ヒト鼻粘膜におけるアドレナリン作働性,コリン作働性受容体

抄録

It is generally accepted that an imbalance of the autonomic nervous system is one of the factors to cause allergic symptoms. It is reported that the parasympathetic nerve is predominant in the patients with allergic rhinitis and that autoantibodies to β₂ adrenergic receptors may mediate β adrenergic hyporesponsiveness in allergic rhinitis and asthma. Our purpose of this study was to investigate α adrenergic, β adrenergic and muscarinic acetylcholine receptors in the inferior turbinate of allergic rhinitis. The nasal mucosa was obtained from 17 patients with allergic rhinitis who demonstrated a positive skin test, positive provocation test and marked eosinophilia in nasal secretion. As a control, samples were obtained from 14 patients with hypertrophic rhinitis and nasal obstruction. The nasal mucosa of the inferior turbinate was resected and stored at -80°C. It was homogenized with a polytron and then centrifuged at 24000g for 20 minutes. The final supernate was made of to suspense the pellet. As radioligand, ³H-DHE, ³H-DHA and ³H-QNB were used. Using these radioligands, a adrenergic, β adrenergic and muscarinic acetylcholine receptors were identified. Binding affinity (Kd) and maximum binding(Bmax) of these receptors were determined according to the method of Scatchard. In patients with allergic rhinitis, the Bmax values of a adrenergic receptors, β adrenergic receptors and muscarinic acetylcholine receptors were 124.8±33.1 (mean±SEM) fmol/mg protein, 45.57±18.20fmol/mg protein and 222±75fmol/mg protein, respectively. In those with hypertrophic rhinitis, the Bmax values of those were 200.2+53.3 (mean±SEM) fmol/mg protein, 59.84± 24.48fmol/mg protein and 184±56fmol/mg protein, respectively. The Smax values of α adrenergic receptors were reduced significantly in patients with allergic rhinitis compared with those with hvpertrophic rhinitis. But those of β adrenergic receptors were not reduced significantly. Those of muscarinic acetylcholine receptors were not increased significantly in patients with allergic rhinitis compared with those with hypertrophic rhinitis. In patients with allergic rhinitis, the Kd values of α adrenergic receptors, β adrenergic receptors and muscarinic acetylcholine receptors were 1.41±1.00 (mean±SEM) nM, 0.56±0.28nM and 2.94±1.00nM, respectively. In those with hypertrophic rhinitis, the Kd values of those were 1.21±0.69nM, 0.48±0.13nM and 2. 72±1.44nM, respectively. There was no significant difference in the Kd values between patients with allergic rhinitis and those with hypertrophic rhinitis. We consider that a significant decrease of the Bmax values of α adrenergic receptors in patients with allergic rhinitis compared with those with hypertrophic rhinitis was based on down regulation.