MR also plays an important role in mediating limbic seizures (Roberts and Keith, 1995). In addition, mice were more susceptible to seizures induced by kainic acid when their plasma corticosterone levels were near their circadian peak (Roberts and Keith, 1994). In accordance with these data, there is a positive association between stress and seizure frequency in CDK inhibitor adult epileptics (Lambie et al., 1986, Temkin and Davis, 1984 and Mattson, 1991). Accordingly, it was recently demonstrated that soldiers in combat units have a higher seizure incidence than soldiers

that work under less stressful conditions (Moshe et al., 2008). We also studied the circadian rhythm of the HPA axis of Wistar rats and WARs, and as expected, we observed that Wistar rats present a normal

circadian rhythm, with higher plasma corticosterone and ACTH levels at 8 p.m. (lights off) as compared with 8 a.m. Moreover, WARs showed preserved KU-60019 cell line daily variation of plasma corticosterone levels; however, they did not show diurnal variation in plasma ACTH levels. Disruption of circadian rhythm and of the HPA axis associated with seizures was previously reported in humans and animal experimental models. Linkowski et al. (1987) showed that the timing of the circadian rhythms of ACTH and cortisol, as well as the duration of the quiescent period of cortisol secretion, was normalized in patients after electroconvulsive therapy. Quigg et al. (1998) showed that electrically-induced seizures modify the circadian rhythm of body temperature in hippocampally kindled rats. Thus,

because WARs are endogenously susceptible to seizures and they have an altered circadian rhythm pattern of ACTH release, it will be interesting to demonstrate in a new set of experiments whether or not WARs also present alterations in circadian rhythms related to other factors (e.g., body temperature control). In light of the strong associations between stress hormones and epilepsy, additional studies are under way in order to test the impact of neuroendocrinological alterations found in WARs on ictogenesis and epileptogenesis. In this direction an example Ribonucleotide reductase is the study by Mazarati et al. (2009) where the use of the dexamethasone/CRH test (Johnson et al., 2006) demonstrated that status epilepticus induced by pilocarpine/LiCl leads to hyperactivity of the HHA axis. We observed morphologic alterations in adrenal medulla in WARs, which is compatible with endogenous hypertension, increased heart rate and increased sympathetic tonus observed in these rats (Fazan et al., 2010). Moreover, the increase in adrenal gland cortical fasciculate layer thickness helps to explain the hyper-responsivity of WARs to HPA axis stimulation, as shown here and by the stressful profile of WARs in the elevated plus maze and the open field (Garcia-Cairasco et al., 1998).