Effect of taxifolin on cisplatin-associated oxidative optic nerve damage in rats.

AIM: To investigate the effect of taxifolin on cisplatin-induced oxidative and proinflammatory optic nerve damage in rats. METHODS: A total of 18 albino Wistar male rats were assigned into 3 groups, as follows; Group 1: Control group, Group 2: Only cisplatin administered group for 14 days (Cisplatin group), and Group 3: Taxifolin + cisplatin administered group for 14 days (CIS + TAX group). Serum malondialdehyde (MDA), total Glutathione (tGSH), Nuclear Factor-Kappa B (NF-ƘB), Total Oxidative Status (TOS) and Total Antioxidant Status (TAS) levels were collected from the left eyes of rats. Rats' right eyes were enucleated for histopathological evaluations of optic nerves. RESULTS: NF-ƘB, MDA and TOS levels were statistically significantly higher (p < 0.001) in cisplatin group when compared to other 2 groups, the tGSH and TAS levels of which were statistically significantly lower (p < 0.001). Regarding these parameters, in cisplatin group NF-ƘB, MDA and TOS levels were statistically significantly increased with cisplatin administration and giving taxifolin concomitantly with cisplatin prevented this elevation. On the other hand, tGSH and TAS levels were statistically significantly decreased with cisplatin administration and routine simultaneous application of taxifolin with cisplatin prevented this decrease. In histopathological findings, haemorrhage was observed in the perineum of the injured optic nerves in the cisplatin treated group. And also edoema and degeneration in nerve fascicles in damaged optic nerves were seen in the cisplatin group. In the taxifolin treated group histopathological examinations were close to normal appearance, except mild edoema in nerve fascicles. CONCLUSION: Cisplatin causes oxidative stress on the rat optic nerves, and these changes lead to significant histopathological damage. Taxifolin, which we used to prevent oxidative damage to the optic nerves caused by cisplatin, has been emphasized as a powerful antioxidant agent in many previous scientific investigations. Concomitant administration of taxifolin may prevent these adverse effects of cisplatin, as well as histopathological damage. Further studies are needed to fully determine the effects of cisplatin and taxifolin on the eye.

The effects of thiamine pyrophosphate on ethanol induced optic nerve damage.

BACKGROUND: We aimed to determine the protective effects of thiamine pyrophosphate on ethanol induced optic neuropathy in an experimental model. METHODS: The rats were assigned into 4 groups, with 6 rats in each group as follows: healthy controls (HC group), only ethanol administered group (EtOH group), ethanol + thiamine pyrophosphate (20 mg/kg) administered group (TEt-20 group), and only thiamine pyrophosphate (20 mg/kg) (TPG group) administered group. To the rats in TEt-20 and TPG groups, 20 mg/kg thiamine pyrophosphate was administered via intraperitoneal route. To the rats in HC and EtOH groups, the same volume (0.5 ml) of distilled water as solvent was applied in the same manner. To the rats in TEt-20 and EtOH groups, one hour after application of thiamine pyrophosphate or distilled water, 32% ethanol with a dose of 5 g/kg was administered via oral gavage. This procedure was repeated once a day for 6 weeks. From the blood samples and tissues obtained from the rats, Malondialdehyde (MDA), reduced glutathione (GSH), interleukin 1 beta (IL-1ß) and tumor necrosis factor alpha (TNF-α) levels were studied. Histopathological evaluations were performed to the optic nerve tissue. RESULTS: Serum and tissue IL-1ß, TNF-α and MDA levels were the highest in EtOH group which were significantly lower in thiamine pyrophosphate administered group (TEt-20 group) (p: 0.001). Serum and tissue reduced GSH levels were the lowest in EtOH group which were also significantly higher in TEt-20 group (p:0.001). In histopathological evaluations, in EtOH group there was obvious destruction and edema with hemorrhage and dilated blood vessels which were not present in any other groups. CONCLUSIONS: There was an apparent destruction in ethanol administered group in histopathological analyses with an augmented level of oxidative stress markers and all those alterations were prevented with concomitant thiamine pyrophosphate administration. These protective effects of thiamine pyrophosphate are extremely important in chronic ethanol consumption. Clinical studies are warranted to define the exact role of thiamine pyrophosphate in prevention of ethanol induced optic neuropathy.

Effect of taxifolin on methanol-induced oxidative and inflammatory optic nerve damage in rats.

