Griffiths A P, Fairney A
Department of Chemical Pathology, St. Marys Hospital Medical School, Paddington, London.
Eur J Appl Physiol Occup Physiol. 1989;59(1-2):68-72. doi: 10.1007/BF02396582.
The hypothesis that sunlight may induce the enzymes involved in the vitamin D pathway has been tested by comparing the ability to synthesize vitamin D3 and its 25 hydroxy metabolite (25-OHD) in 2 groups of male volunteers resident at the British Antarctic base at Rothera Point (67 degrees 34'S.). One group endured the UV depleted winter and the other group received regular phototherapy throughout the winter. Both groups then received a course of 14 days phototherapy in October (Southern Hemisphere spring). The group receiving regular phototherapy had a trend towards a higher level of serum 25-OHD, and the October phototherapy course produced a further small increase in serum 25-OHD values. In the previously non irradiated group the October phototherapy produced a much larger increase in serum 25-OHD so that they attained the previously higher values of the pre-iradiated group. There was a negative correlation between the pre October phototherapy serum concentration of 25-OHD and the subsequent increment (r-0.78, p less than 0.01) but no relationship between the serum 25-OHD and D3 after phototherapy. These results provide evidence against the existence of enzyme induction of vitamin D 25 hydroxylase by light.
通过比较两组居住在罗瑟拉角（南纬67度34分）英国南极基地的男性志愿者合成维生素D3及其25-羟基代谢物（25-OHD）的能力，对阳光可能诱导维生素D途径中相关酶这一假设进行了检验。一组经历了紫外线匮乏的冬季，另一组在整个冬季接受定期光疗。然后两组在10月（南半球春季）都接受了为期14天的光疗疗程。接受定期光疗的组血清25-OHD水平有升高趋势，10月的光疗疗程使血清25-OHD值进一步小幅升高。在之前未接受照射的组中，10月的光疗使血清25-OHD有更大幅度的升高，以至于他们达到了之前接受照射组的较高值。10月光疗前血清25-OHD浓度与随后的增量之间呈负相关（r = -0.78，p < 0.01），但光疗后血清25-OHD与D3之间无关联。这些结果提供了证据，反驳了光照诱导维生素D 25-羟化酶的存在。
