in neonatal rats through the PERK/eIF2α/ATF4/CHOP signaling pathway and inhibits cell apoptosis.

Simvastatin Inhibits NLRP3 Inflammasome Activation and Ameliorates Lung Injury in Hyperoxia-Induced Bronchopulmonary Dysplasia via the KLF2-Mediated Mechanism.

Bronchopulmonary dysplasia (BPD) is a chronic lung disease commonly found in premature infants. Excessive inflammation and oxidative stress contribute to BPD occurrence and development. Simvastatin, as an inhibitor of HMG-CoA reductase, has been reported to have antioxidative and anti-inflammatory effects. However, its effect and possible mechanisms in hyperoxia-induced lung injury are rarely reported. In this study, in vivo and in vitro experiments were conducted to investigate whether simvastatin could ameliorate hyperoxia-induced lung injury and explore its potential mechanism. For the in vivo study, simvastatin could improve alveolar development after hyperoxic lung injury and reduce hyperoxic stress and inflammation. The in vitro study revealed that simvastatin can reduce inflammation in A549 cells after high-oxygen exposure. Simvastatin suppressed NLRP3 inflammasome activation and played anti-inflammatory and antioxidant roles by increasing KLF2 (Krüppel-like factor 2) expression. In vitro experiments also revealed that these effects of simvastatin were partially reversed by KLF2 shRNA, indicating that KLF2 was involved in simvastatin effects. In summary, our findings indicate that simvastatin could downregulate NLRP3 inflammasome activation and attenuate lung injury in hyperoxia-induced bronchopulmonary dysplasia via KLF2-mediated mechanism.

Using a neonatal rat model to explore the therapeutic potential of coenzyme Q10 in prematurity under hyperoxia.

Hyperoxia, is often used in preterm supportive care, leading to high oxygen exposure in neonates. Coenzyme Q10 (CoQ10) is a free radical scavenger that has been studied in older children but never be investigated for its role in preterm care. We hypothesize that the administration of exogenous CoQ10 would raise serum concentrations of CoQ10 and mitigate the adverse effects of hyperoxia on the organs by reducing oxygen-free radicals and inflammation. The aim of this study was to evaluate the effects of oxidative stress, inflammatory response, and survival in neonatal rats after CoQ10 treatment. Neonatal rats delivered from four pregnant Wistar rats were randomly divided into four groups: (a) control, (b) CoQ10, (c) hyperoxia (O2 group), and (d) treatment (CoQ10 + O2 ) groups. The dose of CoQ10 injected was 30 mg/kg. The CoQ9, CoQ10, cytokines, oxidative stress, and antioxidant enzyme activity were measured. Tissue samples were histologically examined and mortality was monitored for 16 days. The level of CoQ9 significantly increased in the liver, kidney, and plasma, while the level of CoQ10 significantly increased in most organ tissues in the CoQ10 + O2 group. Additionally, CoQ10 decrease oxidative stress in the liver, increase antioxidant enzyme activity in the heart, kidney, and brain, and reverse an inclined level of hematopoietic growth factors. However, CoQ10 had no effect on inflammation, organ damage, or mortality. Therefore, the use of CoQ10 in potential adjuvant therapy for neonatal hyperoxia requires further research.

Glucocorticoids in a Neonatal Hyperoxic Lung Injury Model: Pulmonary and Neurotoxic effects.

BACKGROUND: We aimed to compare the effect of dexamethasone (Dex), hydrocortisone (Hc), and methylprednisolone (Mpz) at equivalent doses on somatic growth, lung healing, and neurotoxicity in a hyperoxic rat model. We hypothesized that Mpz and Hc would be superior to Dex with less neurotoxicity by exerting similar therapeutic efficacy on the injured lung. METHODS: Neonatal rats were randomized to control, bronchopulmonary dysplasia (BPD), Dex, Hc, and Mpz groups. All drugs were administered daily following day 15 over 7 days. Histopathological and immunohistochemical analyses of the lung and brain were performed on day 22. RESULTS: All types had much the same impact on lung repair. Oxidative markers in the lung were similar in the steroid groups. While nuclear factor erythroid 2-related factor and heat-shock protein 70 dropped following steroid treatment, no difference was noted in other biochemical markers in the brain between the study groups. Apoptotic activity and neuron loss in the parietal cortex and hippocampus were noted utmost in Dex, but alike in other BPD groups. CONCLUSIONS: Mpz does not appear to be superior to Dex or Hc in terms of pulmonary outcomes and oxidative damage in the brain, but safer than Dex regarding apoptotic neuron loss. IMPACT: This is the first study that compared the pulmonary efficacy and neurotoxic effects of Dex, Hc, and Mpz simultaneously in an established BPD model. This study adds to the literature on the importance of possible antioxidant and protective effects of glucocorticoid therapy in an oxidative stress-exposed brain. Mpz ended up with no more additional neuron loss or apoptosis risk by having interchangeable effects with others for the treatment of established BPD. Mpz and Hc seem safe as a rescue therapy in terms of adverse outcomes for established BPD in which lung and brain tissue is already impaired.

