Discussion
DM, hypertension, cerebral infarct, Cushing’s syndrome
VASODILATION, HYPERTENSION, CEREBRAL INFARCT
In the present study, we demonstrated that there were no significant differences in FMD and NID between control patients with hypertension and/or DM and patients with NFA who had hypertension and/or DM even after adjustment for cardiovascular risk factors. Overnight 1 mg dexamethasone increased FMD and NID in patients with NFA. Increases in FMD after overnight 1 mg dexamethasone were inversely correlated with changes in morning plasma levels of cortisol. This is the first study to assess the impacts of overnight 1 mg dexamethasone on vascular function.The prevalences of hypertension and DM are higher in patients with NFA than in healthy subjects. Androulakis et al.It is well established that there is a relationship of chronic glucocorticoid excess, including Cushing’s syndrome, mild autonomous cortisol secretion and iatrogenic Cushing’s syndrome, with increased incidence of cardiovascular diseaseGlucocorticoids can impact vascular reactivity by regulating either vasoconstriction or vasodilation. In the present study, changes in FMD after 1 mg dexamethasone inversely correlated with changes in morning plasma levels of cortisol, whereas there were no significant relationships between changes in FMD and changes in morning plasma levels of ACTH, blood pressure, and heart rate. These findings suggest that glucocorticoids directly affect vasodilation. Corticosteroids rapidly activate endothelial nitric oxide synthase via a non-transcriptional mechanism involving the glucocorticoid receptor and the PI3K/Akt pathway, leading to increased cerebral blood flow, reduced cerebral infarct size, and diminished vascular inflammationThis study has some limitations. First, the present study included a limited sample size of patients with NFA. However, overnight 1 mg dexamethasone improved vascular function in patients with NFA, even though the number of patients was small, and the sample size is statistically adequate to detect a 2.0% difference before and after administration of 1 mg dexamethasone. Further study is required to validate these findings in larger clinical trials. Second, in the present study, the overnight 1 mg dexamethasone suppression test was only performed for patients with NFA. It is unclear whether similar results apply to healthy subjects or patients without NFA. However, there were no significant differences in vascular function between control patients and patients with NFA. Therefore, similar results may apply to patients without NFA. Future studies are needed to confirm these findings in healthy subjects or patients without NFA.