Dexpanthenol therapy reduces lung damage in a hyperoxic lung injury in neonatal rats

Evaluation of beneficial effects of dexpanthenol on hypoxic-ischemic encephalopathy

Hypoxic-ischemic encephalopathy (HIE) is a cause of serious morbidity and mortality in newborns. Dexpanthenol, which is metabolized into D-pantothenic acid, has antioxidant and other potentially therapeutic properties. We examined some effects of dexpanthenol on the brains of week-old rat pups with HIE induced by obstruction of the right carotid artery followed by keeping in 8% O2 for 2 hours. Dexpanthenol (500 mg/kg) was administered intraperitoneally to 16 of 32 pups with HIE. Protein, DNA, and lipid oxidation degradation products were assayed and hippocampal and cortical cell apoptosis and neuronal cell numbers were evaluated in stained sections. Dexpanthenol application reduced oxidative stress and inflammation. TNF-α and IL-6 cytokine levels in HIE also decreased with dexpanthenol treatment. The numbers of caspase-3 positive cells in the dentate gyrus and CA1/CA2/CA3 regions of the hippocampus was lower, and apoptosis was decreased in the dexpanthenol-treated animals. These findings suggest possible clinical applications of dexpanthenol in human HIE.

Lung injury induced by short-term mechanical ventilation with hyperoxia and its mitigation by deferoxamine in rats

BACKGROUND

Long-term mechanical ventilation with hyperoxia can induce lung injury. General anesthesia is associated with a very high incidence of hyperoxaemia, despite it usually lasts for a relatively short period of time. It remains unclear whether short-term mechanical ventilation with hyperoxia has an adverse impact on or cause injury to the lungs. The present study aimed to assess whether short-term mechanical ventilation with hyperoxia may cause lung injury in rats and whether deferoxamine (DFO), a ferrous ion chelator, could mitigate such injury to the lungs and explore the possible mechanism.

METHODS

Twenty-four SD rats were randomly divided into 3 groups (n = 8/group): mechanical ventilated with normoxia group (MV group, FiO2 = 21%), with hyperoxia group (HMV group, FiO2 = 90%), or with hyperoxia + DFO group (HMV + DFO group, FiO2 = 90%). Mechanical ventilation under different oxygen concentrations was given for 4 h, and ECG was monitored. The HMV + DFO group received continuous intravenous infusion of DFO at 50 mg•kg- 1•h- 1, while the MV and HMV groups received an equal volume of normal saline. Carotid artery cannulation was carried out to monitor the blood gas parameters under mechanical ventilation for 2 and 4 h, respectively, and the PaO2/FiO2 ratio was calculated. After 4 h ventilation, the right anterior lobe of the lung and bronchoalveolar lavage fluid from the right lung was sampled for pathological and biochemical assays.

RESULTS

PaO2 in the HMV and HMV + DFO groups were significantly higher, but the PaO2/FiO2 ratio were significantly lower than those of the MV group (all p < 0.01), while PaO2 and PaO2/FiO2 ratio between HMV + DFO and HMV groups did not differ significantly. The lung pathological scores and the wet-to-dry weight ratio (W/D) in the HMV and HMV + DFO groups were significantly higher than those of the MV group, but the lung pathological score and the W/D ratio were reduced by DFO (p < 0.05, HMV + DFO vs. HMV). Biochemically, HMV resulted in significant reductions in Surfactant protein C (SP-C), Surfactant protein D (SP-D), and Glutathion reductase (GR) levels and elevation of xanthine oxidase (XOD) in both the Bronchoalveolar lavage fluid and the lung tissue homogenate, and all these changes were prevented or significantly reverted by DFO.

CONCLUSIONS

Mechanical ventilation with hyperoxia for 4 h induced oxidative injury of the lungs, accompanied by a dramatic reduction in the concentrations of SP-C and SP-D. DFO could mitigate such injury by lowering XOD activity and elevating GR activity.

The therapeutic efficacy of dexpanthenol on sciatic nerve injury in a rat model

Objective: The aim of this study was to evaluate histopathological, functional and bone densitometry examinations of the beneficial effects of dexpanthenol (DEX) on nerve regeneration in a rat model of peripheral nerve crush injury.Methods: Thirty adult Sprague-Dawley rats were divided equally into three groups. A crush injury was simulated in all rats by clamping the right sciatic nerve for one minute. In group 1, one day before the surgical procedure, 500 mg/kg DEX administered via intraperitoneally (ip) was initiated and continued three times in a week during the experiment period as 28 days. In group 2, rats received a dose of 10 mg/kg DEX to investigate possible effects of DEX alone. Group 3 served as the control (sciatic nerve injury) and was not given any drugs.Results: Performance was significantly lower in group 3 compared to the drug treatment groups during the rotarod test (30 rpm and 40 rpm) (p < 0.05). After a while, the rats which were able to remain on the rod was significantly lower in group 3 during the acceleration test (p < 0.05). Hot plate latency test results in group 3 were significantly lower when compared to the other groups (p < 0.05).Conclusion: DEX appears to be useful as a supportive clinical agent for the treatment of pain and nerve damage.

