Effects of chronic vitamin C treatment on responsiveness to an environmental stressor.
Degree GrantorUniversity of Canterbury
Degree NameMaster of Science
To investigate if the chronic administration of ascorbic acid (vitamin C) would exert anxiolytic effects when rats are exposed to a stressor in the form of bright light, 40 female and 40 male PVG /c hooded rats were individually treated with approximately 61, 114, or 160 mg/kg of ascorbic acid in their drinking water. Following treatment, each rat was exposed to a 5-min trial in the open-field (OF), the elevated plus-maze (EPM), and the light-dark box (LDB) either with or without the presence of a bright light stressor. A number of dose-related anxiolytic effects were observed that appeared to depend on the measure of anxiety used. This was evident with higher frequencies of walking in the OF for rats treated with 114 and 160 mg/kg of ascorbic acid. Furthermore, 114 mg/kg of ascorbic acid led to rats spending more time in the light compartment of the LDB, but this was true only for rats in the low stress condition. Interestingly, 61 mg/kg and 114 mg/kg produced a sex-related anxiogenic effect for rats tested in the EPM, with 61 mg/kg leading to a decrease in open arm entries for females, and 114 mg/kg leading to an increase in open arm entries for both sexes combined. Furthermore, male rats in the high stress condition made a higher percentage of entries into the open arms and fewer entries into the closed arms of the EPM. Male rats treated with 114 mg/kg also had lighter adrenal gland weights compared to controls. These results suggest that a dose of 1.45 g/day of vitamin C may have the potential of reducing anxiety in humans under certain conditions. However, vitamin C may not be as effective under high stress conditions but rather may be useful for anxiety experienced when low levels of stress are present.