Fig. 2. Glucose drinking results in robust but differential changes in NAc glutamate and glucose.

Top graphs show changes in electrochemical currents detected by glutamate (a, c) and glucose (e, g) sensors analyzed at 2-s bins with respect to the start (a, e) and end of drinking (c, g). Each graph also show changes detected by Null sensors under identical conditions (blue). Bottom graphs show changes in [glutamate] (b, d) and [glucose] (f, h) at the start (4-s bins) and end (10-s bins) of drinking. Inset in (h) shows a rapid, but non-significant decrease in [glucose] immediately after the end of drinking (2-s bins). n defines number of tests in each group. While glutamate currents fell with respect to Null currents during drinking (Current × Time interaction F_71,1562=2.60, p<0.05), relative glutamate currents remained significantly lower than Null currents after drinking behavior (Current × Time interaction F_90,1710=2.53, p<0.05). Both behavioral events resulted in a significant decrease in [glutamate] during (F_12,623=4.68, p<0.05) and for 300-400 s post-drinking (F_9,909=6.48, p<0.05). Glucose currents significantly differed from Null currents during the same events (start of drinking, main effect F_1,21=7.14, Current × Time interaction F_71,1491=2.41; end of drinking, main effect F_1,21=5.97, Current × Time interaction F_90,1890=8.48; all p<0.05), resulting in significant increases in [glucose] at the start of drinking for 73.5 s (F_11,575=2.66, p<0.05), that slightly decreased after its end, and began to increase robustly again from ~150 s after the end of glucose consumption (F_11,1091=9.31, p<0.05). n defines number of tests in each group, change in concentration from pre-test baseline shown in boxes, and filled symbols in b, d, f, h show values significantly different from the initial, quiet-rest baseline (p<0.05).