Cytosolic Content Research Articles

Lipidomics of solar-power animals: a tool to unravel the process of kleptoplasty

Lipidomics of solar-power animals: a tool to unravel the process of kleptoplasty

Melatonin actions in the heart; more than a hormone

Due to the broad distribution of extrapineal melatonin in multiple organs and tissues, we analyzed the presence and subcellular distribution of the indoleamine in the heart of rats. Groups of sham-operated and pinealectomized rats were sacrificed at different times along the day, and the melatonin content in myocardial cell membranes, cytosol, nuclei and mitochondria, were measured. Other groups of control animals were treated with different doses of melatonin to monitor its intracellular distribution. The results show that melatonin levels in the cell membrane, cytosol, nucleus, and mitochondria vary along the day, without showing a circadian rhythm. Pinealectomized animals trend to show higher values than sham-operated rats. Exogenous administration of melatonin yields its accumulation in a dose-dependent manner in all subcellular compartments analyzed, with maximal concentrations found in cell membranes at doses of 200 mg/kg bw melatonin. Interestingly, at dose of 40 mg/kg b.w, maximal concentration of melatonin was reached in the nucleus and mitochondrion. The results confirm previous data in other rat tissues including liver and brain, and support that melatonin is not uniformly distributed in the cell, whereas high doses of melatonin may be required for therapeutic purposes.

Effect of different exogenous fatty acids on the cytosolic triacylglycerol content in bovine mammary cells.

The objective of this study was to determine how cytosolic triacylglycerols (TAG) are stored in mammary cells and whether this depends on the individual chemical configuration of fatty acids (FA). This objective was accomplished by addition of different FA to a FA-free medium used to culture mammary alveolar cells-large T antigen cells (MAC-T). Treatments consisted of adding FA (palmitate, stearate, oleate, linoleate, rumenic acid [CLA], elaidate and vaccinate) solutions to the medium at 100, 200, 300 and 400 mmol/L concentrations for a 24-h incubation period. At the end of each incubation period, cytosolic TAG, DNA and protein contents were measured. Palmitate, vaccenate, linoleate and CLA increased (P < 0.05) cytosolic TAG (μg/mg protein). Palmitate and CLA increased (P < 0.05) cytosolic TAG adjusted for DNA content. Overall, effects on cytosolic TAG accumulation depended on individual FA structure (chain length, degree of saturation, and number and orientation of FA double bonds). In addition, the long-chain FA used in this study did not have a detrimental effect on MAC-T cells as indicated by cytosolic protein and DNA contents reflecting their biological role in lipid accumulation.

Aloe-Emodin Induces Endoplasmic Reticulum Stress-Dependent Apoptosis in Colorectal Cancer Cells.

BackgroundRecently, colorectal cancer has become a more common type of tumor in the world. Research has reported that several kinds of single compounds of Chinese herbs have shown anti-tumor activity in colorectal cancer. Aloe-emodin (AE), a natural compound extract from Aloe Vera, has been discovered to suppress cell proliferation and accelerate apoptosis in a variety of tumor cells. Whether AE exerts an effect on colorectal cancer cells has not yet been investigated.Material/MethodsIn this study, we examined the impact of AE on SW620 and HT29 colorectal cancer cell lines. After treatment with various concentrations of AE (10, 20, and 40 μM), cell proliferation, cell apoptosis, reactive oxygen species (ROS) generation, cytosolic calcium level, and related gene expression were analyzed.ResultsOur results indicated that AE suppressed cell viability and induced cell apoptosis in SW620 and HT29 cell lines. Furthermore, both cell lines when exposed to AE generated ROS, which induces endoplasmic reticulum (ER) stress. We then detected the expression of ER stress-related proteins and cytosolic calcium levels. We found that cells exposure to AE had upregulation of unfolded protein response (UPR) proteins like glucose-related protein 78 (GRP78), phosphorylated protein kinase R (PKR)-like ER kinase (p-PERK), phosphorylated eukaryotic initiation factor-2α (p-eIF2α), and transcription factor C/EBP homologous protein (CHOP). Meanwhile, we detected an increased cytosolic calcium content followed by the upregulation of the calpain-1, calpain-2 and caspase-12. CHOP and caspase-12 are important regulatory factors leading to cell apoptosis.ConclusionsAE might serve as a candidate in the treatment of colorectal cancer through inducing ER stress-dependent apoptosis.

