Intraventricular orexin-A improves arousal and early EEG entropy in rats after cardiac arrest

Matthew A. Koenig, Xiaofeng Jia, Xiaoxu Kang, Adrian Velasquez, Nitish V Thakor, Romergryko Geocadin

Research output: Contribution to journalArticle

Abstract

The recovery of arousal after cardiac arrest (CA) is associated with evolution from electroencephalographic (EEG) burst-suppression to continuous activity. Orexin-A elicits arousal EEG during anesthetic burst-suppression. We hypothesized that orexin-A would improve arousal and EEG entropy after CA. Eighteen Wistar rats were subjected to 7-minute asphyxial CA and resuscitation. Rats were divided into treatment (n = 9) and control (n = 9) groups. Twenty minutes after resuscitation, the treatment group received 0.1 mL of 1 nM orexin-A intraventricularly, while controls received saline. EEG was quantified using Information Quantity (IQ), a measure of entropy validated for detection of burst-suppression and arousal patterns. IQ values range from 0 to 1.0. Arousal was quantified using the neurological deficit scale (NDS). The ischemic neuronal fraction of hippocampus CA1 and cortex was histologically determined. Baseline and post-resuscitation characteristics were similar between the groups. The NDS score (mean ± SD) at 4 h was higher in the orexin-A group compared to controls (57.3 ± 5.8 vs. 40.7 ± 5.9, p <0.02), but scores were similar at 72 h. Burst frequency was similar in both groups but the orexin-A group demonstrated higher IQ values compared to controls beginning within 10 min. IQ values remained significantly higher in the orexin-A group for the first 120 min (p = 0.008) and subsequently converged. The ischemic neuronal fraction was similar between groups in cortex (p = 0.54) and hippocampus CA1 (p = 0.14). In rats resuscitated from CA, orexin-A transiently increased arousal and EEG entropy without worsening ischemic neuronal injury. The role of orexin-A in recovery of arousal after CA deserves further investigation.

Original languageEnglish (US)
Pages (from-to)153-161
Number of pages9
JournalBrain Research
Volume1255
DOIs
StatePublished - Feb 19 2009

Fingerprint

Entropy
Arousal
Heart Arrest
Resuscitation
Hippocampus
Orexins
Anesthetics
Wistar Rats
Wounds and Injuries
Therapeutics

Keywords

  • Coma
  • Electrophysiology
  • Global ischemia
  • Hypocretin
  • Hypothalamus

ASJC Scopus subject areas

  • Neuroscience(all)
  • Clinical Neurology
  • Developmental Biology
  • Molecular Biology

Cite this

Intraventricular orexin-A improves arousal and early EEG entropy in rats after cardiac arrest. / Koenig, Matthew A.; Jia, Xiaofeng; Kang, Xiaoxu; Velasquez, Adrian; Thakor, Nitish V; Geocadin, Romergryko.

In: Brain Research, Vol. 1255, 19.02.2009, p. 153-161.

Research output: Contribution to journalArticle

Koenig, Matthew A. ; Jia, Xiaofeng ; Kang, Xiaoxu ; Velasquez, Adrian ; Thakor, Nitish V ; Geocadin, Romergryko. / Intraventricular orexin-A improves arousal and early EEG entropy in rats after cardiac arrest. In: Brain Research. 2009 ; Vol. 1255. pp. 153-161.
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