Effect of morin on the levels of circulatory liver markers and redox status in experimental chronic hyperammonaemic rats

INTRODUCTION

Hyperammonaemia is a major contributing factor to neurological abnormalities observed in hepatic encephalopathy and in congenital defects of ammonia detoxication. Ammonia toxicity results in free radical generation that leads to oxidative stress and tissue damage. Morin is a bioflavonoid, a constituent of many herbs and fruits that are used as herbal medicines and also several biological activities. Our aim was to investigate the effect of morin on circulatory liver markers, lipid peroxidation and antioxidant status in ammonium chloride (AC)-induced hyperammonaemic rats.

METHODS

Male albino Wistar rats weighing 180-200 g were used for the study. The hyperammonaemia was induced by interaperitonial injection of AC (100 mg/kg body weight). Rats were treated with morin (30 mg/kg body weight) via oral administration. Administration of morin in hyperammonaemic rats reduced the levels of ammonia and urea. The antioxidant property of morin was studied by assessing the activities of thiobarbituric acid reactive substances (TBARS), hydroperoxides (HP) and liver markers (alanine transaminase, aspartate transaminase and alkaline phosphatase) and the levels of glutathione peroxidase, superoxide dismutase, catalase, reduced glutathione, vitamins A, C and E in AC-treated rats.

RESULTS

Oxidative stress was effectively modulated by morin administration. Morin significantly improved the status of antioxidants and decreased the levels of ammonia, urea, TBARS, HP and liver markers enzymes, as compared to the AC-treated group.

CONCLUSION

The study offers evidence for the antihyperammonaemic, hepatoprotective and antioxidant effects of morin against oxidative stress induced by AC.

Underdeveloped trabecular bone microarchitecture is detected in children with cerebral palsy using high-resolution magnetic resonance imaging

Using high resolution magnetic resonance imaging, we detected severely underdeveloped trabecular bone microarchitecture in the distal femur of children with cerebral palsy who can not ambulate independently vs. typically developing controls. Furthermore, very good short-term reliability of trabecular bone microarchitecture measurements was observed in both groups of children.

INTRODUCTION

Severe forms of cerebral palsy (CP) are associated with very low areal bone mineral density and a very high incidence of fracture in the distal femur; however, the state of trabecular bone microarchitecture has not been evaluated. Furthermore, the short-term reliability of trabecular bone microarchitecture assessment in children using high-resolution magnetic resonance imaging (MRI) has not been determined.

METHODS

Apparent bone volume to total volume (appBV/TV), trabecular number, (appTb.N), trabecular thickness (appTb.Th) and trabecular separation (appTb.Sp) were determined in the distal femur of non-ambulatory children with CP and typically developing children using MRI.

RESULTS

Children with CP had a 30% lower appBV/TV, a 21% lower appTb.N, a 12% lower appTb.Th and a 48% higher appTb.Sp in the distal femur than controls (n = 10/group; P < 0.001). The short-term reliability of the trabecular bone microarchitecture measures was very good, with coefficients of variation ranging from 2.0 to 3.0% in children with CP (n = 6) and 1.8 to 3.5% in control children (n = 6).

CONCLUSIONS

Underdeveloped trabecular bone microarchitecture can be detected in the distal femur of children with CP who can not ambulate independently using high-resolution MRI. Furthermore, MRI can be used to assess trabecular bone microarchitecture in children with a high degree of reliability.

Anionic lipids activate group IVA cytosolic phospholipase A2 via distinct and separate mechanisms

Previously, ceramide-1-phosphate (C1P) and phosphatidylinositol-4,5-bisphosphate [PI(4,5)P2] were demonstrated to be potent and specific activators of group IVA cytosolic phospholipase A2 (cPLA2alpha). In this study, we hypothesized that these anionic lipids functionally activated the enzyme by distinctly different mechanisms. Indeed, surface plasmon resonance and surface dilution kinetics demonstrated that C1P was a more potent effector than PI(4,5)P2 in decreasing the dissociation constant of the cPLA2alpha-phosphatidylcholine (PC) interaction and increasing the residence time of the enzyme on the vesicles/micelles. PI(4,5)P2, in contrast to C1P, decreased the Michaelis-Menten constant, increasing the catalytic efficiency of the enzyme. Furthermore, PI(4,5)P2 activated cPLA2alpha with a stoichiometry of 1:1 versus C1P at 2.4:1. Lastly, PI(4,5)P2, but not C1P, increased the penetration ability of cPLA2alpha into PC-rich membranes. Therefore, this study demonstrates two distinct mechanisms for the activation of cPLA2alpha by anionic lipids. First, C1P activates cPLA2alpha by increasing the residence time of the enzyme on membranes. Second, PI(4,5)P2 activates the enzyme by increasing catalytic efficiency through increased membrane penetration.