Purpose: Oxidative stress and inflammation have been demonstrated in the pathogenesis of methanol toxicity. Taxifolin has antioxidant and anti-inflammatory properties. In this study, we examined the protective effect of taxifolin against methanol-induced optic nerve toxicity. Materials and methods: Animals were divided into four groups (n = 6): healthy control group (HG), methotrexate (MTX) treated group, methotrexate + methanol treated group (MTX + M), and methotrexate + methanol + taxifolin treated group (MTX + M+T). MTX was administered to all groups except HG group 3 mg/kg via oral gavage for 7 d. After that 20% methanol was orally administered to the MTX + M and MTX + M+T group at a dose of 3 g/kg. After 4 h, taxifolin was orally administered to MTX + M+T group 50 mg/kg. Animals were sacrificed by high-dose thiopental anaesthesia, 8 h after taxifolin administration and biochemical studies were performed. Results: Malondialdehyde (MDA), total oxidant system, nuclear factor kappa B (NF-κB), and tumour necrosis factor-alpha levels were significantly higher in the optic nerve of MTX and MTX + M groups compared to HG group. Otherwise, total glutathione (tGSH) and total antioxidant system levels decreased in MTX and MTX + M groups according to the HG group. MDA, total oxidant system, NF-κB, and tumour necrosis factor-alpha levels were decreased in the MTX + M+T group and tGSH, and total antioxidant system levels increased in the MTX + M+T group according to the MTX + M group. Conclusions: These results indicate that taxifolin prevents oxidative and inflammatory optic nerve damage due to methanol exposure.

Effect of taxifolin on development of retinopathy in alloxan-induced diabetic rats.

Purpose: Diabetic retinopathy (DR) is one of the leading causes of blindness. In DR patients, antioxidant defence is disrupted, and production of reactive oxygen species and pro-inflammatory cytokines such as interleukin 1ß (IL-1ß) and tumour necrosis factor alpha (TNF-α) increases. Taxifolin has been reported to suppress reactive oxygen species, IL-1ß and TNF-α production. The aim of this study is to biochemically and histopathologically examine the protective effect of taxifolin against DR damage induced by alloxan. Materials and methods: Alloxan received rats with a blood glucose level of ≥250 mg/dL were divided into taxifolin-treated (TAX) (n = 6), diabetic control (DC) (n = 6) groups. There were rats received only saline in non-diabetic control (NC) group (n = 6). Taxifolin (50 mg/kg) was orally administered to the TAX group rats. DC and NC rats received the same volume of saline as a solvent. This procedure was repeated once a day for 3 months. At the end of this period, animals were killed by high dose thiopental sodium anaesthesia. Histopathological examinations were then performed on excised rat eyes. Malondialdehyde (MDA), total glutathione (tGSH), IL-1ß and TNF-α levels were measured in obtained blood samples. Results: MDA, IL-1ß and TNF-α levels were significantly increased in blood samples of DC group rats with hyperglycemia induced by alloxan compared with NC group (p < 0.0001), and decreased in the TAX group compared with the DC group (p < 0.0001). The levels of tGSH were significantly decreased in blood samples of DC group rats compared with NC group (p < 0.0001), and increased in the TAX group compared with the DC group (p < 0.0001). Histopathologically, retinal ganglion cells of the TAX group had a slightly dilated and congested blood vessel, and severe damage was inflicted to the retinal ganglion cell layer of the DC group. Conclusions: Experimental results suggest that taxifolin may be beneficial in the treatment of DR.

The effects of lutein on cisplatin-induced retinal injury: an experimental study.

AIM: Lutein is one of the most common carotenoids defined in human plasma as having potent anti-oxidant effects. We aimed to determine the biochemical and histopathological effects of lutein on cisplatin-induced oxidative retinal injury in rats. MATERIALS AND METHODS: Twenty-four rats were equally divided into four groups as healthy controls (HC group), only cisplatin (5 mg/kg) administered group (CIS group), Lutein (0.5 mg/kg) + cisplatin (5 mg/kg) administered group (LC group), and only Lutein (0.5 mg/kg) (LUT group) administered group. From the blood samples obtained, serum malondialdehyde (MDA), total glutathione (tGSH), interleukin 1 beta (IL-1ß), and tumor necrosis factor alpha (TNF-α) levels were investigated. In histopathological analyses, the total retinal thickness, retinal pigment epithelium (RPE), photoreceptor layer (PL), outer nuclear layer (ONL), outer plexiform layer (OPL), inner nuclear layer (INL), inner plexiform layer (IPL), and ganglion cell layer (GCL) were evaluated. RESULTS: MDA, IL-1ß, and TNF-a levels were statistically significantly higher (p < 0.001) in CIS group compared with other three groups while tGSH levels were statistically significantly lower (p < 0.001). In subgroup analyses, there was no any statistically significant difference regarding all four parameters analyzed between HC, LC, and LUT groups. In histopathological analyses, cisplatin-induced retinal damage included atrophy and disorganization on outer segment, degeneration and detachment of RPE and PL from choroid, degeneration and edema of INL and IPL, total degeneration of GCL; while cisplatin-induced retinal damage was determined to be significantly prevented with 0.5 mg lutein treatment on histopathological evaluations. CONCLUSIONS: Lutein co-administration was highly effective in prevention of cisplatin-induced retinal damage due to the anti-oxidant and anti-inflammatory effects of lutein.

