Effect of sodium salicylate on oxidative stress and insulin resistance induced by free fatty acids

BACKGROUND: It has been reported that high-dose salicylates improve free fatty acids (FFAs)-induced insulin resistance and beta-cell dysfunction in vitro, but the mechanism remains uncertain. In insulin-resistant rats, we found that the supplementation of sodium salicylate is associated with a reduction of plasma malondialdehyde (MDA), a marker of oxidative stress. Few studies have investigated the effects of salicylates on oxidative stress levels in insulin-resistant animal models. This study aimed to assess the effect of sodium salicylate on insulin sensitivity and to explore the potential mechanism by which it improves hepatic and peripheral insulin resistance. METHODS: Intralipid+heparin (IH), saline (SAL), or intralipid+heparin+sodium salicylate (IHS) were separately infused for 7 hours in normal Wistar rats. During the last 2 hours of the infusion, hyperinsulinemic-euglycemic clamping was 3 performed with [6-(3)H] glucose tracer. Plasma glucose was measured using the glucose oxygenase method. Plasma insulin and C-peptide were determined by radioimmunoassay. MDA levels and glutathione peroxidase (GSH-PX) activity in the liver and skeletal muscle were measured with colorimetric kits. RESULTS: Compared with infusion of SAL, IH infusion increased hepatic glucose production (HGP), and decreased glucose utilization (GU) (P<0.05). The elevation of plasma free fatty acids increased the MDA levels and decreased the GSH-PX activity in the liver and muscle (P<0.01). Sodium salicylate treatment decreased HGP, elevated GU (P<0.05), reduced MDA content by 60% (P<0.01), and increased the GSH-PX activity by 35% (P<0.05). CONCLUSIONS: Short-term elevation of fatty acids induces insulin resistance by enhancing oxidative stress levels in the liver and muscle. The administration of the anti-inflammatory drug sodium salicylate reduces the degree of oxidative stress, therefore improving hepatic and peripheral insulin resistance. IKK-beta and NF-kappa B provide potential pathogenic links to oxidative stress.

Effects of Sodium Salicylate on the Expression of HSP27 Protein during Oxidative Stress in Tissue-cultured Human Lens Epithelial Cells

The effects of sodium salicylate on the expression of heat shock protein 27 （HSP27） during oxidative stress in tissue-cultured human lens epithelial cells were investigated. Cultured human lens epithelial cells （HLB-3） were divided into 3 groups： control group （group A）, oxidation injury group （group B） and sodium salicylate group （group C）. Apoptosis of human lens epithelial cells cultured in vitro was induced in the presence of 150 μmol/L H2O2. Cells viability and the expression of HSP27 were analyzed. Viability of the cells was measured by methyl thiazole tetrazolium （MTT） chromatometry. The expression of HSP27 in HLB-3 cells was detected by using immunohistochemistry and image analysis system, Sodium salicylate could induce the expression of HSP27, and the cells viability in group C was significantly higher than in group B （0.2667±0.01414 vs 0.2150±0.01080, P=0.012〈0.05）. The average gray value of HSP27 in group B was less than that in group C （P=0.000〈0.05）. The increased expression of HSP27 by sodium salicylate might play an important role in the protection of hydrogen peroxide-induced injury of human lens epithelial cells, suggesting that sodium salicylate could suppress, at least in part, the apoptosis of human lens epithelial cells.

Effects of Mitogen-activated Protein Kinase Signal Pathway on Heat Shock Protein 27 Expression in Human Lens Epithelial Cells Exposed to Sodium Salicylate in vitro