Influences of aspartate on circadian patterns of lipid peroxidation products and antioxidants in Wistar rats

INTRODUCTION

The aim of the present study was to demonstrate the effects of aspartate on the circadian patterns of lipid peroxidation products and antioxidants in aspartate-treated rats, in order to investigate the influences of aspartate and whether it could modulate these rhythms differently, since aspartate is an important excitatory neurotransmitter (present in retinohypothalamic tract and suprachiasmatic nuclei [SCN]) involved in the generation and regulation of circadian rhythmicity.

METHODS

Aspartate (50 mg/kg body weight) was administered orally for 60 days to Wistar rats, and 24-hour rhythms of thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), superoxide dismutase (SOD) and catalase were studied under semi-natural (light/dark 12:12 hr) conditions.

RESULTS

Exogenous aspartate administration caused acrophase advances in TBARS rhythms, and delays in GSH, SOD and catalase rhythms; altered MESOR and decreased amplitude values were also seen in all of these rhythms.

CONCLUSION

Our findings indicate that the orally-treated aspartate could reach the hypothalamus, and various brain centres possibly including SCN, and could modulate the circadian patterns of lipid peroxidation products and antioxidants.

Hibiscus sabdariffa affects ammonium chloride-induced hyperammonemic rats

Hibiscus sabdariffa (HS) is an edible medicinal plant, indigenous to India, China and Thailand and is used in Ayurveda and traditional medicine. Alcoholic extract of HS leaves (HSEt) was studied for its anti-hyperammonemic and antioxidant effects in brain tissues of ammonium chloride-induced hyperammonemic rats. Oral administration of HSEt (250 mg kg(-1) body weight) significantly normalizes the levels of ammonia, urea, uric acid, creatinine and non-protein nitrogen in the blood. HSEt significantly reduced brain levels of lipid peroxidation products such as thiobarbituric acid and reactive substances (TBARS) and hydroperoxides (HP). However, the administered extract significantly increased the levels of antioxidants such as catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and reduced glutathione (GSH) in brain tissues of hyperammonemic rats. This investigation demonstrates significant anti-hyperammonemic and antioxidant activity of HS.

Ceramide-1-phosphate Binds Group IVA Cytosolic Phospholipase a2 via a Novel Site in the C2 Domain

Previously, ceramide-1-phosphate (C1P) was demonstrated to be a potent and specific activator of group IV cytosolic phospholipase A(2)alpha (cPLA(2)alpha) via interaction with the C2 domain. In this study, we hypothesized that the specific interaction site for C1P was localized to the cationic beta-groove (Arg(57), Lys(58), Arg(59)) of the C2 domain of cPLA(2)alpha. In this regard, mutants of this region of cPLA(2)alpha were generated (R57A/K58A/R59A, R57A/R59A, K58A/R59A, R57A/K58A, R57A, K58A, and R59A) and examined for C1P affinity by surface plasmon resonance. The triple mutants (R57A/K58A/R59A), the double mutants (R57A/R59A, K58A/R59A, and R57A/K58A), and the single mutant (R59A) demonstrated significantly reduced affinity for C1P-containing vesicles as compared with wild-type cPLA(2)alpha. Examining these mutants for enzymatic activity demonstrated that these five mutants of cPLA(2)alpha also showed a significant reduction in the ability of C1P to: 1) increase the V(max) of the reaction; and 2) significantly decrease the dissociation constant (K (A)(s)) of the reaction as compared with the wild-type enzyme. The mutational effect was specific for C1P as all of the cationic mutants of cPLA(2)alpha demonstrated normal basal activity as well as normal affinities for phosphatidylcholine and phosphatidylinositol-4,5-bisphosphate as compared with wild-type cPLA(2)alpha. This study, for the first time, demonstrates a novel C1P interaction site mapped to the cationic beta-groove of the C2 domain of cPLA(2)alpha.

