•  
  •  
 

Document Type

Original Article

Abstract

Modern lifestyles reduce sunlight exposure and increase artificial light at night, potentially promoting vitamin D deficiency (VDD) and melatonin (MEL) suppression. The two hormones regulate immunity, erythropoiesis, and platelet (PLT) indices, but their combined hematological effects are not well characterized. We investigated the independent and combined effects of VDD and MEL deficiency on leukocyte profiles, erythrocyte indices, and PLT parameters in albino rats using two 12-week models (n = 8/group): continuous light (CL)-induced MEL suppression (Control, CL, VDD, and CL + VDD) and pinealectomy (Px)-induced MEL deficiency (Sham. Px, VDD, Px + VDD). Complete blood counts (CBCs) and inflammation-related ratios were assessed at study end. In the CL model, CL increased total white blood cells (WBCs) (p = 0.0135), whereas VDD increased the neutrophil to lymphocyte ratio (NLR) and Systemic Immune-Inflammation Index (SII) (p = 0.0021 and p = 0.0034, respectively). Notably, CL + VDD decreased SII (p < 0.0001), indicating non-additive interactions. In the Px model, Px increased granulocyte (GRA), NLR, and SII (p = 0.0136, p < 0.01, and p = 0.0011, respectively), with Px + VDD showing the highest elevations in WBC (p = 0.0482, SII p < 0.0001). Erythrocyte indices showed selective changes: The hematocrit (HCT) decreased after Px and Px + VDD compared to Sham (p < 0.0002 and p = 0.0429, respectively), and the mean corpuscular hemoglobin concentration (MCHC) decreased with VDD (p < 0.0001), consistent with partially distinct effects on red cell volume/turnover versus hemoglobinization. Overall, VDD favored a pro-inflammatory and hypochromic profile, while MEL deficiency, especially via Px, enhanced innate immune activation, together supporting early adaptive hematologic remodeling rather than overt pathology.

Receive Date

24/11/2025

Revise Date

02/02/2026

Accept Date

21/02/2026

Publication Date

4-12-2026

References

[1] Umar M, Sastry KS, Chouchane AI. Role of vitamin D beyond the skeletal function: a review of the molecular and clinical studies. Int J Mol Sci 2018;19(6). https://doi.org/10. 3390/ijms19061618.

[2] Cui A, Zhang T-Y, Xiao P, Fan Z, Wang H, Yan Z. Global and regional prevalence of vitamin D deficiency in population-based studies from 2000 to 2022: a pooled analysis of 7.9 million participants. Front Nutr 2023;10. https://doi. org/10.3390/ijms19061618.

[3] Cashman KD, Dowling KG, Skrabakova Z, GonzalezGross M, Valtuena~ J, De Henauw S, et al. Vitamin D deficiency in Europe: pandemic? Am J Clin Nutr 2016;103(4):10 33—44. https://doi.org/10.3945/ajcn.115.120873.

[4] Monteiro K, Shiroma ME, Damous LL, Simoes ~ MJ, Simoes ~ RDS, Cipolla-Neto J, et al. Antioxidant actions of melatonin: a systematic review of animal studies. Antioxidants (Basel) 2024;13(4). https://doi.org/10.3390/antiox13040 439.

[5] Chitimus DM, Popescu MR, Voiculescu SE, Panaitescu AM, Pavel B, Zagrean L, et al. Melatonin's impact on antioxidative and anti-inflammatory reprogramming in homeostasis and disease. Biomolecules 2020;10(9). https://doi. org/10.3390/biom10091211.

[6] Cho Y, Ryu SH, Lee BR, Kim KH, Lee E, Choi J. Effects of artificial light at night on human health: a literature review of observational and experimental studies applied to exposure assessment. Chronobiol Int 2015;32(9):1294—310. https://doi.org/10.3109/07420528.2015.1073158.

[7] Aranow C. Vitamin D and the immune system. J Invest Med : Off Publ Am Fed Clin Res 2011;59(6):881—6. https://doi. org/10.2310/JIM.0b013e31821b8755.

