Protective effect of complex thrombolysis capsule on high altitude retinopathy in rat models / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To investigate the protective effect of complex thrombolysis capsule on high altitude retinopathy in rat models and its possible mechanism.<p>METHODS: Twenty-four adult male SD rats were randomly divided into 6 groups and were put into plateau environment simulation experimental chamber at simulated altitude of 5 000m for 2, 4, 6, 10, 24, 72h respectively. Retinal pathology, HIF-1α and the b wave amplitudes of Max-R of flash ERG were examined by HE,IHC and flash ERG. Twenty-four adult male SD rats were randomly divided into 4 groups and were given respectively placebo, rhodiolarosea, inosine tablet and compound xueshuantong capsule by gavage for 7d. They were put into plateau environment simulation experimental chamber at simulated altitude of 5 000m for 10h. Retinal pathology, HIF-1α and the b wave amplitudes of Max-R of flash ERG were examined by HE, IHC and flash ERG.<p>RESULTS: In the SD rat model of high-altitude retinopathy, with the increase of experimental time, the ganglion cell layer of rat's retina showed obvious edema and HIF-1α expression increased in the cytoplasm of ganglion cells and core cells. All of them were most obvious at 10h. Compared with the self-comparison of b wave amplitudes of Max-R of flash ERG in each group of SD rats before and after entering in plateau environment simulation experimental chamber, the b wave amplitudes of Max-R in 4h, 6h, 10h and 72h were dramatically decreased(<i>P</i>﹤0.05). And the 2h, 4h(<i>P</i>=0.007), 6h(<i>P</i>=0.008), 10h(<i>P</i>=0.002)were statistically significant differences, the 24h and 4h(<i>P</i>=0.035), the 6h(<i>P</i>=0.040)and 10h(<i>P</i>=0.012)were also statistically significant differences. In the study of protective effect of complex thrombolysis caps on high altitude retinopathy in rat models, the results showed that the rat retinal edema of rhodiolarosea group, inosine tablet group and compound thrombosis capsule group and HIF-1α expression in ganglion cell layer of compound thrombosis group and rhodiolarosea group were significantly reduced comparing with the placebo group. Test for homogeneity of variance and one-way ANOVA were used to test the difference of b wave amplitudes of Max-R of flash ERG in four groups of SD rats after entering in the plateau environment simulation experimental chamber, the results showed the complex thrombolysis caps group(<i>P</i>=0.032)and rhodiola rose group(<i>P</i>=0.001)was significantly lower than placebo group.<p>CONCLUSION: Compound thrombosis caps may have a protective effect on highaltitude retinopathy in rats by inhibiting the expression of HIF-1α, however, the specific mechanism needs to be further studied.

Gap Junction Contributions to the Goldfish Electroretinogram at the Photopic Illumination Level

Understanding how the b-wave of the electroretinogram (ERG) is generated by full-field light stimulation is still a challenge in visual neuroscience. To understand more about the origin of the b-wave, we studied the contributions of gap junctions to the ERG b-wave. Many types of retinal neurons are connected to similar and different neighboring neurons through gap junctions. The photopic (cone-dominated) ERG, stimulated by a small light beam, was recorded from goldfish (Carassius auratus) using a corneal electrode. Data were obtained before and after intravitreal injection of agents into the eye under a photopic illumination level. Several agents were used to affect gap junctions, such as dopamine D1 and D2 receptor agonists and antagonists, a nitric oxide (NO) donor, a nitric oxide synthase (NOS) inhibitor, the gap junction blocker meclofenamic acid (MFA), and mixtures of these agents. The ERG b-waves, which were enhanced by MFA, sodium nitroprusside (SNP), SKF 38393, and sulpiride, remained following application of a further injection of a mixture with MFA. The ERG b-waves decreased following NG-nitro-L-arginine methyl ester (L-NAME), SCH 23390, and quinpirole administration but were enhanced by further injection of a mixture with MFA. These results indicate that gap junction activity influences b-waves of the ERG related to NO and dopamine actions.

