Abstracts

Rationale: Repetitive generalized seizures are associated with brain damage. There is an incomplete understanding of the cellular and molecular alterations that lead to secondary generalized seizures. Precursors of lipid mediators, cleaved by specific phospholipases upon activation by neurotransmitters (such as glutamate) and other neuromodulators, play a crucial role in the genesis of seizures. Synaptic membranes are richly endowed with docosahexaenoic acid (DHA), an omega-3 essential fatty acid. DHA is the precursor of NPD1.Seizure or early cell injury induce the synthesis of NPD1 (10R,17S-dihydroxy-docosa-4Z,7Z,11E,13E,15Z,19Z-hexaenoic acid). We determined the effect of NPD1 on hippocampal neural damage and spontaneous seizures activity as a consequence of status epilepitcus (SE). Methods: One week prior to SE induction, bipolar electrode units and a microcannula connected with Alzet minipumps loaded with artificial cerebral spinal fluid (CSF) were implanted in the dorsal right hippocampus and in the third ventricle, respectively. SE was induced by pilocarpine (350 mg/kg, ip). Diazepam (10mg/kg, ip) was injected 90 min. after SE in order to normalize the SE duration in all groups. Then the rats were randomly selected for NPD1 (2μ l/day) or CSF delivery into the third ventricle immediately after SE, and the treatment was continuously infused for two weeks. Behavior and EEG were monitored daily. Animals were deeply anesthetized and then transcardially perfused with 4% paraformaldehyde 2 weeks after SE, and then brains from NPD1 and vehicle rats were collected. The brains were cut together in a frozen block in 40 μm-thick coronal sections. Standard protocols for Fluoro Jade-C (FJC), Nissl and Silver staining were used for neuronal cellular damage. Immunohistology procedures for atrostrocyte cell detection using glial fibrilar acid protein antibody, for interneuronal cells using somatostatin, parvalbumin and calretinin antibodies, and for microglia cells using Iba1 antibody were performed. Histological analyses in the hippocampal region were compared between NPD1- and vehicle-treated rats using bright and immunofluorescence microscopy and image analysis software. Behavior and EEG recording from hippocampi were analyzed. Results: NPD1 attenuates occurrence of hippocampal spontaneous epileptiform activity. Neuronal damage and interneuronal loss were limited in NPD1 treated rats. Also NPD1 attenuated reactive gliosis and microgliosis in hippocampus. Conclusions: NPD1 downregulates epileptogenesis. The significance of NPD1 could open a new pathway for neuroprotection in epileptogeneis.