The Prophylactic Effects of Glutamine on Muscle Protein Synthesis and Degradation in Rats with Ethanol-Induced Liver Damage.
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ABSTRACT:
SUBMITTER: Xiao Q
PROVIDER: S-EPMC8398394 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:CONTEXTHepatocellular carcinoma (HCC) is among the most well-known threatening tumours around the world, and the outlook remains bleak. Moringa oleifera Lam. (Moringaceae) exhibits antitumor, antioxidant and hepatoprotective properties.OBJECTIVESTo assess the chemo-prophylactic proficiency and other likely activities of Moringa oleifera leaf ethanol extract (MOLEE) against diethyl nitrosamine (DEN)-induced HCC.MATERIALS AND METHODSWistar rats were gastrogavaged with MOLEE (500?mg/kg) for one week and then gastrogavaged with MOLEE and DEN (10?mg/kg) for the following 16?weeks. The progressions of the histological components, serum biomarkers and oxidation of DNA of the liver tissues were resolved to assess the prophylactic impacts. The lipid oxidative biomarker, the cancer prevention agent status and apoptotic proteins were surveyed to assess the potential mechanisms.RESULTSThe MOLEE LD50 was estimated to be 5585?mg/kg. MOLEE (500?mg/kg) administration fundamentally repressed the expansion event of knobs and the normal knob number per knob-bearing livers prompted by DEN, enhanced hepatocellular appearance and altogether significantly decreased (p?<?0.05) DEN-induced elevations in serum biochemical records and hepatic 8-hydroxy-2-deoxyguanosine (8-OHdG) levels by 29%. The robotic studies found that MOLEE disrupted the DEN-activated oxidative reactivity damage in rats by 46.8%. Curiously, the expression of Bcl-2, Bcl-xl and ?-arrestin-2 were fundamentally diminished (p?<?0.05); however, the expression of Bax and caspase-3 were essentially (p?<?0.05) upregulated.DISCUSSION AND CONCLUSIONSThe outcomes presume that MOLEE inspired critical defensive impacts against DEN-induced hepatocarcinogenesis that might be identified with the implementation of antioxidant activity and actuation of apoptosis.
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Project description:The aim of our present study was to investigate the effects of Gln supplementation on liver inflammatory responses as well as protein synthesis and degradation in the muscle of LPS-challenged broilers. A total of 120 one-day-old male broiler chickens (Arbor Acres Plus) were randomly arranged in a 2 × 2 factorial design with five replicates per treatment and six broilers per replicate, containing two main factors: immune challenge (injected with LPS in a dose of 0 or 500 µg/kg of body weight) and dietary treatments (supplemented with 1.22% alanine or 1% Gln). After feeding with an alanine or Gln diet for 15 days, broilers were administrated an LPS or a saline injection at 16 and 21 days. The results showed that Gln supplementation alleviated the increased mRNA expressions of interleukin-6, interleukin-1β, and tumor necrosis factor-α induced by LPS in liver. Moreover, the increased activity of aspartate aminotransferase combined with the decreased expression of glutaminase in muscle were observed following Gln addition. In addition, in comparison with the saline treatment, LPS challenge altered the signaling molecules' mRNA expressions associated with protein synthesis and degradation. However, Gln supplementation reversed the negative effects on protein synthesis and degradation in muscle of LPS-challenged broilers. Taken together, Gln supplementation had beneficial effects: alleviating inflammatory responses, promoting protein synthesis, and inhibiting protein degradation of LPS-challenged broilers.
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Project description:Brain injury after focal cerebral ischemia, the most common cause of stroke, develops from a series of pathological processes, including excitotoxicity, inflammation, and apoptosis. While NMDA receptors have been implicated in excitotoxicity, attempts to prevent ischemic brain damage by blocking NMDA receptors have been disappointing. Disruption of neuroprotective pathways may be another avenue responsible for ischemic damage, and thus preservation of neuronal survival may be important for prevention of ischemic brain injury. Here, we report that suppression of proteolytic degradation of transient receptor potential canonical 6 (TRPC6) prevented ischemic neuronal cell death in a rat model of stroke. The TRPC6 protein level in neurons was greatly reduced in ischemia via NMDA receptor-dependent calpain proteolysis of the N-terminal domain of TRPC6 at Lys¹⁶. This downregulation was specific for TRPC6 and preceded neuronal death. In a rat model of ischemia, activating TRPC6 prevented neuronal death, while blocking TRPC6 increased sensitivity to ischemia. A fusion peptide derived from the calpain cleavage site in TRPC6 inhibited degradation of TRPC6, reduced infarct size, and improved behavioral performance measures via the cAMP response element-binding protein (CREB) signaling pathway. Thus, TRPC6 proteolysis contributed to ischemic neuronal cell death, and suppression of its degradation preserved neuronal survival and prevented ischemic brain damage.
