Objective: To investigate the effect of regulation of VIPhybrid, an unselective antagonist of vasoactive intestinal peptide receptors (VIPR), on the formation and development of form deprivation myopia (FDM) in chick and the expression of protein and mRNA of VIP on the retina and choroids of in chicks.
Methods: Seventy-two 1-day-old yellow healthy leghorn chicks were assigned into 6 groups (12 in each group). Eyes in Group I were covered on the right as a blank control group. Eyes in GroupII were those eyes having been injected with 20 microL saline into vitreous cavity and then covered as a negative control group. Eyes in GroupIII,IV and V were injected with 20 microL VIPhybrid with low (3*10(-12) mol/L), middle (3*10(-10) mol/L) and high (3*10(-8) mol/L) dosage into vitreous cavity and then covered as experimental groups. The above groups had been continuously covered for 1 week. Eyes in Group VI were uncovered and uninjected as a normal control group. Diopter was detected using retinoscopic refraction. The eyeball axis was determined using ophthalmological ultra-A. The expression of protein and mRNA of VIP on retina-choroids-sclera were investigated by SP immunohistochemistry staining and RT-PCR.
Results: Form deprivation for 1 week induced high myopia eyes and elongated eyeball axis in GroupI and GroupII, and there was no difference between the 2 groups (P>0.05). The diopter and eyeball axis were significantly reduced in Group III, IV, and V as compared with Group I and II (P<0.01), but the diopter was higher and the eyeball axis was longer than those of Group VI. The diopter and eyeball axis had negative correlation with the concentration gradient of VIPhybrid. The expressions of protein and mRNA of VIP in Group III, IV, and V were down-regulated as compared with those of Group I and I I(P<0.01)and also down-regulated with the increase of concentration of VIPhybrid.
Conclusion: VIPhybrid can decrease the development of FDM in chicks, which may provide a new pathway for drug therapy of myopia in human beings.