Chronic intermittent hypobaric hypoxia ameliorates vascular reactivity through upregulating adiponectin expression of PVAT in metabolic syndrome rats.

Cumulating evidence demonstrated that chronic intermittent hypobaric hypoxia (CIHH) had beneficial effects on the body. This study investigated the role of perivascular adipose tissue (PVAT) in ameliorating effect of CIHH on vascular reactivity by adiponectin in mesenteric artery of metabolic syndrome (MS) rats. Main methods: 6-week-old male Sprague-Dawley rats were randomly divided into four groups: control (CON), MS model, CIHH treatment, and MS + CIHH treatment group. The size of adipocytes in PVAT was measured by scanning electron microscopy. Serum adiponectin was measured. The microvessel recording technique was used to observe the effect of CIHH on contraction and relaxation in mesenteric artery rings. Also, the expressions of interleukin-1β, tumor necrosis factor-α, adiponectin, AdipoR1, AdipoR2, APPL1, and endothelial nitric oxide synthase (eNOS) were assayed by Western blotting. Key findings: in MS rats, adipocyte size increased, serum adiponectin decreased, contraction reaction increased while relaxation reaction decreased, the expression of pro-inflammatory cytokines was upregulated, while adiponectin was downregulated in PVAT, and the expressions of AdipoR1, AdipoR2, APPL, and phosphorylated-eNOS were downregulated in mesenteric artery. All aforementioned abnormalities of MS were ameliorated in MS + CIHH rats. We concluded that CIHH treatment improves vascular reactivity through upregulating adiponectin expression and downregulating pro-inflammatory cytokine expression of PVAT in MS rats.