Abstract
Deficiency in vitamin D (Vit D) has been widely associated with several musculoskeletal diseases. However, the effects of the exogenous Vit D supplementation are still unclear in the prevention of the latter, especially in the cartilage developmental period. The aim of this study was to compare the effects of Vit D supplementation and restriction on the articular cartilage development in healthy young sedentary rats. To this aim, twelve nine-week-old healthy Sprague–Dawley male rats were subjected to Vit D-based experimental diets: R, with a content in Vit D of 1400 IU/kg; R-DS, with a Vit D supplementation (4000 IU/kg); R-DR, with a Vit D restriction (0 IU/kg) for 10 weeks. The morphology, thickness and expression of cartilage-associated molecules such as collagen type II/X, lubricin and Vit D receptor (VDR), were assessed. Histological, histomorphometric and immunohistochemical evaluations were made on rat tibial cartilage samples. In the present experimental model, restriction of Vit D intake induced: The lower thickness of cartilage compared both to R (p = < 0.0001) and R-DS (p = < 0.0001); reduction of proteoglycans in the extracellular matrix (ECM) compared both to R (p = 0.0359) and R-DS (p = < 0.0001); decreased collagen II (Col II) with respect both to R (p = 0.0076) and R-DS (p = 0.0016); increased collagen X (Col X) immunoexpression when compared both to R (p = < 0.0001) and R-DS (p = < 0.0001), confirming data from the literature. Instead, supplementation of Vit D intake induced: Higher cartilage thickness with respect both to R (p = 0.0071) and R-DR (p = < 0.0001); increase of ECM proteoglycan deposition compared both to R (p = 0.0175) and R-DR (p = < 0.0001); higher immunoexpression of lubricin with respect both to R (p = 0.001) and R-DR (p = 0.0008). These results suggest that Vit D supplementation with diet, already after 10 weeks, has a favorable impact on the articular cartilage thickness development, joint lubrication and ECM fibers deposition in a young healthy rat model.
Highlights
The importance of vitamin D (Vit D) in the musculoskeletal system development and function, is well known, as reported in several studies testifying a range of effects of Vit D deficiency on cartilage, bone and muscle tissues [1,2,3].Nutrients 2019, 11, 1260; doi:10.3390/nu11061260 www.mdpi.com/journal/nutrientsArticular cartilage is an avascular tissue characterized by chondrocytes surrounded by an extracellular matrix (ECM), rich in water and consisting of collagen type II and proteoglycans with sulfated glycosaminoglycan (GAG) side chains
The hematoxylin and eosin (H&E) staining was used to study the general morphology of the tibial articular cartilage in all groups in order to detect eventual alterations and to make a histomorphometric evaluation on the thickness of the articular cartilage
In the restricted diet group (R-DR) group, though the articular cartilage did not show evident alterations, in its middle and deep zones the chondrocytes were poorly organised in columns, and the tidemark was not always perceptible; articular cartilage in the R-DR group showed an apparent reduction of thickness, measuring 130.00 ± 13.19 μm (Figure 1C)
Summary
The importance of vitamin D (Vit D) in the musculoskeletal system development and function, is well known, as reported in several studies testifying a range of effects of Vit D deficiency on cartilage, bone and muscle tissues [1,2,3]. Articular cartilage is an avascular tissue characterized by chondrocytes surrounded by an ECM, rich in water and consisting of collagen type II and proteoglycans with sulfated glycosaminoglycan (GAG) side chains. Healthy cartilage turnover depends on suitable accessibility of Vit D [1]. Suboptimal levels may lead to OA via its adverse effects on cartilage metabolism [6,7]. It has been demonstrated that adequate levels of Vit D stimulate mature chondrocytes to synthesize proteoglycan matrix proteins [8,9]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
