Effect and mechanism of glucocorticoid on glutamatergic and
GABAergic neurons in the amygdala
Abstract
Objective: To investigate the effect and mechanism of glucocorticoid on subcellular compartments and interactions between excitatory and inhibitory neurons in the amygdala, which may be involved in the pathological process of major depression and anxiety. Methods:Glucocorticoid influence was examined by chronically intraperitoneally injecting dexamethasone in the mice or by acutely washing dexamethasone to the brain slices including amygdala. The neurons were recorded by a MultiClamp-700B amplifier under the current-clamp for their intrinsic property and voltage-clamp for their synaptic activity. The functions of GABAergic neurons were studied including their active intrinsic properties and inhibitory outputs. The functions of glutamatergic neurons were studied including the active intrinsic properties and excitatory outputs. Action potentials at the amygdala neurons were induced by injecting the depolarization pul. U transgenic mice with genetically YFP-labeled glutamatergic neurons and GFP-labeled GABAergic neurons in the amygdala as the rearch object, dexamethasone was acutely (25μM) washed onto the brain slices or was chronically given (40mg/kg) by intraperitoneal injection onc
e a day for one week. The neuronal spikes and synaptic transmission were recorded by whole-cell patching in the amygdala neurons of brain slices. The record indicator contained spontaneous inhibitory postsynaptic current and inter-spike-intervals on glutamatergic neurons and spontaneous excitatory postsynaptic current and inter-spike-intervals on GABAergic neurons, to investigate the effect and mechanism of glucocorticoid on subcellular compartments and interactions between excitatory and inhibitory neurons in the amygdala.
Results: The chronic application of dexamethasone increas GABA relea from inhibitory neurons and GABAergic receptor respons in excitatory neurons of the amygdala and the acute applicationof dexamethasone increas GABA relea from inhibitory neurons of the amygdala. Dexamethasone increas the spike capability of inhibitory neurons in the amygdala. The chronic application of dexamethasone decreas glutamate relea from excitatory neurons and increas glutamate receptor respons in the inhibitory neurons of the amygdala. The acute application of dexamethasone decreas glutamate relea from excitatory neurons of the amygdala. Dexamethasone does not affect spike abilities of excitatory neurons in the amygdala. Glucocorticoid
produced the differential effects of on inhibitory and excitatory neurons in the amygdala. The acute or chronic administration of dexamethasone all upregulates GABA relea and GABAergic neuron s
piking as well as downregulates glutamate relea. The chronic administration of glucocorticoid also enhances the responsiveness of GABA receptors. Conclusion: Dexamethasone upregulates the action onto the glutamatergic neurons from GABAergic neurons by elevating presynaptic neuronal excitability, GABA relea as well as postsynaptic GABA A receptor respons. Dexamethasone downregulates the action onto the GABAergic neurons from glutamatergic neurons by lowering glutamate relea. The downregulation of glutamatergic neurons by glucocorticoid and the upregulation of GABAergic neurons impair their balance and the alternations imbalance neural networks in the amygdala toward inhibitory state, which leads to emotional disorders during stress and provide inspiration for the development of antidepressant drugs.