Photoluminescence Lifetime of Black Phosphorus Nanoparticles and Their Applications in Live Cell Imaging.

Black phosphorus (BP) has attracted much attention as a new member of 2D materials due to its unique electronic and optical properties and a wide range of promising applications. Here, for the first time, we report the photoluminescence lifetime of BP nanomaterial and its applications as an efficient agent for live cell imaging. With a lateral size of ∼35 nm and a thickness of ∼6 nm, the fabricated BP nanoparticles (BPNPs) exhibited a unique photoluminescent (PL) emission at ∼690 nm. The photoluminescence lifetime (PLT) of BPNPs was determined to be 110.5 ps. Coating a layer of mesoporous silica on the surface of BPNPs (BPNPs@mSiO2) extended the lifetime to 267 ps, suggesting a change in the microenvironment. The lifetime was also influenced by ionic strength and intracellular microenvironment, which implies BPNPs as valuable probes for sensing variations in the microenvironment. Live cell imaging was achieved via directly probing the photoluminescence intensity or the photoluminescence lifetime. Our findings are significant, implying that BPNPs can be of large value in sensing variations of the cellular microenvironment and in probing cells with distinct cytosolic contents. This research leads to promising prospects for BPNPs in multiple biomedical applications.

Thallium-induced oxalate secretion from rice (Oryza sativa L.) root contributes to the reduction of Tl(III) to Tl(I)

Thallium (Tl) is a non-essential, highly toxic element having Tl(I) and Tl(III) two redox states. Tl(III) is more toxic to organisms than Tl(I) but is less of attention. The objective of this study was to investigate the reason of Tl(III) instability in the presence of plant. The content of Tl(III) was rapidly reduced from 100% to 16.1% in Tl solution cultivating rice seedlings while content of Tl(I) was increased from 0 to 83.8% within 8 h. High performance liquid chromatography (HPLC) analysis showed that organic acids exudates in rice roots caused the pH decline in rhizosphere, but only oxalate was the specific organic acid in root exudates under Tl stress. The anion channel inhibitor, nifiumic acid (NIF), could efficiently inhibit the oxalate exudation but had no effect on oxalate content in root cytosol compared with Tl treatment. The exogenous oxalate, malate and citrate significantly contributed the reduction of Tl(III) to Tl(I). It was concluded that the contact of Tl(III) with organic acids in plant cells or in root exudates promoted the instability of Tl(III) with plants. Meanwhile, the presence of DTPA could effectively restrain the conversion of Tl(III) to Tl(I). This study provided better understanding of the basic biochemical mechanism for the reduction of Tl(III) in contact with plants. It will contribute to controlling relevant factors to stabilize Tl(III) for further toxic assessment on organism and to studying Tl(III) behavior in ecological system.

Intracellular Electrochemical Sensing

AbstractObserving biochemical processes within living cell is imperative for biological and medical research. Fluoresce imaging is widely used for intracellular sensing of cell membranes, nuclei, lysosomes, and pH. Electrochemical assays have been proposed as an alternative to fluorescence‐based assays because of excellent analytical features of electrochemical devices. Notably, thanks to the rapid progress of micro/nanotechnologies and electrochemical techniques, intracellular electrochemical sensing is making rapid progress, leading to a successful detection of intracellular components. Such insight can provide a deep understanding of cellular biological processes and, ultimately, define the human healthy and diseased states. In this review, we present an overview of recent research progress in intracellular electrochemical sensing. We focus on two main topics, electrochemical extraction of cytosolic contents from cells and intracellular electrochemical sensing in situ.

