Influence of the difference of breastfeeding volume on a rat model of oxygen-induced retinopathy

This study aimed to investigate the effects of abundant breast milk intake on rats model of oxygen-induced retinopathy (OIR). Neonatal Sprague-Dawley rats were randomly assigned to expand litters of 7 pups/litter (7-rats group) and 14 pups/litter (14-rats group). They were exposed to 80% oxygen from postnatal day (P) 0 to P12. Body weights were measured daily. At P13 and 18, rats were sacrificed, and the blood and eyes were collected. Retinal neovascularization (NV) score, total retinal area (TRA), avascular area (AVA), and vascularized area (VA) were measured in ADPase stained retinas. Retinal vascular endothelial growth factor (VEGF) and serum insulin-like growth factor (IGF-1) were measured using ELISA. Body weight gain was significantly greater in 7-rats group from P2. Serum IGF-1 levels at P13 and 18 were significantly higher in 7-rats group. Retinal VEGF and TRA at P18 were significantly larger in 7-rats group. NV score at P18 tended to be higher in 7-rats group. There was no significant difference in VA between the 2 groups at P13 and 18. Excess breast milk intake in OIR rat pups caused body weight gain and retinal development, whereas there was less effect on retinal vascularization in our study.