Effect of different doses of paricalcitol on the expression of vitamin D receptors in mice liver tissue

Introduction. The high doses of vitamin D lead to undesirable side effects such as hypercalcemia. Paricalcitol (PC) is a biologically active synthetic substance that selectively binds to intracellular vitamin D receptors and does not cause hypercalcemia. The effect of this drug on metabolic pathways, parathyroid hormone secretion, asthma and liver fibrosis is known, which confirms its wide clinical potential. However, only a few publications have been devoted to the effect of different doses of PC on the state of liver cells, which are the most important site of its metabolism.

Aim. To study the effect of intraperitoneal administration of different doses of paricalcitol on the degree of activation of vitamin D receptors and to conduct a morphological assessment of the state of liver tissue in mice.

Materials and methods. The experiment involved male BALB/c mice without external pathological signs, weighing 16– 18 g and aged 4–6 weeks, which were divided into 4 groups. Healthy animals of the control group received 100 µl of saline solution intraperitoneally. Animals from the groups 2, 3, and 4 received PC intraperitoneally at the doses of 25 ng/mouse, 50 ng/mouse, and 100 ng/mouse, respectively on the days 1, 2, 4, and 7. Sacrifice was performed on the 10th or 21st day after the onset of the experiment. Histological assessment of liver tissues of animals removed from the experiment on day 10 was performed according to generally accepted histological methods. Immunohistochemical examination was performed automatically in a Bond™- maX immunohistostainer (Leica, Germany). Primary rabbit polyclonal antibodies to the vitamin D receptor were used.

Results and discussion. The introduction of PC in different doses consistently increased the total number of liver cells expressing VDR, mainly due to immune cells. An increase in the percentage of intensely stained non-parenchymatous cells (++++ and +++) was observed by the 21st day of the experiment and amounted to 56.0 % in subgroup 2.2, 3.2 – 46.6 % and 4.2 – 48.0 %, in the control group this value was 39.5 %. The liver tissue structure closest to the control was observed in animals that received PC at a dose of 25 ng/mouse. In the groups of mice where the animals received PC at doses of 50 ng/mouse and 100 ng/mouse, certain morphological changes were noted, mainly of a dystrophic and discirculatory nature, which reflected the toxic effect of these doses of PC on the metabolism of hepatocytes.

Conclusion. The administration of different doses of PC leads to an increase in VDR expression mainly in non-parenchymatous liver cells that perform immune functions. VDR expression in hepatocytes of all subgroups increased by the 10th day of observation and decreased by the 21st day, which was probably due to the death of these cells. Microscopic examination showed that the use of PC in healthy mice leads to certain dose-dependent changes in the liver, the least toxic dose of PC is 25 ng/mouse.

1. Wimalawansa S. J. Physiological Basis for Using Vitamin D to Improve Health. Biomedicines. 2023;11(6):1542. DOI: 10.3390/biomedicines11061542.

2. Tan C.-H. N., Yeo B., Vasanwala R. F., Sultana R., Lee J. H., Chan D. Vitamin D Deficiency and Clinical Outcomes in Critically Ill Pediatric Patients: A Systematic Review and Meta-Analysis. Journal of the Endocrine Society. 2025;9(5):bvaf053. DOI: 10.1210/jendso/bvaf053.

3. Chen X., Zhou M., Yan H., Chen J., Wang Y., Mo X. Association of serum total 25-hydroxy-vitamin D concentration and risk of all-cause, cardiovascular and malignancies-specific mortality in patients with hyperlipidemia in the United States. Frontiers in Nutrition. 2022;9:971720. DOI: 10.3389/fnut.2022.971720.

4. Warren M. F., Livingston K. A. Implications of Vitamin D Research in Chickens can Advance Human Nutrition and Perspectives for the Future. Current Developments in Nutrition. 2021;5(5):nzab018. DOI: 10.1093/cdn/nzab018.

5. Radu I. A., Ognean M. L., Ștef L., Giurgiu D. I., Cucerea M., Gheonea C. Vitamin D: What We Know and What We Still Do Not Know About Vitamin D in Preterm Infants-A Literature Review. Children. 2025;12(3):392. DOI: 10.3390/children12030392.

6. Izzo M., Carrizzo A., Izzo C., Cappello E., Cecere D., Ciccarelli M., Iannece P., Damato A., Vecchione C., Pompeo F. Vitamin D: Not Just Bone Metabolism but a Key Player in Cardiovascular Diseases. Life. 2021;11(5):452. DOI: 10.3390/life11050452.