Omega-3 LCPUFA supplementation improves neonatal and maternal bone turnover: A randomized controlled trial

The aim of this study was to evaluate for the first time the effect of omega-3 LC PUFA supplementation during pregnancy and lactation on bone metabolism in mothers and neonates. 110 pregnant women were divided in two groups: control group (400 mL/day of the control dairy drink); supplemented group (400 mL/day of the fish oil-enriched dairy drink). Plasma bone biomarkers and mineral content in erythrocyte cytosol were assessed. In mothers, DHA supplementation increased OC and OPN levels and decreased IL-6 and TNF-α levels at delivery, increasing PTH levels during lactation. In neonates, DHA supplementation increased ACTH, insulin and leptin, decreasing RANKL and IL-6 in umbilical vein; increased OPG and leptin and diminished TNF-α in umbilical artery; increased OC levels, lowered PTH and TNF-α at birth. DHA supplementation during pregnancy and lactation has beneficial effects on bone turnover in both mother and neonates, representing a non-pharmacological pathway to decrease bone loss.

Abstract 428: An Unexpected Role for ACC in Lipid Droplet Formation in Macrophages in Response to Acellular Adipocyte Fat

In adipose tissues of obese mice, macrophages accumulate in crown-like structures (CLS) formed around dying adipocytes. The CLS macrophages are thought to clear the dead adipocytes by exophagy, which involves exocytosis of lysosomes and digestion of apoptotic adipocytes. After digesting the plasma membrane and other cytosolic contents of the adipocyte, CLS macrophages come in contact with the large lipid droplet, however, it is unknown how macrophages response to such acellular adipocytes. We hypothesized that the acelular adipocytes in CLSs promote inflammation and metabolically activate the macrophages to promote clearance of the lipid. To mimic the in vivo scenario, we exposed cultured murine bone marrow-derived macrophages to lipid droplets isolated from the adipocytes of high-fat diet-induced obese C57BL/6 mice. In response to adipocyte lipid, macrophages accumulated lipid droplets, which were similar in size and number to lipid droplets of CLS macrophages in vivo . Acellular lipid exposure significantly increased TNF-α gene expression, which was suppressed by the CD36 inhibitor sulfo-N-succinimidyl oleate, supporting CD36-mediated inflammatory response. Moreover, lipid exposure significantly lowered metabolic activity of macrophages and impaired clearance of apoptotic bodies from 3T3-L1 adipocytes. Using specific inhibitors, unexpectedly we found that lipid droplet accumulation in macrophages was independent of CD36 activity or processes involved in exophagy such as exocytosis of lysosomes, extracellular lipase activity, lipolysis and phagocytosis. Interestingly, lipid droplet accumulation was dependent on acetyl-CoA carboxylase (ACC) as determined by use of ACC inhibitors soraphen A and TOFA, and siRNA knock-down of ACC in macrophages. Furthermore, confocal microscopy of whole mount adipose tissue revealed expression of ACC in CLS macrophages. Altogether, using a novel in vitro model we demonstrate that acelular adipocytes suppress metabolic activity, but induce inflammation and de novo lipogenesis-mediated lipid droplet formation in macrophages.

Migrosome and migrocytosis

Cells communicate with each other through secreting and releasing proteins and vesicles. Many cells can migrate. In this study, we report the discovery of migracytosis, a cell migration-dependent mechanism for releasing cellular contents, and migrasomes, the vesicular structures that mediate migracytosis. As migrating cells move, they leave long tubular strands, called retraction fibers, behind them. Large vesicles, which contain numerous smaller vesicles, grow on the tips and intersections of retraction fibers. These fibers, which connect the vesicles with the main cell body, eventually break, and the vesicles are released into the extracellular space or directly taken up by surrounding cells. Since the formation of these vesicles is migration-dependent, we named them “migrasomes”. We also found that cytosolic contents can be transported into migrasomes and released from the cell through migrasomes. We named this migration-dependent release mechanism “migracytosis”. In this seminar, I will discuss our recent progress on the molecular mechanism for migrasome formation and the physiological roles of migrsome. Migrasome This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

High Fibroblast Growth Factor 23 concentrations in experimental renal failure impair calcium handling in cardiomyocytes.

