Abstract
The present study was designed to examine whether astaxanthin (ASX, 3,3-dihydroxybeta,
beta-carotene-4,4-dione, CAS 472-61-7), a dietary antioxidant carotenoid that is naturally
present in algae, crustaceans, and fish, has a protective effect on endothelial dysfunction
of aortas in diabetic rats and the possible molecular mechanism involved. Male Wistar
rats were randomly divided into four groups: control rats, diabetic rats, diabetic
rats treated with ASX (10 mg/kg/d), and control rats treated with ASX. Type 1 diabetes
was induced by a single intraperitoneal injection of streptozotocin (STZ; 60 mg/kg).
STZ-induced diabetes in rats was complicated with excessive oxidative stress and endothelial
dysfunction, increased serum oxidized low-density lipoprotein (ox-LDL) and aortic
malondialdehyde (MDA) levels, inhibited endothelium-dependent vasorelaxation to acetylcholine
(ACh) and unaffected endothelium-dependent vasorelaxation to sodium nitroprusside
(SNP). Simultaneously, lectin-like oxLDL receptor-1 (LOX-1) expression was enhanced
and endothelial nitric oxide (NO) synthase (eNOS) expression was reduced in the aortas
of diabetic rats. ASX treatment could significantly decrease serum oxLDL and aortic
MDA levels, attenuate blunted endothelium-dependent vasodilator responses to ACh,
upregulate eNOS expression, and decrease LOX-1 expression. These results indicated
that ASX could ameliorate diabetic endothelial dysfunction by inhibiting the ox-LDL-LOX-1-eNOS
pathway. Treatment with ASX might be clinically useful for diabetic complications
associated with endothelial dysfunction.
Key words
Astaxanthin - Diabetes - Endothelial dysfunction - Endothelialnitric oxide synthase
- Lectin-like oxidized low-density lipoprotein receptor-1 - Oxidative stress