Verslag – Rapport – Bericht – Report - GSKE - FMRE

3 Study of markers of enhanced oxidative stress and/or glutamate excitotoxicity in the
brains of xCT-/- mice
A microarray screening was performed on hippocampal mRNA samples of xCT-/- mice and wild type
littermates, in order to identify possible compensatory changes in the xCT-/- mice as a result of the
genetic knockout of xCT. We noticed no changes in genes related to oxidative stress or glutamate
excitotoxicity. Only two genes were significantly changed between both genotypes and one of these
genes may be related to autophagy. Moreover, the phosphoinositide3kinase (PI3K) complex is also
involved in autophagy. Knowing that autophagy is recently being linked to many neurological disorders,
- we will now further investigate whether there is a link between autophagy and system x and if this link
c
might explain the protective effects we observe in our models for TLE.
- 4 The role of system x in validated rodent models of epileptogenesis
c
The models we are currently using for mimicking TLE in mice are the amygdala kindling model, the
6Hz corneal kindling model and the post-status epilepticus pilocarpine model. All are well-accepted
models for epileptogenesis, reliably inducing a persistent epileptic state, demonstrable by behavioural
and/or EEG assessment. We are currently studying xCT mRNA and protein expression levels and xCT
distribution patterns during the various phases of these chronic pilocarpine models for TLE, using
C57BL/6 mice. We will also subject xCT-/- and xCT +/+ mice (C57BL/6 background) to the various clinically
relevant chronic mouse models and compare whether deletion of xCT will affect the process and/or
severity of epileptogenesis.
Preliminary data of the 6Hz kindling model using our xCT -/- mice and their wildtype littermates are shown
in Figure 4. In this model the process of epileptogenesis is mimicked by twice daily initial subconvulsive
corneal stimulations (6Hz, 40mA, 3s) until the mice reach the ‘fully kindled state’, i.e. 10 consecutive
generalized seizures. We noticed a tendency that xCT +/+ mice show more severe generalized seizures
during this kindling process compared to xCT -/- mice (Figure 4B). Subsequently we try to maintain
the ‘fully kindled state’ by corneal stimulations twice a week. During this maintenance phase we
also observed a trend of more generalized seizures in the xCT +/+ mice (Figure 4C). These results are
suggesting a somehow better outcome of xCT -/- mice, compared to their wildtype littermates, in the 6Hz
corneal kindling model.
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Verslag – Rapport – Report 2012
Figure 4 – Preliminary data of 6Hz corneal kindling model using
xCT -/- and xCT +/+ mice.
(A) Mean number of generalized seizures during the kindling process
(xCT -/- n=8 and xCT +/+ n=12; Mann–Whitney U = 33,50; p= 0,2796).
(B) Mean seizure score during the kindling process (xCT -/- n=8 and
xCT +/+ n=12; Mann–Whitney U = 22,50; p= 0,0538)
(C)Mean number of generalized seizures during the maintenance
phase (xCT -/- n=6 and xCT +/+ n=11; Mann–Whitney U = 19,00;
p= 0,1721).