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. 1999 Nov 9;96(23):13468–13473. doi: 10.1073/pnas.96.23.13468

Figure 1.

Figure 1

PACAP modulates the phase-shifting effect of Glu on the rat circadian clock. (A) The mean firing rate of the SCN neuronal ensemble peaked at CT 7 on days 1 and 2 in vitro. Mean peak activity of controls on day 2 is marked by a dashed line for phase reference. (B) PACAP administered at CT 19 did not alter the time of peak. (C) When administered at CT 19, Glu induced a 3.5-h advance in the firing rhythm. (D) When coadministered with Glu at CT 19, PACAP blocked the Glu-induced phase advance. (E) When coadministered with Glu at CT 19, P6–38 potentiated the Glu-induced phase advance to 5.0 h. (F) When administered at CT 14, PACAP did not alter phasing of the neuronal activity rhythm. (G) When applied at CT 14, Glu induced a 3.0-h delay in the rhythm. (H) When coadministered at CT 14, PACAP potentiated the Glu-induced phase delay to 6.0 h. (I) When coadministered with Glu at CT 14, P6–38 blocked the Glu-induced delay. Running averages ± SEM are plotted. Arrows mark the time of drug administration. Subjective night is designated by the horizontal, striped bar.