Lutein downregulates retinal vascular endothelial growth factor possibly via hypoxia inducible factor 1 alpha and X-box binding protein 1 expression in streptozotocin induced diabetic rats.

Lutein, a retinal-specific carotenoid, was assessed for angioprotective efficacy via hypoxia inducible factor
(HIF1a) and X-box binding protein 1 (XBP1) pathway in diabetic retina. Streptozotocin-induced diabetic
rats were orally gavaged with or without lutein (39 nmol/day) for 8 weeks. Lutein mediated regulation of
vascular endothelial growth factor (VEGF) and superoxide dismutase 2 (SOD2) was analyzed using qPCR
and immunoblotting. VEGF transcription factors, Hif1a and XBP1, in retina of streptozotocin induced diabetic
rats were assessed using qPCR. Retinal protein carbonyl and lipid peroxide levels were quantified
and transverse section of retina was stained for histopathology. Results indicate that lutein prevented
the upregulation of VEGF and downregulation of SOD2 in retina of diabetic rats and also prevented abnormalities
in ganglion cell, inner and outer nuclear layer in diabetic retina. This study suggests the anti
VEGF property of lutein is perhaps via decrease in the mRNA expression of Hif1a and Xbp1.