Effects of ultraviolet intensity changes on the levels of serum alkaline phosphatase and 25-hydroxyvitamin D in rats

Objective To study the relationship of indoor sunlight and vitamin D metabolism through studying the changes of serum bone alkaline phosphatase(BALP) and 25-hydroxyvitamin D[25(OH)D] when ultraviolet(UV) intensity changes.Methods Total 36(21 days) Wistar rats were randomly divided into three groups : direct sunlight exposure,indoor sunlight exposure,and no sunlight exposure.All rats are fed with vitamin D deficient diet.Measure the UV intensity everyday.Sixty days later,kill the rats and measure the level of serum BALP and 25(OH)D for comparison.Results(1)The UV intensity changed greatly when sunlight condition changed.After breaking through double-ply glass,about 85.1% UV in the sunlight were weakened.(2)Mean serum BALP of direct sunlight group,indirect sunlight group and away-from-sunlight group were(37.79±3.11)U/L,(36.44±2.95)U/L and(51.82±7.62)U/L respectively.Direct sunlight exposure group and indirect sunlight exposure group showed significant differences against no-sunlight group(P0.05).Direct group and indirect group showed no significant differences(P0.05).(3) Mean serum 25(OH)D of the three groups were(13.06±4.07)nmol/L,(11.14±5.49)nmol/L and(4.91±4.66)nmol/L respectively.Direct-sunlight group and indirect-sunlight group showed significant differences against no-sunlight group(P0.05).However,direct group and indirect group showed no significant differences(P0.05).Conclusion Indoor sunlight exposure can also prevent vitamin D deficiency and rickets as direct sunlight exposure if one accepts indoor sunlight long enough.