Effects of Crystalline Lactose on Expression of Sodium-dependent Glucose Transporter (SGLT)-1 mRNA

Supplementation of crystalline lactose increases SGLT-1 mRNA relative abundance, glucose transport to the basolateral compartment, and reduces the LPS-mediated inhibitory effect on glucose transport in IPEC-J2 cells. 1 Summary A preliminary experiment was conducted to evaluate the effects of crystalline lactose on the relative abundance of sodium-dependent glucose transporter (SGLT)-1 mRNA in vitro in model por-cine jejunal epithelial cells (IPEC-J2). Cells were treated with low (28 mM) or high (56 mM) concentrations of lactose alone or in combination with lipopoly-saccharide (LPS; 10 ng/mL). Total RNA and culture media samples from both apical and basolateral compartments were harvested at 3, 6, 12, and 24 hours following the addition of respective treatments. With respect to relative abundance of SGLT-1 mRNA, there were no interactions of lactose, LPS, and time; however, a main effect of lactose (P < 0.01) was observed. Cells treated with a high concentration of lactose had greater SGLT-1 mRNA expression compared to the control cells (P = 0.003) and low concentration lactose (P = 0.02) treated cells. With respect to glucose quantifi cation, polarization of glucose in the basolateral rather than in the apical compartment (P = 0.04) was observed in a time-dependent manner (P < 0.001). Supplementation of lac-tose in LPS-treated cells reduced LPS-mediated inhibitory effect on glucose transport from the apical to basolateral compartment (P = 0.07). in cultured porcine epithelial cells does not exist. Thus, a preliminary experiment was conducted to evaluate the effects of supplementation of crystalline lactose on glucose transport and expression of mRNA encoding for sodium-dependent glucose transporter (SGLT)-1 in vitro in model porcine jejunal epithelial cells (IPEC-J2). Porcine jejunal intestinal epi-thelial cells have been characterized previously and are non-transformed, jejunal epithelial cells derived from neonatal pigs, and are maintained as a continuous culture. Cell cultures were maintained in DMEM-F12 growth medium supplemented with insulin/transferin/Na selenite media supplement, epidermal growth factor, antibiotic, and fetal bovine serum. For experimentation, IPEC-J2 cells were seeded onto 12-well transwell cell culture plates and maintained in the above media. The cells were incubated for 24 hours before being washed and re-fed every other day for seven days to form a model of the gut epithelium. Twenty-four hours before experimentation , cells were washed and re-fed media devoid of antibiotics. There were six treatments (2 × 3 factorial) included in this experiment: 1) control (CTL; growth media devoid of antibiotics); 2) CTL + Lipopolysac