AIM:To investigate the effect of intravitreal injection of DL-alpha-aminoadipic acid (DL-α-AAA) on ocular refractive state and retinal dopamine, transforming growth factor-β2 (TGFβ2 ), vasoactive intestinal polypeptide (VIP) in guinea pig form-deprived myopia. METHODS:Four-week-old pigmented guinea pigs were randomly assigned to 4 groups:normal control, deprivation, deprivation plus DL-α-AAA, deprivation plus saline. Form deprivation was induced with the self-made translucent eye shields, and lasted for 14 days. 8μg DL-α-AAA was injected into the vitreous chamber of deprived eyes. The corneal radius of curvature, refraction and axial length were measured. Retinal dopamine content was evaluated by the high-performance liquid chromatography with electrochemical detection, and TGFβ2 and VIP protein were detected by Western blotting. RESULTS:Fourteen days of eye occlusion caused the axial length to elongate and become myopic in the form-deprived eyes, with the decrease of retinal dopamine and the increase of TGFβ 2 and vasoactive intestinal polypeptide (VIP) protein. Intravitreal injection of DL-α-AAA could inhibit the myopic shift from (-3.65±1.06)D to (-1.48 ±0.63)D, P <0.01 due to goggles occluding and cause the decrease of retinal TGFβ2 protein in the deprived eyes. However, intravitreal injection of DL-α-AAA had no significant effect on retinal dopamine and VIP protein in deprived eyes. Retinal TGFβ2 protein correlated highly with the ocular refraction (y =-3.34 + 0.31/x , F =74.75, P <0.001) and axial length (y =8.39-0.02/ x , F =48.32, P <0.001) in different treatment groups. ·CONCLUSION:Intravitreal injection of DL-α-AAA is effectively able to suppress the development of form deprivation myopia, which may be associated with retinalTGFβ2 protein in guinea pigs.
AIM: To investigate the effect of protein kinase C (PKC) on transforming growth factor-β2 (TGFβ2) and dopamine in retinal Müller cells of guinea pig myopic eye. METHODS: Myopia was induced by translucent goggles in guinea pig, whose retinal Müller cells were cultured using the enzyme-digesting method. Retinal Müller cells were divided into 5 groups: normal control, myopia, myopia plus GF109203X, myopia plus PMA, myopia plus DMSO. PKC activities were detected by the non-radioactive methods. TGFβ2 and tyrosine hydroxylase (TH) proteins were analyzed by Western Blotting in retinal Müller cells. Dopamine was determined by the high-performance liquid chromatography- electrochemical detection in suspensions. RESULTS: After 14 days deprived, the occluded eyes became myopic with ocular axle elongating. Müller cells of guinea pigs were obtained using enzyme digestion. Compared with normal control group, the increase in PKC activity and the up-regulation in TGFβ2 expression were found in retinal Müller cells of myopic eyes, with the decrease of TH and dopamine content (P <0.05). After PKC activated by PMA, TGFβ2 and TH content were up-regulated with the increase of dopamine content (P <0.05). While the PKC activities was inhibited by GF109203X, proteins of TGFβ2 and TH were down-regulated in the myopic eyes, with the decrease of dopamine content (P <0.05). CONCLUSION: TGFβ2 and dopamine are modulated by PKC in Müller cells of the myopic eyes in guinea pig.
Jun-Feng Mao, Shuang-Zhen Liu, Wen-Juan Qin, Qian Xiang Department of Ophthalmology, Xiangya Hospital of Central South University, Changsha 410008, Hunan Province, China
Purpose:In our previous work,it has been shown that intraperitoneal injection of L-DOPA can inhibit the development of occlusion myopia in guinea pigs,and increase levels of retinal dopamine.The aim of this study was to investigate whether exogenous L-DOPA can be converted into dopamine in cultured retina of guinea pig eyes subjected to visual deprivation,and to evaluate whether müller cells are involved in the processing of retinal dopamine induced by L-DOPA.Methods:Fifty-eight guinea pigs were randomly divided into 2 groups at the age of 4 weeks:normal control and visual deprivation.Form deprivation was induced with translucent eye shields over the right eye,and lasted for ten days.Corneal curvature,refraction and axial length were measured in all animals.In vitro,neuro-retina and müller cell were cultured,and L-DOPA was added to the culture medium at three concentrations:1 μM,10 μMand 100 μM.Subsequently,dopamine content was evaluated by high-performance liquid chromatography,and apoptotic cells were identified by TUNEL staining.Results:Ten days of occlusion caused the affected eyes to elongate and become myopic in guinea pigs.Compared with the deprivation group,10 μML-DOPA treament significantly raised dopamine content in cultured retina and müller cells (P<0.05).However,1 μMand 100 μML-DOPA treatment caused no increase in dopamine levels(P>0.05).Apoptotic nuclei were detected in the ganglion cell layer (92.5%±8.3%) and inner nuclear layer (46.8%±9.1%)of cultured retina treated with 100 μML-DOPA.Moreover,100 μML-DOPA also caused apoptosis of retinal müller cells,at a mean rate of 59.4 ±11.3%.Conclusion:.Our results suggest that exogenous L-DOPA can cause an increase in retinal dopamine in form-deprived guinea pig eyes in vitro,and that müller cells are involved in the increase in retinal dopamine.
Junfeng Mao Shuangzhen Liu Wenjuan Qin Qian Xiang Xiaoying Wu
