FIG. 1.

A: Experimental design to analyze the effect of an intragastric glucose infusion. Mice bearing intragastric, femoral, and intracerebroventricular catheters underwent infusions after the surgery recovery period. On days 1, 2, 4, and 5 of the training period, mice were trained to the intragastric water infusion. On day 3, an intragastric glucose infusion (30 mg · kg⁻¹ · min⁻¹) was performed, and those mice developing immediate hyperglycemia demonstrated a correct intragastric catheter implantation and were studied on day 6 when they underwent an intragastric glucose or water infusion after 6 h of fasting. Two protocols were set up. In protocol 1, glucose turnover was assessed and the mice underwent a continuous intragastric glucose infusion for 2 h. In protocol 2, the mice underwent a 10-min intragastric glucose or water infusion, and 2 h later, the brain was fixed in vivo for histological studies. B: Schematic representation in gray of brain areas analyzed to quantify the number of c-Fos–positive cells (37). C: Glycemic profiles (mmol/l) in mice infused with glucose (▪) or saline (□). The inset represents the corresponding AUC (arbitrary units). No differences were noticed.