The amygdala via the paraventricular nucleus regulates asthma attack in rats.

Aims: This study aimed to investigate the functions of the amygdala in rat asthma model.

Main Methods: Wheat 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.

Results: This 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.

Conclusions: Asthma 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.