[8] Smith EM, Tangpricha V. Vitamin D and anemia: insights into an emerging association. Curr Opin Endocrinol Diabetes Obes 2015;22(6):432—8. https://doi.org/10.1097/ med.0000000000000199.

[9] Medrano M, Carrillo-Cruz E, Montero I, Perez-Sim on J. Vitamin D: effect on haematopoiesis and immune system and clinical applications. Int J Mol Sci 2018;19. https://doi. org/10.3390/ijms19092663.

[10] Carlberg C, Velleuer E. Vitamin D and aging: central role of immunocompetence. Nutrients 2024;16. https://doi.org/10. 3390/nu16030398.

[11] Daryabor G, Gholijani N, Kahmini FR. A review of the critical role of vitamin D axis on the immune system. Exp Mol Pathol 2023:104866. https://doi.org/10.1016/j.yexmp.20 23.104866.

[12] Aihara K, Azuma H, Akaike M, Ikeda Y, Yamashita M, Sudo T, et al. Disruption of nuclear vitamin D receptor gene causes enhanced thrombogenicity in mice. J Biol Chem 200 4;279(34):35798—802. https://doi.org/10.1074/jbc.M404865200.

[13] Hardeland R. Melatonin and inflammation-story of a double-edged blade. J Pineal Res 2018;65(4):e12525. https://doi. org/10.1111/jpi.12525.

[14] Yousefi T, Memar MY, Jazi AA, Zand S, Reiter R, Amirkhanlou S, et al. Molecular pathways and biological roles of melatonin and vitamin D; effects on immune system and oxidative stress. Int Immunopharmacol 2024;143(Pt 3):113548. https://doi.org/10.1016/j.intimp.2024.113548.

[15] Cardinali DP, Esquifino AI, Srinivasan V, PandiPerumal SR. Melatonin and the immune system in aging.Neuroimmunomodulation 2008;15(4—6):272—8. https://doi. org/10.1159/000156470.

[16] Minich D, Henning M, Darley C, Fahoum M, Schuler C, Frame J. Is melatonin the “next vitamin D”?: a review of emerging science, clinical uses, safety, and dietary supplements. Nutrients 2022;14. https://doi.org/10.3390/nu141 93934.

[17] Sonkaya Z_ I, Yazgan B, Kurtagoz€ A, Demir AD, Irgat S_ I. Examination of correlations between vitamin D and melatonin levels with sleep among women aged 18-49 years. Cent Eur J Publ Health 2023;31(1):19—24. https://doi.org/10. 21101/cejph.a7324.

[18] Alqasim A. Hematological changes in diabetic rats receiving melatonin, vitamin D and vitamin E are not reliable indices of inflammatory changes. J Umm Al-Qura Univ Med Sci 2020;6(2):13—7. https://doi.org/10.54940/ms84898451.

[19] Maulood I. Effects of L-arginine and melatonin on plasma endothelin-1 level in rats with induced diabetes mellitus or pulmonary fibrosis. Salahaddin University; 2005. Academic thesis.

[20] Hoffman RA, Reiter RJ. Rapid pinealectomy in hamsters and other small rodents. Anat Rec 1965;153(1):19—21. https://doi.org/10.1002/ar.1091530103.

[21] Ding J, Chen P, Qi C. Circadian rhythm regulation in the immune system. Immunology 2024;171(4):525—33. https:// doi.org/10.1111/imm.13747.

[22] Okuyan O, Dumur S, Elgormus N, Uzun H. The relationship between vitamin D, inflammatory markers, and insulin resistance in children. Nutrients 2024;16(17). https://doi. org/10.3390/nu16173005.

[23] Moustafa A. Chronic exposure to continuous brightness or darkness modulates immune responses and ameliorates the antioxidant enzyme system in male rats. Front Vet Sci 2021; 8. https://doi.org/10.3389/fvets.2021.621188. 2021.

[24] Atanasova D, Krushovlieva D, Rashev P, Mourdjeva M, Pupaki D, Tchekalarova J. Pinealectomy-induced neuroinflammation varies with age in rats. Int J Mol Sci 2025;26(1 6). https://doi.org/10.3390/ijms26168093.

