Vulnerability of calbindin-positive interneurons to status epilepticus varies in different regions of rat hippocampus

To determine the dynamic alteration of the number of calbindin (CB)-positive interneurons in different hippocampal regions of epileptic rats. Rats were given lithium chloride followed by repeated pilocarpine administration to develop status epilepticus (SE). The degree of seizure was scored according to Racine’s scale. Histological examination was performed using Nissl staining. The distribution and number of CB-positive neurons was evaluated using immunohistochemical analysis. Loss of neuronal cells was observed in hippocampal CA1, CA3, dentate gyrus and hilus following 7 days (resting phase) or 60 days (chronic phase) of SE. Significant decrease of neuronal cells was seen in hippocampal CA1, CA3 and hilus following SE (P 0.05 compared with controls). In hilus region, evident loss of CB-positive interneurons was found only on the first day after SE (P < 0.05). Our findings showed that the sensitivity of CB-positive interneurons to SE varied in different regions of hippocampus.