Sushma Srivastava

Lycopene attenuates oxidative stress induced experimental cataract development: an in vitro and in vivo study.

OBJECTIVES Lycopene, a nutritional antioxidant, was evaluated for its anticataract potential to further establish its role in cataract prevention. METHODS The ability of lycopene to modulate the biochemical parameters was investigated by in vitro studies. Enucleated rat lenses were maintained in organ culture containing Dulbeccos Modified Eagles Medium alone or in addition with 100 microM selenite and served as the normal and control groups, respectively. For the test group, the control medium was supplemented with 10 microM lycopene. The lenses were incubated for 24 h at 37 degrees C. At the end of the incubation period, the lenses were examined for morphologic variation, and biochemical parameters such as reduced glutathione, the lipid peroxidation product malondialdehyde, and the antioxidant enzymes glutathione peroxidase, glutathione S-transferase, superoxide dismutase, and catalase were estimated. In vivo selenite cataract was induced in 9-d-old rats by subcutaneous injection of sodium selenite (25 micromoles/kg of body weight). The rats in the test group were injected with lycopene (200 microg/kg body weight, intraperitoneally) 4 h before the selenite challenge. The incidence of cataract was observed when the rats first opened their eyes. Galactose cataract was induced in rats by feeding 30% galactose in the diet. Rats in the test group were fed orally with 200 microg/kg of lycopene daily, and rats in the control group received only vehicle. Cataract stages were graded at regular intervals. RESULTS A fall (25%) in the glutathione level and a rise (32%) in the malondialdehyde content were observed in control as opposed to normal lenses. Lycopene supplementation in the medium significantly (P < 0.001) restored glutathione and malondialdehyde levels. A significant decrease in the activity of antioxidant enzymes also was observed in the control lenses. A significant restoration in the activities of superoxide dismutase (P < 0.05) and catalase and glutathione S-transferase (P < 0.01), with no effect on glutathione peroxidase, was observed in the lycopene-supplemented group. Lycopene also reduced the incidence of selenite cataract. Only 9% of the eyes in the test group developed dense nuclear opacity as opposed to 83% in the control group. A significant delay in the onset and progression of galactose cataract was observed with oral feeding of lycopene. Only 35% of the eyes developed mature cataract as opposed to 100% in the control group. CONCLUSIONS Lycopene protects against experimental cataract development by virtue of its antioxidant properties, and it may be useful for prophylaxis or therapy against cataracts.

Hesperetin rescues retinal oxidative stress, neuroinflammation and apoptosis in diabetic rats.

The purpose of the study was to evaluate the effects of hesperetin (Hsp) on diabetes-induced retinal oxidative stress, neuroinflammation and apoptosis in rats. The Hsp treatment (100 mg/kg body weight) was carried for twenty four weeks in STZ-induced diabetic rats and evaluated for antioxidant (Superoxide dismutase; SOD, Catalase; CAT and glutathione; GSH) enzymes, inflammatory cytokines (TNF-α, IL-1β), caspase-3, glial fibrillary acidic protein (GFAP) and aquaporin-4(AQP4) expression. Histological changes were evaluated by light and transmission electron microscopic (LM and TEM) studies. Retinal GSH levels and anti-oxidant enzymes (SOD and CAT) activity were significantly decreased in diabetic group as compared to normal group. However, in Hsp-treated rats, retinal GSH levels were restored close to normal levels and positive modulation of anti-oxidant enzyme activity was observed. Diabetic retinae showed significantly increased expression of Pro-inflammatory cytokines (TNF-α and IL-1β) as compared to normal retinae. While Hsp-treated retinae showed significantly lower levels of cytokines as compared to diabetic retinae. Diabetic retinae showed increased caspase-3, GFAP and AQP4 expression. However, Hsp-treated retinae showed inhibitory effect on caspase-3, GFAP and AQP4 expression. LM images showed edematous Müller cell endfeet, and also degenerated photoreceptor layer; however, protective effect of Hsp was seen on Müller cell processes and photoreceptors. TEM study showed increased basement membrane (BM) thickness in diabetic retina, while relatively thin BM was recorded in Hsp-treated retina. It can be postulated that dietary flavanoids, like Hsp, can be effective for the prevention of diabetes induced neurovascular complications such as diabetic retinopathy.