Normal values of Positive wave in the Multifocal Electroretinography in Korean

PURPOSE: To obtain normal values of positive wave (b-wave) in the multifocal ERG in terms of age and sex of Koreans. METHODS: The multifocal ERGs by using RETIscan visual evoked response imaging system were tested for 80 eyes. 61 retinal locations were stimulated concurrently. We analyzed the average responses of 5 concentric rings. RESULTS: In the amplitudes of b-wave, ring 1, 84.1 5.4 nV/deg, was the largest of all the other rings and ring 5, 23.1+/-1.5 nV/deg, was the smallest of all the other rings (P<0.05). No statistically significant difference was observed in amplitude between sexs. The implicit time of b-wave was the longest in the ring 1, 40.8 1.6 ms, and shortest in the ring 4, 36.7+/-0.9 ms (P<0.05). CONCLUSIONS: The amplitude of b-wave was the largest in the fovea, and became smaller with eccentricity. The largest amplitude of b-wave was observed in the age of twenties. The amplitude of b-wave was decreased with age in the ring 3, 4, and 5. The interindividual variation of the amplitude of b-wave was greatest in the fovea. The implicit time of b-wave in the fovea was the longest, and that in the ring 4 was the shortest. It became longer from the ring 5, again.

Us efulness of Standard Electro retinogram in the Early Diagnosis of Diabetic Retinopathy: Analysis using Receiver Operating Characteristic(ROC) Curve

Authors recorded standard electroretinogram in two groups of diabetic patients. Group A, consisted of 60 eyes with no visible diabetic retinopathy and Group B, 30 eyes with mild nonproliferative diabetic retinopathy. The electroretinogram was recorded according to the standard electroretinogram procedure recommanded by the ISCEV. In rod and cone response, the amplitude of b wave were 329.0+/-46.9 microvoltin Group A and 308.8+/-37.8 microvoltin Group B. The implicit time of b wave were 40.5+/-3. 0microvoltin Group A and 45.8+/-5.4microvolti n Group B. The summed amplitude of oscillatory potentials were 125.7+/-38.7microvolt in Group A and 112.0+/-17.7microvoltin Group B. Above results indicate that for the disgnostic criteria for diabetic retinopathy, the amplitude and implict time of b wave, and the summed amplitude of oscillatory potentials in maximal combined response were useful. On receiver operating characteristic(ROC) curves in maximal combined response, cut off value for the amplitude and implicit time of b wave were 315 microvoltand 42ms espectively. Cut off value for the summed amplitude of oscillatory potentia-als was 118 microvolt. In results, on ROC curve, the implicit time of b wave in maximal combined response was most accurate, and the summed amplitude of oscillary potentials was the next, followed by the amplitude of b wave in the maximal combined response.

The luminance-response function of the dark-adapted rabbit electroretinogram

The Naka-Rushton equation of the form, R = R(max) I(n)/(I(n)+K(n)), has been used to describe the b-wave luminance-response function of the scotopic electroretinogram. Rmax is the asymptotic value of the b-wave amplitude as a function of stimulus luminance I, K is the luminance that produces a b-wave amplitude that is one-half R(max), and n is a dimensionless constant that controls the slope of the function. These three parameters are often used in research laboratories, since it can show selective changes in each parameter. The present study describes these parameters (R(max) = 354 +/- 28 uV, n = 0.80 +/- 0.06, log K = -2.26 +/- 0.15 log cd. sec/m2) and the values obtained from the derivative analysis of Naka-Rushton equation (Anastasi et al) in 20 normal pigmented rabbit eyes. However, Naka-Rushton equation accurately describes the function only at low to moderate flash luminances. At high flash luminances, a second amplitude increase appears in the function.

The luminance-response function of the dark-adapted rabbit electroretinogram

The Naka-Rushton equation of the form, R = R(max) I(n)/(I(n)+K(n)), has been used to describe the b-wave luminance-response function of the scotopic electroretinogram. Rmax is the asymptotic value of the b-wave amplitude as a function of stimulus luminance I, K is the luminance that produces a b-wave amplitude that is one-half R(max), and n is a dimensionless constant that controls the slope of the function. These three parameters are often used in research laboratories, since it can show selective changes in each parameter. The present study describes these parameters (R(max) = 354 +/- 28 uV, n = 0.80 +/- 0.06, log K = -2.26 +/- 0.15 log cd. sec/m2) and the values obtained from the derivative analysis of Naka-Rushton equation (Anastasi et al) in 20 normal pigmented rabbit eyes. However, Naka-Rushton equation accurately describes the function only at low to moderate flash luminances. At high flash luminances, a second amplitude increase appears in the function.

