P2X2和P2X3受体在小鼠咽粘膜味蕾内的分布

应用免疫组织化学双标记技术研究ATP受体的P2X2和P2X3受体亚型在小鼠咽部粘膜味蕾和邻近组织内的分布,探究ATP在咽部味觉及一般感觉信号传导中的作用。在咽部各水平粘膜味蕾内均可观察到许多P2X2受体阳性味细胞和基细胞,未见P2X2受体阳性的神经纤维。许多降钙素基因相关肽(CGRP)阳性神经纤维围绕在味蕾周围,并发出分支与P2X2受体阳性味细胞和基细胞形成密切接触。P2X3受体多在咽部粘膜上皮味蕾内的神经终末表达,P2X3受体阳性纤维在粘膜基底部形成纤维束并与粘膜下P2X3受体阳性纤维相连,其分支在味蕾基底部形成神经丛,由神经丛发出神经终末到达顶部的味孔和味蕾各部,未见味蕾细胞表达P2X3受体。在无味蕾的粘膜上皮内,也观察到少量P2X3受体阳性神经终末。CGRP阳性纤维缠绕在味蕾周围,并发出分支与味蕾内的P2X3受体阳性纤维形成密切接触。上述结果表明ATP可能是咽粘膜内味觉信号感受与传导的神经递质。

LOCALIZATION OF P2X2 AND P2X3 RECEPTORS IN MOUSE PHARYNGEAL TASTE BUD

To explore the role of ATP in the signal transduction of taste and other sensory suimuli, the localization of P2X_2 and P2X_3 receptors in mouse pharyngeal taste bud and surrounding tissues was examined by using immunohistochemical double-labeling technique. The results showed that P2X_2 receptor immunoreactivity expressed in the taste receptor cells and basal cells within pharyngeal taste bud of the mouse. P2X_2 receptor immunoreactive fibers were not observed. Calcitonin gene-related peptide (CGRP) immunopositive fibers surrounding the taste bud were seen and made close association with P2X_2 receptor immunoreactive taste receptor cells and basal cells. P2X_3 receptor immunoreactive fibers were seen to enter the pharyngeal base, then diverge to the taste bud and terminate in a nerve plexus at the base of the taste buds of pharyngeal epithelium. Nerve terminalis from the plexus extend into the apex as well as the entire taste bud. CGRP immunopositive fibers diverged within taste bud and intermingled with P2X_3 receptor immunoreactive terminalis. These results suggest that ATP miglt be a neurotransmitter in taste signals reception and transduction by activating P2X receptors at the synapses.