Plasma alpha-tochopherol determined by HPLC in dogs at different stages of chronic kidney disease: a retrospective study

Supplementation of vitamin E as an addition to a commercial renal diet does not prolong survival of cats with chronic kidney disease

BACKGROUND

The aim of this double-blind, placebo-controlled study was to investigate the effect of vitamin E supplementation as an addition to a commercial renal diet on survival time of cats with different stages of chronic kidney disease (CKD). In addition, we were interested whether vitamin E supplementation affects selected oxidative stress and clinical parameters. Thirty-four cats with CKD and 38 healthy cats were included in the study. Cats with CKD were classified according to the IRIS Guidelines; seven in IRIS stage 1, 15 in IRIS stage 2, five in IRIS stage 3 and seven in IRIS stage 4. Cats with CKD were treated according to IRIS Guidelines. Cats with CKD were randomly assigned to receive vitamin E (100 IU/cat/day) or placebo (mineral oil) for 24 weeks in addition to standard therapy. Plasma malondialdehyde (MDA) and protein carbonyl (PC) concentrations, DNA damage of peripheral lymphocytes and plasma vitamin E concentrations were measured at baseline and four, eight, 16 and 24 weeks thereafter. Routine laboratory analyses and assessment of clinical signs were performed at each visit.

RESULTS

Vitamin E supplementation had no effect on the survival time and did not reduce the severity of clinical signs. Before vitamin E supplementation, no significant differences in vitamin E, MDA and PC concentrations were found between healthy and CKD cats. However, plasma MDA concentration was statistically significantly higher (p = 0.043) in cats with early CKD (IRIS stages 1 and 2) than in cats with advanced CKD (IRIS stages 3 and 4). Additionally, DNA damage was statistically significantly higher in healthy cats (p ≤ 0.001) than in CKD cats. Plasma vitamin E concentrations increased statistically significantly in the vitamin E group compared to the placebo group four (p = 0.013) and eight (p = 0.017) weeks after the start of vitamin E supplementation. During the study and after 24 weeks of vitamin E supplementation, plasma MDA and PC concentrations and DNA damage remained similar to pre-supplementation levels in both the placebo and vitamin E groups.

CONCLUSIONS

Vitamin E supplementation as an addition to standard therapy does not prolong survival in feline CKD.

Oxidative stress and the antioxidant system in salivary glands of rats with experimental chronic kidney disease

OBJECTIVE

This study aims to analyze the presence of oxidative stress and activity of the antioxidant system in the parotid and submandibular salivary glands of rats with Chronic Kidney Disease (CKD).

DESIGN

Sixteen male wistar rats were divided into two groups (n = 8, each): control rats and rats with CKD. CKD was induced by 5/6 nephrectomy. Blood urea nitrogen and serum creatinine clearance were quantified. Malondialdehyde, superoxide dismutase, glutathione peroxidase, glutathione reductase, catalase, total antioxidant status, ascorbic acid, α-tocopherol, superoxide anion, and hydrogen peroxide concentrations were assessed.

RESULTS

In CKD rats, blood urea nitrogen, serum creatinine, and proteinuria concentrations were increased, while creatinine clearance was reduced. In the submandibular gland, superoxide anion concentration was increased significantly (p < 0.05). Hydrogen peroxide and superoxide anion concentrations were reduced in the parotid gland. CKD rats presented increased malondialdehyde concentration, total antioxidant status, superoxide dismutase, and glutathione reductase activities only in the parotid gland (p < 0.05).

CONCLUSION

Oxidative stress and changes in the antioxidant system were found in the parotid and submandibular salivary glands in an experimental model of CKD induced by 5/6 nephrectomy.

CHANGES IN ANTIOXIDANT CAPACITY OF KOALAS (PHASCOLARCTOS CINEREUS) BASED ON HEALTH STATUS AND MEASUREMENT OF THE ANTIOXIDANT ASCORBATE IN EUCALYPT LEAVES

Antioxidants have a crucial role in protecting the body from oxidative stress, which would otherwise result in cellular damage and possibly predispose animals to disease. The antioxidant capacity of koalas (Phascolarctos cinereus) and its association with health or disease status is currently unknown. Ascorbate, a dietary antioxidant, has previously been identified in a few eucalypt species eaten by koalas. This study aimed to determine 1) differences between the antioxidant capacity of healthy and diseased koalas, and 2) concentration of the antioxidant ascorbate in Eucalyptus spp. leaves eaten by koalas. To determine differences in antioxidant capacity of koalas, plasma samples from clinically healthy koalas in Kangaroo Island, South Australia (SA) (n = 23), euthanized koalas with oxalate nephrosis from Mount Lofty Ranges, SA (n = 11), and euthanized koalas with chlamydiosis from Moggill, Queensland (n = 11) were analyzed for the three antioxidants α-tocopherol, ascorbate, and retinol and for two measures of antioxidant capacity, ferric reducing ability of plasma (FRAP), and trolox equivalent antioxidant capacity (TEAC). The thiobarbituric acid reactive substance (TBARS) measured formation of oxidants, and an oxidative stress index (OSI) was calculated by TBARS/(TEAC + FRAP). Ascorbate concentration was measured in dietary eucalypt leaves from Mount Lofty Ranges and Moggill. Results showed that in diseased Mount Lofty Ranges and Moggill koalas, plasma α-tocopherol concentrations were significantly lower, and ascorbate, TBARS, and OSI was significantly higher compared with clinically healthy koalas from Kangaroo Island. Ascorbate was high in eucalypt leaves, particularly young leaves from the Mount Lofty Ranges. This study showed that disease was associated with some measures of poor antioxidant capacity in koalas and also found that ascorbate is high in the dietary eucalypts of koalas.