Green Tea (Camellia sinensis) Protects against Selenite-Induced Oxidative Stress in Experimental Cataractogenesis

Cataract is the leading cause of blindness worldwide. It is a multifactorial disease primarily associated with oxidative stress produced by free radicals. The protection offered by various antioxidants in cataract development is well established. Polyphenolic compounds present in green tea (Camellia sinensis) are reported to possess antioxidant property in various pathological conditions. The present study was undertaken to evaluate the anticataract potential of green tea leaf (GTL) extract in the development of lens opacification. Enucleated rat lenses were randomly divided into normal, control and treated groups and incubated for 24 h at 37°C. Oxidative stress was induced by sodium selenite in the culture medium of the two groups (except the normal group). The medium of the treated group was additionally supplemented with GTL extract. After incubation, lenses were subjected to glutathione and malondialdehyde estimation. Enzyme activity of superoxide dismutase, catalase and glutathione peroxidase was also measured in different sets of the experiment. In vivo cataract was induced in 9-day-old rat pups of both control and treated groups by a single subcutaneous injection of sodium selenite. The treated pups were injected GTL extract intraperitoneally prior to selenite challenge and continued for 2 consecutive days thereafter. Cataract incidence was evaluated on 16th postnatal day by slit lamp examination. There was positive modulation of biochemical parameters in the organ culture study. Green tea was also found to reduce the incidence of selenite cataract in vivo. The results suggest that green tea possesses significant anticataract potential and acts primarily by preserving the antioxidant defense system.

Ocimum sanctum Modulates Selenite-Induced Cataractogenic Changes and Prevents Rat Lens Opacification

Purpose: To study the effect of Ocimum sanctum (OS) on selenite-induced morphological and biochemical changes in isolated rat lenses as well as on cataract incidence in rat pups. Methods: Transparent rat lenses were divided into normal, selenite-only, and four treated groups. Selenite-only and treated group lenses were subjected to oxidative stress in vitro by incorporating sodium selenite (100 μ M) in the culture medium. The effect of OS (70, 140, 280, and 560 μ g/ml) was studied on the levels of reduced glutathione (GSH) and thiobarbituric acid reacting substances (TBARS) in selenite-challenged lenses. The lowest concentration of OS offering significant modulation on these two parameters was determined. Subsequently, the effect of prior and cotreatment with the lowest effective concentration of OS was studied on TBARS, GSH, and on lens antioxidant enzymes such as superoxide dismutase (SOD), glutathione peroxidase (GSHPx), catalase (CAT), and glutathione-S-transferase (GST). Changes in lens protein profiles under different incubation conditions were analyzed by SDS gel-electrophoresis. In vivo, cataract was induced by a single subcutaneous injection of sodium selenite (25 μ mole/kg b.w.) to 9-day-old rat pups. The anticataract effect of OS (5 and 10 mg/kg b.w.) injected intraperitoneally 4 hr prior to selenite challenge was evaluated by the presence of lens nuclear opacity in rat pups on the 16th postnatal day. Insolubilization of lens proteins post–selenite injection was monitored for 4 days. Results: The lenses in the selenite-only group developed cortical opacities in 24 hr. OS showed different degrees of positive modulation in selenite-induced morphological as well as biochemical changes. The lowest effective dose of OS that significantly modulated glutathione and thiobarbituric acid reacting substances was found to be 140 μ g/ml. At this dose, a significant increase in antioxidant enzyme levels and preservation of normal lens protein profile was observed. OS at the dose of 70 μ g/ml did not show any significant protection with respect to either morphology or biochemistry of lenses. In vivo, 5 and 10 mg/kg of OS reduced the incidence of selenite cataract by 20% and 60%, respectively, and prevented protein insolubilization as well. Conclusions: Aqueous extract of OS possesses potential anticataract activity against selenite-induced experimental cataractogenesis. The protective effect was supported by restoration of the antioxidant defense system and inhibition of protein insolubilization of rat lenses as well.

The Anti-inflammatory Effects of Curcuma longa and Berberis aristata in Endotoxin-Induced Uveitis in Rabbits

