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Seizures induce phase shifts of rat circadian rhythms

Authors
Journal
Brain Research
0006-8993
Publisher
Elsevier
Publication Date
Volume
913
Issue
2
Identifiers
DOI: 10.1016/s0006-8993(01)02780-9
Keywords
  • Circadian Rhythm
  • Complex Partial Seizure
  • Thermoregulation
  • Epilepsy
  • Kindling
Disciplines
  • Medicine

Abstract

Abstract Rationale: Epileptic seizures may alter neuroendocrinological cycles. Light pulses induce phase shifts in circadian rhythms. Using hippocampal-kindled rats to ensure maximal clinical expression, we determined if seizures likewise induce phase shifts. Methods: We monitored the circadian rhythm of temperature (CRT) with intraperitoneal radiotelemetry in rats ( n=21) isolated from time cues and light for 3-week trials. Seizures were triggered with hippocampal electrical stimulation at different circadian phases. Optimized, least-error phase shifts were calculated from preictal and postictal CRTs. Induced seizures were referenced to CRT ( t max=00:00, 24-h circadian cycle). Results: Phase shifts (individual responses=57) differed across the circadian cycle. Rather than forming a clear phase–response curve, phase shifts were especially variable between 00:00 and 06:00 h. Conclusions: This study demonstrates that electrically-induced seizures induce advances and delays in CRT in a phase-dependent fashion but in a pattern different from typical light-induced phase shifts. Disorders of circadian regulation may contribute to some of the altered endogenous cycles associated with epilepsy.

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