Effect of 17b-Estradiol on Learning and Memory in Adult Female Rats afterStatus Epilepticus

• Main Authors: Pi-Lang Kao, 高碧蓮
• Other Authors: Fong-Sen Wu
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/04833885277435454950

碩士 === 國立成功大學 === 生理學研究所 === 90 === Accumulating evidence from a variety of human and experimental animal studies indicates that 17b estradiol (E2) may act as a memory enhancer. Memory deficits, particularly deficits of long term memory, have often been reported in patients with temporal lobe epilepsy. Previous studies from our laboratory demonstrate that memory deficits also occur in kainic acid-induced seizure rats. However, whether memory impairments are also present in pilocarpine-induced seizure rats and whether E2 treatments can prevent or reverse memory impairments in seizure rats remain largely unknown. In present study, we used the one-way inhibitory avoidance learning task to explore the effect of intraperitoneally injected pilocarpine on rat memory performance. In addition, we also investigated the effect of E2 treatments on memory retention in normal and pilocarpine-induced seizure rats. Ten days after ovariectomy, the adult female rats were injected intraperitoneally with pilocarpine (400 mg/kg) to induce prolonged (40- or 60-min) seizures (status epilepticus). Seven days later, memory performance in normal, seizure, E2 pretreatment, E2 posttreatment and E2 pretreatment plus posttreatment rats was measured and compared. Results revealed that the retention latency in 40- or 60-min seizure rats was shorter than that in normal rats, indicating poorer memory performance in seizure rats. Rotarod treadmill performance and electric shock sensitivity test excluded the possibility that the shorter retention latency in 40- or 60-min seizure rats was due to their higher motor activity or lower shock sensitivity. Moreover, whereas 40-min seizures had no damaging effect on hippocampal neurons, 60-min seizures produced extensive neuronal damage in rat hippocampal CA1 area. These results suggest that neuronal loss in hippocampal CA1 area might be the cause of memory deficits in 60-min seizure rats. E2 treatment for 9 days increased memory performance in normal rats. However, all E2 treatments, including pretreatment, posttreatment and pretreatment plus posttreatment, did not prevent or reverse memory deficits in pilocarpine-induced seizure (40 or 60 min) rats. Unexpectedly, E2 pretreatment, posttreatment or pretreatment plus posttreatment prevented or reversed pilocarpine-induced neuronal damage in the hippocampal CA1 area of 60-min seizure rats.