miR-208a as a biomarker of isoproterenol-induced cardiac injury in Sod2+/- and C57BL/6J wild-type mice.

This investigation examined microRNA-208a (miR-208a) as a potential biomarker of isoproterenol (ISO)-induced cardiac injury in superoxide dismutase-2 (Sod2(+/-) ) and the wild-type mice, and the potential sensitivity of Sod2(+/-) mice to ISO-induced toxicity. A single intraperitoneal injection of ISO was administered to age-matched wild-type and Sod2(+/-) mice at 0, 80, or 160 mg/kg. Plasma miR-208a, cardiac troponin I (cTnI), and ISO systemic exposure were measured at various time points postdose. Hearts were collected for histopathology examination and for tissue expression of miR-208a and myosin heavy chain 7. ISO administration caused increases in cTnI and miR-208a plasma levels that correlated with myocardial damage; however, the magnitude of increase differed according to the types of mice. At similar ISO systemic exposure, the magnitude of cTnI was greater in wild-type mice compared to Sod2(+/) (-) mice; however, the magnitude of miR-208a was greater in Sod2(+/-) mice than that of the wild-type mice. Myocardial degeneration occurred at ≥3 hr in the wild-type and ≥6 hr in Sod2(+/) (-) mice. At ≥24 hr after ISO administration, miR-208a appeared superior to cTnI in indicating myocardial injury in both wild-type and Sod2(+/-) mice. Sod2(+/-) mice were not more sensitive than wild-type mice to ISO-induced toxicity.

Antisense inhibition of 11betahydroxysteroid dehydrogenase type 1 improves diabetes in a novel cortisone-induced diabetic KK mouse model.

The inhibition of 11betahydroxysteroid dehydrogenase 1 (11betaHSD1), an enzyme that catalyzes the conversion of inactive cortisone to active cortisol, is an attractive target to treat diabetes by suppressing hepatic gluconeogenesis. To test this hypothesis, we developed a novel glucocorticoid-induced diabetic KK mouse model and used 11betaHSD1 antisense oligonucleotide (ASO) as an inhibitory tool. KK mice were treated with 25 or 50mg/kg/day of 11betaHSD1 ASO for 28 days. On day 25, cortisone pellets were surgically implanted to induce diabetes. In the ASO-treated mice, plasma blood glucose levels were significantly reduced by up to 54%. In parallel, cortisol and other diabetes endpoints were also significantly reduced. Hepatic 11betaHSD1 mRNA was suppressed by up to 84% with a concomitant respective decrease of up to 49% in the expression of PEPCK. The results suggest that inhibition of 11betaHSD1 activity reduces the availability of cortisol to activate the glucocorticoid receptor, down regulates gluconeogenesis and thus reduces plasma glucose levels in cortisone-induced diabetic KK mice.