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Project description:Melatonin, a neuroendocrine hormone synthesized by the pineal gland and cholangiocytes, decreases biliary hyperplasia and liver fibrosis during cholestasis-induced biliary injury via melatonin-dependent autocrine signaling through increased biliary arylalkylamine N-acetyltransferase (AANAT) expression and melatonin secretion, downregulation of miR-200b and specific circadian clock genes. Melatonin synthesis is decreased by pinealectomy (PINX) or chronic exposure to light. We evaluated the effect of PINX or prolonged light exposure on melatonin-dependent modulation of biliary damage/ductular reaction/liver fibrosis. Studies were performed in male rats with/without BDL for 1?week with 12:12?h dark/light cycles, continuous light or after 1?week of PINX. The expression of AANAT and melatonin levels in serum and cholangiocyte supernatant were increased in BDL rats, while decreased in BDL rats following PINX or continuous light exposure. BDL-induced increase in serum chemistry, ductular reaction, liver fibrosis, inflammation, angiogenesis and ROS generation were significantly enhanced by PINX or light exposure. Concomitant with enhanced liver fibrosis, we observed increased biliary senescence and enhanced clock genes and miR-200b expression in total liver and cholangiocytes. In vitro, the expression of AANAT, clock genes and miR-200b was increased in PSC human cholangiocyte cell lines (hPSCL). The proliferation and activation of HHStecs (human hepatic stellate cell lines) were increased after stimulating with BDL cholangiocyte supernatant and further enhanced when stimulated with BDL rats following PINX or continuous light exposure cholangiocyte supernatant via intracellular ROS generation. Conclusion: Melatonin plays an important role in the protection of liver against cholestasis-induced damage and ductular reaction.
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Project description:Silkworm, Bombyx mori, contains high amounts of beneficial nutrients, including amino acids, proteins, essential minerals, and omega-3 fatty acids. We have previously reported a technique for producing steamed and freeze-dried mature silkworm larval powder (SMSP), which makes it easier to digest mature silkworm. In this study, we investigated the preventive effects of SMSP on alcoholic fatty liver disease and elucidated its mechanism of action. Male Sprague-Dawley rats treated with SMSP (50 mg/kg) or normal diet (AIN-76A) were administered 25% ethanol (3 g/kg body weight) by oral gavage for 4 weeks. SMSP administration for 4 weeks significantly decreased hepatic fat accumulation in ethanol-treated rats by modulating lipogenesis and fatty acid oxidation-related molecules such as sirtuin 1, AMP-activated protein kinase, and acetyl-CoA carboxylase 1. Moreover, SMSP administration significantly diminished the levels of triglyceride in liver tissues by as much as 35%, as well as lowering the serum levels of triglyceride, gamma glutamyl transpeptidase, alanine transaminase, and aspartate aminotransferase in ethanol-treated rats. SMSP supplementation also decreased the pro-inflammatory tumor necrosis factor-alpha and interleukin 1 beta levels and cytochrome P450 2E1 generating oxidative stress. These results suggest that SMSP administration may be possible for the prevention of alcoholic liver disease.
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Project description:Ethanol-induced liver injury is characterized by increased formation of reactive oxygen species (ROS) and inflammatory cytokines, resulting in the development of hepatic steatosis, injury, and cell death by necrosis and apoptosis. Thioredoxin (Trx), a potent antioxidant and antiinflammatory molecule with antiapoptotic properties, protects animals from a number of inflammatory diseases. However, the effects of ethanol on Trx or its role in ethanol-induced liver injury are not known. Female C57BL/6 mice were allowed ad libitum access to a Lieber-deCarli ethanol diet with 5.4% of calories as ethanol for 2 days to acclimate them to the diet, followed by 2 days with 32.4% of calories as ethanol or pair-fed control diet. Hepatic Trx-1 was decreased by ethanol feeding; daily supplementation with recombinant human Trx (rhTrx) prevented this ethanol-induced decrease. Therefore, we tested the hypothesis that administration of rhTrx during ethanol exposure would attenuate ethanol-induced oxidative stress, inflammatory cytokine production, and apoptosis. Mice were treated with a daily intraperitoneal injection of either 5 g/kg of rhTrx or phosphate-buffered saline (PBS).Ethanol feeding increased accumulation of hepatic 4-hydroxynonenal protein adducts, expression of hepatic tumor necrosis factor alpha, and resulted in hepatic steatosis and increased plasma aspartate aminotransferase and alanine aminotransferase. In ethanol-fed mice, treatment with rhTrx reduced 4-hydroxynonenal adduct accumulation, inflammatory cytokine expression, decreased hepatic triglyceride, and improved liver enzyme profiles. Ethanol feeding also increased transferase-mediated dUTP-biotin nick-end labeling-positive cells, caspase-3 activity, and cytokeratin-18 staining in the liver. rhTrx treatment prevented these increases. In summary, rhTrx attenuated ethanol-induced increases in markers of oxidative stress, inflammatory cytokine expression, and apoptosis.
