2-B-P-023 〇石井 利明¹、嘉屋 元博²、室井 喜景¹ Toshiaki Ishii¹, Motohiro Kaya², Yoshikage Muroi^{1 1}帯広畜産大・畜産、²帯広畜産大・産学連携センター ¹Lab. Vet. Pharmacol., Dept. Basic Vet. Med., Obihiro Univ. of Agri. and Vet. Med., ²Ctr. Ind.-Univ. Collaboration, Obihiro Univ. of Agri. and Vet. Med. Repetitive low-dose administration of the GABA_A receptor antagonist pentylenetetrazole (PTZ) to mice gradually lowers the threshold for convulsive seizures and induces tonic-clonic seizures. Therefore, PTZ has been used to create chemical-kindling mouse models for epilepsy research. Recently, it has been reported that administration of probiotics has various beneficial effects on central nervous system function. The purpose of the present study was to investigate the effects of oral administration of probiotic Bifidobacterium breve strain A1 (B. breve A1) on the tonic-clonic seizure of PTZ-induced kindling model mice (KD mice). PTZ (37 mg/kg) was administered intraperitoneally to mice every other day for 15 days. On the other hand, living or heat-killed B. breve A1 at a volume of 0.25 mL (3.25 x 10⁹ cfu organisms) was administered orally every other day for 15 days starting the day before the first PTZ injection. The mean seizure score in KD mice gradually increased with repetitive injections of PTZ. Oral administration of viable but not nonviable B. breve A1 to KD mice resulted in a significant decrease in mean seizure score at all injections after the fourth PTZ injection. These results suggest that at least B. breve A1 living in the gut lumen leads to amelioration of tonic-clonic seizures in PTZ-induced KD mice via an unknown signaling pathway.