PURPOSE To investigate the anti-inflammatory effect of topical application of Curcuma longa (C. longa) and Berberis aristata (B. aristata) aqueous extracts on experimental uveitis in the rabbit. METHODS Anterior uveitis was induced in rabbits by intravitreal injection of lipopolysaccharide from Escherichia coli after pretreatment with C. longa and B. aristata aqueous extracts. Subsequently, the anti-inflammatory activity of C. longa and B. aristata was evaluated by grading the clinical signs and histopathologic changes and estimating the inflammatory cell count, protein, and TNF-alpha levels in the aqueous humor. RESULTS The anterior segment inflammation in the control group was significantly higher than in both the extract-treated groups, as observed by clinical and histopathologic grading. The inflammatory cell count in the control group was 30.75 +/- 7.33 x 10(5) cells/mL, whereas it was 2.39 +/- 0.59 x 10(5) (P < 0.001 vs. control) and 11.56 +/- 2.44 x 10(5) (P = 0.001 vs. control) cells/mL in the C. longa- and B. aristata-treated groups, respectively. The protein content of the aqueous humor was 18.14 +/- 4.98, 3.16 +/- 0.55 (P < 0.001 vs. control), and 8.24 +/- 1.42 (P < 0.01 vs. control) mg/mL in the control, C. longa-, and B. aristata-treated groups, respectively. The aqueous TNF-alpha level in the control group was 976.29 +/- 66.38 pg/mL and was 311.96 +/- 28.50 (P < 0.0001 vs. control) and 654.09 +/- 47.66 (P < 0.001vs. control) pg/mL in the C. longa- and B. aristata-treated groups, respectively. CONCLUSIONS Topical instillation of aqueous extracts of C. longa and B. aristata showed potent anti-inflammatory activity against endotoxin-induced uveitis in rabbits.

Green Tea Prevents Hyperglycemia-Induced Retinal Oxidative Stress and Inflammation in Streptozotocin-Induced Diabetic Rats

Purpose: Our objective was to investigate the effect of green tea (GT) on diabetes-induced retinal oxidative stress and proinflammatory parameters in rats. Methods: Treatment (200 mg/kg body weight) was carried out for a period of 16 weeks in streptozotocin-induced diabetic rats and was evaluated for hypoglycemic, antioxidant [reduced glutathione (GSH), superoxide dismutase (SOD) and catalase (CAT)] and anti-inflammatory [tumor necrosis factor (TNF) α, vascular endothelial growth factor (VEGF)] activity. Histological changes were evaluated by transmission electron microscopy. Results: Retinal GSH levels were 1.5-fold lower in diabetic rats as compared to normal rats (p < 0.05). However, in GT-treated rats, retinal GSH levels were restored close to those of the normal group. The antioxidant enzymes SOD and CAT showed a more than 2-fold decrease in activity in diabetic retinae as compared to normal retinae (p < 0.05). Both SOD and CAT enzymatic activities were restored close to normal in the GT-treated group. Expression of proinflammatory parameters (TNF-α and VEGF) was significantly inhibited in GT-treated retinae as compared to diabetic retinae (p < 0.05). Moreover, GT treatment prevented retinal capillary basement membrane thickness. Conclusion: The beneficial effects of GT suggest its potential role in the prevention and treatment of diabetic retinopathy in human subjects.

Hesperetin ameliorates hyperglycemia induced retinal vasculopathy via anti-angiogenic effects in experimental diabetic rats.

The purpose of the study was to evaluate vasculoprotective effects of Hesperetin (Hsp) in Streptozotocin induced diabetic rats. The study was carried out for a period of 24weeks and evaluated for angiogenic parameters (VEGF and PKC-β), retinal vascular leakage by fluorescein angiography and, vessel (arteriolar and venular) diameters and any morphological abnormality through fundus photographs. Apart from this, transmission electron microscopy (TEM) was done to determine capillary basement membrane (BM) thickness. The results of the present study showed a significant increase in the expression of VEGF and PKC-β in diabetic retinae as compared to normal retinae. On the other hand, Hsp-treated retinae showed marked inhibition in the expression of VEGF and PKC-β. In the present study, diabetic retinae showed increase vascular permeability and leakage as compared to normal retinae. However, Hsp-treated retinae have not shown any such vascular dysfunctions. Moreover, there was significant increase in vessel caliber recorded in diabetic retinae compared to normal retinae, on the contrary Hsp-treated retinae showed lesser dilated vessels. Further, TEM study showed thickened BM in diabetic group as compared to normal group. However, Hsp-treated retinae showed marked prevention in BM thickness. In conclusion, it can be sated that Hsp has potential vasoprotective effects and can be useful in preventing diabetes induced vasculopathy.

Comparative efficacy of pilocarpine, timolol and latanoprost in experimental models of glaucoma.