The overwhelming majority of patients with chronic kidney disease (CKD) die prematurely before reaching end‐stage renal disease, mainly due to cardiovascular causes, of which heart failure is the predominant clinical presentation. We hypothesized that CKD‐induced increases of plasma FGF23 impair cardiac diastolic and systolic function. To test this, mice were subjected to 5/6 nephrectomy (5/6Nx) or were injected with FGF23 for seven consecutive days. Six weeks after surgery, plasma FGF23 was higher in 5/6Nx mice compared to sham mice (720 ± 31 vs. 256 ± 3 pg/mL, respectively, P = 0.034). In cardiomyocytes isolated from both 5/6Nx and FGF23 injected animals the rise of cytosolic calcium during systole was slowed (−13% and −19%, respectively) as was the decay of cytosolic calcium during diastole (−15% and −21%, respectively) compared to controls. Furthermore, both groups had similarly decreased peak cytosolic calcium content during systole. Despite lower cytosolic calcium contents in CKD or FGF23 pretreated animals, no changes were observed in contractile parameters of cardiomyocytes between the groups. Expression of calcium handling proteins and cardiac troponin I phosphorylation were similar between groups. Blood pressure, the heart weight:tibia length ratio, α‐MHC/β‐MHC ratio and ANF mRNA expression, and systolic and diastolic function as measured by MRI did not differ between groups. In conclusion, the rapid, CKD‐induced rise in plasma FGF23 and the similar decrease in cardiomyocyte calcium transients in modeled kidney disease and following 1‐week treatment with FGF23 indicate that FGF23 partly mediates cardiomyocyte dysfunction in CKD.

HSP90 modulates the myosin replacement rate in myofibrils.

Myosin is a major myofibrillar component in skeletal muscles. In myofibrils, ~300 myosin molecules form a single thick filament in which there is constant turnover of myosin. Our previous study demonstrated that the myosin replacement rate is reduced by inhibition of protein synthesis (Ojima K, Ichimura E, Yasukawa Y, Wakamatsu J, Nishimura T, Am J Physiol Cell Physiol 309: C669-C679, 2015); however, additional factors influencing myosin replacement were unknown. Here, we showed that rapid myosin replacement requires heat shock protein 90 (HSP90) activity. We utilized the fluorescence recovery after photobleaching technique to measure the replacement rate of green fluorescent protein-fused myosin heavy chain (GFP-MYH) in myotubes overexpressing HSP90. Intriguingly, the myosin replacement rate was significantly increased in HSP90-overexpressing myotubes, whereas the myosin replacement rate slowed markedly in the presence of an HSP90-specific inhibitor, indicating that HSP90 activity promotes myosin replacement. To determine the mechanism of this effect, we investigated whether HSP90 activity increased the amount of myosin available for incorporation into myofibrils. Strikingly, the gene expression levels of MYHs were significantly elevated by HSP90 overexpression but downregulated by inhibition of HSP90 activity. Cytosolic myosin content was also increased in myotubes overexpressing HSP90. Taken together, our results demonstrate that HSP90 activity facilitates myosin replacement by upregulating MYH gene expression and thereby increasing cytosolic myosin content.

Sticholysin II-mediated cytotoxicity involves the activation of regulated intracellular responses that anticipates cell death

