Tea Polyphenols Enhanced the Antioxidant Capacity and Induced Hsps to Relieve Heat Stress Injury

Keap1-Nrf2-ARE and heat shock proteins (Hsps) are important endogenous protection mechanisms initiated by heat stress to play a double protective role for cell adaptation and survival. H9C2 cells and 80 300-day-old specific pathogen-free chickens were randomly divided into the control and tea polyphenol groups and used to establish a heat stress model in vitro and in vivo. This task was conducted to explore the protection and mechanism of tea polyphenols in relieving thermal injury. A supplement with 10 μg/mL tea polyphenols could effectively relieve the heat damage of H9C2 cells at 42°C. Accordingly, weaker granular degeneration, vacuolar degeneration, and nucleus deep staining were shown. A strong antioxidant capacity was manifested in the upregulation of the total antioxidant capacity (T-AOC) (at 5 h, P < 0.05 ), Hemeoxygenase-1 mRNA (at 2 h, P < 0.01 ), superoxide dismutase (SOD) (at 2, 3, and 5 h, P < 0.05 ), and Nrf2 (at 0 and 5 h, P < 0.01 ). A high expression of Hsps was reflected in CRYAB at 3 h; Hsp27 at 0, 2, and 3 h ( P < 0.01 ); and Hsp70 at 3 and 5 h ( P < 0.01 ). The supplement with 0.2 g/L tea polyphenols in the drinking water also had a good effect in alleviating the heat stress damage of the myocardial cells of hens at 38°C. Accordingly, light pathological lesions and downregulation of the myocardial injury-related indicators (LDH, CK, CK-MB, and TNF-α) were shown. The mechanism was related to the upregulation of T-AOC (at 0 h, P < 0.05 ), GSH-PX (at 0.5 d, P < 0.01 ), SOD (at 0.5 d), and Nrf2 (at 0 d with P < 0.01 and 2 d with P < 0.05 ) and the induced expression of CRYAB (at 0.5 and 2 d), Hsp27 (at 0, 0.5, and 5 d), and Hsp70 (at 0 and 0.5 d). In conclusion, the tea polyphenols enhanced the antioxidant capacity and induced Hsps to relieve heat stress injury.

Endogenous Pituitary Adenylate Cyclase-Activating Polypeptide (PACAP) Plays a Protective Effect Against Noise-Induced Hearing Loss

Pituitary adenylyl cyclase-activating polypeptide (PACAP) is a member of the vasoactive intestinal polypeptide (VIP)-the secretin-glucagon family of neuropeptides. They act through two classes of receptors: PACAP type 1 (PAC1) and type 2 (VPAC1 and VPAC2). Among their pleiotropic effects throughout the body, PACAP functions as neuromodulators and neuroprotectors, rescuing neurons from apoptosis, mostly through the PAC1 receptor. To explore the potential protective effect of endogenous PACAP against Noise-induced hearing loss (NIHL), we used a knockout mouse model lacking PAC1 receptor expression (PACR1−/−) and a transgenic humanized mouse model expressing the human PAC1 receptor (TgHPAC1R). Based on complementary approaches combining electrophysiological, histochemical, and molecular biological evaluations, we show PAC1R expression in spiral ganglion neurons and in cochlear apical cells of the organ of Corti. Wild-type (WT), PAC1R−/−, and TgHPAC1R mice exhibit similar auditory thresholds. For most of the frequencies tested after acute noise damage, however, PAC1R−/− mice showed a larger elevation of the auditory threshold than did their WT counterparts. By contrast, in a transgene copy number-dependent fashion, TgHPAC1R mice showed smaller noise-induced elevations of auditory thresholds compared to their WT counterparts. Together, these findings suggest that PACAP could be a candidate for endogenous protection against noise-induced hearing loss.

Abstract MP56: Nitric Oxide-Therapy but Not Remote Ischemic Conditioning is Cerebroprotective in Stroke: A Study in Mouse Model of Endothelial Dysfunction and Hypertension

Background: Remote Ischemic Conditioning (RIC) was found effective in stroke models, likely via increased endothelial nitric oxide (NO); yet RIC failed to improve clinical outcomes ( NCT02342522 ; NCT02189928 ). We anticipated that comorbidities neutralize the benefits of RIC in stroke. Hypothesis: NO-therapy but not RIC is vasculoprotective in hypertensive stroke. Methods: Aged (18±1-mo old) S100A1-hets mutant (S100A +/- ) and wild-type (WT) mice were used. As needed, mice were treated with RIC, s-nitrosoglutathione (GSNO) reductase inhibitor (GRI; 5 mg/kg nebulized once daily for 2-wks), GSNO (100-ug/kg; nebulized once daily at 2h post-TES), and/or intravenous thrombolysis (IVT; 10mg/kg at 4h post-TES). Stroke and outcome measures were performed as mentioned below. Statistical significance was determined at P &lt 0.05. Results: S100A +/- compared to WT-type mice showed significantly higher mean arterial pressure (MAP) and lower plasma-NO, supporting a hypertensive phenotype with endothelial dysfunction in S100A +/- mice. In photothrombotic stroke (PTS), RIC significantly improved cerebral blood flow (CBF), behavior and reduced infarction in WT but not in S100A +/- mice at 48h. GRI in S100A +/- mice enhanced plasma NO, improved behavior and CBF, and reduced infarction significantly as compared to vehicle-treated S100A +/- at 48h post-PTS. RIC with GRI did not produce additive protection in S100A +/- mice at 48h post-PTS, demonstrating that the preservation of NO-pool with GRI protects against stroke, but RIC is not effective to enhance this endogenous protection in hypertensive mice. Moreover, GSNO nebulization but not RIC enhanced PbtO 2 , reduced BBB-leakage and brain hemoglobin (Hb)-content at 24h after thromboembolic stroke with and without IVT. Conclusions: NO-therapies but not RIC is effective in hypertensive stroke. RIC- and NO- therapies need further validation in comorbid stroke before embarking on the clinical trial.

