Vitamin D3 exerts immunomodulatory and memory improving properties in rats with lipopolysaccharide-induced inflammation

Abstract

Introduction: Vitamin D is a fat-soluble secosteroid, its primary function being regulation of calcium-phosphate homeostasis and maintenance of bone integrity and mineralization. Recently, pleotropic effects of this vitamin have been recognized, including an immunomodulatory role and involvement in normal brain development and functioning. Aim: The aim of the present study was to investigate the influence of cholecalciferol on serum inflammatory markers and memory functions in lipopolysaccharide (LPS) model of inflammation. Materials and methods: Male Wistar rats were randomly divided into 4 groups (n=8): control group, LPS control group, LPS + cholecalciferol (vitamin D3) 500 UI group, and 1000 IU/kg bw group. Step-down passive avoidance test, novel object recognition test (NORT), Y- and T-maze were performed to assess the memory functions. Latency, recognition index (RI), % spontaneous alteration (SA), and working memory index were registered. Tumor necrosis factor-alpha (TNF-α), IL-1β, transforming growth factor-β1 (TGF-β1), and brain derived neurotrophic factor (BDNF) serum levels were measured by ELISA. Results: LPS administration caused significant impairment in memory functions in all memory tasks. Cholecalciferol treatment caused significant increase in % SA, RI, and working memory index. In the step-down passive avoidance test, cholecalciferol-treated groups showed statistically significant increase in latency in the long-term memory test. Vitamin D3-treated rats showed decreased TNF-α and IL-1β serum levels whereas the concentration of TGF-β1 and BDNF increased. Conclusions: Cholecalciferol improves spatial working and episodic memory, which can at least partially be explained with its effect on systemic inflammatory response that is closely related with the development of neuroinflammation.