Intraocular pressure (IOP)-lowering effects of investigational antiglaucoma drugs often need comparison with existing drugs, but detailed data showing comparative efficacy of antiglaucoma drugs with different mechanism of action has not been reported so far. This study was designed to establish baseline information of the IOP-lowering effect of three currently used antiglaucoma drugs in three experimental models in rabbits, so that they act as a benchmark for the efficacy evaluation of the future experimental antiglaucoma drugs. The IOP-lowering effect of single-drop application of pilocarpine, timolol and latanoprost was studied in normotensive, water loading and steroid-induced models of glaucoma in rabbits. The noncontact tonometer was used for the first time to estimate IOP in rabbits. The peak IOP-lowering effect of pilocarpine, timolol and latanoprost in normotensive rabbit eye was 18.23%, 20% and 22.56%, respectively. In water-loading model, the maximum protection against the rise in IOP was shown by latanoprost (40.27%), followed by timolol (31.39%) and pilocarpine (28.91%). In steroid-pretreated rabbit eyes, peak IOP-lowering effects of pilocarpine, timolol and latanoprost were 25.65%, 34.21% and 35.06%, respectively. Therefore, the latanoprost was found to be most effective in all three models followed by timolol and pilocarpine. The results of this study can be used for future preclinical investigations for the assessment of IOP-lowering activity of potential antiglaucoma drugs.

Current trends in the pharmacotherapy of diabetic retinopathy

Diabetic retinopathy (DR) is one of the most debilitating disorders of microvasculature of the retina and one of the leading causes of vision loss among the working class worldwide. At present, intravitreal anti-inflammatory (corticosteroids) and anti-angiogenesis (anti-Vascular Endothelial Growth Factor) agents are being used as wide options for the pharmacotherapy of DR and diabetic macular edema (DME). Anti-inflammatory agents (Triamcinolone acetonide and other agents) have shown evidence-based clinical benefits in various randomized clinical trials for the treatment of DR and DME, and also shown improvement in best corrected visual acuity. However, direct intravitreal injections are associated with serious side-effects like cataract and elevation of Intra Ocular Pressure. Despite this, corticosteroid therapy has been effective for DR and DME, therefore current focus is on the development of novel intravitreal steroid delivery devices that release a small quantity over a prolonged period of time. In addition to corticosteroids, anti-angiogenic agents are found to be effective for the treatment of DR and DME. The most popular target of these agents is the subfamily of proteins known as VEGF, whose over-expression is believed to play a role in numerous diseases including DR and Age-related Macular Degeneration. Intravitreal bevacizumab (Avastin®) and Ranibizumab (Lucentis®) are gaining popularity as a clinical adjunct to panretinal photocoagulation in patients with proliferative DR. Moreover, Lucentis has been recently approved by the United States Food and Drug Administration for macular edema following retinal vein occlusion. Further, systemic agents (specially, hypoglycemic, hypolipidemic and anti-hypertensive agents) have shown beneficial results in reducing the progression of DR. In conclusion, it can be stated that for the present scenario systematic use of available pharmacotherapy as an adjunct to laser photocoagulation, which is gold standard therapy, can be a useful tool in the prevention of vision loss from DR and related disorders. This article summarizes the up-to-date developments in the pharmacotherapy of DR. Method- Literature search was done on online database, Pubmed, Google Scholar, clinitrials.gov and browsing through individual ophthalmology journals and leading pharmaceutical company websites.

Prevention and management of diabetic retinopathy in STZ diabetic rats by Tinospora cordifolia and its molecular mechanisms

We investigated the potential of Tinospora cordifolia (TC) in treatment of diabetic retinopathy in STZ-induced rats due to its antihyperglycemic, angiogenic, antiinflammatory and antioxidant effects. The diabetic rats, treated for 24 weeks with TC extract (250 mg/kg), were evaluated for lenticular and fundus changes. Biochemical parameters were estimated and histopathological studies performed. TC significantly reduced blood glucose and glycated hemoglobin in treated rats. It prevented cataract development in treated group. Angiogenic markers VEGF and PKC increased in diabetic retina, which reduced significantly with TC. Anti-inflammatory parameters TNF-α and IL-1β elevated in diabetic group unlike that in treated group. TC also provided defense against depletion of antioxidant enzymes- glutathione and catalase. Histopathological studies revealed thickening of basement membrane of the retinal and glomerular vasculature of diabetic rat, but no basement membrane widening was seen in treated animals. Destruction of pancreatic islet structure was observed in diabetic group, but not in treated. Thus, TC reduces blood glucose and inhibits overexpression of angiogenic and inflammatory mediators, which are distinct markers of diabetic retinopathy. It also prevents retinal oxidative stress and restores antioxidant enzyme levels. These data provide evidence for the safety and potential effect of TC in the management of experimental diabetic retinopathy.