The Observation Of Inherit Phenotype In Model Rats With Congenital Stationary Night Blindness

Congenital stationary night blindness (CSNB) is a nonprogressive retinal disorder characterized by a negativetype ERG in which the amplitude of the b-wave is smaller than that of the a-wave even though the fundus of CSNB patients is essentially normal. The disease is transmitted in an autosomal recessive, autosomal dominant or X-linked mode of inheritance. there are several subtypes of CSNB, but the most important symptom is damaged function of rod cells. Modle animal will be ensscel condition for the reseach of hereditary disease; our spontaneous CSNB modle rats will us central means to study the mechanism of CSNB.Several groups have shown genetic heterogeneity of the X-linked form of congenital stationary night blindness (XLCSNB) by identification of two different loci on chromosome X the incomplete type and the complete type. The elucidation of the molecular basis has identified the matrix protein nyctalopin in cCSNB and the a-1 subunit of a retina-specific calcium channel in iCSNB, which are both predicted to function of retinal signal transduction. Our CSNB rats have been determined as iCSNB because of Cacna1f mutating. The Cacna1f gene encodes Cav1.4 channel protein which expresses in retinal. The mutationof it can lead to neural dysfunction between photoreceptors and bipolar cells.According to the results of our experiments in step by step progress, the main subjects of this reseach were as follows: 1,The function and development of retinal in model rats with retinal disorder. In this subject works must be the basic research. There were several small topics. First was that to measure the basic data of physiology and chemical of the blood in model rats. Second, we researched the electroretinogram changes and histology of model rats'retinal following the CSNB rats growing up. Third, the characteristics of theflicker ERG were studied in model rats. 2,To study several behaviors of visual deficit rats. The accomplishment of negative avoidance response, Morris water maze, open-field test, rota-rod test and gripping rod test were discovered.Methods and materialThe visual function damaged modle rats(inbred strain) and contral SD rats (same age) were used in present reseach. Take the automatic biochemistry analyzer, the automatic electrolytes analyzer and conventional analysis to determine the basic physiological and biochemical data ; use the technology of vision electrophysiology to analysis the function development of retinal in modle rats; make use of light microscope and electronic microscope to observe morphology of retina; several behaviors methods to appraise the subjective behaviors.Results1.The results of basic data of physiology and chemical of the blood There were significant differences in organ weight between two sexes in CSNB rat(P < 0.05),except for spleen,adrenal gland, pituitary.The coefficients of organs were significantly higher in female CSNB rats than that of the male except for kidney. The GLU, CHO,ALB were higher,and ALT,AST, ALP, BUN, CRE, TG, TP were lower in female rats;the result of electrolyte was that K,Na and iCa were higher in the male,Cl was higher in female, but there were no significant differences between female and male in statistics( P > 0.05).2.The development of retina and vision functionThe a wave of Max-ERG of CSNB rats have significant longer latence than SD rats from opening eye to 6 month (P < 0.05), the amplitude of a wave arrivaled the biggest at 2 month in CSNB rats, while the biggest amplitude at 4 month in SD rats, there were significant difference in amplitude 4 month, 5 month and 6 month (P < 0.05). Compared cone-ERG of CSNB rats with SD rats, there were significant difference in latency and amplitude except4 month. The results of HE stain showed the outer nuclear layer were thinner in CSNB rats at 2, 4, 6month respectively. PKC staining showed there were no significant in CSNB rats and SD rats at every period. Calbindin D-28k staining showed that the number of horizon cells and dendrons sharply reduced in CSNB rats compared with SD rats. The number of ribbons of CSNB rats were significantly reduced in outer plexiform compared with SD rats.3.The Characteristics of Flicker ERGs in Model RatsIn dark adaptation, the flicker response amplitudes obtained from SD,CSNB and RCD rats declined progressively with in creasing stimulus frequency.â‘ there were significant lower in the amplitudes of the CSNB rats than that of SD rats, the waveforms of the CSNB rats were similar to SD rats, excepting after at 15Hz.â‘¡the waveform of the RCD rats had no much of difference compared with SD rats', and have no significant alteration in their amplitude. From 20 Hz, there was yet a little difference in their waveforms. In light adaptation,â‘ RCD rats failed to elicited at any frequency.â‘¡CSNB rats resembled SD rats in waveform, but the amplitude of them have a significant difference. Using dim blue light in dark adaptation,â‘ CSNB rats couldn't be recorded waves,â‘¡the amplitudes of the RCD rats gotten with dim blue light were bigger than that elicited with dim white light.4.The characterize of the model rats with decreased visual acuity in the behaviourMorris water maze test showed that the escaping distance of RCD and CSNB rats were significantly longer than the distance of SD rats; the staying time of second quarter were shorter in the two model rats than control rats which showed an impaired performance in space navigation. The result of negative avoidance response demonstrated the statistical significance in latency of entering dark box in CSNB rats and SD rats; and the error times in RCD rats more than SD rats(P < 0.05). There were significant difference in the escaping distance and escaping time comparing the two model rats with SD rats by new environmental stimuli. Rota rod test showed that latency of falling from rod were shorter in the decreased vision rats than SD rats everyday. Electroretinogram indicated that the retinal function of RCD and CSNB rats were decreased.Conclutions1.The basic physiological and biochemical data of CSNB rat strain are in normal range. The inhred strain of CSNB rats have displaied stable physiological index. 2.The visual function of CSNB worse than SD rats at every period. The structure of retinal and the immunohistochemistry results support the results of ERG. 3.CSNB rat'rod system damaged badly associated with some functions of the cone-system suffered. RCD rat rod system function was excellent, but the cone system function was completely dystrophy. The rods of SD rat are sensitive to ficker ERG until 20 Hz under dark-adapted condition; cones are sensitive to ficker ERG until 62 Hz under light-adapted condition. 4.The space and nonspace learning memory function, spontaneous activity and exercise tolerance of CSNB rats are impaired.