PURPOSE: Excitotoxic injury of the dendrites of inhibitory interneurons could lead to decrease in their synaptic activation, and explain subsequent local circuit hyperexcitability and epilepsy. A hallmark of dendrotoxicity at least in principal neurons of the hippocampus and cortex are focal or varicose swellings of dendritic abors. This research was designed to study morphologic changes of interneuron dendrite in kainate-treated hippocampal slice culture overtime. METHODS: Cultures aged 15-16 Equivalent Postnatal Days (EPD) were exposed to 10 microM kainic acid (KA), and analyzed at 0, 8, 24, 48, 72 hours after transient (1 hour) KA exposure. Neuronal injury was determined by morphologic changes of interneuron dendrites in area CA1 of DiI stained sections. RESULTS: 1) Transient (1 hour) exposure of hippocampal explant cultures to KA produced marked focal swellings of the dendrites of DiI stained interneurons in a highly reproducible manner. 2) The presence of focal swellings was reversible with kainate washout. The dendrites of KA treated explants were no longer beaded at 8, 24, 48, 72 hours after KA exposure. 3) There was no significant difference in the thickness of dendrites in DiI stained interneuron among 8hr, 24hr, 48hr and 72hr recovery group, compared with control group. CONCLUSION: The presence of focal swellings was reversible with kainate washout, and was not accompanied by interneuronal cell death.