Graduate student: Guangyan Wang (pharmacology)
Directed by Prof. Jinhui Wang
Key Words: glucocorticoid; depression; amygdala; glutamatergic neurons; GABAergic neuron
reputation意思目录
引言 (1)
材料与方法 (3)
1实验动物 (3)
2试剂和试药 (3)
2.1 小鼠荧光鉴定试剂 (3)
bowel
2.2 电生理实验试剂 (3)
3仪器设备 (3)
3.1 小鼠基因型鉴定实验设备 (3)
go through
3.2 电生理实验设备 (4)movieclip
4小鼠GAD荧光鉴定实验方法 (4)
4.1 提取小鼠的整个基因组 (4)
4.2 提取小鼠的DNA (4)报告如何写
4.3 PCR反应 (5)
4.4 进行电泳并观察结果 (5)reliable
5电生理实验方法 (6)
5.1 准备工作 (6)
5.2 小鼠麻醉和脑片的制备 (8)
5.3 全细胞膜片钳 (8)
6糖皮质激素的应用方法 (11)
6.1 急性应用地塞米松 (11)
6.2 慢性应用地塞米松 (12)
7统计学处理 (12)
结果 (13)
newsletter
1地塞米松对于杏仁核GABA的释放能力和GABA A受体的影响 (13)
2地塞米松对于杏仁核GABA能神经元自身兴奋能力的影响 (16)
3地塞米松对于杏仁核谷氨酸能神经元释放能力的影响 (19)
4地塞米松对于杏仁核谷氨酸能神经元自身兴奋能力的影响的影响 (22)
5地塞米松导致杏仁核的GABA能神经元和谷氨酸能神经元相互作用不协调 (25)
讨论 (26)
结论 (28)
参考文献 (29)
综述 (33)
综述参考文献 (44)
urland
攻读学位期间的研究成果 (50)
个人简历 (51)
缩略词表（附录） (52)
我期待的大学生活致谢 (54)
学位论文独创性声明、学位论文知识产权权属声明 (55)
引言
引言
抑郁症是一种情感精神疾病，由社会因素、遗传因素、心理因素等多种因素引起，
以持续性情绪低落、快感缺失、认知功能障碍、睡眠紊乱等为主要特征，严重者甚至自杀行为，危害身心健康，降低生活质量，增加社会负担[1]。近年来，随着生活节奏的加快，生活压力的增大，抑郁症的发病率呈现出逐年升高的趋势。世界卫生组织统计表明，抑郁症发病率达12.8%，预计到2020年抑郁症或将成为仅次于心脏病的全球第大疾病[2]。近年来，研究表明，抑郁症是涉及多种发病机制，多个脑区的复杂疾病，但是具体的发病机制不是很清楚。目前的研究表明抑郁症发病涉及的主要机制有：遗传因素、5- 羟色胺（5- HT）假说、去甲肾上腺素（norepinephrine, NE）假说、多巴胺（Dop
刷赞平台推广网站便宜amine, DA）学说、乙酰胆碱（acetylcholine, Ach）假说、神经内分泌假说、细胞因子学说、心理应激等[3]。
抑郁症的发病涉及多个脑区，与边缘系统和奖赏环路密切相关，并且脑内的GABA能神经元和谷氨酸能神经元发生了一系列病理的改变。磁共振光谱研究显示抑郁症患者前脑谷氨酸能和GABA能神经递质的含量减少[4]。经颅磁刺激的研究表明前脑皮层GABA的反应性减弱，还有研究表明手术损毁大脑扣带回可以改善反复发作的重度抑郁患者的病情[5]。这些研究结果提示前脑皮层和边缘系统神经环路结构和功能异常或许是抑郁症患者的病理学基础。重度抑郁症患者前脑的GABA能神经元数量减少，应激诱导的神经生长因子分泌和新生神经元的减少[6, 7]。或许由于神经元的减少导致兴奋和抑制网络的失平衡，神经环路功能的失稳态可能是由于海马压抑性突触可塑性和杏仁核亢进性突触可塑性[8,9]。但是，这些患者的神经元减少不一定是由于抑郁症所致，此外，兴奋和抑制性神经环路失衡比例，以及神经元和神经胶质细胞相互作用异常的机理仍然不清楚。
研究表明，抑郁症的发病与应激激素密切相关。外源性的应激会促进糖皮质激释放释放，使下丘脑-垂体-肾上腺皮质轴（hypothalamus-pituitary-adrenal axis, HPA轴）处于持续亢奋状态，而体内长期的高糖皮质激素水平会损伤某些脑区并且导致边缘系统的细胞萎缩而导致抑郁症。应激激素会影响突触和神经元的结构和功能，以前的研究表明，糖皮质激素在产前期调节GABA A受体的功能[10]并且减少GABA能神经元的密度[11]。慢性应激损坏逆转电位和GABA A受体的密度[12-14]，并且增强GABA 的
突触传递[15-18]。应激激素是如何影响神经元的亚细胞结构和兴奋性神经元与抑制性神经元之间的相互作用等细胞特异性病理机制需要进一步研究[19]，因为他们之间的协调对于神经元保持良好的的认知编码非常重要。
杏仁核作为边缘系统和奖赏环路的重要结构，是产生、识别和调节情绪的重要脑
区，并且能够控制学习和记忆。研究发现，幼儿自闭症可能也与杏仁核的扩大有关。
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