Bilirubin improves renal function by reversing the endoplasmic reticulum stress and inflammation in the kidneys of type 2 diabetic rats fed high-fat diet.

Diabetic kidney disease (DKD), as a chronic diabetes-induced complication, is considered the most frequent leading cause of end-stage renal disease (ESRD). Regarding the observed protective effects of bilirubin, as a potential endogenous antioxidant/anti-inflammatory compound, against DKD progression, we planned to evaluate the effects of bilirubin administration on endoplasmic reticulum (ER) stress and inflammation in type 2 diabetic (T2D) rats fed high-fat diet (HFD). In this regard, thirty 8-week adult male Sprague Dawley rats were divided into five groups (n = 6). T2D and obesity were induced by streptozotocin (STZ) (35 mg/kg) and HFD (700 kcal/day), respectively. Bilirubin treatment was carried out for 6- and 14-week intervals (10 mg/kg/day), intraperitoneally. Then, the expression levels of ER stress-related genes (i.e. binding immunoglobulin protein (Bip), C/EBP homologous protein (Chop), and spliced x-box-binding protein 1 (sXbp1), as well as nuclear factor-κB (NF-κB) were analyzed using quantitative Real-time PCR experiments. Moreover, histopathological and stereological changes of kidney and its related structures were investigated for the studied rats. Bip, Chop, and NF-κB expression levels were significantly decreased under bilirubin treatment, while sXbp1 was up-regulated following the bilirubin administration. More interestingly, glomerular constructive damages seen in HFD-T2D rats, were considerably improved in the animals received bilirubin. Stereological assessments also revealed that bilirubin could desirably reverse the mitigation of kidney's total volume and its related structures, such as cortex, glomeruli, and convoluted tubules. Taken together, bilirubin has potential protective/ameliorative effects on DKD progression, especially through alleviating the renal ER stress and inflammatory responses in T2D rats with injured kidneys. In this era, clinical benefits of mild hyperbilirubinemia can be considered in human DKD.

Evaluating the activity of salivary enzymes as stress biomarkers under psychological stress and their relationship with rumination and personality traits.

BACKGROUND: Salivary enzymes are used as non-invasive biomarkers to assess the activity of the sympathetic-adrenal-medullary system. The aim of this study was to evaluated levels of acid phosphatase, beta-glucuronidase and cathepsin salivary enzymes under psychological tension and their connection with rumination and personality traits. METHODS: A total of 60 medical students, who wanted to participate in the final exam, two months before the exam, the inventory emotional control questionnaire and the neo-short form were completed. Saliva samples were taken in both the basal conditions and under exam stress. RESULTS: A significant difference was found between the mean of level salivary enzymes in rest and under exam stress. Also, we found a positive and significant correlation between the activity of salivary enzymes and personality traits such as neuroticism, extraversion, agreeableness and rumination (p < .01, p < .05) level. Neuroticism, agreeableness and rumination predicted 45% of the variance of salivary acid phosphatase, neuroticism and rumination predicted 49% of the variance of salivary beta-glucuronidase and neuroticism, extraversion and rumination predicted 38% of the variance of salivary cathepsin under stress exam. CONCLUSION: The results of this study show, levels of salivary enzymes may increase in individuals with traits of neuroticism, extraversion, agreeableness and rumination through response to psychological stressors.