Electron paramagnetic resonance study on manganese doped tetrathioureacopper(I) chloride single crystal

Electron paramagnetic resonance (EPR) spectrum of a NLO material, manganese doped tetrathioureacopper(I) chloride single crystal was investigated at room temperature. The spectra reveal that manganese exists in tetravalent state in the host lattice in interstitial position and the crystal becomes NLO material whereas the pure crystal does not show NLO property. The spin Hamiltonian parameters are evaluated as g=1.9872 and A=157G. The transmission spectrum and the second harmonic generation efficiency confirm that the manganese doped single crystal exhibit NLO property.

Cytochrome P450-dependent monooxygenase system mediated hydrocarbon metabolism and antioxidant enzyme responses in prawn, Macrobrachium malcolmsonii

We investigated the alteration of cytochrome P450-dependent monooxygenase enzymes and antioxidant enzymes in response to oil effluent in freshwater prawn, Macrobrachium malcolmsonii. The prawns were exposed to two sublethal (10% [0.91 ppt] and 25% [2.3 ppt] of 5-day median lethal concentration) concentrations of oil. After 30 days, treated prawns were transferred into untreated freshwater and depuration was followed for another 30 days. At 7-day intervals, hydrocarbons and detoxifying enzymes were analysed in the hepatopancreas. Accumulation of hydrocarbon in the tissues gradually increased when exposed to sublethal concentration of oil effluent associated with enhanced levels of cytochrome P450, NADPH cytochrome c reductase and cytochrome b(5). During depuration, the levels of accumulated hydrocarbons decreased due to the induction of these detoxifying enzymes. Oil derived hydrocarbon mediated oxyradical production would have occurred in M. malcolmsonii. This was confirmed by elevated levels of superoxide dismutase (SOD) and catalase (CAT). Thus, cytochrome P450-dependent monooxygenase enzymes and antioxidant enzymes in oil-exposed prawns demonstrate a well-established detoxifying mechanism in M. malcolmsonii.

The immunosuppressant drug FTY720 inhibits cytosolic phospholipase A2 independently of sphingosine-1-phosphate receptors

FTY720 is a potent immunomodulator drug that inhibits the egress of lymphocytes from secondary lymphoid tissues and thymus. FTY720 is phosphorylated in vivo by sphingosine kinase 2 to FTY720-phosphate, which acts as a potent sphingosine-1-phosphate (S1P) receptor agonist. However, in contrast to S1P, FTY720 has no effect on mast-cell degranulation, yet significantly reduces antigen-induced secretion of PGD2 and cysteinyl-leukotriene. Unexpectedly, this effect of FTY720 was independent of its phosphorylation and S1P receptor functions. The rate-limiting step in the biosynthesis of all eicosanoids is the phospholipase A2 (PLA2)-mediated release of arachidonic acid from glycerol phospholipids. Although FTY720 also reduced arachidonic acid release in response to antigen, it had no effect on translocation of cPLA2 or ERK1/2 activation, suggesting that it does not interfere with FcepsilonRI-mediated events leading to cPLA2 activation. Remarkably, however, FTY720 drastically inhibited recombinant cPLA2alpha activity, whereas FTY720-phosphate, sphingosine, or S1P had no effect. This study has uncovered a unique action of FTY720 as an inhibitor of cPLA2alpha and hence on production of all eicosanoids. Our results have important implications for the potential therapeutic mechanism of action of FTY720 in eicosanoid-driven inflammatory disorders such as asthma and multiple sclerosis.

Metabolic normalization of ?-ketoglutarate against N-nitrosodiethylamine-induced hepatocarcinogenesis in rats

Chemoprevention of cancer is one of the reliable approaches to control the incidence of cancer. In the present study, we investigated the chemopreventive role of alpha-ketoglutarate (alpha-KG) during N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis. The activities of serum aspartate and alanine transaminases were found to be significantly higher in NDEA + CCl(4)-treated animals when compared with control animals. Administration of alpha-KG restored the activities of transaminases to near normal range. The levels of lipid peroxides, thiobarbituric acid reactive substances were decreased in the liver tissue of NDEA + CCl(4)-treated animals when compared with control animals. alpha-KG reversed the lipid peroxide levels to near normal range. Levels of antioxidants, reduced glutathione and activities of its dependent enzymes, glutathione peroxidase and glutathione-S-transferase were found to be significantly higher in liver tissue of NDEA + CCl(4)-treated animals when compared with control animals. alpha-KG administration positively modulated the antioxidant levels to near normal range. In conclusion, it can be suggested that alpha-KG exerts chemopreventive role which may attributable to its ability to positively modulate the transaminase activities and oxidant-antioxidant imbalance during hepatocarcinogenesis.

