Amygdaloid projections to the feeding-related neurons in the lateral hypothalamus

下丘脑外侧（LH）中含有食欲素（ORX）和黑色素浓缩激素（MCH）的神经元以及表达黑素皮质素4受体（MC4-R）的神经元参与了摄食行为的调节。为了了解这些神经元是否受到杏仁核的影响，我们研究了这些神经元与源自中央杏仁核（CeA）的轴突终末之间的突触组织。在MC4-R启动子控制下产生绿色荧光蛋白（GFP）的转基因小鼠模型中，表达MC4-R的神经元被可视化为绿色荧光蛋白免疫反应（ir）神经元。将生物素化右旋糖酐胺（BDA）注射到CeA后，在LH区可以看到BDA标记的纤维和ORX-、MCH-或GFP-ir神经元的重叠分布。在该区域，bda标记的按钮与ORX-、MCH-或GFP-ir神经元的细胞体和近端树突相邻。电镜下，CeA轴突末端主要与mch和GFP-ir神经元的体细胞和树突形成不对称突触，偶尔与ORX-ir神经元的体细胞和树突形成不对称突触。

Orexin (ORX)-and melanin-concentrating hormone (MCH)-containing neurons as well as melanocortin 4 receptor (MC4-R)-expressing neurons in the lateral hypothalamus (LH) are involved in the regulation of feeding behavior. To know whether or not these neurons are under the influence of the amygdala, here we examine synaptic organization between these neurons and axon terminals originating from the central amygdaloid nucleus (CeA). MC4-R-expressing neurons were visualized as green fluorescent protein (GFP)-immunoreactive (ir) neurons using a transgenic mouse model in which GFP is produced under the control of the MC4-R promoter. After biotinylated dextran amine (BDA) injection into the CeA, overlapping distribution of BDA-labeled fibers and ORX-, MCH-, or GFP-ir neurons was seen in the LH region. In this region, BDA-labeled boutons were in contiguity with cell bodies and proximal dendrites of ORX-, MCH-, or GFP-ir neurons. Under the electron microscope, the CeA axon terminals formed asymmetrical synapses predominantly with somata and dendrites of MCH-and GFP-ir neurons, and occasionally with those of ORX-ir neurons.