The roles of mitogen-activated protein kinase （MAPK） signal pathway in sodium salieylate-induced expression of heat shock protein 27 （HSP27） in human lens epithelial cells （HLECs-B3） in vitro were investigated. HLECs-B3 were incubated in the fresh media containing sodium salicylate at different concentrations for different durations, and allowed to be recovered in fresh medium without sodium salicylate for different durations with or without pretreatment with p38MAPK inhibitor （SB203580）, ERK1/2 inhibitor （PD98059） and JNK/SAPK inhibitor （SP600125）. The expression of P38MAPK, ERK1/2, JNK/SAPK, phosphorylated P38MAPK, phosphorylated ERK1/2, phosphorylated JNK/SAPK and HSP27 was detected by Western blot. The expression of HSP27 mRNA and protein was detected by RT-PCR and immunohistochemistry respectively. It was found there was only weak expression of HSP27 in normal HLECs. The expression of HSP27 was not detectable in HLECs-B3 that were exposed to sodium salicylate （55 retool/L） for 1-5 h. It was indicated that recovery from sodium salicylate （〉35 mmol/L） significantly increased the synthesis of HSP27. The expression of HSP27 was up-regulated in HLECs-B3 under sodium salicylate recovery for 3 h, reached the peak level for 6 h, and returned to the level of control cells by 24 h. Activation of P38MAPK from sodium salicylate stimulation occurred at 30th rain, and increased significantly at 1st h, then declined and renamed to baseline level at 3rd h under sodium salicylate recovery. Activation of ERK1/2 occurred at 1st h and reached the peak level at 6th h under sodium salicylate recovery. However, JNK/SAPK was inactivated by sodium salicylate. The expression of HSP27 could be down-regulated with the pretreatment of SB203580 and PD98059 jointly. It is concluded that sodium salicylate can induce the expression of HSP27 in HLECs-B3. The effects are mediated, at least in part, through the activation of P38MAPK and ERK1/2 signaling pathway.

Determination of Sodium Salicylate in Milk and Milk Power by High Performance Liquid Chromatography

[Objectives]This study was conducted to explore the application of high performance liquid chromatography to detect sodium salicylate in different milk powder and milk.[Methods]A high performance liquid chromatographic(HPLC)method was established for determining the sodium salicylate in milk and milk power,with Agilent ZORBAX Eclips XDB C18 column.The recovery and precision of the method were analyzed and discussed.[Results]The experimental conditions were determined as mobile phase:methanol+0.02 mol/L ammonium acetate solution,flow rate:0.8 ml/min,detection wavelength:300 nm,and column temperature:30℃.The peak area had a good linear relationship with the standard solution in the range of 0.2-10.0 mg/L,and the correlation coefficient(R 2)was greater than 0.999.The standard was added into different matrices at four levels.The average recovery of sodium salicylate in milk powder was 90.5%-101.0%,with RSD less than 5.0%,and the average recovery of sodium salicylate in milk was 90.5%-101.4%,with RSD less than 5.0%.The limit of quantification was 1.25 mg/kg in cow milk and 5.00 mg/kg in milk powder.[Conclusions]The accuracy and precision of sodium salicylate detection in milk powder and milk samples of the experimental method met the requirements.The method is simple,accurate,and reliable,and can meet the needs of actual detection.

Role of the caudate-putamen nucleus in sensory gating in induced tinnitus in rats

Tinnitus can be described as the conscious perception of sound without external stimulation,and it is often accompanied by anxiety,depression,and insomnia.Current clinical treatments for tinnitus are ineffective.Although recent studies have indicated that the caudateputamen nucleus may be a sensory gating area involved in noise elimination in tinnitus,the underlying mechanisms of this disorder are yet to be determined.To investigate the potential role of the caudate-putamen nucleus in experimentally induced tinnitus,we created a rat model of tinnitus induced by intraperitoneal administration of 350 mg/kg sodium salicylate.Our results revealed that the mean spontaneous firing rate of the caudate-putamen nucleus was increased by sodium salicylate treatment,while dopamine levels were decreased.In addition,electrical stimulation of the caudate-putamen nucleus markedly reduced the spontaneous firing rate of neurons in the primary auditory cortex.These findings suggest that the caudate-putamen nucleus plays a sensory gating role in sodium salicylate-induced tinnitus.This study was approved by the Institutional Animal Care and Use Committee of Peking University Health Science Center(approval No.A2010031)on December 6,2017.