Serum levels of 25-hydroxy vitamin D in normal Biozzi and C57BL/6 mice and during the course of chronic relapsing experimental autoimmune encephalomyelitis (CR EAE)

Objective and design

The aim of the study was to examine possible variations in the levels of 25-hydroxy vitamin D 25-(OH)D] in sera from normal Biozzi and C57BL/6 mice and during the course of chronic relapsing experimental autoimmune encephalomyelitis (CR EAE).

Material

Serum concentrations of 25-(OH)D were measured in normal male and female Biozzi and C57BL/6 mice, at 3–4 weeks old and 8–10 weeks old, with a minimum of six animals/group. Levels of the vitamin were also determined in CR EAE-inoculated mice, and controls, during the course of the disease using a minimum of six animals/treatment.

Methods

Cardiac blood was collected from the groups of normal, control and CR EAE-sensitised mice and sera prepared, by centrifugation of clotted samples, and assayed for 25-(OH)D levels by chemiluminescence assay.

Results

Normal male and female Biozzi and C57BL/6 mice had significantly higher levels of 25-(OH)D at 8–10 weeks old compared to concentrations at 3–4 weeks of age (P < 0.005). Also, levels of the vitamin were significantly raised in C57BL/6 male and female mice compared to values in samples from corresponding Biozzi mice. In addition, the amounts of 25-(OH)D in sera from female Biozzi and C57BL/6 mice were significantly increased compared to strain and aged-matched male mice. The CR EAE mice with acute stage disease had significantly higher 25-(OH)D levels compared to controls (P < 0.005). Vitamin concentrations fell to within controls values with the progression of CR EAE.

Conclusions

Our preliminary studies have revealed marked differences between the amounts of 25-(OH)D in sera from Biozzi and C57BL/6 mice together with clear gender bias. The investigations also show significant, but selective changes, in levels of the vitamin during the course of CR EAE that are not always associated with the neurological disease state.