Combined Astragalus, vitamin C, and vitamin E alleviate DEHP-induced oxidative stress and the decreased of insulin synthesis and secretion in INS-1 cells.

Di-(2-ethylhexyl)-phthalate (DEHP), a common Phthalic acid ester (PAEs), has been reported to be associated with diabetes mellitus, yet the underlying mechanisms remain unknown. Combined nutrient interventions have been shown to alleviate the diabetic toxicity of DEHP. However, the effects and mechanisms of the combined intervention of Astragalus and vitamins (C and E) are currently unknown. In this study, we investigated the potential mechanisms of DEHP-induced diabetes mellitus through transcriptome analysis and vitro experiments using rat insulinoma cells (INS-1 cells). Furthermore, we explored the protection of the combined Astragalus, vitamin C, and vitamin E on DEHP-induced diabetes mellitus through these mechanisms. INS-1 cells in the logarithmic growth period were exposed to 125 umol/L DEHP followed by high-throughput sequencing analysis. The cell proliferation inhibition rate was determined using MTT assay for each group, and the cell apoptosis rate and intracellular ROS level were measured using flow cytometer. Finally, insulin levels and markers of oxidative stress were detected using ELISA kits in different groups. A total of 372 differentially expressed genes were found between the 125 umol/L DEHP and control groups, subsequent functional enrichment analyses indicated that DEHP induced oxidative stress and disturbed insulin levels. In INS-1 cells, the rate of cell proliferation inhibition, apoptosis, and the degree of oxidative stress increased concentration-dependently with increasing DEHP concentrations, while antioxidant intervention could reverse these changes. Insulin synthesis and secretion decreased after 240 µmol/L DEHP exposure stimulated by 25 mM glucose in INS-1 cells, also could antioxidant intervention alleviate these reductions. Based on these results, the underlying mechanism of DEHP impairing the function of INS-1 cells might be through apoptosis pathways induced by oxidative stress and direct reduction of insulin levels (both synthesis and secretion), while the optimal combination of Astragalus and vitamins (C and E) could exert an alleviating effect.

Risk assessment of combined exposure to lead, cadmium, and total mercury among the elderly in Shanghai, China.

Lead (Pb), cadmium (Cd) and total mercury (THg) are toxic heavy metals (THMs) that are widely present in the environment and can cause substantial health problems. However, previous risk assessment studies have rarely focused on the elderly population and have usually targeted a single heavy metal, which might underestimate the long-term accumulative and synergistic effects of THMs in humans. Based on the food frequency questionnaire and inductively coupled plasma mass spectrometry, this study assessed external and internal exposures to Pb, Cd and THg in 1747 elderly people in Shanghai. Probabilistic risk assessment with the relative potential factor (RPF) model was used to assess the neurotoxicity and nephrotoxicity risks of combined THMs exposures. The mean external exposures of Pb, Cd and THg in Shanghai elderly were 46.8, 27.2 and 4.9 µg/day, respectively. Plant-based foods are the main source of Pb and THg exposure, while Cd is mainly from animal-based foods. The mean concentrations of Pb, Cd and THg were 23.3, 1.1 and 2.3 µg/L in the whole blood, and 6.2, 1.0 and 2.0 µg/L in the morning urine, respectively. Combined exposure to THMs leading to 10.0 % and 7.1 % of Shanghai elderly at risk of neurotoxicity and nephrotoxicity. The results of this study have important implications for understanding the profiles of Pb, Cd and THg exposure in the elderly living in Shanghai and provide data support for risk assessment and control of nephrotoxicity and neurotoxicity from combined THMs exposure in the elderly.

Dibutyl phthalate affects insulin synthesis and secretion by regulating the mitochondrial apoptotic pathway and oxidative stress in rat insulinoma cells.

Dibutyl phthalate (DBP) is a typical phthalate (PAEs). The environmental health risks of DBP have gradually attracted attention due to the common use in the production of plastics, cosmetics and skin care products. DBP was associated with diabetes, but its mechanism is not clear. In this study, an in vitro culture system of rat insulinoma (INS-1) cells was established to explore the effect of DBP on insulin synthesis and secretion and the potential mechanisms. INS-1 cells were cultured in RPMI-1640 medium containing 10% fetal bovine serum and treated with 15, 30, 60 and 120 µmol/L of DBP and dimethyl sulfoxide (vehicle, < 0.1%) for 24 h. The contents of insulin in the intracellular fluid and the extracellular fluid of the cells were measured. The results showed that insulin synthesis and secretion in INS-1 cells were significantly decreased in 120 µmol/L DBP group. The apoptosis rate and mitochondrial membrane potential of INS-1 cells were measured by flow cytometry with annexin V-FITC conjugate and PI, and JC-1, respectively. The results showed that DBP caused an increase in the apoptosis rate and a significant decrease in the mitochondrial membrane potential in INS-1 cells in 60 µmol/L and 120 µmol/L DBP group. The results of western blot showed that the expression of Bax/Bcl-2, caspase-3, caspase-9 and Cyt-C were significantly increased. Meanwhile, the level of oxidative stress in INS-1 cells was detected by fluorescent probes DCFH-DA and western blot. With the increase of DBP exposure, the oxidative stress levels (MDA, GSH/GSSG) were increased; and the antioxidant index (SOD) levels were decreased. Our experimental results provide reliable evidence that DBP induced apoptosis and functional impairment in INS-1 cells through the mitochondrial apoptotic pathway and oxidative stress. Therefore, we hypothesized that interference with these two pathways could be considered in the development of preventive protection measures.