Sticholysin II (StII) is a pore-forming toxin of biomedical interest that belongs to the actinoporin protein family. Sticholysins are currently under examination as an active immunomodulating component of a vaccinal platform against tumoral cells and as a key element of a nucleic acids delivery system to cell cytosol. These proteins form pores in the plasma membrane leading to ion imbalance and cell lysis. However, the intracellular mechanisms triggered by actinoporins upon binding to membranes and its consequences for cell death are barely understood. Here, we have examined the cytotoxicity and intracellular responses induced by StII upon binding to human B-cell lymphoma Raji in vitro. StII cytotoxicity involves a functional actin cytoskeleton, induces cellular swelling, lysis and the concomitant release of cytosol content. In addition, StII induces calcium release mainly from the Endoplasmic Reticulum, activates Mitogen-Activated Protein Kinase ERK and impairs mitochondrial membrane potential. Furthermore, StII stimulates the expression of receptor interacting protein kinase 1 (RIP1), normally related to different forms of regulated cell death such as apoptosis and necroptosis. In correspondence, necrostatin-1, an inhibitor of this kinase, reduces StII cytotoxicity. However, the mechanism of cell death activated by StII does not involve caspases activation, typical molecular features of apoptosis and pyroptosis. Our results suggest that, beyond pore-formation and cell lysis, StII-induced cytotoxicity could involve other regulated intracellular mechanisms connected to RIP1-MEK1/2 –ERK1/2- pathways. This opens new perspectives and challenges the general point of view that these toxins induce a completely unregulated mechanism of necrotic cell death. This study contributes to a better understanding of the molecular mechanisms involved in toxin-cell interaction and the implications for cell functioning, with connotation for the exploitations of these toxins in clinical settings.

Vertically Aligned Graphene Coating is Bactericidal and Prevents the Formation of Bacterial Biofilms

AbstractThe key first step in developing bacterial infections related to implants and medical devices is the attachment of planktonic bacterial cells, and subsequent formation of biofilms. Herein, it is reported that graphene, a 2D carbon‐based material, can be effectively used to prevent bacterial attachment. The key parameter for this effect is the orientation of graphene with respect to the coated surface. Chemical vapor deposition (CVD) graphene, deposited horizontally on the surface, exhibits no antibacterial effect. By contrast, an array of graphene flakes grown perpendicularly to the surface by a plasma‐enhanced CVD (PECVD) process prevent biofilm formation. Electron microscopy reveals that the exposed edges of vertically aligned graphene flakes penetrate the bacterial membrane and drain the cytosolic content. Bacteria are not able to develop resistance to this killing mechanism during multiple exposures. By keeping the height of the vertical graphene coating between 60 and 100 nm, the coating is able to effectively kill bacteria, while being completely harmless to mammalian cells.

Flexibility of the Myelin Scaffolding Protein Periaxin

Rapid nerve impulse conduction is necessary for a correctly functioning vertebrate nervous system. This is enabled by myelin, an insulating lipid-rich structure that encloses selected axonal segments. The insulation arises from compact myelin, which is composed of tightly stacked lipid bilayers devoid of cytosolic content. Non-compact myelin is richer in cytosol, has a role in myelin maintenance, and resides mostly under the inner- and outermost myelin membranes. In the peripheral nervous system, myelin is produced by Schwann cells, which in addition to their outermost abaxonal membrane, are surrounded by a carbohydrate-rich basal lamina that is connected to the abaxonal membrane via dystroglycans. These penetrate the membrane and connect to a network of intramyelin proteins, including periaxin (PRX) - a scaffolding molecule for other proteins within this network that links the abaxonal membrane to the cytoskeleton. Both PRX isoforms, S- and L-PRX, contain a folded 100-amino acid PDZ-like domain. Additionally, the longer isoform contains a ∼1300-residue tail, which - based on sequence analysis - can be divided into several distinct regions that are predicted to be disordered. This tail is a protein scaffolding unit, which is crucial for the correct morphology and stability of peripheral myelin, as point mutations in the tail region result in Charcot-Marie-Tooth disease (CMT) - an incurable demyelinating neuropathy. We characterized L-PRX using different biophysical methods, including X-ray crystallography, NMR spectroscopy, synchrotron-radiation circular dichroism (SRCD) spectroscopy, and small-angle X-ray scattering (SAXS). The crystal structure is an intertwined, domain-swapped PDZ-like homodimer with potential membrane interactions, as suggested by detergent titrations. Different parts of the tail are very flexible and functional in vitro. Quantitative studies regarding the affinities and structural implications of these interactions are underway. Our study will contribute to understanding the structure-function relationships of myelin proteins in health and disease.

