摘要
Objective:To anatomically and phenotypically characterize the insular cortex(IC)-nucleus tractus soli-tari(NTS)neural pathway.Methods:Adult male Sprague-Dawley rats were divided into three experimental cohorts for neural circuit tracing.Anterograde labeling was achieved by injecting anterograde self-complementary adeno-associated viruses(scAAVs)into the IC.Retrograde tracing involved NTS injections of either retrograde scAAVs or FluoroGold(FG),combined with immunofluorescence histochemical staining to identify IC-originating projection neurons.For postsynaptic neurochemical phenotype characterization,IC was injected with AAV2/1-CaMKII-Cre,while a mixture of AAV2/9-Syn-DIO-mCherry and AAV2/9-VGAT1-EGFP was injected into the NTS.The rats were allowed to survive for one week following scAAVs or FG injection or four weeks after recombinase-dependent systems injection.Then the rats were sacrificed,and serial brain sections were prepared for immunofluorescence histochemical staining(brain section containing FG)and subsequent fluorescence/confocal microscopic analysis.Results:(1)Anterograde viral tracing re-vealed dense axonal terminals from the IC projecting to the medial subnucleus of the NTS,while retrograde tracing re-vealed that IC neurons projecting to the NTS were predominantly localized within the dysgranular layer;(2)IC-NTS projection neurons were exclusive glutamatergic(100%,n=3);(3)NTS neurons receiving IC inputs were mainly lo-calized in the medial subnucleus,and were predominantly GABAergic(79.8±3.2%,n=3).Conclusion:The pres-ent results indicate that a descending pathway from excitatory neurons of the IC terminates onto inhibitory neurons of the NTS,which might represent a potential neuromodulatory target for visceral pain disorders.
目的:明确岛叶(IC)-孤束核(NTS)神经通路及相关神经元神经化学特征。方法:实验选用成年雄性SD大鼠,分3组进行神经示踪。IC注射自互补型腺相关病毒(scAAVs)进行顺向标记;NTS注射逆行型scAAVs或荧光金(FG)进行逆向标记并结合免疫荧光染色;IC注射AAV2/1-CaMKI-Cre,NTS注射混合病毒(AAV2/9-Syn-DIO-mCherry+AAV2/9-VGAT1-EGFP)解析孤束核内神经元亚型。注射后动物存活时间分别为1周(scAAVs和FG)或4周(启动子特性病毒工具组),最终经心脏灌注后取脑、切片(含FG标记的脑切片经免疫荧光组织化学染色),最后通过荧光显微镜或激光共聚焦显微镜观察。结果:(1)顺行病毒示踪显示岛叶皮质投射至孤束核的轴突终末密集分布于孤束核内侧亚核;逆行示踪进一步揭示IC内向NTS投射的神经元主要分布于少颗粒层;(2)所有从IC向NTS投射的神经元均为谷氨酸能神经元(100%,n=3);(3)NTS内接受IC投射的神经元主要分布于内侧亚核,且有79.8%±3.2%的神经元为GABA能神经元。结论:本研究证实了ICClm NTSCABA下行通路,为靶向调控内脏痛觉的中枢机制研究提供了新方向。
出处
《神经解剖学杂志》
北大核心
2025年第4期411-421,共11页
Chinese Journal of Neuroanatomy
基金
福建省自然科学基金(2021J01340)
山东省自然科学基金(ZR2023MC005)
山东大学海右计划(CYLJ20231811290)。
