ABSTRACT
Background Retinitis pigmentosa (RP) is one of the causes of congenital blindness.It is well known that the degeneration process of rod cells is difficult to detect in RP.Retinal degeneration 12 (rd12) mice is a new,spontaneously arising mouse model for human Leber congenital amaurosis (LCA),and it is helpful for us to explore the pathogenesis and determine the treating target of RP.Objective This study was to investigate the natural disease process of short-length sensitive cone cells in rd12 mice,a LCA Rpe65rd12 (B6 [A]-Rpe65rd12/J) mouse.Methods The rd12 mice at postnatal (P) 14,P21,P35 and P90 were selected (5 mice for each),and the wild-type C57BL/6J (B6) mice with matched ages were included as controls.Photopic full-field electroretinogram (ERG) was recorded with Roland Q450SC UV visual physiology instrument.Cone response was recorded using single white light-emitting diode (LED) stimulation with the flash intensity of 1.00 cds/m2 and 1.96 cds/m2,and short wave-length sensitive cone response was recorded using ultraviolet light ([363 ±6] nm) stimulation with the flash intensity of 2.0 mWs/m2 and 3.0 mW/m2.The mice were sacrificed and retinal whole-mounts were prepared.The distribution and number of cone cells and UV-sensitive cone cells were detected by FITC-peanut agglutinin (FITC-PNA) and Cy3 immunofluorescence stainning,respectively.Results In P14 rd12 mice,the ERG responses of overall cone cells presented the negative waveform and the latency was delayed,and UV-sensitive cone response was unrecordable.The b-wave amplitude of overall cone cells reduced by 75％ in P21 rd12 mice compared with wild-type B6 mice,and the mean latency of b-wave in the P21 rd12 mice was significantly longer than that in the wild-type B6 mice ([102.80± 11.39] ms vs.[43.40± 5.60] ms) (t =-8.106,P =0.001).The mean b-wave amplitudes of U Vsensitive cone cells were (59.60± 36.00),(82.40± 12.22) and (68.43 ± 17.63) μV in the wild-type B6 mice,andthose in the rd12 mice were unrecordable.Immunofluorescence showed that a lager number of cone cells with green fluorescence were seen,and the expression of opsin with red fluorescence was displayed in the UV-sensitive cone cells of nasal lateral on retinal ventral side in P14 wild-type B6 mice;while only a few opsin positive-response cells were seen in P14,P21 and P35 rd12 mice.Conclusions In rd12 mice,the functional abnormality and quantitative reduction of cone cells appear in the early postnatal days,and the loss of UV-sensitive cone cells is earlier and more obvious.
ABSTRACT
Background Age-related cataract is a common cause of blindness.However,its cause and pathogenic mechanism have not been fully understood.Recent studies revealed that aquaporin 1 (AQP1) and AQP0 are closely related to the pathogenesis of cataract.Objective This study was to investigate the differential distribution and expression of AQP0 and AQP1 in lenses with age-related cataract and explore its effect on pathogenesis of age-related cataract.Methods Seventeen anterior capsular membrane samples and nucleus samples of lenses were collected from age-related cataract patients during the small incision nonphacoemulsification cataract extraction,and 6 normal lens samples were obtained from health donors in the First Affiliated Hospital of Fujian Medical University.The expression and distribution of AQP1 and AQP0 in the lenses were detected by immunohistochemistry,and the relative expression levels of AQP1 and AQP0 proteins in the lenses were assayed by using Western blot assay.This study protocol was approved by Ethic Committee of this hospital,and written informed consent was obtained from each patient.Results Immunohistochemistry showed that in the normal lenses,AQP1 expressed mainly in LECs;while AQP0 primarily expressed in fiber cells of the lens cortex and nucleus.The relative expression levels of AQP1 and AQP0 in the lenses with age-related cataract (absorbance) were 0.223±0.008 and 0.118±0.015,which were significantly lower than 0.246±0.007 and 0.149±0.007 in the normal lenses (t =-4.508,-3.291,both at P＜0.01).Western blot revealed that the relative expression levels of AQP1 and AQP0 in the lenses with age-related cataract (absorbance) were 0.663 ± 0.012 and 0.599 ± 0.015,which were significantly reduced in comparison with 0.844±0.041 and 0.955 ±0.064 in the normal lenses (t =-7.492,P＜0.05;t =-9.570,P＜0.01).Conclusions AQP1 and AQP0 distribute in different sites of lenses.The expressions of AQP1 and AQP0 are obviously down-regulated in lenses with age-related cataract,suggesting that AQP1 and AQP0 probably play different roles in the pathogenesis of age-related cataract.