Abstract
Only few studies have focus on animals that received Pilocarpine (Pilo) and did not develop behavioral status epilepticus (SE) and, whether they may become epileptic in the model's chronic phase. Previews works observed mossy fiber sprouting in the hippocampus of Non-SE (NSE) rats, while others observed spontaneous and recurrent seizures (SRS) 6 - 8 months after animals received Pilo. It is known that neuronal excitability is influenced by female hormones, as well as, the occurrence of SE in castrated and non-castrated female rats. However, it is not known whether females that received Pilo and did not show SE, may have SRS. The aim of this work was to investigate whether castrated and non-castrated female rats that did not show behavioral SE after Pilo, will develop SRS in the following one-year. For that, animals received 360 mg/kg of Pilo and were video monitored for 12 months. SE females from castrated and non-castrated groups became epileptic since the first month after drug injection. Epileptic behaviors were identified watching video monitoring recordings in the fast speed. Castrated and Non-castrated NSE animals showed behaviors resembling seizures described by Racine Scale stages 1 - 3. Motor alterations showed by NSE groups could be observed only when recordings were analyzed in slow speed. In addition, behavioral manifestations as, rhythmic head movements, sudden head movements, whole body movements and immobility were also observed in both, SE and NSE groups. We concluded that NSE female rats may have become epileptic. Adding to it, slow speed analysis of motor alterations was essential for the observation of NSE findings, which suggests that possibly many motor alterations have been underestimated in epilepsy experimental research.
Highlights
Pilocarpine (Pilo) experimental model of epilepsy was first described in male rats by Turski et al (1983), and in female rats by Amado and Cavalheiro (1998)
Forty non-SE animals (NSE) and 30 status epilepticus (SE) rats out of 86 regular estrous cycle females were obtained after Pilo administration in the estrus day of the cycle (16 died due to tonic seizure) (Figure 1)
This work was based on a one-year video monitoring follow-up of castrated and non-castrated SE and NSE female rats that showed 4 classes of behavioral manifestations in the Pilo models chronic phase
Summary
Pilocarpine (Pilo) experimental model of epilepsy was first described in male rats by Turski et al (1983), and in female rats by Amado and Cavalheiro (1998). Behavioral, pathologic and electroencephalographic characteristics found in male and female epileptic rats treated with Pilo resemble those observed in Temporal Lobe Epilepsy (TLE) patients, making this a very useful experimental model of study (Cavalheiro et al, 1994). Many experimental research groups around the world have devoted to the study of epilepsy, but only few of them have reported the number or percentage of non-SE animals (NSE) obtained in their experiments. Despite the common and variable occurrence of NSE rats in this model of epilepsy, the discard of this animals or the use as controls are not unusual among researchers (Mora et al, 2009). Few studies have been done toward the comprehension of such animals
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