Analyses revealed an overall main effect of time (F [5] , [49] = 5.60, p = 0.0004) and a significant interaction (F [5] , [49] = 5.39, p = 0.0005) for the number of pERK cells, and a main effect of time (F [5] , [50] = 11.12, p <0.0001) and a marginally significant interaction (F [5] , [50] = 2.23, p = 0.0654) for pNR1.
Analysis of pERK immunostaining at CT16 revealed a significant effect of treatment (F [2] , [15] = 4.19,, p = 0.0358) where the higher dose of MK-801 significantly decreased SCN core pERK compared to vehicle ( p = 0.0151), and the low dose had an intermediate effect that failed to reach statistical significance (p = 0.1819, Fig. 7A-D ). pERK immunostaining in the SON was unaffected by MK-801 administration ( Fig. 7E ) , suggesting that MK-801 acted locally in the SCN to exert its effects.