功夫菊酯通过干扰雌激素的作用影响海马突触发育的研究

Research of λ-cyhalothrin affect synaptic development in hippocampus by interfering with estrogen action

目的探讨功夫菊酯（LCT）是否干扰雌激素作用而影响海马突触发育。方法出生后28d（PND28）的健康雌性ICR小鼠随机分为假手术和卵巢切除两大组，假手术组分为假手术对照组、假手术LCT组（3．0μg／g）、假手术来曲唑组（1．0μg／g）及假手术LCT＋来曲唑组，卵巢切除组分为卵巢切除对照组、卵巢切除雌激素组（10．0μg／g）、卵巢切除LCT组、卵巢切除来曲唑组、卵巢切除雌激素＋LCT组、卵巢切除雌激素＋来曲唑组、卵巢切除LCT＋来曲唑组、卵巢切除雌激素＋LCT＋来曲唑组，共12小组，每组10只，经腹腔注射给药，连续2d，末次给药24h后对各组半数动物进行行为学测试，余下动物麻醉取脑做冰冻切片，用免疫荧光组织化学技术检测突触后致密蛋白95（PSD95）。结果行为学测试发现，与假手术对照组比较，卵巢切除对照组小鼠在旷场第1格潜伏期和水迷宫登台潜伏期明显延长，差异有统计学意义（P〈0．05）；与卵巢切除对照组比较，卵巢切除雌激素组小鼠在旷场中跨越的总格数增加，水迷宫登台潜伏期缩短，差异有统计学意义（P〈0．05）；与卵巢切除雌激素组比较，卵巢切除雌激素＋LCT组总格数和站立次数明显减少，登台潜伏期延长，差异有统计学意义（P〈0．05）；与假手术对照组比较，假手术LCT小鼠登台潜伏期延长，差异有统计学意义（P〈0．05）；与卵巢切除对照组比，卵巢切除LCT组小鼠第1格潜伏期及登台潜伏期缩短，差异有统计学意义（P〈0．05）；与假手术来曲唑组比较，假手术LCT＋来曲唑组小鼠在旷场第1格潜伏期延长，跨越总格数和站立次数减少，差异有统计学意义（P〈0．05）。免疫荧光组织化学检测发现，与假手术对照组比较，卵巢切除对照组海马CAl、CA3和DG区PSD95表达明显降低，差异有统计学意义（P〈0．05）；与卵巢切除对照组比较，卵巢切除雌激素（或LCT）组PSD95表达有所上调，差异有统计学意义（P〈0．05）；与假手术对照组比较，假手术LCT组PSD95表达下调，差异有统计学意义（P〈0．05）；与卵巢切除雌激素组比较，卵巢切除雌激素＋LCT组PSD95表达下调，差异有统计学意义（P〈0．05）；与卵巢切除雌激素＋来曲唑组比较，卵巢切除雌激素＋LCT＋来曲唑组CA3区PSD95表达下调，差异有统计学意义（P〈0．05）；与卵巢切除来曲唑组比较，卵巢切除LCT＋来曲唑组DG区PSD95表达上调，差异有统计学意义（P〈0．05）。结论在体内雌激素极低或被清除的条件下，LCT可模拟雌激素对海马突触发育的促进作用；循环雌激素存在时，LCT可干扰雌激素的效应，抑制海马突触发育。这很可能是LCT神经发育毒性的重要作用机制。

Objective To explore the effects of λ-cyhalothrin on hippocampus by interfering with estrogen. Methods The healthy female ICR mice of postnatal 28 days were random divided into 12 groups, 4 of those were sham-operation include control, λ-cyhalothrin（ LCT, 3.0 μg/g）, Letrozole （ Let, 1.0 μg/g）, and LCT （3.0 μg/g）＋Let（ 1.0 μg/g）; and the last 8 were ovariectomized include OVX, Estradiol （ E2, 10.0μg/g）, LCT, Let, E2 ＋LCT, E2 ＋Let, LCT＋Let, E2 ＋LCT＋Let. 10 mice in every group received drugs by intraperitoneal injection for 2 days. Then half of every group initiate the ethological test（open field test and Morris water maze ） 24 h later. The last half animals were sacrificed to made frozen section for immunofluorescent assay of postsynaptic density protein 95 （PSD95）. Results In ethological test, campared with Sham, OVX can lengthen incubation period in the first grid and to get on the platform （P〈0.05）; campared with OVX, OVX＋E2 can increase the total numbers of through grid and shorten the incubation period to get on the platform （P〈0.05）; campared with OVX ＋E2, OVX ＋E2 ＋LCT can reduce the number of grid and standing, lengthen incubation period to the platform （P〈0.05）; campared with Sham, Sham＋LCT can lengthen incubation period to the platform of Sham mice （P〈0.05）, but campared with OVX, OVX＋LCT can shoten incubation period in the first grid and to get on the platform in OVX mice （P〈0.05）; campared with Sham＋Let, Sham＋LCT＋Let can lengthen incubation period in the first grid, reduce the the number of grid and standing （P 〈0.05）. In the Immunohistochemical fluorescence experiment we find that, campared with Sham, OVX can reduce the expression of PSD95 in CA1,CA3 and DG（P〈0.05）, however campared with OVX, E2 or LCT can both inhibit the effect of OVX （P〈0.05）; campared with Sham, Sham＋LCT can reduce the expression of PSD95, the same result when OVX＋E2＋LCT campared with OVX＋E2 （P〈0.05）; campared with OVX＋E2＋Let, OVX＋E2＋LCT＋ Let can reduce the expression of PSD95 in CA3 （P〈O.05）; campared with OVX＋Let, OVX＋LCT＋Let can increase the expression of PSD95 in DG（P〈0.05 ）. Conclusions When few estrogen exist in the body, LCT can show estrogen-like action to promote hippocampal synaptic development; but when circulating estrogen exist, LCT can inhibit synaptic development by interfering estrogen.