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Endothelins exert pathological effects in the eye and much interest centres on their role in causing retinal neuronal death in ischemic diseases like glaucoma. In the present study the influence of the non-selective endothelin antagonist, sulfisoxazole on raised intraocular pressure-induced ischemia to the rat retina was investigated. Moreover, in vitro studies on primary rat retinal cultures were undertaken to see whether sulfisoxazole is able to blunt the toxic effect of lipopolysaccharide (LPS) to retinal neurones. In order to determine whether sulfisoxazole provides protection to the retina the a- and b-wave amplitudes of the electroretinogram (ERG), the localisation of retinal choline acetyltransferase (ChAT), nitric oxide synthase (nNOS) and Thy-1 and the retinal mRNA levels of Thy-1 and FGF-2 were deduced in retinas subjected to ischemia in the absence or presence of sulfisoxazole. The results showed that the ischemia-induced changes to the a- and b-wave amplitudes of the ERG and changes associated with the localisation of ChAT, nNOS and Thy-1 to be significantly blunted by sulfisoxazole. However, while the ischemia-induced changes to Thy-1 and FGF-2 mRNAs were reduced by sulfisoxazole, the reduction was non-significant. The in vitro studies provided support for the protective effect of sulfisoxazole. Here, it was clearly shown that sulfisoxazole attenuated the elevation of nitric oxide (deduced by measuring nitrite) and the reduction in numbers of GABA-containing neurones caused by LPS. The present study provides evidence for the first time that endothelin antagonist can protect the retina from ischemic-like insults as occurs in glaucoma.

Carotid artery occlusion (two vessel occlusion; 2-VO) for 3 or 9 months causes a suppression of the electroretinogram. However, after 3 months the retinal morphology appears unaffected judging from the localisation of GABA, ChAT, αPKC, Thy-1 and GFAP immunoreactivities. Moreover, no difference in NMDA-R1, opsin or Thy-1 mRNA levels were detected. In contrast, after 9 months 2-VO photoreceptor degeneration occurred as indicated by thinning of the outer nuclear layer and reduced Ret-P1 immunoreactivity. All other immunoreactivities appeared normal. These findings were supported by analysis of retinal mRNA levels. We conclude that the major effect of prolonged 2-VO is photoreceptor degeneration.

The aim of this study was to examine whether the antioxidant epigallocatechin gallate (EGCG), a catechin-base flavonoid derived from green tea protects retina neurones in situ from ischemia/reperfusion and in vitro from an oxidative stress insult of hydrogen peroxide (H(2)O(2)). Similar results were obtained when rats were injected by two different regimes of EGCG. Ischemia was delivered by raising the intraocular pressure above the systolic blood pressure (120 mm Hg) generally for 45 min. The electroretinogram (ERG) was measured prior to ischemia and 5 days after reperfusion. Rats were killed 7 days after ischemia and processed for immunohistochemistry and for determining of mRNA and protein levels by RT-PCR and electrophoresis/western blotting, respectively. In addition, optic nerves 7 days after ischemia were subjected to protein analysis. Ischemia/reperfusion caused a significant reduction in the a- and b-wave amplitudes of the ERGs, a decrease in retinal ganglion cell and photoreceptor specific proteins and mRNAs, an increase in retinal caspase-3 mRNA and protein, an increase in retinal caspase-8 mRNA, an increase in retinal GFAP protein and mRNA and a decrease in optic nerve proteins associated with ganglion cell axons. All these changes were significantly counteracted by EGCG. Moreover, EGCG clearly blunted ischemia/reperfusion-induced changes in the localisation of retinal Thy-1 and ChAT immunoreactivities. EGCG also significantly reduced the apoptosis to retinal ganglion cells (RGC-5 cells) in culture caused by H(2)O(2). The results of the study demonstrate that EGCG provides protection to retinal neurones from oxidative stress and ischemia/reperfusion.

Glial-derived monocarboxylate lactate is thought to be an important energy source for neurons during brain activation or in hypoxia–ischemia. Treatment with α-cyano-4-hydroxycinnamate (4-CIN), a monocarboxylate transporter inhibitor, has been recently reported to exacerbate delayed neuronal damage in a rat model of cerebral ischemia, an effect ascribed to inhibition of lactate/pyruvate transport. Since monocarboxylate transporters are abundant in the retina, we examined the effect of 4-CIN administration on the outcome of high intraocular pressure-induced retinal ischemia in rats. Retinal ischemic damage was assessed by changes in the electroretinogram (ERG), the retinal localization of choline acetyltransferase (ChAT) and neuronal nitric oxide synthase (nNOS) immunoreactivities, and the loss of retinal mRNA for Thy-1. Intraperitoneal or intravitreal administration of 4-CIN had no effect on the ERG or the localization of ChAT and nNOS immunoreactivities in either the control retina or a retina subjected to ischemia/reperfusion. In addition, intravitreal injection of 4-CIN had no effect on ischemia-induced reduction of retinal mRNA levels for Thy-1. These results provide no evidence to support the view that blockade of lactate uptake and/or pyruvate entry into mitochondria for oxidative metabolism has an influence on the outcome of retinal ischemia/reperfusion.