Polymorphic Human Sulfotransferase 2A1 Mediates the Formation of 25-Hydroxyvitamin D3-3-O-Sulfate, a Major Circulating Vitamin D Metabolite in Humans.

Metabolism of 25-hydroxyvitamin D3 (25OHD3) plays a central role in regulating the biologic effects of vitamin D in the body. Although cytochrome P450-dependent hydroxylation of 25OHD3 has been extensively investigated, limited information is available on the conjugation of 25OHD3 In this study, we report that 25OHD3 is selectively conjugated to 25OHD3-3-O-sulfate by human sulfotransferase 2A1 (SULT2A1) and that the liver is a primary site of metabolite formation. At a low (50 nM) concentration of 25OHD3, 25OHD3-3-O-sulfate was the most abundant metabolite, with an intrinsic clearance approximately 8-fold higher than the next most efficient metabolic route. In addition, 25OHD3 sulfonation was not inducible by the potent human pregnane X receptor agonist, rifampicin. The 25OHD3 sulfonation rates in a bank of 258 different human liver cytosols were highly variable but correlated with the rates of dehydroepiandrosterone sulfonation. Further analysis revealed a significant association between a common single nucleotide variant within intron 1 of SULT2A1 (rs296361; minor allele frequency = 15% in whites) and liver cytosolic SULT2A1 content as well as 25OHD3-3-O-sulfate formation rate, suggesting that variation in the SULT2A1 gene contributes importantly to interindividual differences in vitamin D homeostasis. Finally, 25OHD3-3-O-sulfate exhibited high affinity for the vitamin D binding protein and was detectable in human plasma and bile but not in urine samples. Thus, circulating concentrations of 25OHD3-3-O-sulfate appear to be protected from rapid renal elimination, raising the possibility that the sulfate metabolite may serve as a reservoir of 25OHD3 in vivo, and contribute indirectly to the biologic effects of vitamin D.

Interfering RNA against PKC-α inhibits TNF-α-induced IP3R1 expression and improves glomerular filtration rate in rats with fulminant hepatic failure.

We have reported that tumor necrosis factor-α (TNF-α) is critical for reduction of glomerular filtration rate (GFR) in rats with fulminant hepatic failure (FHF). The present study aims to evaluate the underlying mechanisms of decreased GFR during acute hepatic failure. Rats with FHF induced by d-galactosamine plus lipopolysaccharide (GalN/LPS) were injected intravenously with recombinant lentivirus harboring short hairpin RNA against the protein kinase C-α ( PKC-α) gene (Lenti-shRNA-PKC-α). GFR, serum levels of aminotransferases, creatinine, urea nitrogen, potassium, sodium, chloride, TNF-α, and endothelin-1 (ET-1), as well as type 1 inositol 1,4,5-trisphosphate receptor (IP3R1) expression in renal tissue were assessed. The effects of PKC-α silencing on TNF-α-induced IP3R1, specificity protein 1 (SP-1), and c-Jun NH2-terminal kinase (JNK) expression, as well as cytosolic calcium content were determined in glomerular mesangial cell (GMCs) with RNAi against PKC-α. Renal IP3R1 overexpression was abrogated by pre-treatment with Lenti-shRNA-PKC-α. The PKC-α silence significantly improved the compromised GFR, reduced Cr levels, and reversed the decrease in glomerular inulin space and the increase in glomerular calcium content in GalN/LPS-exposed rats. TNF-α treatment increased expression of PKC-α, IP3R1, specificity protein 1 (SP-1), JNK, and p-JNK in GMCs and increased Ca2 + release and binding activity of SP-1 to the IP3R1 promoter. These effects were blocked by transfection of siRNA against the PKC-α gene, and the PKC-α gene silence also restored cytosolic Ca2+ concentration. RNAi targeting PKC-α inhibited TNF-α-induced IP3R1 overexpression and in turn improved compromised GFR in the development of acute kidney injury during FHF in rats.

