Neuroprotective profile of pyruvate against ethanol-induced neurodegeneration in developing mice brain

Conditioned media from dental pulp stem cells to counteract age-related macular degeneration

PURPOSE

Age-related macular degeneration (AMD) is the leading cause of blindness in the elderly. To date, there are no effective therapies to counteract AMD towards the most severe stages characterised by a progressive loss of photoreceptors triggered by retinal pigmented epithelium dysfunction. Given their easy source and their high proliferative potential, Dental Pulp Stem Cells (DPSCs) are considered promising for regenerative medicine. The main advantage of DPSCs is related to their paracrine immunosuppressive and immunoregulatory abilities, including the capability to promote regeneration of damaged tissues. Recent studies demonstrated the therapeutic potential of DPSCs-conditioned media (CM) in neurodegenerative diseases. In addition, we have already shown a differential expression of some growth factors and cytokines in CM derived from DPSCs cultured in hypoxia and normoxia conditions.

AIM

In this study we evaluated the capability of DPSCs-CM to counteract retinal degeneration in an animal model of AMD. DPSCs-CM were intravitreally injected the day before the exposure of albino rats to high intensity light (LD).

RESULTS

We evaluated the retinal function, and we performed morphological and molecular analysis a week after the LD, in accordance with the well-established protocol of our light damage model. DPSCs-CM obtained from hypoxia (HYPO-CM) or normoxia (NORM-CM), were able to preserve the retinal function, to reduce the damaged area and to counteract the upregulation of key factors involved in retinal degeneration, like FGF-2. Furthermore, we demonstrated that neither conditioned media modified inflammatory activation, as shown by both microglia activation and GFAP upregulation, but in vitro studies demonstrated a significant effect of both CM to counteract oxidative stress, one of the main causes of AMD.

CONCLUSION

Taken together, our study demonstrated that NORM-CM and HYPO-CM, albeit with a different chemical composition, could represent eligible candidates to counteract retinal degeneration in an animal model of AMD. Further studies are needed to obtain conditioned media with the best performance in term of retinal protection.

Current knowledge about pyruvate supplementation: A brief review

Pyruvate is a three-carbon ketoacid that occurs naturally in cells. It is produced through enzymatic reactions in the glycolytic pathway and plays a crucial role in energy metabolism. Despite promising early results, later well-controlled studies of physically active people have shown that pyruvate supplementation lasting more than 1 week has no ergogenic effects. However, some data suggest that ingested pyruvate may be preferentially metabolized without accumulation in the bloodstream. Pyruvate exhibits antioxidant activity and can affect the cellular redox state, and exogenous pyruvate can influence metabolism by affecting the acid-base balance of the blood. This brief review focuses on the potential effects of pyruvate as a supplement for active people. The current state of understanding suggests that studies of the effects of pyruvate supplementation should prioritize investigating the timing of pyruvate intake.

HUANGKUISIWUFANG inhibits pyruvate dehydrogenase to improve glomerular injury in anti-Thy1 nephritis model

ETHNOPHARMACOLOGICAL RELEVANCE

Huangkuisiwufang (HKSWF) is composed of Abelmoschus manihot (L.) Medik., Astragalus mongholicus, Polygonum cuspidatum, Curcuma longa L. Abelmoschus Manihot (L.) Medik. has been widely used for the treatment of chronic renal disease, oral ulcers and burn in China for centuries (Committee of the Pharmacopoeia of PR China, 2010). Abelmoschus manihot (L.) Medik., Polygonum cuspidatum, Curcuma longa L. have been mainly applied in folk medicine for their therapeutic effects on diabetes, cancer, heart disease and other diseases.

AIM OF THE STUDY

We aimed to investigate the renoprotective function of HKSWF in anti-Thy nephritis model and clarify the relevant mechanisms.

MATERIALS AND METHODS

One week after the model of glomerulonephritis created by injecting anti-thymocyte serum (ATS), rats were treated with Huangkui capsule, enalapril or HKSWF by gavage for a period of 8 weeks. The therapeutic effect was evaluated by detection of proteinuria, plasma creatine, blood urea nitrogen (BUN), podocyte injury, glomerular accumulation of extracellular matrix (ECM) and the markers of oxidative stress and renal fibrosis. RNA Sequencing (RNA-seq), KEGG and western blotting analysis were performed to indicate the signaling pathway involved in the therapeutic effect of HKSWF.

RESULTS

Nephritic rats presented the increase of BUN, serum creatinine (Scr), proteinuria, podocyte damage, glomerular fibrosis, Ang II type 1 receptor (AT1R), and the reduction of creatinine clearance (Ccr). In contrast, application of HKSWF to nephritic rats decreased the levels of BUN and proteinuria, promoted mesangial cell recovery and improved oxidative stress level and podocyte injury. KEGG analysis revealed that pyruvate metabolism was the most significantly upregulated pathway in rats treated with HKSWF compared to disease control group. Increased pyruvate dehydrogenase and PAI-1 caused by nephritis was inhibited by HKSWF interposition. Furthermore, dichloroacetate sodium (DCA), an agonist of pyruvate dehydrogenase, could stimulate PAI-1 expression, which was suppressed by HKSWF.

