Diabetes-induced overexpression of endothelin-1 and endothelin receptors in the rat renal cortex is mediated via poly(ADP-ribose) polymerase activation

We hypothesize that poly (ADP‐ribosyl)ation, that is, poly (ADP‐ribose) polymerase (PARP)‐dependent transfer of ADP‐ribose moieties from NAD to nuclear proteins, plays a role in diabetic nephropathy. We evaluated whether PARP activation is present and whether two unrelated PARP inhibitors, 3‐aminobenzamide (ABA) and 1,5‐isoquinolinediol (ISO), counteract overexpression of endothelin‐1 (ET‐1) and ET receptors in the renal cortex in short‐term diabetes. The studies were performed in control rats and streptozotocin‐diabetic rats treated with/without ABA or ISO (30 and 3 mg*kg−1*day−1, intraperitoneally, for 2 weeks after 2 weeks of diabetes). Poly (ADP‐ribose) immunoreactivity was increased in tubuli, but not glomeruli, of diabetic rats and this increase was corrected by ISO, whereas ABA had a weaker effect. ET‐1 concentration (ELISA) was increased in diabetic rats, and this elevation was blunted by ISO. ET‐1, ET(A), and ET(B) mRNA (ribonuclease protection assay), but not ET‐3 mRNA (RT/PCR), abundance was increased in diabetic rats, and three variables were, at least, partially corrected by ISO. ABA produced a trend towards normalization of ET‐1 concentration and ET‐1, ET(A), and ET(B) mRNA abundance, but the differences with untreated diabetic group were not significant. Poly(ADP‐ribosyl)ation is involved in diabetes‐induced renal overexpression of ET‐1 and ET receptors. PARP inhibitors could provide a novel therapeutic approach for diabetic complications including nephropathy, and other diseases that involve the endothelin system.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154516/1/fsb2fj030013fje-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154516/2/fsb2fj030013fje.pd

A refined blood collection method for quantifying corticosterone

In many rodent laboratories, blood samples are collected from rats using the tail vein nick procedure and analyzed to quantify blood corticosterone levels as an indicator of stress. The standard method of corticosterone quantification often requires the collection of a relatively large volume of blood, followed by the extraction of the blood plasma. An alternative blood sampling method requires the collection of only a drop of blood on paper (the \u27drop\u27 method), minimizing handling of the animals, and does not require plasma extraction. The authors aimed to validate the drop method of blood sampling for use in corticosterone quantification. They induced stress in rats by cerebral ischemia, collected blood samples at various intervals using both the drop method and the plasma extraction method and then quantified corticosterone by radioimmunoassay. Corticosterone levels of the ischemic rats were compared with those of sham-operated rats and those of ischemic rats that had been given metyrapone, a glucocorticoid synthesis inhibitor, prior to vessel occlusion. Blood corticosterone levels in the samples obtained from the same animal using the two different methods were highly correlated for all rats. The authors further provide a regression model that can be used to predict plasma corticosterone values from those obtained from the drop blood samples. Quantification of corticosterone from only a small drop of blood has many practical and ethical advantages and should be considered as an alternative to standard methods