Time-of-day determines neuronal damage and mortality after cardiac arrest.
Ischemic events in humans are not evenly distributed across the day. To discriminate between temporal differences in the incidence of ischemia and susceptibility to ischemic events, we examined the outcome of global ischemia in a murine model at three time points during the day. Global cerebral ischemia in mice during the light phase impairs survival and exacerbates outcome compared to ischemia at other times of the day. Specifically, mice that underwent cardiac arrest during the light phase had greater numbers of degenerating neurons, greater microglial activation, and increased proinflammatory cytokine production in the ischemia-vulnerable hippocampus, as well as increased locomotor activity. Time-of-day differences were not altered by the melatonin receptor antagonist luzindole. Our results document that brain tissue displays endogenous fluctuations in susceptibility to ischemic damage and demonstrate that small differences in time of onset can significantly influence ischemic outcomes.
Weil
Zachary M
ZM
Department of Psychology, The Ohio State University, Columbus, OH 43210, USA. zweil@rockefeller.edu
Karelina
Kate
K
Su
Alan J
AJ
Barker
Jacqueline M
JM
Norman
Greg J
GJ
Zhang
Ning
N
Devries
A Courtney
AC
Nelson
Randy J
RJ
D000818:Animals; D016923:Cell Death / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology; D006323:Heart Arrest / Q000401:mortality* / Q000473:pathology*; D008297:Male; D051379:Mice; D008809:Mice, Inbred C3H; D009474:Neurons / Q000473:pathology*; D015996:Survival Rate / Q000639:trends; D013997:Time Factors