测序解析3种肥胖模型小鼠下丘脑神经通讯特征:抑制性调控减弱,谷氨酸、NO与电突触信号各显主导OA

Objective To compare the hypothalamic cellular composition and neuron-neuron communication networks across 3 etiologically distinct mouse models of obesity,high-fat diet(HFD),leptin-deficient(ob/ob),and leptin receptor-deficient(db/db)so as to identify universal mechanistic clues that can be validated across etiologies and searching for etiology-specific targets applicable to stratified treatment.Methods Six-week-old male C57 mice were fed with HFD continuously until 18 weeks of age to establish a HFD model.In parallel,18-week-old male ob/ob mice and db/db mice were subjected as genetic obesity models,and age-matched male C57 mice served as controls.Three mice were included per group(n=3),totaling 12 mice,were euthanized,and the hypothalamic tissues were meticulously dissected under a stereomicroscope.Single-nucleus transcriptome sequencing(snRNA-seq)was performed using the 10x Genomics v3.1 platform.The obtained sequencing data were aligned with Cell Ranger and processed in Seurat for quality control,dimensionality reduction,and clustering.Subsequently,neuron-neuron communication networks were inferred based on NeuronChat and its nervous system-specific ligand-receptor database,systematically comparing changes in differential communication networks,signal output/input strength,information flow,and interaction quantity between each obesity model and C57 controls.Results Dimensionality reduction and clustering of hypothalamic snRNA-seq data from C57,HFD,ob/ob,and db/db mice identified several major cell populations,including excitatory neurons,inhibitory neurons,and multiple non-neuronal cell types,with cells of the same type showing model-dependent shifts in uniform manifold approximation and projection(UMAP)space.Neuronal subclustering resolved 7 GABAergic and 10 glutamatergic subtypes,indicating pronounced neuronal heterogeneity in the hypothalamus.Across the 3 obese models,GABAergic inhibitory incoming signaling and the neurexin-neuroligin(Nrxn-Nlgn)pathway were broadly downregulated.Meanwhile,each model exhibited a distinct communication-network signature:the HFD model was characterized by enhanced electrical synapses mediated by gap junction protein alpha-1(Gja1-Gja1)and reduced Nrxn-Nlgn output;the db/db model showed dominant nitric oxide-soluble guanylate cyclase signaling(NO-Gucy1a2)together with enrichment of prodynorphin(Pdyn)-related pathways;the ob/ob model was primarily marked by enhanced glutamate receptor interactions.Pairwise comparisons among models further validated these patterns:HFD relatively enriched Gja1-related signaling and certain metabotropic glutamate receptor interactions;db/db relatively enriched NO-Gucy1a2 and synaptic adhesion-related pathways;ob/ob relatively enriched in ionotropic/metabotropic glutamate receptor interactions.Conclusion Distinct neural communication network patterns exist in the hypothalamus across obesity models of different etiologies:diet-induced obesity preferentially exhibits enhanced electrical synapse-related pathways,leptin receptor-deficient model is primarily characterized by increased NO-related signaling,and the leptin-deficient model is centrally distinguished by enhanced glutamatergic excitatory interactions.Notably,attenuated inhibitory regulation emerges as a common feature across models,providing novel insights into understanding the pathological mechanisms underlying obesity development.