The neuroendocrine effects of dehydroepiandrosterone and 17ß-estradiol in the in vitro preterm hyperoxia infant model.

Preterm birth causes neurological deficits. Previously, we demonstrated that fetal zone steroids reduce hyperoxia-mediated cell death in vitro. In immature oligodendrocytes (OLN-93 cells), dehydroepiandrosterone + 17ß-estradiol co-treatment had synergistic beneficial effects while signals were transduced through different receptors. In immature astrocytes (C6 cells), both hormones compete for the same receptor and no synergistic effects were observed. 17ß-estradiol and progesterone drastically decrease while fetal zone steroids, mainly dehydroepiandrosterone, remain persistently high within preterm infants until term. Substitution of 17ß-estradiol and progesterone does not improve neurological outcomes. We investigated the influence of dehydroepiandrosterone, 17ß-estradiol or dehydroepiandrosterone + 17ß-estradiol treatment in C6 or OLN-93 cells on steroid receptor availability and activation of intracellular signaling molecules in hyperoxic cell culture. We sought explanations of the observed synergistic effect in preliminary study. In C6 cells, the generated signaling of dehydroepiandrosterone + 17ß-estradiol treatment has no synergistic effects. The combined effect on this particular pathway does not potentiate cell survival. In OLN-93 cells, we observed significant differences in the early generated signaling of 17ß-estradiol + dehydroepiandrosterone treatment to either 17ß-estradiol dehydroepiandrosterone alone but never to both at the same time. The latter finding needs, therefore, further investigation to explain synergistic effects. Nevertheless, we add insight into the receptor and signaling cascade alterations induced by 17ß-estradiol, dehydroepiandrosterone or 17ß-estradiol + dehydroepiandrosterone treatment of C6 and OLN-93 cells in hyperoxia.

Astaxanthin Prevents Lung Injury Due to Hyperoxia and Inflammation.

BACKGROUND/AIM: This study aimed to ascertain the effects of astaxanthin on the lungs of rat pups with bronchopulmonary dysplasia (BPD) induced by hyperoxia and lipopolysaccharide (LPS). MATERIALS AND METHODS: Forty-two newborn Wistar rats, born to spontaneous pregnant rats, were divided into three groups: Hyperoxia (95% O2) + lipopolysaccharide (LPS) group, hyperoxia + LPS + astaxhantin group, and control: no treatment group (21% O2). Pups in the hyperoxia + LPS + astaxanthin group were given 100 mg/kg/day oral astaxanthin from the first day to the fifth day. Histopathologic and biochemical evaluations, including glutathione (GSH), total anti-oxidant status (TAS), total oxidant status (TOS), lipid hydroperoxide (LPO), 8-hydroxydeoxyguanosine (8-OHdG), advanced oxidation protein products (AOPP), myeloperoxidase (MPO), total thiol, tumor necrosis factor-alpha (TNF-α), interleukin 1 beta (IL-1ß), and caspase-3 activities, were performed. RESULTS: Better survival rates and weight gain were demonstrated in the hyperoxia + LPS + astaxanthin group (p <0.001). In the histopathologic evaluation, the severity of lung damage was significantly reduced in the hyperoxia+LPS+astaxanthin group, as well as decreased apoptosis (ELISA for caspase-3) (p <0.001). The biochemical analyses of lung tissues showed that TAS, GSH, and Total thiol levels were significantly higher in the astaxanthin treated group compared to the hyperoxia + LPS group (p <0.05) while TOS, AOPP, LPO, 8-OHdG, MPO levels were significantly lower (p <0.001). In addition, unlike the hyperoxia + LPS group, TNF-α and IL-1ß levels in lung tissue were significantly lower in the astaxanthin-treated group (p <0.001). CONCLUSION: Astaxanthin was shown to reduce lung damage caused by inflammation and hyperoxia with its anti-inflammatory, anti-oxidant, anti-apoptotic properties, and to protect the lung from severe destruction.

Interactions among Genetic Background, Anesthetic Agent, and Oxygen Concentration Shape Blunt Traumatic Brain Injury Outcomes in Drosophila melanogaster.

