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AimsThis study aimed to investigate the functions of the amygdala in rat asthma model.Main methodsWheat germ agglutinin‐horseradish peroxidase (WGA‐HRP) was used for tracing from the paraventricular nucleus (PVN) to the amygdala, and nuclear lesions were performed to observe changes in respiratory function and airway inflammation.ResultsThis study showed that the extracellular neuronal discharged in the medial amygdala (MeA) and central amygdala (CeA), and the expression of Fos significantly increased in asthmatic rat compared to control group. The distribution of Fos‐ and oxytocin (OT)‐positive neurons and Fos/OT dual‐positive neurons evidently increased in the PVN. WGA‐HRP was injected into the PVN for tracing, and Fos/HRP‐dual‐positive neurons were observed to be distributed in the MeA. By using kainic acid (KA) to injure the MeA and CeA in asthmatic rats, expiratory and inspiratory times (TE/TI) and airway resistance (Raw) decreased, and minute ventilation volume (MVV) and dynamic pulmonary compliance (Cdyn) increased accordingly. In the bronchoalveolar lavage fluid (BALF), the number of eosinophils and the concentration of IL‐4 were lower than those of the control group, and the ratio of Th1/Th2 cells was higher than that of the control group. In the PVN, the distribution of Fos‐, OT‐positive cells and Fos/OT double‐positive cells decreased compared with those of the control group. The activities of the MeA and CeA and of OT neurons in the PVN of the rats were correlated with the occurrence of asthma.ConclusionsAsthma attack could induce neural activities in the MeA and CeA, and OT neurons in the PVN may be involved in the process of asthma attack.

Asthma is a heterogeneous disease, and the central nervous system (CNS) also participates in the pathogenesis of asthma. We previously reported the amygdala might regulate asthmatic attacks via projecting to the paraventricular hypothalamic nucleus (PVN). The dorsal vagal complex (DVC) is a crucial region that modulates respiratory. This study aimed to observe the activity in both PVN and DVC and the connection between PVN and DVC in asthmatic rats. Immunohistochemistry was conducted to observe the changes in Fos and oxytocin (OT) expression. Retrograde tracing using wheat germ agglutinin-horseradish peroxidase (WGA-HRP) and double immunohistochemistry for OT and Fos was used to observe the HRP/OT/Fos positive neurons distribution in the PVN. The results showed that during an asthma attack, the Fos positive neurons increased in both PVN and DVC over time. The expression of OT positive neurons in PVN showed a similar trend in parallel to the c-Fos positive neurons in PVN. The HRP retrograde-labeled neurons were densely distributed in the medial and lateral subnucleus in the PVN. OT + /HRP + and Fos + /OT + /HRP + accounted for 18.14%, and 2.37% of HRP-labeled neurons, respectively. Our study showed PVN and DVC were activated and the expression of OT positive neurons in PVN were increased over time during an asthma attack. The existence of connection between PVN and DVC suggested the OT neurons in PVN might project to DVC which might be involved in the pathogenesis of asthma.