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. During ischemia-reperfusion damage, enzyme-mediated oxygenation pathways are activated and the stereospecific mediator, 10R,17S-DHA, neuroprotectin D1 (NPD1), is generated. This mediator also has been found to have neuroprotective functions in retinal cells and brain. We have shown previously that kindling-induced seizures trigger the synthesis of NPD1. Here, we show the effect of NPD1, directly infused into the brain or bolstering its synthesis with DHA, on the progression of seizures during kindling in mice. Methods: Bipolar electrode units were implanted in the dorsal right hippocampus. One week post surgery, kindling was achieved by stimulating 6 times daily for 4 days with a subconvulsive electrical stimulation (a 10-s train containing 50-Hz biphasic pulses of 75- to 200-μA amplitude) at 30-min intervals. Seizure severity and EEG were analyzed during kindling. An alzet minipump (loaded with artificial cerebrospinal fluid) was implanted in the mouse neck and connected with a microcannula to the third ventricle 7 days prior to kindling. Then, the minipump was loaded with NPD1 (50µM/day) or vehicle and delivered into the third ventricle over the course of 4 days of kindling. DHA was constantly infused during kindling using Alzet mini-pumps into intraperitoneal cavity. Simultaneously, epileptic events were recorded (through the stimulating/recording electrode) as well as the behavioral seizures. Results: We observed that the icv infusion of NPD1 during kindling prevented stage 4-5 (Racine’s score). A similar effect was observed in DHA-treated mice. These changes were associated with lower numbers of spikes from each afterdischarge, compared with vehicle-treated mice. Conclusions: These results indicate that NPD1 modulates the physiopathology process of generalized seizures. Since our kindling model may be strong enough to overcome endogenous NPD1 bioactivity, this indicates that NPD1 availability limits epileptogenesis. The significance of this novel neuroprotective signaling in epileptogenesis could open a new avenue for using the NPD1 chemical structure as a template to develop synthetic analogs that bear similar bioactivity.