Differences in serum selenoprotein P profile between C57BL/6 and BALB/c mice fed high-fat diet

Background: C57BL/6 mice generally show hyperglycaemia and insulin resistance when fed a high-fat diet (HFD) compared to those of BALB/c mice. However, whether these strains also show different expression profiles of selenoprotein P, a diabetes-related hepatokine, after HFD feeding is unclear. We investigated the effects of HFD on body weight, glucose metabolism, and plasma selenoprotein P levels in C57BL/6 and BALB/c mice.

Methods: Male C57BL/6 and BALB/c mice aged seven weeks were divided into normal diet (ND) and HFD groups. Fasting body weights and blood sugar levels were measured weekly. Blood specimens were collected after 16 h of fasting (in weeks 7, 9, and 11) and after 24 h of subsequent refeeding (in weeks 9 and 11) to analyse plasma selenoprotein P and insulin levels.

Results: The mean body weight of the HFD group was consistently higher than that of the ND group for both strains. However, a significant elevation in fasting plasma glucose levels from the early stage was observed only in the HFD group of C57BL/6 mice. In BALB/c mice, a difference in fasting glucose levels between the HFD and ND groups was observed after nine weeks. After seven, nine, and eleven weeks, the fasting plasma insulin levels were higher in the HFD group than in the ND group for both strains. During this period, plasma selenoprotein P levels in the HFD group were significantly higher than those in the ND group of C57BL/6 mice. However, BALB/c mice did not show a significant difference in plasma levels of selenoprotein P between the ND and HFD groups. After refeeding, the plasma insulin and selenoprotein P levels increased compared to those observed during fasting in the ND group for both strains. Elevation of insulin levels, but not of selenoprotein P levels, after refeeding was noticed in the HFD group for both strains. Plasma selenoprotein P level after refeeding was significantly lower than that during fasting in the HFD group of C57BL/6 mice.

Conclusion: Unlike C57BL/6 mice, BALB/c mice did not show elevated fasting plasma selenoprotein P levels despite HFD feeding. Additionally, the pattern of selenoprotein P levels in the plasma after refeeding differed between C57BL/6 and BALB/c mice. These differences in selenoprotein P expression among strains may be related to different susceptibilities of individuals to diabetes.