Pongamia pinnata modulates the oxidant-antioxidant imbalance in ammonium chloride-induced hyperammonemic rats

The effect of Pongamia pinnata (an indigenous plant used in Ayurvedic Medicine in India) leaf extract (PPEt) on circulatory lipid peroxidation and antioxidant status was evaluated in ammonium chloride-induced hyperammonemic rats. Enhanced lipid peroxidation in the circulation of ammonium chloride-treated rats was accompanied by a significant decrease in the levels of vitamin A, vitamin C, vitamin E, reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT). PPEt-administered rats experienced a significant reduction in lipid peroxidation with a simultaneous elevation in antioxidant levels. Our results indicate that PPEt modulates these changes by reversing the oxidant-antioxidant imbalance during ammonium chloride-induced hyperammonemia and this could be due to its (i) antihyperammonemic effect by means of detoxifying excess ammonia, urea and creatinine and (ii) antioxidant property. The exact mechanism has to be still investigated and isolation of active constituents is required.

Subcellular/tissue distribution and responses to oil exposure of the cytochrome P450-dependent monooxygenase system and glutathione S-transferase in freshwater prawns (Macrobrachium malcolmsonii, M. lamarrei lamarrei)

Subcellular fractions (mitochondrial, cytosolic and microsomal) prepared from the tissues (hepatopancreas, muscle and gill) of freshwater prawns Macrobrachium malcolmsonii and Macrobrachium lamarrei lamarrei were scrutinized to investigate the presence of mixed function oxygenase (MFO) and conjugating enzymes (glutathione-S-transferase, GST). Cytochrome P450 (CYP) and other components (cytochrome b(5); NADPH-cytochrome c (CYP) reductase and NADH-cytochrome c-reductase activities) of the MFO system were predominantly present in the hepatic microsomal fraction of M. malcolmsonii and M. lamarrei lamarrei. The results are in agreement with the notion that monooxygenase system is mainly membrane bound in the endoplasmic reticulum, and that the hepatopancreas is the major metabolic tissue for production of biotransformation enzymes in crustaceans. Further, the prawns were exposed to two sublethal (0.9 ppt (parts per thousand) and 2.3 ppt) concentrations of oil effluent. At the end of 30th day, hydrocarbons and detoxifying enzymes were analysed in the hepatopancreas. The accumulations of hydrocarbon in the tissues gradually increased when exposed to sublethal concentrations of oil effluent and were associated with significantly enhanced levels of cytochrome P450 (180.6+/-6.34 pmol mg(-1) protein (P<0.05 versus control, 136.5+/-7.1 pmol mg(-1) protein) for 2.3 ppt and 305.6+/-8.5 pmol mg(-1) protein (P<0.001 versus control, 132.3+/-6.8 pmol mg(-1) protein] for 0.9 ppt of oil exposed M. malcolmsonii; 150+/-6.5 pmol mg(-1 )protein (P<0.01 versus control, 84.6+/-5.2 pmol mg(-1) protein) for 2.3 ppt and 175+/-5.5 pmol mg(-1) protein (P<0.01 versus control, 87.6+/-5.4 pmol mg(-1) protein) for 0.9 ppt of oil exposed M. lamarrei lamarrei), NADPH cytochrome c-reductase activity (14.7+/-0.6 nmol min(-1 )mg(-1) protein (P<0.05 versus control, 6.8+/-0.55 nmol min(-1 )mg(-1) protein) for 2.3 ppt and 12.1+/-0.45 nmol min(-1 )mg(-1) protein (P<0.01 versus control, 6.9+/-0.42 nmol min(-1 )mg(-1) protein) for 0.9 ppt of oil exposed M. malcolmsonii; 12.5+/-0.31 nmol min(-1 )mg(-1) protein (P<0.001 versus control, 4.6+/-0.45 nmol min(-1 )mg(-1) protein) for 2.3 ppt and 9.6+/-0.32 nmol min(-1 )mg(-1) protein (P<0.01 versus control, 4.9+/-0.41 nmol min(-1 )mg(-1) protein) for 0.9 ppt of oil exposed M. lamarrei lamarrei) and cytochrome b(5 )(124.8+/-3.73 pmol mg(-1) protein (P<0.01 versus control, 76.8+/-4.2 pmol mg(-1) protein) for 2.3 ppt and 115.3+/-3.86 pmol mg(-1) protein (P<0.01 versus control, 76.4+/-4.25 pmol mg(-1 )protein) for 0.9 ppt of oil exposed M. malcolmsonii and 110+/-3.11 pmol mg(-1) protein (P<0.01 versus control, 63.7+/-3.24 pmol mg(-1 )protein) for 2.3 ppt and 95.3+/-2.63 pmol mg(-1) protein (P<0.01 versus control, 61.4+/-2.82 pmol mg(-1) protein) for 0.9 ppt of oil exposed M. lamarrei lamarrei). The enhanced levels of biotransformation enzymes in oil-exposed prawns demonstrate a well-established detoxifying mechanism in crustaceans, and the response offers the possibility of use as a biomarker for the early detection of oil pollution.