7. Phillips E. A., Hendricks N., Bucher M., Maloyan A. Vitamin D Supplementation Improves Mitochondrial Function and Reduces Inflammation in Placentae of Obese Women. Frontiers in Endocrinology. 2022;13:893848. DOI: 10.3389/fendo.2022.893848.

8. Menger J., Lee Z.-Y., Notz Q., Wallqvist J., Hasan M. S., Elke G., Dworschak M., Meybohm P., Heyland D. K., Stoppe C. Administration of vitamin D and its metabolites in critically ill adult patients: an updated systematic review with meta-analysis of randomized controlled trials. Critical Care. 2022;26(1):268. DOI: 10.1186/s13054-022-04139-1.

9. Huang H.-Y., Lin T.-W., Hong Z.-X., Lim L.-M. Vitamin D and Diabetic Kidney Disease. International Journal of Molecular Sciences. 2023;24(4):3751. DOI: 10.3390/ijms24043751.

10. Masbough F., Kouchek M., Koosha M., Salarian S., Miri M., Raoufi M., Taherpour N., Amniati S., Sistanizad M. Investigating the Effect of High-Dose Vitamin D3 Administration on Inflammatory Biomarkers in Patients with Moderate to Severe Traumatic Brain Injury: A Randomized Clinical Trial. Iranian Journal of Medical Sciences. 2024;49(10):643– 651. DOI: 10.30476/ijms.2023.99465.3156.

11. Wimalawansa S. J. Rapidly Increasing Serum 25(OH)D Boosts the Immune System, against Infections–Sepsis and COVID-19. Nutrients. 2022;14(14):2997. DOI: 10.3390/nu14142997.

12. Zhang Y., Zhou J., Hua L., Li P., Wu J., Shang S., Deng F., Luo J., Liao M., Wang N., Pan X., Yuan Y., Zheng Y., Lu Y., Huang Y., Zheng J., Liu X., Li X., Zhou H. Vitamin D receptor (VDR) on the cell membrane of mouse macrophages participates in the formation of lipopolysaccharide tolerance: mVDR is related to the effect of artesunate to reverse LPS tolerance. Cell Communication and Signaling. 2023;21(1):124. DOI: 10.1186/s12964-023-01137-w.

13. Brandenburg V., Ketteler M. Vitamin D and Secondary Hyperparathyroidism in Chronic Kidney Disease: A Critical Appraisal of the Past, Present, and the Future. Nutrients. 2022;14(15):3009. DOI: 10.3390/nu14153009.

14. Izzo C., Secondulfo C., Bilancio G., Visco V., Virtuoso N., Migliarino S., Ciccarelli M., Di Pietro P., La Mura L., Damato A., Carrizzo A., Vecchione C. Chronic Kidney Disease with Mineral Bone Disorder and Vascular Calcification: An Overview. Life. 2024;14:418. DOI: 10.3390/life14030418.

15. Magagnoli L., Cassia M., Galassi A., Ciceri P., Massó E., Gelpi R., Bover J., Cozzolino M. Vitamin D: are all compounds equal? Clinical Kidney Journal. 2025;18(1):i61–i96. DOI: 10.1093/ckj/sfae417.

16. Patel R., Nandini, Kharkwal H., Saha M., Sankaranarayanan M., Sharma S., Chander S. Recent Advancements Towards the Use of Vitamin D Isoforms and the Development of Their Synthetic Analogues as New Therapeutics. Biomedicines. 2025;13(4):1002. DOI: 10.3390/biomedicines13041002.

17. Qu Y., Wu Y., Jiang H. Research progress in the pharmacological actions of the multiple effects and selectivity of the vitamin D analogue paricalcitol: a narrative review. Annals of Palliative Medicine. 2021;10(10):11177–11190. DOI: 10.21037/apm-21-2249.

18. Jia R., Yang F., Yan P., Ma L., Yang L., Li L. Paricalcitol inhibits oxidative stress-induced cell senescence of the bile duct epithelium dependent on modulating Sirt1 pathway in cholestatic mice. Free Radical Biology and Medicine. 2021;169:158–168. DOI: 10.1016/j.freeradbiomed.2021.04.019.

19. Wang S., Huang S., Liu X., He Y., Liu Y. Paricalcitol ameliorates acute kidney injury in mice by suppressing oxidative stress and inflammation via Nrf2/HO-1 signaling. International Journal of Molecular Sciences. 2023;24(2):969. DOI: 10.3390/ijms24020969.