Effect of thiamine pyrophosphate on retinopathy induced by hyperglycemia in rats: A biochemical and pathological evaluation.

PURPOSE: Information is lacking on the protective effects of thiamine pyrophosphate (TPP) against hyperglycemia-induced retinopathy in rats. This study investigated the biochemical and histopathological aspects of the effect of TPP on hyperglycemia-induced retinopathy induced by alloxan in rats. MATERIALS AND METHODS: The rats were separated into a diabetic TPP-administered group (DTPG), a diabetes control group (DCG) and a healthy group (HG). While the DTPG was given TPP, the DCG and HG were administered distilled water as a solvent at the same concentrations. This procedure was repeated daily for 3 months. At the end of this period, all of the rats were euthanized under thiopental sodium anesthesia, and biochemical and histopathological analyses of the ocular retinal tissues were performed. The results of the DTPG were compared with those of the DCG and HG. RESULTS: TPP prevented hyperglycemia by increasing the amount of malondialdehyde and decreasing endogen antioxidants, including total glutathione, glutathione reductase, glutathione S-transferase and superoxide dismutase. In addition, the amounts of the DNA oxidation product 8-hydroxyguanine were significantly lower in the retinas of the DTPG compared to the DCG. In the retinas of the DCG, there was a marked increase in vascular structures and congestion, in addition to edema. In contrast, little vascularization and edema were observed in the DTPG, and there was no congestion. The results suggest that TPP significantly reduced the degree of hyperglycemia-induced retinopathy. CONCLUSIONS: The results of this study indicate that TPP may be useful for prophylaxis against diabetic retinopathy.

The effect of thiamine pyrophosphate on ethambutol-induced ocular toxicity.

CONTEXT: Ethambutol-induced retinal oxidative damage in patients with tuberculosis is still not being adequately treated. The protective effect of thiamine pyrophosphate against oxidative damage in some tissues has been reported, but no information on the protective effects of thiamine pyrophosphate against ethambutol-induced oxidative retinal damage has been found in the medical literature. OBJECTIVE: The objective is to investigate whether thiamine pyrophosphate has a protective effect against oxidative retinal damage in rats induced by ethambutol. MATERIALS AND METHODS: Experimental animals divided into four groups (n = 10): the healthy group (HG), the ethambutol control group (EMB), thiamine + ethambutol group (Thi-EMB) and thiamine pyrophosphate + ethambutol group (TPP-EMB). The rats in the TPP-EMB and Thi-EMB groups were administered thiamine pyrophosphate and thiamine, respectively, at doses of 20 mg/kg intraperitoneally. Distilled water was administered intraperitoneally to the HG and the EMB groups as a solvent in the same volumes. One hour after drug injection, 30 mg/kg ethambutol was administered via an oral gavage to the TPP-EMB, Thi-EMB and EMB groups. This procedure was repeated once a day for 90 days. At the end of this period, all rats were euthanized under high-dose thiopental sodium anesthesia, and biochemical and histopathological investigations of the retinal tissue were performed. RESULTS: Malondialdehyde (MDA) and DNA damage product 8-hydroxyguanine levels were significantly lower in the retinal tissue of TPP-EMB and HG groups compared to those of the Thi-EMB and EMB groups, and total glutathione (tGSH) was also found to be higher. In addition, severe retinal tissue vascularization, edema and loss of ganglion cells were observed in the Thi-EMB and EMB groups, whereas histopathological findings for the TPP-EMB group were observed to be close to normal. DISCUSSION AND CONCLUSION: These findings suggest that thiamine pyrophosphate protects retinal tissues from ethambutol-induced oxidative damage, and thiamine does not. This positive effect of thiamine pyrophosphate may be useful in the prevention of ocular toxicity that occurs during ethambutol use.