Vascular dysfunction in a mouse model of Rett Syndrome and effects of Curcumin treatment

Mutations in the coding sequence of the X-linked gene MeCP2 (Methyl CpG–binding protein), are present in around 80% of patients with Rett Syndrome, a common cause of mental retardation in female and to date without any effective pharmacological treatment. A relevant, and so far unexplored feature of RTT patients is a marked reduction in peripheral circulation. To investigate the relationship between loss of MeCP2 and this clinical aspect, we used a MeCP2 null mouse model, male (MeCP2y/-) and female (MeCP2+/-), for functional, pharmacological and behavioural studies. The functional studies performed on dissected branches of mesenteric arterial tree mounted on glass microcannule in a pressurized myograph, demonstrated a dramatic endothelial-dependent vascular reactivity impairment in MeCP2+/- compared to control littermate. The mesenteric arteriole preincubation with NOS inhibitors or ascorbic acid indicate a decrease Nitric Oxide (NO) availability and the increased presence of Reactive Oxygen Species (ROS). Consistently, the RTT mouse model exhibited a decreased expression in both mRNA and peptide eNOS in the arterioles and a higher systemic oxidative level. MeCP2 knockout mice show stereotyped movements and less resting time when compared to control littermates. Chronic curcumin treatment of female MeCP2+/- mice was able to reverse this vascular phenotype and ameliorate the mouse RTT behavioural symptomatology by decreasing stereotyped movements and by increasing resting time. These data indicate that in the absence of MeCP2 peripheral circulation is impaired by an altered vascular reactivity and decreased arteriolar eNOS expression and NO production. Further, they provide a physiological/molecular rational for the use of curcumin as a treatment to improve the health of RTT patients

Vascular Dysfunction in a Mouse Model of Rett Syndrome and Effects of Curcumin Treatment

Mutations in the coding sequence of the X-linked gene MeCP2 (Methyl CpG–binding protein) are present in around 80% of patients with Rett Syndrome, a common cause of intellectual disability in female and to date without any effective pharmacological treatment. A relevant, and so far unexplored feature of RTT patients, is a marked reduction in peripheral circulation. To investigate the relationship between loss of MeCP2 and this clinical aspect, we used the MeCP2 null mouse model B6.129SF1-MeCP2tm1Jae for functional and pharmacological studies. Functional experiments were performed on isolated resistance mesenteric vessels, mounted on a pressurized myograph. Vessels from female MeCP2(+/−) mice show a reduced endothelium-dependent relaxation, due to a reduced Nitric Oxide (NO) availability secondary to an increased Reactive Oxygen Species (ROS) generation. Such functional aspects are associated with an intravascular increase in superoxide anion production, and a decreased vascular eNOS expression. These alterations are reversed by curcumin administration (5% (w/w) dietary curcumin for 21 days), which restores endothelial NO availability, decreases intravascular ROS production and normalizes vascular eNOS gene expression. In conclusion our findings highlight alterations in the vascular/endothelial system in the absence of a correct function of MeCP2, and uncover related cellular/molecular mechanisms that are rescued by an anti-oxidant treatment