Effects of fluoxetine on the anticonvulsant action of valproate and ethosuximide in mouse model of myoclonic convulsions

Depression is becoming a growing problem in rural areas. This psychiatric disorder often accompanies epilepsy. The aim of this study was to assess the influence of fluoxetine (FXT), a commonly used antidepressant, on the protective action of two conventional antiepileptic drugs: ethosuximide (ETX) and valproate (VPA), against pentylenetetrazole (PTZ)-induced convulsions in mice. Motor coordination and long-term memory deficits induced by FXT, antiepileptic drugs alone and in combinations with FXT were assessed in the chimney test and passive-avoidance task, respectively. Brain concentrations of ETX and VPA were measured by immunofluorescence. Obtained results indicate that FXT at the dose of 15 mg/kg (ip, 30 min before the test) significantly increased the threshold for clonic convulsions. The antidepressant drug at lower doses remained ineffective in this respect. Moreover, FXT at the highest subprotective dose (10 mg/kg, ip) markedly enhanced the anticonvulsant effects of VPA, but not of ETX, against PTZ-induced seizures. The interaction between FXT and VPA seems to be pharmacodynamic because the antidepressant drug did not alter the brain concentration of VPA. With regard to adverse effects, FXT, VPA, ETX, and the combinations of FXT with antiepileptic drugs, did not impair motor coordination and long-term memory in mice. In conclusion, the combination of FXT with VPA may be advantageous in the treatment of myoclonic epilepsy, and therefore it should be recommended for further study in clinical conditions.