CONCLUSION

Chinese herbal preparation HKSWF has remarkable curative effects on glomerulonephritis animals. HKSWF attenuates pyruvate dehydrogenase to improve glomerular injury.

Multiplexed proteome profiling of carbon source perturbations in two yeast species with SL-SP3-TMT

Saccharomyces cerevisiae and Schizosaccharomyces pombe are the most commonly studied yeast model systems, yet comparisons of global proteome remodeling between these yeast species are scarce. Here, we profile the proteomes of S. cerevisiae and S. pombe cultured with either glucose or pyruvate as the sole carbon source to define common and distinctive alterations in the protein landscape across species. In addition, we develop an updated streamlined-tandem mass tag (SL-TMT) strategy that substitutes chemical-based precipitation with more versatile bead-based protein aggregation method (SP3) prior to enzymatic digestion and TMT labeling. Our new workflow, SL-SP3-TMT, allow for near-complete proteome profiles in a single experiment for each species. The data reveal expected alterations in protein abundance and differences between species, highlighted complete canonical biochemical pathways, and provided insight into previously uncharacterized proteins. The techniques used herein, namely SL-SP3-TMT, can be applied to virtually any experiment aiming to study remodeling of the proteome using a high-throughput, comprehensive, yet streamlined mass spectrometry-based strategy. SIGNIFICANCE: Saccharomyces cerevisiae and Schizosaccharomyces pombe are single-celled eukaryotes that diverged from a common ancestor over a period of 100 million years, such that evolution has driven fundamental differences between the two species. Cellular metabolism and the regulation thereof are vital for living organisms. Here, we hypothesize that large scale proteomic alterations are prevalent upon the substitution of glucose with another carbon source, in this case pyruvate. To efficiently process our samples, we developed an updated streamlined-tandem mass tag (SL-TMT) strategy with more versatile bead-based protein aggregation. The data revealed expected alterations in protein abundance and illustrated differences between species. We highlighted complete canonical biochemical pathways and provided insight into previously uncharacterized proteins.

Natural Dietary Supplementation of Curcumin Protects Mice Brains against Ethanol-Induced Oxidative Stress-Mediated Neurodegeneration and Memory Impairment via Nrf2/TLR4/RAGE Signaling

The aim of the current study was to explore the underlying neuroprotective mechanisms of curcumin (50 mg/kg, for six weeks) against ethanol (5 mg/kg i.p., for six weeks) induced oxidative stress and inflammation-mediated cognitive dysfunction in mice. According to our findings, ethanol triggered reactive oxygen species (ROS), apoptosis, neuroinflammation, and memory impairment, which were significantly inhibited with the administration of curcumin, as assessed by ROS, lipid peroxidation (LPO), and Nrf2/HO-1 (nuclear factor erythroid 2-related factor 2/Heme-oxygenase-1) expression in the experimental mice brains. Moreover, curcumin regulated the expression of the glial cell markers in ethanol-treated mice brains, as analyzed by the relative expression TLR4 (Toll like Receptor 4), RAGE (Receptor for Advanced Glycations End products), GFAP (Glial fibrillary acidic protein), and Iba-1 (Ionized calcium binding adaptor molecule 1), through Western blot and confocal microscopic analysis. Moreover, our results showed that curcumin downregulated the expression of p-JNK (Phospo c-Jun N-Terminal Kinase), p-NF-kB (nuclear factor kappa-light-chain-enhancer of activated B cells), and its downstream targets, as assessed by Western blot and confocal microscopic analysis. Finally, the expression of synaptic proteins and the behavioral results also supported the hypothesis that curcumin may inhibit memory dysfunction and behavioral alterations associated with ethanol intoxication. Altogether, to the best of our knowledge, we believe that curcumin may serve as a potential, promising, and cheaply available neuroprotective compound against ethanol-associated neurodegenerative diseases.

Neurotoxic Agent-Induced Injury in Neurodegenerative Disease Model: Focus on Involvement of Glutamate Receptors

Glutamate receptors play a crucial role in the central nervous system and are implicated in different brain disorders. They play a significant role in the pathogenesis of neurodegenerative diseases (NDDs) such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Although many studies on NDDs have been conducted, their exact pathophysiological characteristics are still not fully understood. In in vivo and in vitro models of neurotoxic-induced NDDs, neurotoxic agents are used to induce several neuronal injuries for the purpose of correlating them with the pathological characteristics of NDDs. Moreover, therapeutic drugs might be discovered based on the studies employing these models. In NDD models, different neurotoxic agents, namely, kainic acid, domoic acid, glutamate, β-N-Methylamino-L-alanine, amyloid beta, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, 1-methyl-4-phenylpyridinium, rotenone, 3-Nitropropionic acid and methamphetamine can potently impair both ionotropic and metabotropic glutamate receptors, leading to the progression of toxicity. Many other neurotoxic agents mainly affect the functions of ionotropic glutamate receptors. We discuss particular neurotoxic agents that can act upon glutamate receptors so as to effectively mimic NDDs. The correlation of neurotoxic agent-induced disease characteristics with glutamate receptors would aid the discovery and development of therapeutic drugs for NDDs.