[25] Xu J, Liang C, Yao S, Wang F. Melatonin exerts positive effects on sepsis through various beneficial mechanisms. Drug Des Dev Ther 2025;19:1333—45. https://doi.org/10.21 47/dddt.S509735.

[26] Akbas EM, Gungor A, Ozcicek A, Akbas N, Askin S, Polat M. Vitamin D and inflammation: evaluation with neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio. Arch Med Sci 2016;12(4):721—7. https://doi.org/10.511 4/aoms.2015.50625.

[27] Chen X, Li A, Ma Q. Neutrophil-lymphocyte ratio and systemic immune-inflammation index as predictors of cardiovascular risk and mortality in prediabetes and diabetes: a population-based study. Inflammopharmacology 2024; 32(5):3213—27. https://doi.org/10.1007/s10787-024-01559-z.

[28] Walker 2nd WH, Bumgarner JR, Becker-Krail DD, May LE, Liu JA, Nelson RJ. Light at night disrupts biological clocks, calendars, and immune function. Semin Immunopathol 20 22;44(2):165—73. https://doi.org/10.1007/s00281-021-00899-0.

[29] Morabito R, Remigante A, Marino A. Melatonin protects band 3 protein in human erythrocytes against H(2)O(2)- induced oxidative stress. Molecules 2019;24(15). https://doi. org/10.3390/molecules24152741.

[30] Greenwood A, von Hurst PR, Beck KL, Mazahery H, Lim K, Badenhorst CE. Relationship between vitamin D, iron, and hepcidin in premenopausal females, potentially confounded by ethnicity. Eur J Nutr 2023;62(8):3361—8. https://doi.org/10.1007/s00394-023-03240-7.

[31] Tan D, Manchester L, Esteban-Zubero E, Zhou Z, Reiter R. Melatonin as a potent and inducible endogenous antioxidant: synthesis and metabolism. Molecules 2015;20:1 8886—906. https://doi.org/10.3390/molecules201018886.

[32] Hardeland R, Cardinali D, Srinivasan V, Spence D, Brown G, Pandi-Perumal S. Melatonin―A pleiotropic, orchestrating regulator molecule. Prog Neurobiol 2011;93: 350—84. https://doi.org/10.1016/j.pneurobio.2010.12.004.

[33] Smith EM, Alvarez JA, Kearns MD, Hao L, Sloan JH, Konrad RJ, et al. High-dose vitamin D(3) reduces circulating hepcidin concentrations: a pilot, randomized, double-blind, placebo-controlled trial in healthy adults. Clin Nutr 2017; 36(4):980—5. https://doi.org/10.1016/j.clnu.2016.06.015.

[34] Bunn H. What can we learn from variation of red cell size distribution. Am J Hematol 2015;90:369—70. https://doi. org/10.1002/ajh.24003.

[35] Cure C, Cüre E, Yuce S, Yazici T, Karakoyun I, Efe H. Mean platelet volume and vitamin D level. Annal Lab Med 2014; 34:98—103. https://doi.org/10.3343/alm.2014.34.2.98.

[36] Inuzuka R, Abe J. Red blood cell distribution width as a link between ineffective erythropoiesis and chronic inflammation in heart failure. Circ J : Off J Japan Circ Soc 2015;79(5):974—5. https://doi.org/10.1253/circj.cj-15-0254.

[37] Megaloikonomos P, Nakashima K. Red cell distribution width in cardiac diseases: role of hemorheology and chronic inflammation. J Biorheol 2023. https://doi.org/10.17106/jbr. 37.13.

[38] Pritchett D, Reddy A. Circadian clocks in the hematologic system. J Biol Rhythm 2015;30:374—88. https://doi.org/10.11 77/0748730415592729.

[39] Campos LA, Bueno C, Barcelos IP, Halpern B, Brito LC, Amaral FG, et al. Melatonin therapy improves cardiac autonomic modulation in pinealectomized patients. Front Endocrinol 2020;11. https://doi.org/10.3389/fendo.2020.00239. 2020.

Download

Share

COinS