科研之友
微信
新浪微博
Facebook
分享链接
摘要
Purpose: Cerebral hypoxia is a major cause of neonatal seizures, and can lead to epilepsy. Pathologic anatomic and physiologic changes in the dentate gyrus have been associated with epileptogenesis in many experimental models, as this region is widely believed to gate the propagation of limbic seizures. However, the consequences of hypoxia-induced seizures for the immature dentate gyrus have not been extensively examined.
Methods: Seizures were induced by global hypoxia (5-7% O-2 for 15 min) in rat pups on postnatal day 10. Whole-cell voltage-clamp recordings were used to examine A-type potassium currents (I-A) in dentate granule cells in hippocampal slices obtained 1-17 days after hypoxia treatment.
Key Findings: Seizure-inducing hypoxia resulted in decreased maximum I-A amplitude in dentate granule cells recorded within the first week but not at later times after hypoxia treatment. The decreased I-A amplitude was not associated with changes in the voltage-dependence of activation or inactivation removal, or in sensitivity to inhibition by 4-aminopyridine (4-AP). However, consistent with the role of I-A in shaping firing patterns, we observed in the hypoxia group a significantly decreased latency to first spike with depolarizing current injection from hyperpolarized potentials. These differences were not associated with changes in resting membrane potential or input resistance, and were eliminated by application of 10 m 4-AP.
Significance: Given the role of I-A to slow action potential firing, decreased I-A could contribute to long-term hippocampal pathology after neonatal seizure-inducing hypoxia by increasing dentate granule cell excitability during a critical window of activity-dependent hippocampal maturation.
- 出版日期2013-7
- 单位武汉大学
