Figure 3. Prolonged elevated glucose levels reduced sensitivity of hypothalamic cells towards glucose.

A, mHypoA-2/10-CRE cells were incubated with the indicated glucose concentration for 24 hours. Data of 5 independent experiments performed in quadruplicates were compiled by calculating the x-fold over the values obtained for 0.1mM glucose (24 h) and expressed as the mean ± SEM. Asterisks indicate a significant difference to the values obtained for 0.1 (18 h) and 1.0mM (6 h) glucose. B, mHypoA-2/10-CRE cells were incubated with 0.1mM glucose for 12 hours. Afterwards, cells were incubated with 0.1mM, 0.5mM, 1.0mM, 2.5mM, or 5.0mM glucose for additional 12 hours. Next, cells were cultured for 30 minutes without glucose, stimulated or not with 1.0mM glucose for 6 hours, and CRE-dependent reporter activity measured (left panel) or glucose uptake monitored by measuring ³H-2-DG uptake for 1 hour (right panel). Left panel, Data of 4 independent experiments performed in quadruplicates were compiled by calculating the x-fold over basal of 1.0mM glucose for each condition and expressed as the mean ± SEM. Asterisks indicate a significant difference to the values obtained for 0.1mM glucose preincubation. Right panel, Data of 4 independent experiments performed in quadruplicates were compiled by calculating glucose uptake as percentage per hour for each condition and expressed as the mean ± SEM. Asterisks indicate a significant difference to the values obtained for 0.1mM glucose preincubation. Lower panel, Data of both experiments was normalized by setting values obtained with 0.1mM glucose as 100%. Hash signs indicate a significant difference to 100%.