title: Storage of GABA in chromaffin granules and not in synaptic-like microvesicles in rat adrenal medullary cells.
abstract: Neurons and certain kinds of endocrine cells, such as adrenal medullary (AM) cells, have large dense-core vesicles (LDCVs) and synaptic vesicles or synaptic-like microvesicles (SLMVs). These secretory vesicles differ in Ca(2+) sensitivity and contain different signaling substances. We have recently reported that GABA functions as a paracrine factor in rat AM cells and modulates catecholamine secretion. The present experiment was undertaken to examine the subcellular localization of the GABA system including GABA itself in AM cells. Fractionation analysis with sucrose density gradient and immunocytochemistry indicated that vesicular GABA transporter (VGAT) was localized in LDCVs and not SLMVs in rat and bovine AM cells. In addition, significant amounts of GABA were detected in high density fractions, which contained LDCVs. When green fluorescence protein-VGAT and green fluorescence protein-vesicular ACh transporter were exogenously expressed in PC12 cells, the former and the latter were selectively targeted to LDCVs and SLMVs, respectively. We conclude that GABA is stored in chromaffin granules in rat and bovine AM cells through VGAT.
authors.affiliation: Department of Cell and Systems Physiology, University of Occupational and Environmental Health School of Medicine, Kitakyushu, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Harada
authors.forename: Hidetada
authors.initials: H
authors.lastname: Matsuoka
authors.forename: Jun
authors.initials: J
authors.lastname: Nakamura
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Fukuda
authors.forename: Masumi
authors.initials: M
authors.lastname: Inoue
mesh_terms: D000313:Adrenal Medulla / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002458:Cell Fractionation; D002837:Chromaffin Granules / Q000378:metabolism*; D008297:Male; D016716:PC12 Cells; D051381:Rats; D017208:Rats, Wistar; D022142:Secretory Vesicles / Q000378:metabolism*; D050495:Vesicular Inhibitory Amino Acid Transport Proteins / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: C118623:Slc32a1 protein, rat; D050495:Vesicular Inhibitory Amino Acid Transport Proteins; D005680:gamma-Aminobutyric Acid