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

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

JOURNAL=Frontiers in Physiology

VOLUME=11

YEAR=2020

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2020.00025

DOI=10.3389/fphys.2020.00025

ISSN=1664-042X

ABSTRACT=<sec><title>Background and Objective</title><p>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.</p></sec><sec><title>Methods</title><p>Sixteen healthy weaned male albino rats were randomly divided into two groups: a group fed a normal balanced growth diet (group A: <italic>n</italic> = 8) and a group fed a normocalcemic diet that is vitamin D deficient with limited ultraviolet (UV) light exposure (group B, <italic>n</italic> = 8). After 6 weeks, the volumes of respiratory gases were measured by open-circuit indirect calorimetry. Serum irisin, 25-OHVD<sub>3</sub>, 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.</p></sec><sec><title>Results</title><p>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 (<italic>r</italic> = 0.905, <italic>p</italic> &lt; 0.01), and a moderate negative correlation in group B (<italic>r</italic> = −0.429, <italic>p</italic> &lt; 0.05). TEE and irisin showed no significant correlation.</p></sec><sec><title>Conclusion</title><p>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.</p></sec>