Abstracts

RATIONALE: Neuregulins are peptide growth factors expressed during development and may influence neuronal survival/recovery after excitotoxic injury. In rats, we assessed immunoreactivity (IR) for neuregulin (NRG) and its receptors, erb B3 and erb B4 during post-natal development and following pilocarpine-induced status epilepticus (SE). METHODS: Post-natal rats were studied at day 7, 12, 15, and 30, and adult rats were sampled 2, 15, and 30 days after SE. We measured NRG, erb B3, and erb B4 IR in the hippocampus (HC), neocortex (CO), globus pallidus (GB), thalamus (TH), and reuniens/rhomboid thalamic nuclei (RE/RH) using image analysis techniques. RESULTS: In SE rats, brain NRG, erb B3 and B4 IR were increased at day 2 (P<0.005) and decreased at day 30(P<0.05) compared with controls. However, brain regions showed different patterns of IR. Post-SE, NRG IR was greatest in HC, CO, and RE/RH compared with GB and TH. Erb B3 and B4 IR were increased in TH compared with other brain regions. NRG and erbB IR after SE did not follow the profile observed during post-natal development. CONCLUSIONS: IR for NRG and its receptors was altered after pilocarpine-induced SE, and the pattern of IR differed depending on the brain region, with NRG receptor IR greatest in regions with the least SE-induced neuronal injury. These findings suggest that while NRG expression may be important for neuronal survival after excitotoxic injury, increased receptor expression may be what predicts neuronal survival. Supported by Epilepsy Foundation of America (CJP), and NIH grants NS02808, and NS38992.