Metabolomics reveals the mechanism of (−)-hydroxycitric acid promotion of protein synthesis and inhibition of fatty acid synthesis in broiler chickens

(−)-Hydroxycitric acid (HCA), a major component of Garcinia cambogia extracts, has been shown to suppress BW gain and fat accumulation in animals and humans. However, the mechanism remains unknown. In this study, gas chromatography-mass spectrometry was used to analyse serum metabolites, and principal component analysis and partial least-squares-discriminant analysis models were generated to analyse serum metabolite changes in broiler chickens after the administration of (−)-HCA at 0, 1000, 2000 and 3000 mg/kg diets for 28 days. Metabolites showing significant changes were screened by ‘variable importance in the projection’ plots. The results showed that 20 metabolites in the 1000 mg/kg (−)-HCA treatment group and 16 metabolites in 3000 mg/kg (−)-HCA treatment group were significantly altered. Metabolites pathway enrichment analysis indicated that these metabolites were mainly associated with metabolism of amino acids, protein synthesis, citric acid cycle, and uric acid and fatty acid synthesis. The data indicated that (−)-HCA promoted protein synthesis by regulating the metabolic directions of amino acids. At the same time, (−)-HCA treatment inhibited fatty acid synthesis by promoting the citric acid cycle, resulting in reduced cytosolic acetyl-CoA content in broiler chickens. The present study identified global changes in metabolites and analysed the main canonical metabolic pathways in broiler chickens supplemented with (−)-HCA. These results will deepen our understanding of the mechanism of (−)-HCA’s effects in animals.

Uric acid contributes greatly to hepatic antioxidant capacity besides protein.

Uric acid is the end-product of purine nucleotide metabolism and an increase in uric acid concentration in the body results in hyperuricemia, ultimately leading to gout. However, uric acid is a potent antioxidant and interacts with reactive oxygen species (ROS) to be non-enzymatically converted to allantoin. Uric acid accounts for approximately 60 % of antioxidant capacity in the plasma; however, its contribution to tissue antioxidant capacity is unknown. In this study, the contribution of uric acid to tissue antioxidant capacity and its conversion to allantoin by scavenging ROS in tissue were examined. The results showed that a decrease in hepatic uric acid content via allopurinol administration significantly reduced hepatic total-radical trapping antioxidant parameter (TRAP) content in protein-free cytosol. Additionally, treating protein-free cytosol with uricase led to a further reduction of hepatic TRAP content. Allantoin was also detected in the solution containing protein-free cytosol that reacted with ROS. These findings suggest that in the absence of protein, uric acid contributes greatly to antioxidant capacity in the liver, where uric acid is converted to allantoin by scavenging ROS.

Ferulic acid protects against radiation-induced testicular damage in male rats: impact on SIRT1 and PARP1.

Ionizing radiation is a major contributor to male infertility by destroying spermatogenesis. Therefore, the need for an effective radio-protective agent is evident. The objective of the present study was to investigate the potential radio-protective effect of ferulic acid (FA) on radiation-induced testicular damage. Mature male Sprague-Dawley rats were either exposed to a single-dose gamma radiation (5Gy) and/or treated with FA (50mg/kg), daily for 7days before irradiation. Sirtuin1 (SIRT1), poly (ADP-ribose) polymerase 1 (PARP1), cytosolic calcium content, and the male reproductive functions (sperm head abnormality) as well as oxidative stress markers were assessed 7days after irradiation. FA significantly maintained active spermatogenesis. Moreover, it reversed the oxidative stress effects of irradiation. The irradiated group showed marked elevation in both PARP1 expression and activity as well as in cytosolic calcium concentration, whereas SIRT1 activity and expression markedly decreased; in contrast, FA treatment prevented these alterations. Results of histopathological examination of testicular tissues indicated coincidence with those recorded by biochemical analyses. Our data show for the first time that FA had radio-protective effect against radiation-induced testicular damage. It improved spermatogenesis through increasing testicular SIRT1 and testosterone levels and decreasing oxidative stress, PARP1, and cytosolic calcium.