Abstract: TH-PO425

Combination of Cholecalciferol and Omega-3 Fatty Acid Increases 1, 25 Dihydroxy Vitamin D Level by Inhibiting 24-Hydroxylase of Kidney and Liver in 5/6 Nephrectomized Rats

Session Information

Category: Nutrition, Inflammation, and Metabolism

  • 1401 Nutrition, Inflammation, Metabolism

Authors

  • Lee, Su mi, Dong-A University, Busan, Not Applicable, Korea (the Republic of)
  • Choi, Hyuck jae, Dong-A University, Busan, Not Applicable, Korea (the Republic of)
  • Kim, Kitae, BHS Han Seo Hospital, Busan, Korea (the Republic of)
  • Son, Sung Hyun, BHS Han Seo Hospital, Busan, Korea (the Republic of)
  • Son, Young ki, Dong-A University, Busan, Not Applicable, Korea (the Republic of)
  • Kim, Seong Eun, Dong-A University, Busan, Not Applicable, Korea (the Republic of)
  • An, Won Suk, Dong-A University, Busan, Not Applicable, Korea (the Republic of)
Background

The 1α-hydroxylase (CYP27b1) and 24-hydroxylase (CYP24) in renal proximal tubules primarily involve vitamin D metabolsim. Increased activity of CYP24 contributes vitamin D metabolism in chronic kidney disease (CKD). Recent reports showed that CYP27b1 was strongly expressed in monocytes developing into hepatic macrophages and omega-3 fatty acid (FA) elevated 1, 25-dihydroxy vitamin D level in dialysis patients with scanty renal function. In this study, we evaluated whether the effect of omega-3 FA and cholecalciferol on vitamin D metabolism are related with the activity of CYP27b1 and CYP24 in liver and kidney of 5/6 nephrectomy (Nx) rat model.

Methods

Male Sprague Dawley rats were divided into five groups and treated for 6 weeks: sham control (0.9% saline), 5/6 Nx control (0.9% saline), 5/6 Nx treated with vitamin D (cholecalciferol 3000 IU/kg/week by gastric gavage), 5/6 Nx treated with omega-3 FA (300 mg/kg/day by gastric gavage), 5/6 Nx treated with vitamin D and omega-3 FA. CYP27b1 and CYP24 in remnant kidney and liver were measured by western blot analysis.

Results

Serum BUN and creatinine were the lowest in 5/6 Nx group treated with omega-3 FA and vitamin D among other 5/6 Nx groups. The levels of serum 1, 25-dihydroxy vitamin D and 25-hydroxy vitamin D were the highest in 5/6 Nx group treated with omega-3 FA and vitamin D among other 5/6 Nx groups. The expression of CYP24 was significantly increased in remnant kidney and liver of 5/6 Nx control compared to sham control. Increased expression of CYP24 in remnant kidney and liver of 5/6 Nx control was significantly decreased by combined treatment with omega-3 FA and cholecalciferol. The expression of CYP27b1 was significantly increased in remnant kidney and significantly decreased in liver of 5/6 Nx control compared to sham control. The increased expression of CYP27b1 in remnant kidney and decreased expression of CYP27b1 in liver of 5/6 Nx control was nearly normalized by combined treatment with omega-3 FA and vitamin D.

Conclusion

Combined treatment with omega-3 FA and cholecalciferol definitely increases 1, 25-dihydroxy vitamin D level by inhibiting expression of 24-hydroxylase in remnant kidney and liver and activating expression of 1 α-hydroxylase in liver of 5/6 Nx rats.