Expression of glucose and magnesium transport-associated genes in whole blood RNA of lactating ewes supplemented with magnesium

Abstract

Lactation is characterized by an increase in energy demand and glucose consumption, which may also be linked to the concurrent compromise in immune function during early lactation. Magnesium (Mg) could be involved in this link based on its role for more than 600 metabolic reactions associated with energy metabolism, in addition to its essential role in glucose metabolism. Therefore, the current study aimed to investigate the influence of Mg supplementation on the expression of glucose and Mg transport-associated genes in blood cells (predominantly leukocytes) of lactating ewes and to identify possible correlations between the expression of these genes and leukocyte subpopulations. Pregnant ewes were divided into a control group (Control, n = 8) and a Mg group (Mg, n = 8), the latter supplemented with magnesium oxide at a daily Mg intake of approximately 0.30% and 0.38% of dry matter during the last four weeks of gestation and the first four weeks after lambing, respectively. At the end of the supplementation period, blood samples were collected in PAXgene tubes in order to determine the mRNA expression of glucose transporters (GLUT1, GLUT3 and GLUT4) and genes linked to Mg transport (SLC41A1, CNNM2, TRPM6, TRPM7 and MagT1) in blood cells. Mg supplementation tended to increase the expression of GLUT1 in blood cells (P = 0.087). Expression values of GLUT3, SLC41A1, CNNM2, TRPM6, TRPM7, and MagT1 were not significantly changed (P > 0.1). Interestingly, GLUT4 was not detected in either group. Counts of circulating neutrophils, lymphocytes and monocytes showed no significant differences between the two groups. Furthermore, no correlations were observed between the expression of the investigated genes and specific leukocyte subpopulation percentages/frequenciies. In conclusion, the expression of a variety of glucose and Mg transport-associated genes did not respond to dietary Mg supplementation. Nonetheless, a tendency towards higher expression of GLUT1 in the Mg group might support an involvement of Mg in the regulation of glucose metabolism of ovine blood cells.