Enhanced pulmonary absorption of recombinant human insulin by pulmonary surfactant and phospholipid hexadecanol tyloxapol through Calu-3 monolayers.

Natural pulmonary surfactant (PS) and its artificial substitute phospholipid hexadecanol tyloxapol (PHT) are effective absorption enhancers on promoting recombinant human insulin (Rh-ins) absorption in vivo, but the in vitro efficacy and underlying mechanism remains unclear. In the current study, the permeation promoting effects of PS and PHT of insulin through Calu-3 monolayers in Transwell were evaluated. The viability of Calu-3 cells on conducting the permeation study was confirmed by TER and Electron Microscopy. Both PS and PHT significantly enhanced the permeation of Rh-ins and FD4 through calu-3 cells, with PS having a greater absorption enhancing effect than that of PHT. PS and PHT may interact directly with the tight junctions between cells and then result in intercellular permeation of peptide drugs. LDH release assay showed no significant acute toxicity of PS and PHT. The results indicated that these absorption enhancing agents may be useful as an absorption enhancer for pulmonary delivery of peptide and protein drugs.

Effects of SLCO1B1 polymorphisms on the pharmacokinetics and pharmacodynamics of repaglinide in healthy Chinese volunteers.

PURPOSE: Repaglinide is commonly used in the treatment of patients with type 2 diabetes mellitus to reduce postprandial hyperglycemia. The objective of this research was to study the effects of SLCO1B1 polymorphisms on the pharmacokinetics and pharmacodynamics of repaglinide in healthy Chinese volunteers. METHODS: A total of 22 healthy young male participants were recruited from a pool of pharmacogenetically characterized participants genotyped for SLCO1B1, CYP3A4, and CYP2C8 SNPs by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Volunteers with CYP2C8*3 and CYP3A4*4 alleles were excluded from the clinical study. Then selected volunteers took part in the clinical pharmacokinetic study, receiving 2 mg repaglinide. RESULTS: Healthy participants with SLCO1B1*1A/*1B or *1A/*1A genotype and SLCO1B1 *15/*1A or *5/*1A genotype had significantly higher AUC(0-∞) than participants with SLCO1B1*1B/*1B genotype, with the former showing an increase over the latter of 39.81 and 42.09%, respectively (P = 0.028, 0.032). The clearance in the former two genotype groups was significantly attenuated (by 27.39 and 28.55%, respectively) compared with individuals with SLCO1B1*1B/*1B genotype (P = 0.015, 0.019). No significant differences in blood glucose-lowering effect were observed among three genotype groups. CONCLUSIONS: SLCO1B1*1B/*1B genotype is associated with reduced pharmacokinetic exposure after a single dose oral administration of 2 mg repaglinide, including decreased AUC(0-∞) and increased clearance of repaglinide. Moreover, this polymorphism of SLCO1B1 has significant influence on the pharmacokinetics of repaglinide, but no effects on its pharmacodynamics.

Effect of pulmonary surfactant and phospholipid hexadecanol tyloxapol on recombinant human-insulin absorption from intratracheally administered dry powders in diabetic rats.

The purpose of the present study was to evaluate the enhancement effect of the natural pulmonary surfactant (PS) or its artificial substitute, phospholipid hexadecanol tyloxapol (PHT) on the bioavailability and hypoglycemic activity of recombinant human insulin (rh-insulin) in a pulmonary delivery system. PS- or PHT-loaded insulin formulation was administered to streptozotocin induced diabetic rats, at doses of 5 U/kg, 10 U/kg and 20 U/kg insulin, respectively. The hypoglycemic effect caused by PS or PHT containing rh-insulin was analyzed and the area above the curves (AAC) of serum glucose levels versus time, the minimum glucose concentration (C(min)), the time to C(min) (T(min)) and the pharmacological availability (PA%) were derived from the serum glucose profiles. Results showed that PS and PHT caused significantly decrease in serum glucose levels. The decrease in plasma glucose levels continued for about 5 h after the nadir. The highest AAC value was obtained when 20 U/kg rh-insulin with PS or PHT as absorption enhancer was administered to rats. AAC(0-360 min) of PS- or PHT-loaded rh-insulin was 2-3 times as much as that without PS or PHT and PA% increased by 1.3-2 fold. Thus, the extent of oral absorption of insulin from PS- or PHT-loaded particles was significantly greater when compared with that without them. In addition, PHT as well as PS did not change the lactate dehydrogenase (LDH) activity, alkaline phosphatase (AKP) activity and N-acetyl-ß-D-glucoaminidase (NAG) activity in bronch fluid which are sensitive indicators of acute toxicity to lung cells in bronchoalveolar lavage (BAL). It is concluded that PS and PHT is a promising absorption enhancer for pulmonary delivery systems of large molecule drugs as rh-insulin.

[Research progress on drug metabolism of flavanoids].

Flavanoids are important phytochemistry compositions in foods and traditional Chinese medicines (TCM) and are mainly oxidized by CYP1A family in vivo. Some methoxyflavones could also be metabolized through demethylation. Usually, flavanoids own one or more phenolic hydroxyl group in their molecular structures, which facilitate conjugation with glucuronic acid and sulphuric acid, forming metabolites with good water-solubility to excrete. Natural flavanoids mainly exist in glycoside, and after oral ,they would be easily metabolized to aglycone by hydratase in gut microflora and then absorbed into blood. Besides, many flavanoids have strong inhibitory actions on Cytochrome P450 enzymes, which are significant mechanisms in cancer precaution and tumor inhibition. In this paper, we reviewed lots of articles and summarized metabolism characteristics of flavanoids and metabolism interaction with Cytochrome P450 enzymes.