Proximal Tubular Development Is Impaired with Downregulation of MAPK/ERK Signaling, HIF-1α, and Catalase by Hyperoxia Exposure in Neonatal Rats

Supplemental oxygen therapy (hyperoxia) is a widely used treatment for alveolar hypoxia in preterm infants. Despite being closely monitored, hyperoxia exposure is believed to undermine neonatal nephrogenesis and renal function caused by elevated oxidative stress. Previous studies have mostly focused on the hyperoxia-induced impairment of glomerular development, while the long-term impact of neonatal hyperoxia on tubular development and the regulatory component involved in this process remain to be clarified. Here, we examined tubular histology and apoptosis, along with the expression profile of mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling, hypoxia-inducible factor 1α (HIF-1α), and catalase, following hyperoxia exposure in neonatal rats. Hematoxylin and eosin (H&E) staining revealed the early disappearance of the nephrogenic zone, as well as dilated lumens and reduced epithelial cells, of mature proximal tubules following neonatal hyperoxia. A robust increase in tubular cell apoptosis caused by neonatal hyperoxia was found using a TUNEL assay. Moreover, neonatal hyperoxia altered renal MAPK/ERK signaling activity and downregulated the expression of HIF-1α and catalase in the proximal tubules throughout nephrogenesis from S-shaped bodies to mature proximal tubules. Cell apoptosis in the proximal tubules was positively correlated with HIF-1α expression on the 14th postnatal day. Our data indicates that proximal tubular development is impaired by neonatal hyperoxia, which is accompanied by altered MAPK/ERK signaling as well as downregulated HIF-1α and catalase. Therapeutic management that targets MAPK/ERK signaling, HIF-1α, or catalase may serve as a protective agent against hyperoxia-induced oxidative damage to neonatal proximal tubules.

Urine metabolomics insight into acute kidney injury point to oxidative stress disruptions in energy generation and H2S availability

Acute kidney injury (AKI) is one of the main complications in acute care medicine and a risk factor for chronic kidney disease (CKD). AKI incidence has increased; however, its diagnosis has limitations and physiopathological mechanisms are underexplored. We investigated urine samples, aiming to identify major metabolite changes during human AKI evolution. Metabolic signatures found were further explored for a potential link to severity of injury. Twenty-four control subjects and 38 hospitalized patients with AKI were recruited and urine samples were collected at the time of diagnosis, during follow-up and at discharge. Nuclear magnetic resonance (NMR) was used in a first discovery phase for identifying potential metabolic differences. Target metabolites of interest were confirmed by liquid chromatography-mass spectrometry (LC-MS/MS) in an independent group. Underlying metabolic defects were further explored by kidney transcriptomics of murine toxic AKI. Urinary 2-hydroxybutyric acid, pantothenic acid, and hippuric acid were significantly downregulated and urinary N-acetylneuraminic acid, phosphoethanolamine, and serine were upregulated during AKI. Hippuric acid, phosphoethanolamine, and serine showed further downregulation/upregulation depending on the metabolite in acute tubular necrosis (ATN) AKI compared to prerenal AKI. Kidney transcriptomics disclosed decreased expression of cystathionase, cystathionine-β-synthase, and ethanolamine-phosphate cytidylyltransferase, and increased N-acetylneuraminate synthase as the potentially underlying cause of changes in urinary metabolites. A urinary metabolite panel identified AKI patients and provided insight into intrarenal events. A urine fingerprint made up of six metabolites may be related to pathophysiological changes in oxidative stress, energy generation, and H₂S availability associated with AKI.

KEY MESSAGES

The urinary metabolome reflects AKI evolution and severity of injury. Kidney transcriptomics revealed enzymatic expression changes. Enzymatic expression changes may be the potentially underlying cause of changes in urine metabolites. Identified metabolite changes link oxidative stress, energy generation, and H₂S availability to AKI.

Recent advances in our understanding of the mechanisms of late lung development and bronchopulmonary dysplasia

The objective of lung development is to generate an organ of gas exchange that provides both a thin gas diffusion barrier and a large gas diffusion surface area, which concomitantly generates a steep gas diffusion concentration gradient. As such, the lung is perfectly structured to undertake the function of gas exchange: a large number of small alveoli provide extensive surface area within the limited volume of the lung, and a delicate alveolo-capillary barrier brings circulating blood into close proximity to the inspired air. Efficient movement of inspired air and circulating blood through the conducting airways and conducting vessels, respectively, generates steep oxygen and carbon dioxide concentration gradients across the alveolo-capillary barrier, providing ideal conditions for effective diffusion of both gases during breathing. The development of the gas exchange apparatus of the lung occurs during the second phase of lung development-namely, late lung development-which includes the canalicular, saccular, and alveolar stages of lung development. It is during these stages of lung development that preterm-born infants are delivered, when the lung is not yet competent for effective gas exchange. These infants may develop bronchopulmonary dysplasia (BPD), a syndrome complicated by disturbances to the development of the alveoli and the pulmonary vasculature. It is the objective of this review to update the reader about recent developments that further our understanding of the mechanisms of lung alveolarization and vascularization and the pathogenesis of BPD and other neonatal lung diseases that feature lung hypoplasia.