Effects of vitamin C on function of different subtypes of glycine receptors / 中国药理学通报

Aim To investigate the effects of vitamin C (VC) on glycine receptor (GlyR) subtypes. Methods The HEK-293T cells were transfected with plasmids expressing different subtypes of GlyR. Then the cells were incubated with different concentrations of VC. The EC2 concentration of glycine-activated currents were recorded by patch clamp before or after incubation of VC. The effects of the sodium-dependent vitamin C transporter-type 2 ( SVCT2 ) inhibitor sulfinpyrazone on VC induced potentiation of GlyRs were also examined. The method of amino acid point mutation was used to explore the critical site for interaction between VC and GlyR. Results Ascorbic acid dose-dependently increased the currents mediated by GlyRal and GlyRa3, with a3 subunits being the most sensitive to VC. Ascorbic acid had no significant effect on the current mediated by the al subunit of GlyRs. Cell incubation with sulfinpyrazone did not affect the VC induced potentiation of GlyR function. The mutation of Ser296 at the third transmembrane domain of a3 GlyR significantly reduced the potentiation of VC on GlyR func-tion. Conclusions Ascorbic acid can enhance the function of GlyR al and a3 subunits, but not a2 sub- unit. Such enhancement is not likely to be an effect oc- curing inside cells. The Ser296 of GlyR plays a key role in the VC induced enhancement of GlyR function.

Vitamin C is taken up by human T cells via sodium-dependent vitamin C transporter 2 (SVCT2) and exerts inhibitory effects on the activation of these cells in vitro / 대한해부학회지

Vitamin C is an essential micronutrient that affects immune responses. T cells are one of the main players in acquired immunity and have been reported to be influenced by in vivo vitamin C supplementation. Yet, the way by which T cells uptake vitamin C and what direct effects vitamin C exerts on the cells are not known. To elucidate, we isolated human peripheral blood T cells and analyzed the expression of sodium-dependent vitamin C transporters (SVCT). T cells were activated in vitro in the absence or presence of vitamin C, before or after activation. As results, human T cells expressed SVCT2, but not SVCT1, and the expression level increased following activation. Vitamin C added in the culture media generally did not affect T-cell behaviors following activation, such as proliferation, apoptosis, expression of CD25 and CD69, and interleukin 2 secretion, regardless whether it was added before or after activation. However, exceptionally, high concentration vitamin C, when it was added before activation, but not after activation, did exert toxic effects on cell activation with respect to the above-mentioned parameters. In conclusion, we showed the expression of SVCT2 in human T cells for the first time. Vitamin C exerted toxic effects, at least in vitro, when the concentration was high and when it was given before activation. These toxic effects are not thought to be via anti-oxidant effects of vitamin C.

Expression of Sodium-dependent Vitamin C Transporter in Rat Dermal Fibroblasts / 대한피부과학회지

BACKGROUND: Vitamin C is one of the most typical types of water-soluble antioxidants that exerts a variety of biochemical actions on a living body. It acts on the skin by promoting wound healing, preventing skin aging, and inhibiting skin cancer. It also works not only as an antioxidant, protecting the skin from UV radiation but also as an anti-inflammatory agent. It reinforces immunity as well. Recent studies proved the whitening effect of vitamin C, and it can be instilled into the skin by way of iontophoresis. When vitamin C is transported in vivo it is either by simple diffusion or by a transporter. Only a small amount is transported by simple diffusion and the transporter is responsible for most of the vitamin C transport. This study was designed to evaluate the presence of sodium dependent vitamin C transporter (SVCT) and to identify which factor controls its expression. METHODS: Expressions of SVCT 1 and 2 mRNA in the rats' dermal fibroblast were measured by RT-PCR at 3, 6, 12, 24, and 48 hours. RESULTS: The results were used to compare the expression levels of SVCT-1 and SVCT-2 when treated with TGF-beta, estradiol, and retinoic acid. Estradiol showed the highest level of expression of SVCT-1 and SVCT-2. The next highest was TGF-beta, followed by retinoic acid. CONCLUSION: SVCT-1 and SVCT-2 were found to be expressed in the rats' dermal fibroblasts, and exposure to estradiol, TGF-beta and retinoic acid resulted in a higher degree of their expression.