Immunocytochemical study of trans-Golgi-network (TGN)-associated protein in salivary acinar cells under varying condition of salivary secretion

用抗Rab 3A、Rab 3B、Rab 3D、Rab 4和Rab 6（小CTP结合蛋白）和反式高尔基体网络（trans-Golgi network，TGN）标记物TGN 38的特异性抗血清，用免疫荧光法检测了这些Rab蛋白在小鼠和大鼠几种内分泌腺和外分泌腺中的分布。抗Rab 3A和Rab 6免疫反应阳性细胞分布于大鼠垂体内分泌细胞，推测Rab 3A免疫反应阳性细胞可能是ACTH细胞。抗Rab 3A抗体仅对大鼠胰岛的几种内分泌细胞进行免疫染色。当用抗胰腺激素的抗体对凝聚切片进行免疫染色时，发现这些免疫染色的细胞是α细胞。与此相反，抗Rab 3D免疫染色胰腺腺泡细胞，和免疫反应区域定位于酶原颗粒领域。在这些材料中已经尝试了Rab 3A或Rab 3D和TGN 38的双电子显微镜免疫金定位，但是通过电子显微镜没有获得最佳分辨率。然而，在光镜下发现，这些Rab蛋白的免疫反应定位应在分泌颗粒的领域。由于Rab与分泌颗粒相关，Rab蛋白可能在调节胞吐中起作用。

Specific antisera against Rab3A, Rab3B, Rab3D, Rab4, and Rab6, small CTP-binding proteins, and TGN38, a marker of trans-Golgi network (TGN), have been used to examine the distribution of these Rab proteins in several endocrine and exocrine glands of mouse and rat by immunofluorescence method. The anti-Rab3A and Rab6 immunostained some rat pituitary endocrine cells, It is conceivable by these distribution that the Rab3A-immunoreactive cells may be ACTH cells. The anti-Rab3A immunostained exclusively several endocrine cells of pancreatic islets of rat. When cosecutive sections were immunostained with antibodies against pancreatic hormones, these immunostained cells were found to be alpha cells. In contrast, anti-Rab3D immunostained pancreatic acinar cells, and the immunoreacted region localized to the zymogen granule field. Double electron microscopic immunogold localizations for Rab3A or Rab3D and TGN38 have been tried in these materials, but no optimal resolution has not obtained by electron microscope. However, it was found in the light microscopy that these immunoreactive localization of Rab proteins should be in the field of secretion granules. Because of the Rab associated with secretion granules, Rab proteins may play a role in regulated exocytosis.