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 to 15-16 Equivalent Postnatal Day (EPD) were exposed to 10microM kainic acid (KA), and were analyzed at 0, 8, 24, 48, 72 hours after transient (1 hour) KA exposure. Neuronal injury was determined by morphologic changes of parvalbumin (PV) positive interneuron dendrites in area CA1 of PV-immunohistochemically stained sections. RESULTS: 1) Transient (1 hour) exposure of hippocampal explant cultures to KA produced marked focal swellings of the dendrites of PV-immunoreactive 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, 72hours after KA exposure.3) The number of cells in PV-immunoreactive interneuron was decreased at 0, 8, 24 hours after exposure. But there was no significant difference among 48hr and 72hr recovery group compare with control group.4) The total length of dendrites was decreased between 0 and 8hours after exposure. But there was no significant difference among 24, 48, and 72hr recovery group compare with control group.5) The branches of dendrites were decreased just after exposure. But there was no significant difference among 8hr, 24hr, 48hr, and 72hr recovery group compare with control group. CONCLUSION: The presence of focal swellings was reversible with kainate washout, and was not accompanied by interneuronal cell death.