GABA AND PANCREATIC BETA-CELLS - COLOCALIZATION OF GLUTAMIC-ACID DECARBOXYLASE (GAD) AND GABA WITH SYNAPTIC-LIKE MICROVESICLES SUGGESTS THEIR ROLE IN GABA STORAGE AND SECRETION
GABA AND PANCREATIC BETA-CELLS - COLOCALIZATION OF GLUTAMIC-ACID DECARBOXYLASE (GAD) AND GABA WITH SYNAPTIC-LIKE MICROVESICLES SUGGESTS THEIR ROLE IN GABA STORAGE AND SECRETION
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DOI：
10.1002/j.1460-2075.1991.tb08069.x
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发表时间：
1991-05-01
期刊：
影响因子：
11.4
通讯作者：
DECAMILLI, P
中科院分区：
文献类型：
--
作者：
REETZ, A;SOLIMENA, M;DECAMILLI, P
GABA, a major inhibitory neurotransmitter of the brain, is also present at high concentration in pancreatic islets. Current evidence suggests that within islets GABA is secreted from beta-cells and regulates the function of mantle cells (alpha- and delta-cells). In the nervous system GABA is stored in, and secreted from, synaptic vesicles. The mechanism of GABA secretion from beta-cells remains to be elucidated. Recently the existence of synaptic-like microvesicles has been demonstrated in some peptide-secreting endocrine cells. The function of these vesicles is so far unknown. The proposed paracrine action of GABA in pancreatic islets makes beta-cells a useful model system to explore the possibility that synaptic-like microvesicles, like synaptic vesicles, are involved in the storage and release of non-peptide neurotransmitters. We report here the presence of synaptic-like microvesicles in beta-cells and in beta-cell lines. Some beta-cells in culture were found to extend neurite-like processes. When these were present, synaptic-like microvesicles were particularly concentrated in their distal portions. The GABA synthesizing enzyme, glutamic acid decarboxylase (GAD), was found to be localized around synaptic-like microvesicles. This was similar to the localization of GAD around synaptic vesicles in GABA-secreting neurons. GABA immunoreactivity was found to be concentrated in regions of beta-cells which were enriched in synaptic-like microvesicles. These findings suggest that in beta-cells synaptic-like microvesicles are storage organelles for GABA and support the hypothesis that storage of non-peptide signal molecules destined for secretion might be a general feature of synaptic-like microvesicles of endocrine cells.