The electroretinogram sensitivity in patients with diabetes

Electroretinograms (ERGs) were measured in 65 patients with diabetes and 10 control subjects. The single flash ERGs were recorded as a function of the stimulus intensity. A Naka-Rushton-type function was fit to b-wave amplitudes, measured as a function of stimulus intensity, to evaluate changes in ERG amplitude and sensitivity. We also measured the temporal aspects of the ERG b-waves. The ERG sensitivity tended to decrease as the retinopathy progressed. An average sensitivity loss in eyes with diabetic retinopathy was statistically significant. However, the eyes of diabetic patients without visible retinopathy did not show significant ERG sensitivity loss. There was less variability in temporal compared with amplitude measurements of ERG components, and significantly prolonged b-wave implicit times were found in all stages of retinopathy and in eyes of diabetic patients without retinopathy.

The Effect of Experimental Ocular Hypertension on the Electroretinogram in Laser Treated Rabbit Eyes

The argon laser is widely used to coagulate the diabetic retina in order to inhibit the progression of diabetic retinopathy. To compare the electrophysiological changes of the photocoagulated retina according to the level of intraocular pressure(IOP), the right eyes of 24 pigmented rabbits underwent retinal photocoagulation with an argon laser. Retinal function was assessed electroretinographically at 4 weeks after retinal photocoagulation before treatment and under elevated IOP(40 mmHg, 60 mmHg, 80 mmHg) for 4 hours. In the 40 mmHg group, the amplitude of the a-, b-, oscillatory potentials(OPs) of the photocoagulated eyes showed a more rapid drop than the control eyes, and there was no recovery stage seen in the control eyes. In the 60 mmHg group the amplitude of the a-wave, b-wave, and OPs of photocoagulated eyes showed a rapid drop and were abolished after 3.5 hours, but that of the control eyes showed biphasic changes; first, a rapid drop with the same velocity as the photocoagulated eyes during the first 2 hours, then a steady stage for the last 1.5 hours. In the 80 mmHg group, electroretinogram was totally abolished within 20 minutes after elevation of IOP in both eyes. The above results showed that the photocoagulated eyes treated 4 weeks ago were more vulnerable to elevated IOP than the control, healthy eyes.

The electroretinographic change by the acute effects of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

The electrophysiological effects of N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (NMPTP), a chemical inducer of Parkinsonism in man and monkey, on the pigmented rabbit retina were determined under acute conditions. The amplitude of the b-wave of the rabbit electroretinogram was affected, but both the implirit time and half-amplitude duration of it werenot. The amplitude of the photopic b-wave was increased by 72.9 +/- 32.1% 5hours after the intravenous injection of NMPTP (P[t] < 0.05), whereas that of the scotopic b-wave was decreased by 31.2 +/- 6.4% 4hours after injection (P[t] < 0.05). The above results suggest or support that: 1, the dopaminergic amacrine cells are related to the modulation of the b-wave of the rabbit electroretinogram. 2. during light adaptation, the dopaminergic amacrine cells uncouple the rod and cone systems in the inner plexiform layer and are involved in functions of the rod system. 3. the hypothesis that the funrtion of tyrosine hydroxylase may be affected by NMPTP.

The Acute Effects of N-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine on the Inner Plexiform Layer of Rabbits

The electrophysiological effects of N-methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine(NMPTP), a chemical inducer of Parkinsonism in man and monkey, on the pigmented rabbit retina were determined under acute condition. The amplitude of the b-wave of the rabbit electroretinogram was affected, but both the implicit time and half-amplitude duration of it were not. The amplitude of the photopic b-wave was increased by 72.9 +/- 32.1% 5 hours after NMPTP administration(P[t]<0.05), Whereas the scotopic b-wave was decreased by 31.2 +/- 6.4% 4 hours after injection(P[t]<0.05). The above results suggest or support that: (1) the dopaminergic amacrine cells are related to the modulation of the b-wave of the rabbit electroretinogram. (2) during light adaptation, the dopaminergic amacrine cells uncouple the rod and cone systems in the inner plexiform layer and are involved in functions of the rod system. (3) the hypothesis that the function of tyrosine hydroxylase may be affected by NMPTP.