Evaluation of renal markers of T1D in Sprague-Dawley exposed to 2-aminoanthracene

The incidence of type 1 diabetes (T1D) and its associated risks of chronic kidney disease or end-stage renal disease development are on the rise. T1D is an autoimmune disease in which insulin-producing beta cells are destroyed. Increased incidence of T1D has been suggested to be a result of environmental factors such as exposure to polycyclic aromatic hydrocarbons (PAHs). 2-aminoanthracene (2AA) is a PAH that has been associated with the onset of early diabetic symptoms. This study was conducted to assess if 2AA dietary ingestion would induce T1D renal injuries. To accomplish study goals, Sprague-Dawley rats were assigned into three 2AA dietary (0, 50, and 100 mg/kg-2AA) ingestion groups for 12 weeks. Animals were evaluated for various morphometric indices, clinical markers, and gene expression. The rats in the 100 mg/kg group lost 5% less weight than the other treatment groups and converted roughly 3% more of their food intake into body mass. Renal histopathology indicated no significant difference between groups. The kidney weight per bodyweight of the 100 mg/kg treatment group was 30.1% greater than the control group. Creatinine concentration of the 100 mg/kg group was 46.2% greater than the control group. Serum glucose levels were significantly elevated in rats exposed to 2AA. On the contrary, serum albumin concentration was significantly reduced in 2AA-treated rats. T1D and genetic markers of renal injury such as FABP1, SPP1, IL-1B, and IL-7 were elevated in treated groups. These results suggest that 2AA may induce the early diabetic renal injuries.

Inflammatory effect of 2-aminoanthracene (2AA) on adipose tissue gene expression in pregnant Sprague Dawley rats

Adipocyte dysfunction may be a critical link between obesity and insulin resistance as a result of abnormal fat storage and mobilization. Adipocytes uniquely secrete adipokines and cytokines, such as leptin and TNFα, wich promote insulin sensitivity. Previously we reported insulin-signaling related altered gene expression in animals exposed to 2-Aminoanthracene (2AA). 2AA is an amino-substituted polycyclic aromatic hydrocarbon used in manufacturing dyes, chemicals, inks, resins, and polyurethanes. The objective of this study was to examine the inflammation related effects of 2AA exposure from gestation to postnatal period on dams that ingested 2AA. To examine 2AA effects, pregnant dams were assigned into dose regimens of 2AA. Dams were fed 2AA contaminated diet during the period of gestation and postpartum. The expression of key gene transcripts reported to be important in mediating inflammatory processes was examined via quantitative RT-PCR. Histologic examination of adipose tissue (AT) was also carried out to understand the anatomy of AT due to 2AA exposure during gestation and two weeks postpartum. Examination of the adipose tissue for microscopic changes revealed no alterations between control and low-dose animals. However, AT of the high-dose animals was infiltrated by increased numbers of CD68+mononuclear cells (macrophages) and small numbers of eosinophils and mast cells, consistent with inflammation. In addition, analysis of the mRNA expression of cytokines and adipokines demonstrated the importance of inflammation in AT dysfunction. For instance, TNFα, LEPTIN and IL-6 transcripts were relatively more expressed in the low dose animals than in the high dose and control rats. At the protein level, however, high amounts of cytokines were noted. The effects of 2AA on pregnant dams appear to be more pronounced in the high dose group than in the low dose group, possibly indicating increased susceptibility of rat offspring within this group to elicit a diabetic-type response.

Time-Dependent Regulation of Apoptosis by AEN and BAX in Response to 2-Aminoanthracene Dietary Consumption

Background/Objective:

The modulation of the toxic effects of 2-aminoanthracene (2AA) on the liver by apoptosis was investigated. Fisher-344 (F344) rats were exposed to various concentrations of 2AA for 14 and 28 days. The arylamine 2AA is an aromatic hydrocarbon employed in manufacturing chemicals, dyes, inks, and it is also a curing agent in epoxy resins and polyurethanes. 2AA has been detected in tobacco smoke and cooked foods.

Methods:

Analysis of total messenger ribonucleic acid (mRNA) extracts from liver for apoptosis-related gene expression changes in apoptosis enhancing nuclease (AEN), Bcl2-associated X protein (BAX), CASP3, Jun proto-oncogene (JUN), murine double minute-2 p53 binding protein homolog (MDM2), tumor protein p53 (p53), and GAPDH genes by quantitative real-time polymerase chain reaction (qRT-PCR) was coupled with terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) and caspase-3 (Casp3) activity assays.

Results:

Specific apoptosis staining result does not seem to show significant difference between control and treated animals. This may be due to freeze-thaw artifacts observed in the liver samples. However, there appears to be a greater level of apoptosis in medium- and high-dose (MD and HD) 2AA treated animals. Analyses of apoptosis-related genes seem to show AEN and BAX as the main targets in the induction of apoptosis in response to 2AA exposure, though p53, MDM2, and JUN may play supporting roles.

Conclusion:

Dose-dependent increases in mRNA expression were observed in all genes except Casp3. BAX was very highly expressed in the HD rats belonging to the 2-week exposure group. This trend was not observed in the animals treated for 4 weeks. Instead, AEN was rather very highly expressed in the liver of the MD animals that were treated with 2AA for 28 days.

Genotoxicity of pyrroloquinoline quinone (PQQ) disodium salt (BioPQQ™)

The genotoxic potential of pyrroloquinoline quinone (PQQ) disodium salt (BioPQQ™) was evaluated in a battery of genotoxicity tests. The results of the bacterial mutation assay (Ames test) were negative. Weak positive results were obtained in 2 separate in vitro chromosomal aberration test in Chinese hamster lung (CHL) fibroblasts. Upon testing in an in vitro chromosomal aberration test in human peripheral blood lymphocytes, no genotoxic activity of PQQ was noted. In the in vivo micronucleus assay in mice, PQQ at doses up to 2,000 mg/kg body weight demonstrated that no genotoxic effects are expressed in vivo in bone marrow erythrocytes. The weak responses in the in vitro test CHL cells were considered of little relevance under conditions of likely human exposure. PQQ disodium was concluded to have no genotoxic activity in vivo.