Background: Vitiligo is a progressive depigmenting disorder characterized by the loss of functional melanocytes from the epidermis. The etiopathogenesis of vitiligo is still unclear. Vitamin D has both stimulatory and protective effects on melanocytes and acts through its nuclear vitamin D receptor (VDR) on target cells. Aim: The aim of this study was to investigate the association between VDR gene polymorphisms and susceptibility to vitiligo. Methods: 98 patients with vitiligo and 216 age- and sex-matched controls recruited from dermatology outpatients attending the same department were included in the study. Genomic DNA was extracted from peripheral blood leukocytes using a DNA isolation kit. The VDR polymorphisms of BsmI, ApaI, TaqI, FokI and Cdx2 were investigated by rapid capillary PCR with melting curve analysis. Differences in genotype distributions and allele frequencies in vitiligo cases versus controls were compared for statistical significance using χ² test. Results: Subjects with TaqI polymorphism had a 2.23-fold increased risk of developing vitiligo. Furthermore, a haplotype analysis showed that BsmI/ApaI/TaqI/FokI/Cdx2 GCCCG wassignificantly overrepresented in the vitiligo patients in comparison with controls (p = 0.031). Conclusion: This study showed that VDR TaqI gene polymorphism and the haplotype BsmI/ApaI/ TaqI/FokI/Cdx2 GCCCG may be considered as novel risk factors in vitiligo.

High-fat diet (HFD) and low-dose streptozotocin (STZ)-treated rats provide useful animal model for type II diabetes mellitus. Oxidative stress and advanced glycation end products (AGEs) play a role in the development of diabetic complications. Carnosine (CAR) has anti-oxidant and anti-glycating properties. We investigated the effects of CAR on oxidation and glycation products in HFD+STZ rats. Rats were fed with HFD (60% of total calories from fat) for 4 weeks, and then a single dose of STZ (40 mg/kg; i.p.) was applied. Rats with blood glucose levels above 200 mg/dl were fed with HFD until the end of the 12th week. CAR (250 mg/kg body weight; i.p.; five times a week) was administered to the rats for the last four weeks. CAR significantly decreased serum triglyceride (TG) (57.7%), cholesterol (35.6%) levels and hepatic marker enzyme activities of HFD+STZ rats. It significantly reduced serum reactive oxygen species (ROS) (23.7%), AGEs (13.4%) and advanced oxidized protein products (AOPP) (35.9%) and hepatic TG (59%), ROS (26%), malondialdehyde (MDA) (11.5%), protein carbonyl (PC) (19.2%) and AGE (20.2%) levels. Liver steatosis and hepatocyte ballooning were also significantly reduced. However, CAR treatment did not alter serum glucose and blood glycated haemoglobin and hepatic anti-oxidant enzyme activities/mRNA expressions in HFD+STZ rats. Our results indicate that CAR decreased accumulation of oxidation and glycation products, such as MDA, AGE, AOPP and PC in the serum and liver and ameliorated hepatic dysfunction in HFD+STZ rats. This effect may be related to its anti-oxidative, anti-glycating, and anti-lipogenic potential.

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Oxidative stress plays an important role in aging. Effects of several antioxidants on age-related oxidative stress have been investigated. Carnosine (CAR) and betaine have antioxidant actions. The combination of CAR with vitamin E(CAR+E) increases its antioxidant efficiency. We investigated the effects of CAR+E and betaine treatments on oxidative and antioxidative status in liver, heart and brain tissues of aged rats. Experiments were carried out on young (5 months)and aged (22 months) male Wistar rats. Aged rats were given CAR (250 mg/kg; i.p.; 5 days per week) and vitamin E (200mg/kg; i.m.; twice per week) or betaine (1% w/v) for two months. Malondialdehyde (MDA) and diene conjugate (DC)levels and antioxidants were measured. MDA and DC levels were higher in tissues of aged rats than young rats. Glutathione(GSH) levels decreased in liver, but not heart and brain. There were no changes in vitamin E and vitamin C levels and superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glutathione transferase (GST) activities in tissues of aged rats. CAR+E treatment was observed to decrease MDA and DC levels in tissues of aged rats. However, betaine decreased only hepatic MDA and DC levels. Both CAR+E and betaine increased hepatic GSH and vitamin E levels, but these treatments did not affect antioxidant enzyme activities. These results suggest that CAR+E treatment seems to be useful to decrease oxidative stress in liver, heart and brain tissues, but betaine is only effective in liver tissue of aged rats.

The present results suggest that OLE seems to be useful for decreasing oxidative stress in examined tissues by acting as an anti-oxidant itself without affecting the anti-oxidant system.