Induction of metallothionein expression in vascular and perivascular adipose tissue of mice treated with a single administration of arsenite

<p>Metallothionein (MT) is a metal-binding protein that maintains essential metal homeostasis, detoxifies toxic metals, and reduces oxidative stress. It is well known that MT expression is induced by exposure to heavy metals such as cadmium, but there is little information on MT induction by arsenic. Chronic arsenic exposure is known to induce vascular diseases such as atherosclerosis, but the defense response mechanisms against arsenic toxicity in vascular tissue remain unclear. In this study, we examined the induction of MT expression in the thoracic aorta and its perivascular adipose tissue (PVAT) of mice treated with a single administration of arsenite. Male C57BL6/J mice aged 7 weeks received a single intraperitoneal administration of saline 10 mL/kg or sodium arsenite (1.5, 3.0, and 5.0 mg/kg as the total dosage of arsenic). Three hours after administration, the thoracic aorta and PVAT were separated and collected. The thoracic aorta was further divided into the intima fraction and the tunica media/adventitia fraction. Expression levels of MT genes were measured by real-time RT-PCR. The results showed that both mRNA levels of MT isoform Mt1 and Mt2 were significantly increased in the thoracic aorta and PVAT. Also, arsenite significantly increased Mt1 and Mt2 mRNA levels in the intimal and the tunica media/adventitia fractions. These results indicate that exposure to arsenite induces MT gene expression in thoracic aorta and PVAT. It is possible that MT in vascular tissue and PVAT induced by arsenite exposure may play a protective role against arsenic vascular toxicity.</p>