Immunolocalization of AQP-5 in rat parotid and submandibular salivary glands after stimulation or inhibition of secretion in vivo
Immunolocalization of AQP-5 in rat parotid and submandibular salivary glands after stimulation or inhibition of secretion in vivo
复制标题
DOI：
10.1152/ajpgi.00480.2003
复制
发表时间：
2004-07-01
影响因子：
4.5
通讯作者：
Nielsen, S
中科院分区：
文献类型：
--
作者：
Gresz, V;Kwon, TH;Nielsen, S
体外培养的唾液腺细胞和腺体切片的研究表明，可能有调节水通道蛋白（AQP）-5之间的顶端质膜和分泌细胞的细胞内室的易位。然而，目前还不清楚唾液腺中的AQP-5是否受到体内调节运输。为了研究这种可能性，我们研究了刺激或抑制唾液分泌条件下，在体内固定的大鼠腮腺和下颌下腺中AQP-5的亚细胞定位。免疫荧光和免疫电子显微镜被用来确定AQP-5的亚细胞分布在控制条件下的刺激分泌与毛果芸香碱（毒蕈碱激动剂）或肾上腺素（α-肾上腺素受体激动剂）或在抑制基础分泌与阿托品（毒蕈碱拮抗剂）或酚妥拉明（α-肾上腺素受体拮抗剂）。在对照条件下，> 90%的AQP-5与腺泡和闰管细胞的顶端质膜相关，只有罕见的金颗粒与细胞内膜结构域相关。毛果芸香碱治疗显着增加唾液的产生，但对AQP-5的分布没有明显的影响。然而，增加的唾液分泌与管腔扩张和显着点状AQP-5标记模式的外观，由于AQP-5在微绒毛（特别是在腮腺中明显）药物注射10分钟后的集群。与对照组织相比，肾上腺素、阿托品或酚妥拉明处理后AQP-5的亚细胞定位没有变化。因此，AQP-5是本地化的主要在顶端质膜在控制条件下，和无论是发病或停止分泌是相关的在体内与任何显着的短期易位的AQP-细胞内结构和顶端质膜之间。
In vitro studies of cultured salivary gland cells and gland slices have indicated that there may be regulated translocation of aquaporin (AQP)-5 between the apical plasma membrane and intracellular compartments of the secretory cells. However, it remains unknown whether AQP-5 in salivary glands is subject to regulated trafficking in vivo. To examine this possibility, we have investigated the subcellular localization of AQP-5 in rat parotid and submandibular glands fixed in vivo under conditions of stimulated or inhibited salivary secretion. Immunofluorescence and immunoelectron microscopy was used to determine the subcellular distribution of AQP-5 in control conditions following the stimulation of secretion with pilocarpine ( a muscarinic agonist) or epinephrine (an alpha-adrenoceptor agonist) or during inhibition of basal secretion with atropine ( a muscarinic antagonist) or phentolamine (an alpha-adrenoceptor antagonist). Under control conditions, > 90% of AQP-5 was associated with the apical plasma membrane of acinar and intercalated duct cells, with only rare gold particles associated with intracellular membrane domains. Pilocarpine treatment dramatically increased saliva production but had no discernible effect on AQP-5 distribution. However, the increased salivary secretion was associated with luminal dilation and the appearance of a markedly punctate AQP-5 labeling pattern due to clustering of AQP-5 at the microvilli ( especially evident in the parotid gland) after 10 min of drug injection. No changes in the subcellular localization of AQP-5 were seen in response to epinephrine, atropine, or phentolamine treatment compared with control tissues. Thus AQP-5 is localized predominantly in the apical plasma membrane under control conditions, and neither the onset nor the cessation of secretion is associated in vivo with any significant short-term translocation of AQP-between intracellular structures and the apical plasma membrane.