Ni Hong, Chen Su-Hong, Li Li-Li, Jin Mei-Fang
Neurology Laboratory, Institute of Pediatric Research, Children's Hospital of Soochow University, No. 303, Jingde Road, 215003, Suzhou, PR China.
Neurology Laboratory, Institute of Pediatric Research, Children's Hospital of Soochow University, No. 303, Jingde Road, 215003, Suzhou, PR China.
Epilepsy Res. 2018 Jan;139:164-170. doi: 10.1016/j.eplepsyres.2017.12.009. Epub 2017 Dec 26.
The mechanism of linking neonatal seizures with long-term brain damage is unclear, and there is no effective drug to block this long-term pathological process. Recently, the fat-derived hormone leptin has been appreciated for its neuroprotective function in neurodegenerative processes, although less is known about the effects of leptin on neonatal seizure-induced brain damage. Here, we developed a "twist" seizure model by coupling pilocarpine-induced neonatal status epilepticus (SE) with later exposure to penicillin to test whether leptin treatment immediately after neonatal SE would exert neuroprotective effects on cognition, seizure threshold and hippocampal mossy fiber sprouting, as well if leptin had any influence on the expression of zinc transporter 3 (ZnT3) and calcium homeostasis-related CB-D28k in the hippocampus. Fifty Sprague-Dawley rats (postnatal day 6, P6) were randomly assigned to four groups: control (n = 10), control with intraperitoneal (i.p.) injection of leptin (Leptin, n = 10), pilocarpine-induced neonatal SE (RS), and RS i.p. leptin injection (RS+Leptin). At P6, all the rats in the RS group and RS+Leptin group were injected with lithium chloride i.p. (5 mEq/kg). Pilocarpine (320 mg/kg, i.p.) was administered 30 min after scopolamine methyl chloride (1 mg/kg) injection at P7 to block the peripheral effect of pilocarpine. From P8 to P14, the animals in the Leptin group and RS+Leptin group were given leptin (4 mg/kg, i.p.). The Morris water maze test was performed during P28-P33. Following routine seizure threshold detection and Timm staining procedures, Western blot analysis was performed for each group. Pilocarpine-induced neonatal SE severely impaired learning and memory abilities, reduced seizure threshold, and induced aberrant hippocampal CA3 mossy fiber sprouting. In parallel, there was a significantly down-regulated protein level of CB-D28k and an up-regulated protein level of ZnT3 in the hippocampus of the RS group. Furthermore, leptin treatment soon after neonatal SE for seven consecutive days counteracted these hyperexcitability-related alterations. These novel findings established that leptin has a neuroprotective role in the model of cholinergic neonatal SE and highlights ZnT3/CB-D28k associated-Zn (2+)/Ca (2+) signaling as a promising therapeutic target.
新生儿癫痫与长期脑损伤之间的联系机制尚不清楚，且尚无有效的药物来阻断这一长期病理过程。最近，脂肪源性激素瘦素因其在神经退行性过程中的神经保护作用而受到关注，尽管关于瘦素对新生儿癫痫诱导的脑损伤的影响知之甚少。在此，我们通过将毛果芸香碱诱导的新生儿癫痫持续状态（SE）与后期暴露于青霉素相结合，建立了一种“扭转”癫痫模型，以测试新生儿SE后立即给予瘦素治疗是否会对认知、癫痫阈值和海马苔藓纤维出芽产生神经保护作用，以及瘦素是否对海马中锌转运体3（ZnT3）和钙稳态相关的CB-D28k的表达有任何影响。50只Sprague-Dawley大鼠（出生后第6天，P6）被随机分为四组：对照组（n = 10）、腹腔注射（i.p.）瘦素的对照组（瘦素组，n = 10）、毛果芸香碱诱导的新生儿SE组（RS组）和RS组腹腔注射瘦素组（RS + 瘦素组）。在P6时，RS组和RS + 瘦素组的所有大鼠均腹腔注射氯化锂（5 mEq/kg）。在P7时，在注射甲基氯化东莨菪碱（1 mg/kg）30分钟后腹腔注射毛果芸香碱（320 mg/kg），以阻断毛果芸香碱的外周作用。从P8到P14，瘦素组和RS + 瘦素组的动物给予瘦素（4 mg/kg，腹腔注射）。在P28 - P33期间进行莫里斯水迷宫试验。按照常规癫痫阈值检测和Timm染色程序进行操作后，对每组进行蛋白质免疫印迹分析。毛果芸香碱诱导的新生儿SE严重损害了学习和记忆能力，降低了癫痫阈值，并诱导了海马CA3区异常的苔藓纤维出芽。同时，RS组海马中CB-D28k的蛋白质水平显著下调，ZnT3的蛋白质水平上调。此外，新生儿SE后立即连续7天给予瘦素治疗可抵消这些与过度兴奋相关的改变。这些新发现证实了瘦素在胆碱能新生儿SE模型中具有神经保护作用，并突出了ZnT3/CB-D28k相关的锌（2+）/钙（2+）信号作为一个有前景的治疗靶点。
