The correlation between the regulation of recombinant human IGF-2 on eye growth and form-deprivation in guinea pig

By investigating the effects of recombinant human IGF-2 (rhIGF-2) on the diopter, axial eye length and the expression of IGF-2 in non-form-deprivation (FD) and FD eyes of guinea pig, we tried to elucidate the relationship between the effects of rhIGF-2 on eye growth and FD in guinea pig. Eighty 3-week-old guinea pigs were included in the study, which were divided into two groups randomly. Group A (n = 40) was the non-FD group, Thirty-two guinea pigs received intravitreal injections of either 1 ng, 10 ng, 100 ng rhIGF-2 or bovine serum albumin (BSA) to the right eye; eight guinea pigs who received no intravitreal injections served as control. Group B (n = 40) was the FD group; the right eyes were form-deprived, and received the same disposals as group A. The diopter and the axial eye length of all guinea pigs were measured at day 14. The expression of IGF-2 in the retina was measured by Western blot. After 14 days, FD eyes were high myopia. The axial length of FD eyes was significant for longer than that of non-FD eyes. The expression of IGF-2 in the retina of FD eyes was up-regulated. In non-FD group, there was no significant difference in the diopter and axial eye length among rhIGF-2 injection eyes, BSA injection eyes and control eyes, but the expression of IGF-2 in the retina of 10 ng and 100 ng rhIGF-2 injection eyes was obviously down-regulated. In the FDM (form-deprivation myopia) group, the myopic diopter and axial eye length increased in 10 ng and 100 ng rhIGF-2 injection eyes compared with those in BSA injection eyes and control eyes. The level of IGF-2 expression in the retina of 10 ng and 100 ng rhIGF-2 injection eyes was obviously down-regulated. The diopter and expression of IGF-2 in the retina of rhIGF-2 injection eyes was negatively correlated with the dose of each injection, which was positively correlated with the axial length. RhIGF-2 intravitreous injection does not affect the diopter and axial length in non-FD eyes of guinea pig, while it can induce a significant increase in myopic diopter and axial length of FD eyes. RhIGF-2 can promote the development of FDM on the condition of FD.