CHRONOBIOLOGICAL VARIATION OF SPIKE-AND-WAVE DISCHARGE DURATION (SWD) IN THE AY-9944 RAT MODEL OF ATYPICAL ABSENCE SEIZURES
Abstract number :
1.111
Submission category :
Year :
2002
Submission ID :
1488
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Miguel A. Cortez, Ruchika Shukla, Edward Bercovici, Irina Serbanescu, Niraj Mistry, O. Carter Snead III. Division of Neurology, The Brain and Behaviour Program, The Hospital for Sick Children, Toronto, Ontario, Canada
RATIONALE: Serotonergic mechanisms appear to be involved in experimental atypical absence seizures (Cortez et al. Epilepsia 2001; 42 (7): 81). We set out to investigate the possibility of chronobiological variations in SWD duration in the AY-9944 (AY) model (Cortez et al. Neurology 2001; 56:341- 349). Diurnal and seasonal variations in cholesterol homeostasis are well-documented (Proc. Natl. Acad. Sci. USA 1996; 93: 9799- 9804).
METHODS: ECoG recordings in AY rats from postnatal day (P) 55, onwards over a 24-hour (h) period. SWD quantification over 24 h (N=4) and winter-summer comparisons of Video EEG and ECoG recordings (N= 8) in AY rats and control were made by two independent and blinded ECoG readers (RS and IS). All animals were kept under a controlled 12L-12D cycle, with lights on at 6 AM.
RESULTS: The highest SWD duration (Mean SWD + SEM) was found at 03:00 and 15:00 h (229.9 + 64.02) and the lowest at 05:00 h (16.87 + 14.10) over a 24 hour period (F= 20.63, Two-tailed p= 0.01, Unpaired t test). SWD in winter (495.33 +14.74) was greater that the SWD in summer (229.62 + 45.27) (Mean difference -265.71, t= 5.58, 14 DF, F= 9.42, Two-tailed p= 0.001), Unpaired t test.
CONCLUSIONS: Under controlled environmental conditions, there are diurnal and seasonal changes in AY-induced SWD duration. Whether there is any variation in levels of circulating 24-hydroxycholesterol and photoperiodic effects in the AY Model remain to be determined.
[Supported by: The Hospital for Sick Children Pediatric Consultants]