Abstracts

Rationale: We have previously shown that in vivo disruption of F-actin filaments with latrunculin A induces acute and chronic seizures in rats, as well as long-term changes in neuronal excitability as measured by picrotoxin seizure thresholds. On these basis, we have studied the effect of latrunculin A microperfusion in mice. Methods: Mouse hippocampus was continuously perfused with a latrunculin A solution (4μM) through CMA/7 microdialysis probes with continuous video and EEG monitoring during three consecutive days (8 hours/day). The probe was connected via polyethylene tubing to a syringe selector (CMA/111), and to 1 ml syringes mounted on a microinjection pump (CMA/100). Flow rate was 1 μl/min. Control EEG monitoring was performed at least once a week on each animal during the following two months. Results: EEG seizure activity was observed in all the animals studied during the third day of latrunculin A perfusion. Differently from rats, latrunculin A induced mainly focal EEG activity in the ipsilateral hemisphere, often not accompanied by motor convlusions or any observable behavioural changes. In the month following latrunculin A treatment, ipsilatareal focal activity not accompanied by motor convulsions was frequently observed (fig 1). Conclusions: CONCLUSIONS: Our results show that hippocampal F-actin disruption with latrunculin A induces a different pattern of seizure activity in mice and rats. Latrunculin A microperfusion in mice may be a good new experimental model of partial chronic epilepsy. (Supported by grant XUGA PGIDIT03PXIB20803PR from the Consellería de Educación e Ordenación Universitaria, Xunta de Galicia, Galicia, Spain.)