Skip to main content
. Author manuscript; available in PMC: 2024 May 1.
Published in final edited form as: J Physiol. 2023 Apr 13;601(10):1881–1896. doi: 10.1113/JP284370

FIGURE 4: Glutamate drives diurnal rhythmicity in basal action potential firing.

FIGURE 4:

A) Representative extracellular voltage traces showing spontaneous action potentials during the day (ZT5–9) and night (ZT17–21) under control conditions and following bath application of ionotropic glutamate antagonists (NBQX 25 μM and AP5 25 μM). B) Baseline action potential frequency was significantly greater during the day compared to night (Mann-Whitney Rank Sum Test, N = 50 – 53 neurons / 6 mice, ***P < 0.001). Bath application of NBQX + AP5 lowered frequency during the day (Mann-Whitney Rank Sum Test, N = 44 – 50 neurons / 6 mice, ***P < 0.001) and night (Mann-Whitney Rank Sum Test, N = 46 – 53 neurons / 6 mice, ***P < 0.001); eliminating the day / night difference in action potential firing (Mann-Whitney, N = 44 – 46 neurons / 6 mice, P = 0.12). C) Similarly, the percent of neurons firing action potentials spontaneously under control conditions was greater during the day compared to the night (Chi-square, N = 103 neurons / 6 mice, ***P < 0.001). This day / night difference was reduced following NBQX + AP5 and no longer statistically significant (Chi-square, N = 100 neurons / 6 mice, P = 0.21). D) Whole-cell recordings from NTS neurons confirmed the day / night difference in action potential frequency. E) While there was no significant difference in the resting membrane potentials (RMP) (T-test, N = 32 – 35 neurons / 6 mice, P = 0.08) spontaneous action potential firing frequencies were significantly faster during the day (F, Mann-Whitney Ranked Sum Test, N = 32 – 35 neurons / 6 mice, *P = 0.03).