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Project description:AimTo examine the effects of ethanol-induced proteasome inhibition, and the effects of proteasome inhibition in the regulation of epigenetic mechanisms.MethodsRats were fed ethanol for 1 mo using the Tsukamoto-French model and were compared to rats given the proteasome inhibitor PS-341 (Bortezomib, Velcade(TM)) by intraperitoneal injection. Microarray analysis and real time PCR were performed and proteasome activity assays and Western blot analysis were performed using isolated nuclei.ResultsChronic ethanol feeding caused a significant inhibition of the ubiquitin proteasome pathway in the nucleus, which led to changes in the turnover of transcriptional factors, histone-modifying enzymes, and, therefore, affected epigenetic mechanisms. Chronic ethanol feeding was related to an increase in histone acetylation, and it is hypothesized that the proteasome proteolytic activity regulated histone modifications by controlling the stability of histone modifying enzymes, and, therefore, regulated the chromatin structure, allowing easy access to chromatin by RNA polymerase, and, thus, proper gene expression. Proteasome inhibition by PS-341 increased histone acetylation similar to chronic ethanol feeding. In addition, proteasome inhibition caused dramatic changes in hepatic remethylation reactions as there was a significant decrease in the enzymes responsible for the regeneration of S-adenosylmethionine, and, in particular, a significant decrease in the betaine-homocysteine methyltransferase enzyme. This suggested that hypomethylation was associated with proteasome inhibition, as indicated by the decrease in histone methylation.ConclusionThe role of proteasome inhibition in regulating epigenetic mechanisms, and its link to liver injury in alcoholic liver disease, is thus a promising approach to study liver injury due to chronic ethanol consumption.
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Project description:1. On perfusion of livers from fed rats with a semi-synthetic medium containing no added amino acids there is a rapid release of glutamine during the first 15min (15.6+/-0.8mumol/h per g wet wt.; mean+/-s.e.m. of 35 experiments), followed by a low linear rate of production (3.6+/-0.3mumol/h per g wet wt.; mean+/-s.e.m. of three experiments). The rapid initial release can be accounted for as wash-out of preexisting intracellular glutamine. 2. Addition of readily permeating substrates, or substrate combinations, giving rise to intracellular glutamate or ammonia, or both, did not appreciably increase the rate of glutamine production over the endogenous rate. The maximum rate obtained was from proline plus alanine; even then the rate represented less than one-fortieth of the capacity of glutamine synthetase measured in vitro. 3. Complete inhibition of respiration in the perfusions [no erythrocytes in the medium; 1mm-cyanide; N(2)+CO(2) (95:5) in the gas phase] or perfusion with glutamine synthetase inhibitors [l-methionine dl-sulphoximine; dl-(+)-allo-delta-hydroxylysine] abolishes the low linear rate of glutamine synthesis, but not the initial rapid release of glutamine. 4. In livers from 48h-starved rats initial release (0-15min) of glutamine was decreased (10.6+/-1.1mumol/h per g wet wt.; mean+/-s.e.m. of 11 experiments) and the subsequent rate of glutamine production was lower than in livers from fed rats. Again proline plus alanine was the only substrate combination giving an increase significantly above the endogenous rate. 5. The rate of glutamine synthesis de novo by the liver is apparently unrelated to the tissue content of glutamate or ammonia. 6. The blood glutamine concentration is increased by 50% within 1h of elimination of the liver from the circulation of rats in vivo. 7. There is an output of glutamine by the brain under normal conditions; the mean arterio-venous difference for six rats was 0.023mumol/ml. 8. The high potential activity of liver glutamine synthetase appears to be inhibited by some unknown mechanism: the function of the liver under normal conditions is probably the disposal of glutamine produced by extrahepatic tissues.
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Project description:Disuse is a potent inducer of muscle atrophy, but the molecular mechanisms driving this loss of muscle mass are highly debated. In particular, the extent to which disuse triggers decreases in protein synthesis or increases in protein degradation, and whether these changes are uniform across muscles or influenced by age, is unclear. We aimed to determine the impact of disuse on protein synthesis and protein degradation in lower limb muscles of varied function and fiber type in adult and old rats. Alterations in protein synthesis and degradation were measured in the soleus, medial gastrocnemius, and tibialis anterior (TA) muscles of adult and old rats subjected to hindlimb unloading (HU) for 3, 7, or 14 days. Loss of muscle mass was progressive during the unloading period, but highly variable (-9 to -38%) across muscle types and between ages. Protein synthesis decreased significantly in all muscles, except for the old TA. Atrophy-associated gene expression was only loosely associated with protein degradation as muscle RING finger-1, muscle atrophy F-box (MAFbx), and Forkhead box O1 expression significantly increased in all muscles, but an increase in proteasome activity was only observed in the adult soleus. MAFbx protein levels were significantly higher in the old muscles compared with adult muscles, despite the old having higher expression of microRNA-23a. These results indicate that adult and old muscles respond similarly to HU, and the greatest loss in muscle mass occurs in predominantly slow-twitch extensor muscles due to a concomitant decrease in protein synthesis and increase in protein degradation.NEW & NOTEWORTHY In this study, we showed that age did not intensify the atrophy response to unloading in rats, but rather that the degree of atrophy was highly variable across muscles, indicating that changes in protein synthesis and protein degradation occur in a muscle-specific manner. Our data emphasize the importance of studying muscles of varying fiber-type and physiological function at multiple time points to fully understand the molecular mechanisms responsible for disuse atrophy.
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