Following traumatic brain injury (TBI), the time window during which secondary injuries develop provides a window for therapeutic interventions. During this time, many TBI victims undergo exposure to hyperoxia and anesthetics. We investigated the effects of genetic background on the interaction of oxygen and volatile general anesthetics with brain pathophysiology after closed-head TBI in the fruit fly Drosophila melanogaster. To test whether sevoflurane shares genetic risk factors for mortality with isoflurane and whether locomotion is affected similarly to mortality, we used a device that generates acceleration-deceleration forces to induce TBI in ten inbred fly lines. After TBI, we exposed flies to hyperoxia alone or in combination with isoflurane or sevoflurane and quantified mortality and locomotion 24 and 48 h after TBI. Modulation of TBI-induced mortality and locomotor impairment by hyperoxia with or without anesthetics varied among fly strains and among combinations of agents. Resistance to increased mortality from hyperoxic isoflurane predicted resistance to increased mortality from hyperoxic sevoflurane but did not predict the degree of locomotion impairment under any condition. These findings are important because they demonstrate that, in the context of TBI, genetic background determines the latent toxic potentials of oxygen and anesthetics.

Decreased AMP-activated protein kinase (AMPK) function and protective effect of metformin in neonatal rat pups exposed to hyperoxia lung injury.

We investigated the hypothesis that exposure of lungs at the saccular stage of development to hyperoxia leads to persistent growth arrest and dysfunction of 5'AMP-activated protein kinase (AMPK), a key energy sensor in the cell. We exposed neonatal rat pups from postnatal day 1- day 10 (P1-P10) to ≥90% oxygen or control normoxia. Pups were euthanized at P4 or P10 or recovered in normoxia until euthanasia at P21. Half of the pups in each group received AMPK activator, metformin, or saline intraperitoneally from P1 to P10. Lung histology, morphometric analysis, immunofluorescence, and immunoblots were done for changes in lung structure at P10 and P21 and AMPK function at P4, P10, and P21. Phosphorylation of AMPK (p-AMPK) was decreased in lungs at P10 and P21 in hyperoxia-exposed pups. Metformin increased the levels of p-AMPK and PGC-1α, a downstream AMPK target which regulates mitochondrial biogenesis, at P4, P10, and P21 in hyperoxia pups. Lung ATP levels decreased during hyperoxia and were increased by metformin at P10 and P21. Radial alveolar count and alveolar septal tips were decreased and mean linear intercept increased in hyperoxia-exposed pups at P10 and the changes persisted at P21; these were improved by metformin. Lung capillary number was decreased in hyperoxia-exposed pups at P10 and P21 and was restored by metformin. Hyperoxia leads to impaired AMPK function, energy balance and alveolar simplification. The AMPK activator, metformin improves AMPK function and alveolar and vascular growth in this rat pup model of hyperoxia-induced lung injury.

Curcumin analogs (B2BrBC and C66) supplementation attenuates airway hyperreactivity and promote airway relaxation in neonatal rats exposed to hyperoxia.

BACKGROUND: This study was undertaken to test the hypothesis that the newly synthesized curcuminoids B2BrBC and C66 supplementation will overcome hyperoxia-induced tracheal hyperreactivity and impairment of relaxation of tracheal smooth muscle (TSM). MATERIALS AND METHODS: Rat pups (P5) were exposed to hyperoxia (>95% O2 ) or normoxia for 7 days. At P12, tracheal cylinders were used to study in vitro contractile responses induced by methacholine (10-8 -10-4 M) or relaxation induced by electrical field stimulation (5-60 V) in the presence/absence of B2BrBC or C66, or to study the direct relaxant effects elicited by both analogs. RESULTS: Hyperoxia significantly increased contraction and decreased relaxation of TSM compared to normoxia controls. Presence of B2BrBC or C66 normalized both contractile and relaxant responses altered by hyperoxia. Both, curcuminoids directly induced dose-dependent relaxation of preconstricted TSM. Supplementation of hyperoxic animals with B2BrBC or C66, significantly increased catalase activity. Lung TNF-α was significantly increased in hyperoxia-exposed animals. Both curcumin analogs attenuated increases in TNF-α in hyperoxic animals. CONCLUSION: We show that B2BrBC and C66 provide protection against adverse contractility and relaxant effect of hyperoxia on TSM, and whole lung inflammation. Both analogs induced direct relaxation of TSM. Through restoration of catalase activity in hyperoxia, we speculate that analogs are protective against hyperoxia-induced tracheal hyperreactivity by augmenting H2 O2 catabolism. Neonatal hyperoxia induces increased tracheal contractility, attenuates tracheal relaxation, diminishes lung antioxidant capacity, and increases lung inflammation, while monocarbonyl CUR analogs were protective of these adverse effects of hyperoxia. Analogs may be promising new therapies for neonatal hyperoxic airway and lung disease.