Role of anterior hypothalamus on asthma

ObjectiveAsthma is well known as one of the allergic diseases under the influence of autonomic nervous system, endocrine system and psychosocial factors. In the present study, we investigated the involvement of the hypothalamus, the center of autonomic nervous system and endocrine system, in pathophysiology of asthma using excitotoxin of glutamatergic system.MethodsBrown Norway rats sensitized by ovalbumin (OA) were used as the animal model of late asthma. Selected neuronal damage was performed by microinjection of kainic acid (KA) 50 nl to the medial preoptic (MPO) area in the anterior hypothalamus 1 week before inhalation challenge of OA (MPO group). Artificial cerebrospinal fluid was injected to the same area of the control rats (sham group). kainic acid was injected to the 3 mm lateral from MPO area (non-MPO group).The numbers of eosinophils and subpopulation of lymphocytes were counted in bronchoalveolar lavage fluid (BALF). Histological staining was also performed to examine infiltrated eosinophils in the airway tract.ResultsThe MPO-lesioned group showed the significantly lower number of eosinophils and helper T-cells in the BALF. Eosinophilic infiltration to peribronchial tissues was also significantly reduced. The plasma catecholamine levels in the MPO group were significantly higher than those in the control (non-MPO and sham) groups. No differences were found in the plasma corticosterone levels of three groups.ConclusionThis study provides evidence that AHA lesions inhibit the late asthmatic response related to airway eosinophilic infiltration, possibly via a suppression of the parasympathetic nervous function.