Pyruvic acid prevents Cu2+/Zn2+-induced neurotoxicity by suppressing mitochondrial injury

Zinc (Zn) is known as a co-factor for over 300 metalloproteins or enzymes, and has essential roles in many physiological functions. However, excessively high Zn concentrations are induced in pathological conditions such as interruption of blood flow in stroke or transient global ischemia-induced neuronal cell death. Furthermore, we recently found that copper (Cu²⁺) significantly exacerbates Zn²⁺ neurotoxicity in mouse hypothalamic neuronal cells, suggesting that Zn²⁺ interaction with Cu²⁺ is important for the development of neurological disease. Meanwhile, organic acids such as pyruvic acid and citric acid are reported to prevent neuronal cell death induced by various stresses. Thus, in this study, we focused on organic acids and searched for compounds that inhibit Cu²⁺/Zn²⁺-induced neurotoxicity. Initially, we examined the protective effect of various organic acids on Cu²⁺/Zn²⁺-induced neurotoxicity, and found that pyruvic acid clearly suppresses Cu²⁺/Zn²⁺-induced neurotoxicity in GT1-7 cells. Next, we examined the protective mechanisms of pyruvic acid against Cu²⁺/Zn²⁺-induced neurotoxicity. Specifically, we examined the possibilities that pyruvic acid chelates Cu²⁺ and Zn²⁺ or suppresses the ER stress response, but found that neither was suppressed by pyruvic acid treatment. In contrast, pyruvic acid significantly suppressed cytochrome c release into cytoplasm, an index of mitochondrial injury, in a dose-dependent manner. These results suggest that pyruvic acid prevents Cu²⁺/Zn²⁺-induced neuronal cell death by suppressing mitochondrial injury. Based on our results, we assume that pyruvic acid may be therapeutically beneficial for neurological diseases involving neuronal cell death such as vascular dementia.

Chronic Pyruvate Supplementation Increases Exploratory Activity and Brain Energy Reserves in Young and Middle-Aged Mice

Numerous studies have reported neuroprotective effects of pyruvate when given in systemic injections. Impaired glucose uptake and metabolism are found in Alzheimer's disease (AD) and in AD mouse models. We tested whether dietary pyruvate supplementation is able to provide added energy supply to brain and thereby attenuate aging- or AD-related cognitive impairment. Mice received ~800 mg/kg/day Na-pyruvate in their chow for 2-6 months. In middle-aged wild-type mice and in 6.5-month-old APP/PS1 mice, pyruvate facilitated spatial learning and increased exploration of a novel odor. However, in passive avoidance task for fear memory, the treatment group was clearly impaired. Independent of age, long-term pyruvate increased explorative behavior, which likely explains the paradoxical impairment in passive avoidance. We also assessed pyruvate effects on body weight, muscle force, and endurance, and found no effects. Metabolic postmortem assays revealed increased energy compounds in nuclear magnetic resonance spectroscopy as well as increased brain glycogen storages in the pyruvate group. Pyruvate supplementation may counteract aging-related behavioral impairment, but its beneficial effect seems related to increased explorative activity rather than direct memory enhancement.

Downregulation of dopamine D₁ receptors and increased neuronal apoptosis upon ethanol and PTZ exposure in prenatal rat cortical and hippocampal neurons

The objective of this study was to evaluate the effect of ethanol and pentylenetetrazol (PTZ) on the expression of dopamine receptors (D1R) and to observe the apoptotic neurodegeneration in prenatal rat cortical and hippocampal neurons at gestational days (GD) 17.5. In the present study, ethanol (100 mM) and PTZ (15 mM) were exposed to the prenatal rat cortical and hippocampal neuronal cell cultures for 1 h. For mRNA RT-PCR and for protein Western blot analysis was done to elucidate D1R, Bax, Bak, Bcl-2 and cleaved caspase-3 expression upon ethanol and PTZ exposure in neuronal cell cultures. Furthermore, ethanol and PTZ-induced apoptotic neurodegeneration was also observed using TUNEL staining and propidium iodide (PI) used as counter stain under confocal microscopy. The results of present study showed that ethanol and PTZ exposure significantly decreased D1R expression and induced neuronal death by significantly increasing the expression of pro-apoptotic Bax, Bak and decreasing anti-apoptotic protein Bcl-2 leading to the apoptosis by increasing cleaved caspase-3 expression in cortical and hippocampal primary neuronal cell cultures. Our findings indicated that ethanol and PTZ exposure to the prenatal neurons showed not only downregulation of D1R but also causes neuronal apoptosis in the developing rat brain. Further, this explains the possibility of higher risk of developmental disturbances and malformations during early developmental stage.