α-Ketoglutarate Modulates the Circadian Patterns of Lipid Peroxidation and Antioxidant Status During N-Nitrosodiethylamine-Induced Hepatocarcinogenesis in Rats

The effect of alpha-ketoglutarate (alpha-KG) on circadian patterns of lipid peroxides and antioxidants in N-nitrosodiethylamine (NDEA)-induced hepatocarcinogenesis in rats has been studied. The circadian rhythm characteristics (acrophase, amplitude, and mesor) of thiobarbituric acid-reactive substances (TBARS), antioxidants, superoxide dismutase, catalase, glutathione peroxidase, and reduced glutathione were markedly altered in NDEA-treated rats. The delays in acrophase observed in NDEA-treated rats were brought back to near normal range by the administration of alpha-KG. An increase in mesor values of TBARS and a decrease in mesor values of antioxidants in NDEA-administered rats were reversed by alpha-KG administration. It can be concluded that alpha-KG exerts its chemopreventive effect by restoring antioxidants and their circadian rhythms.

Modulation of biochemical circadian rhythms during long-term melatonin treatment in rats

INTRODUCTION

The influences of chronic administration of low and high doses of melatonin on the characteristics of circadian rhythms of glucose, reduced glutathione, total protein were studied, in order to investigate whether melatonin could modulate these rhythms differently.

METHODS

Pharmacological doses of melatonin (0.5 mg/kg and 1.0mg/kg body weight) were administered chronically for 45 days to Wistar rats, and 24-hour rhythms of glucose, reduced glutathione (GSH), total protein and melatonin (MLT) were studied under semi-natural (LD 12:12 hours) conditions.

RESULTS

Exogenous melatonin administered caused delays in the acrophase of glucose, total protein and melatonin rhythms, whereas advances in the acrophases of reduced glutathione were observed. This indicated that the chronic administration of melatonin could act as the modulated internal zeitgeber and this could be the reason for altered acrophase (peak time of the variable) and other characteristics of rhythms in the melatonin-treated groups. Significant dose-dependent effects of melatonin were absent in the study.

CONCLUSION

The present study demonstrates that the exogenous administration of melatonin could influence the biochemical rhythms.

Substrate specificity of human ceramide kinase

Previous studies in our laboratory have established ceramide kinase (CERK) as a critical mediator of eicosanoid synthesis. To date, CERK has not been well characterized in vitro. In this study, we investigated the substrate specificity of CERK using baculovirus-expressed human CERK (6 x His) and a newly designed assay based on mixed micelles of Triton X-100. The results indicate that the ability of CERK to recognize ceramide as a substrate is stereospecific. A minimum of a 12 carbon acyl chain was required for normal CERK activity, and the 4-5 trans double bond was important for substrate recognition. A significant discrimination by CERK was not observed between ceramides with long saturated and long unsaturated fatty acyl chains. Methylation of the primary hydroxyl group resulted in a loss of activity, confirming that CERK produces ceramide-1-phosphate versus ceramide-3-phosphate. In addition, methylation of the secondary hydroxyl group drastically decreased the phosphorylation by CERK. These results also indicated that the free hydrogen of the secondary amide group is critical for substrate recognition. Lastly, the sphingoid chain was also required for substrate recognition by CERK. Together, these results indicate a very high specificity for substrate recognition by CERK, explaining the use of ceramide and not sphingosine or diacylglycerol as substrates.