PURPOSE: Although visual impairment is a well-recognized consequence of cataract development, little is known about the ability of the melanopsin-based photosensitive retinal ganglion cells (pRGCs) to regulate sleep-wake timing in the presence of cataract. In this study, we replaced a cataractous natural crystalline lens with two different types of artificial intraocular lenses, a UV-blocking lens or a blue-filtering lens. We investigated the level of sleep disturbance before cataract surgery and any change in sleep due to improved light transmission following surgery and compared this in both types of intraocular lens. METHODS: Quality of sleep in 961 patients undergoing cataract surgery was assessed by administering the validated self-reported Pittsburgh Sleep Quality Index (PSQI) questionnaire. The PSQI distinguishes good sleepers from poor sleepers by scoring seven different sleep components over the last month, which are combined to produce an overall score for sleep quality. Patients received either an ultraviolet-blocking (UVB) clear intraocular lens (IOL) or a blue-filtering (BF) IOL. Questionnaires were completed four times: 1 month preoperatively and again 1, 6 (UVB-IOL only), and 12 months postoperatively. RESULTS: Half of the patients reported poor sleep in the presence of cataract in both the UVB-IOL (mean PSQI = 6.35; SD = 3.82) and BF-IOL (mean PSQI = 6.39; SD = 4.04) groups. Cataract removal improved overall sleep quality significantly 1 month postoperatively in the UVB-IOL (mean PSQI = 5.89; SD = 3.71) and BF-IOL (mean PSQI = 6.08; SD = 3.88) groups. Sleep latency also improved for the UVB-IOL (preoperative mean = 1.16; SD = 1.003) and BF-IOL (preoperative mean = 1.17; SD = 1.03) groups at 1 month (UVB-IOL group mean = 1.01; SD = 0.923 and BF-IOL group mean = 1.00; SD = 0.95), which was sustained at 6 months for the UVB-IOL group (mean = 1.02; SD = 0.93) and 12 months for both the UVB-IOL and BF-IOL groups (6 months: UVB-IOL group mean = 0.96; SD = 0.92 and for the BF-IOL group mean = 0.99; SD = 0.96). CONCLUSIONS: Overall sleep quality and sleep latency improves after removal of cataract irrespective of the type of IOL implanted. These data show that implantation of BF-IOL does not have a negative impact on the sleep-wake cycle.

Age- and sex-matched pigmented (Lister Hooded) and albino (Wistar) rats were used in this study. The retinas of the animals were subjected to pressure-induced ischaemia (35 min, 120 mmHg) and reperfusion (3 days) in precisely the same way. The b-wave of the electroretinogram (ERG) in the pigmented animals recovered to normal levels while those of the albino rats were reduced by more than 80%. Moreover, the choline acetyltransferase (ChAT) immunoreactivity associated with a sub-set of amacrine cells was almost completely obliterated in the retinas from the albino rats but unaffected in the retinas of the pigmented rats. Also, in certain areas of the retina from albino rats there was a suggestion that the calretinin-immunoreactivity was affected. This was never seen in the retinas of the pigmented animals. The GABA-immunoreactivity in the retina of both albino and pigmented rats appeared to be unaffected by ischaemia/reperfusion. The data presented show that retinas from albino rats are more susceptible to ischaemia/reperfusion than retinas from pigmented animals. The results also show that reduction of the b-wave of the ERG and changes in the nature of the ChAT immunoreactivity represent sensitive markers to detect the effect of ischaemia/reperfusion to the retina.

Melatonin is synthesised primarily in the pineal organ and is released into the blood stream and cerebrospinal fluid. The release of melatonin is controlled by biological clock(s) and is synchronised to the prevalent photoperiod of light (1,2). The peripheral blood and cerebral spinal fluid levels of the indole in man are extremely high at night and low to undetectable during daytime; this appears to vary from species to species and is related to the importance of circadian organisation (3). Binding studies have demonstrated that melatonin receptors are located to discrete areas of the brain and in some cases signal-transducing mechanisms have been reported. Molecular biological studies suggest that at least three different types of melatonin receptors exist (4). Thus the present evidence shows clearly that melatonin functions as a mediator/hormone although many more data are necessary to understand the functional significance of the various melatonin receptors.