Antioxidants in Sport Sarcopenia

The decline of skeletal muscle mass and strength that leads to sarcopenia is a pathology that might represent an emergency healthcare issue in future years. Decreased muscle mass is also a condition that mainly affects master athletes involved in endurance physical activities. Skeletal muscles respond to exercise by reshaping the biochemical, morphological, and physiological state of myofibrils. Adaptive responses involve the activation of intracellular signaling pathways and genetic reprogramming, causing alterations in contractile properties, metabolic status, and muscle mass. One of the mechanisms leading to sarcopenia is an increase in reactive oxygen and nitrogen species levels and a reduction in enzymatic antioxidant protection. The present review shows the recent experimental models of sarcopenia that explore molecular mechanisms. Furthermore, the clinical aspect of sport sarcopenia will be highlighted, and new strategies based on nutritional supplements, which may contribute to reducing indices of oxidative stress by reinforcing natural endogenous protection, will be suggested.

Once delayed non-invasive remote ischemic preconditioning protects against early stroke by modulating neuroinflammatory responses in rats

Once delayed non-invasive remote ischemic preconditioning (RIPC) has been proven to provide endogenous protection against injury induced by ischemia–reperfusion in the central nervous system. However, for thus ischemic preconditioning method, it is still unclear how long this protection can maintain and what the underlying mechanism is. In this study, we tested the hypothesis that once delayed non-invasive RIPC protects brain injury at short reperfusion time. The rat was stimulated by transient middle cerebral artery occlusion (MCAo) for 90 min, and subsequent reperfusion was performed at 6 h, 72 h and 7 days after MCAo. RIPC was conducted in both hind limbs 24 h before MCAo for 3 cycles (10 min ischemia/ 10 min reperfusion). The infarct size was measured by 2, 3, 5-triphenyl-2H-tetrazolium chloride (TTC) staining and Cresyl violet (CV) staining. The mRNA and protein levels of inflammatory cytokines in the brain were measured by real-time RT-PCR and ELISA. The results showed that once delayed non-invasive RIPC reduced the infarct size, improved neurological functions and behavioral performance at 6 and 72 h post-stroke. There was no change by reperfusion at 7 d after MCAo. RIPC reduced the levels of TNFα, IL-1β and IL-6 in the brain at 72 h post stroke. It also reduced the levels of TNFα and IL-1β when reperfusion at 6 h after MCAo. Our results strongly supported that once delayed non-invasive RIPC protects against stroke as a non-invasive neuroprotective strategy, which maintained for both short and middle term ischemic reperfusion time. The protective effect is mediated by the modulation of inflammatory response in the ischemic brain.

The Role of BDNF on Aging-Modulation Markers

An important link between brain aging and a class of growth/survival factors called neurotrophins has recently been demonstrated. In particular, brain-derived neurotrophic factor (BDNF) plays a fundamental role during age-related synaptic loss, preventing cerebral atrophy and cognitive decline. The aim of the present study was to investigate whether the use of low dose BDNF sequentially kinetic activated (SKA) was able to counteract some mechanisms underlying the degeneration and aging of nervous tissue by increasing endogenous protection mechanisms. Both in vitro and in vivo experiments were performed to assess the ability of BDNF SKA to protect and regenerate survival-related molecular pathways, studying intestinal absorption in vitro and brain function in vivo. Our pioneering results show that BDNF SKA is able to induce the endogenous production of BDNF, using its receptor TrkB and influencing the apolipoprotein E expression. Moreover, BDNF SKA exerted effects on β-Amyloid and Sirtuin 1 proteins, confirming the hypothesis of a fine endogenous regulatory effect exerted by BDNF SKA in maintaining the health of both neurons and astrocytes. For this reason, a change in BDNF turnover is considered as a positive factor against brain aging.

TET3 regulates DNA hydroxymethylation of neuroprotective genes following focal ischemia

The 5-hydroxymethylcytosine (5hmC) epigenetic modification is highly enriched in the CNS and a critical modulator of neuronal function and development. We found that cortical 5hmC was enhanced from 5 min to three days of reperfusion following focal ischemia in adult mice. Blockade of the 5hmC-producing enzyme ten-eleven translocase 3 (TET3) increased edema, infarct volume, and motor function impairments. To determine the mechanism by which TET3 provides ischemic neuroprotection, we assessed the genomic regions where TET3 modulates 5hmC. Genome-wide sequencing analysis of differentially hydroxymethylated regions (DhMRs) revealed that focal ischemia robustly increased 5hmC at the promoters of thousands of genes in a TET3-dependent manner. TET3 inhibition reduced 5hmC at the promoters of neuroprotective genes involved in cell survival, angiogenesis, neurogenesis, antioxidant defense, DNA repair, and metabolism demonstrating a role for TET3 in endogenous protection against stroke. The mRNA expression of several genes with known involvement in ischemic neuroprotection were also reduced with TET3 knockdown in both male and female mice, establishing a correlation between decreased promoter 5hmC levels and decreased gene expression. Collectively, our results indicate that TET3 globally increases 5hmC at regulatory regions and overwhelmingly modulates 5hmC in several neuroprotective pathways that may improve outcome after ischemic injury.