Resumo

The estrogen receptors (ERs) are widely distributed in the central nervous system (CNS) and their role in neuroplasticity processes are well-described. Conversely the function of ERs in the neuroplasticity associated with the epileptogenic process it is already unknown. Here we investigated the temporal expression of ERs in the hippocampus and neocortex of rats previously submitted to the pilocarpine-induced status epilepticus (PISE). Additionally, we observed the relationship between ER expression and neurodegeneration. Male wistar rats were treated with pilocarpine (300 mg/kg, i.p) or saline (NaCl 0.9%) and sacrificed in 1 h, 12 h, 5 or 50 days after. In pilocarpine treated group, only animals which exhibited motor PISE were used. Brains were collected and prepared for immunohistochemical analysis. Hippocampal and neocortical brain slices were marked with antibody against ER or Fluoro-Jade, aiming ER detection and degeneration respectively. In comparison with the respective control group, ER expression significantly increased in hippocampal regions (CA1, CA2, CA3 and DG) 1 h (acute phase), 12 h (toxic period) and 5 days (silent period) after the PISE induction. In all related regions, except the CA3, the ER expression returns to the basal levels 50 days after the SE. In the neocortex the ER expression increased 1 h and returned to the basal level in 12 h, 5 and 50 days after the SE induction. Interestingly neurons strongly labeled for ER did not presented Fluoro-Jade detection suggesting an association between ER and neuronal survival after epileptogenic events. Our findings indicate that CNS ER expression responds in a time-dependent manner after the PISE stimulus, and that the mentioned temporal modulation depends of the brain region analyzed. Still, we suggest a direct relationship between increased ER expression and neuroprotection after PISE.