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(487) IMMUNOCYTOCHEMICAL LOCALIZATION OF SNAP-23 IN RAT TESTIS AND CAUDA EPIDIDYMIS. Dominguez, Luis1, Cavicchia, Juan1, Burgos, Mario1, 1 Instituto de Histologia y Embriologia, Facultad de Ciencias Medicas, Universidad Nacional de Cuyo - CONICET, Mendoza, Argentina ABSTRACT- Cells release different substances to their surrounding environment by exocytosis. This is a highly regulated cellular process and it involves the fusion of membrane of secretory vesicles with the plasma membrane. The SNARE hypothesis postulates that a large set of proteins is involved in exocytosis regulation. One of them is SNAP-25, a protein anchored to the plasma membrane cytosolic face of neuronal and neuroendocrine cells, which is part of an exocytosis fusion complex. SNAP-23, a ubiquitous isoform of SNAP-25, is also considered a plasma membrane protein. To determine the presence and structural localization of SNAP-23 in the rat cauda epididymis and testis, we have performed colloidal gold immunoelectron microscopy in Lowicryl-embedding sections. In cauda epididymis, SNAP-23 was found in epithelial cells, sperm cells and fluid and it mostly localized in the apical plasma membrane of epithelial cells. In testis, SNAP-23 was found throughout the cytoplasm of seminiferous tubule cells (such as Sertoli cells, round and late spermatids), interstitial cells (such as Leydig cells, macrophages) and interstitial lymph. SNAP-23 mostly localized in late spermatids and tubule-associated lymph. The localization of SNAP-23 may be related to its putative role in exocytosis regulation. (Supported by grants from CONICET and CIUNC, Argentina). KEY WORDS: SNAP-23, SNARE proteins, testis, cauda epididymis |
