The Relationship Between Hippocampal Mossy Fiber Sprouting And ATF3Expression In The Rat Model Kindled By PTZ

Object To observe the expressional changes of ATF3protein in the stratum granulosum of dentate gyrus (DG) and the CA3region of hippocampus associated with the changes of hippocampal mossy fiber sprouting in the pentylenetetrazole (PTZ) kindling model and to investigate the role of ATF3in epileptogenesis.Methods150healthy male Sprague-Dawley rats were divided randomly into control and PTZ treated groups. The PTZ treated rats were intraperitoneally injected PTZ (30mg/kg) every24hours and stopped injection once were kindled. The control rats were intraperitoneally injected0.9%saline at the same time. Seizure manifestations were evaluated according to Racine. At3d,lw,2w,4w,6w after the first PTZ injection, Timm staining was scored at different times in the CA3region and dentate gyrus of hippocampus. The protein of ATF3was analyzed at different times in the stratum granulosum of the CA3region and dentate gyrus of the hippocampus, using immunohistochemistry, immunofluorescence and Western Blot.Results1. Animal modelSubsequent injection with the same dose of PTZ induced convulsive responses of gradually increasing severity. After21-28 injections(23.7±1.9days),94.4%of animals were kindled, the mortality is5.33%. All rats were kindled successfully except2rat in4weeks group and6weeks group. The control rats have not seizures.2. Changes of hippocampal mossy fiber sproutingThe Timm scores in the CA3region were gradually increased from3d to4w. It reached peak at4weeks and maintained high level in the6w groups. All PTZ groups were significantly higher than that in controls at different times(P<0.05) in the CA3regions. There were no significantly differences in dentate gyrus between the PTZ treated groups and the control groups at different times.3. Changes of ATF3protein expressionThe experimental results revealed that expression of ATF3in the CA3area in PTZ group was significantly up-regulated (p<0.05). ATF3rose gradually from3days to4weeks, peaked at4weeks and fell slightly at6weeks in PTZ groups. No obvious distinction of their expression was observed in dentate gyrus areas between PTZ group and control group (p>0.05).ConclusionsThe upregulation of ATF3expression in the CA3region of hippocampus might promote the procession of mossy fiber sprouting in the kindling process of PTZ and induce the occurrence and development of temporal lobe epilepsy.