Effects of acute seizures on cell proliferation, synaptic plasticity and long-term behavior in adult zebrafish

Abstract

Acute seizures may cause permanent brain damage depending on the severity. The pilocarpine animal model has been broadly used to study the acute effects of seizures on neurogenesis and plasticity processes and the resulting epileptogenesis. Likewise, zebrafish is a good model to study neurogenesis and plasticity processes even in adulthood. Thus, the aim of this study is to evaluate the effects of pilocarpine-induced acute seizures-like behavior on neuroplasticity and long-term behavior in adult zebrafish. To address this issue, adult zebrafish were injected with Pilocarpine (350 mg/Kg, i.p; PILO group) or Saline (control group). Experiments were performed at 1, 2, 3, 10 or 30 days after injection. We evaluated behavior using the Light/Dark preference, Open Tank and aggressiveness tests. Flow cytometry and BrdU were carried out to detect changes in cell death and proliferation, while Western blotting was used to verify different proliferative, synaptic and neural markers in the adult zebrafish telencephalon. We identified an increased aggressive behavior and increase in cell death in the PILO group, with increased levels of cleaved caspase 3 and PARP1 1 day after seizure-like behavior induction. In addition, there were decreased levels of PSD95 and SNAP25 and increased BrdU positive cells 3 days after seizure-like behavior induction. Although most synaptic and cell death markers levels seemed normal by 30 days after seizures-like behavior, persistent aggressive and anxiolytic-like behaviors were still detected as long-term effects. These findings might indicate that acute severe seizures induce short-term biochemical alterations that ultimately reflects in a long-term altered phenotype.