Relationship of Vitamin D-Deficient Diet and Irisin, and Their Impact on Energy Homeostasis in Rats

Mahmoud Mustafa Ali Abulmeaty; Ali M Almajwal; Iftikhar Alam; Suhail Razak; Mohamed F ElSadek; Ghadeer S Aljuraiban; Khulood S Hussein; Asmaa M Malash

doi:10.3389/fphys.2020.00025

Relationship of Vitamin D-Deficient Diet and Irisin, and Their Impact on Energy Homeostasis in Rats

Front Physiol. 2020 Jan 31:11:25. doi: 10.3389/fphys.2020.00025. eCollection 2020.

Authors

Mahmoud Mustafa Ali Abulmeaty^{1

2}, Ali M Almajwal¹, Iftikhar Alam¹, Suhail Razak¹, Mohamed F ElSadek¹, Ghadeer S Aljuraiban¹, Khulood S Hussein³, Asmaa M Malash⁴

Affiliations

¹ Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia.
² Medical Physiology Department, Faculty of Medicine, Zagazig University, Zagazig, Egypt.
³ Department of Physiology, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.
⁴ Department of Basic Medical Sciences, College of Medicine, Alfarabi Colleges, Riyadh, Saudi Arabia.

Abstract

Background and objective: Previous studies have identified the role of irisin and vitamin D in energy homeostasis. However, the effect of irisin and vitamin D on energy regulation has not been thoroughly investigated. Therefore, in this study, the effects of a vitamin D-deficient diet and irisin on total energy expenditure (TEE), food intake, and blood metabolites were investigated in rats.

Methods: Sixteen healthy weaned male albino rats were randomly divided into two groups: a group fed a normal balanced growth diet (group A: n = 8) and a group fed a normocalcemic diet that is vitamin D deficient with limited ultraviolet (UV) light exposure (group B, n = 8). After 6 weeks, the volumes of respiratory gases were measured by open-circuit indirect calorimetry. Serum irisin, 25-OHVD₃, calcium, insulin, and glucose levels were measured using ELISA. The respiratory quotient (RQ), energy expenditure, and Homeostatic Model Assessment for Insulin Resistance (HOMA-IR) were calculated.

Results: Rats with hypovitaminosis D were hypoirisinemic. Food intake, RQ (to the range of using endogenous fat), and glucose levels reduced significantly, while insulin levels increased. Body weight and TEE were non-significant changed. Additionally, irisin was strongly and positively correlated with body weight under normal conditions (r = 0.905, p < 0.01), and a moderate negative correlation in group B (r = -0.429, p < 0.05). TEE and irisin showed no significant correlation.

Conclusion: This study demonstrated that the early changes in energy homeostasis and irisin levels during states of hypovitaminosis D are affected by long-term consumption of a vitamin D-deficient diet with limited UV exposure.

Keywords: energy homeostasis; indirect calorimetry; irisin; vitamin D; vitamin D deficiency.