Ultrastructural localization of gamma amino butyric acid immunoreactivity in B cells of the rat pancreas

D. J. Garry, R. L. Sorenson, H. D. Coulter

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28 Scopus citations

Abstract

The purpose of this study was to determine the ultrastructural localization of gamma amino butyric acid (GABA) within the B cell of isolated rat islets, particularly with respect to the B cell secretion granules. GABA immunoreactivity was localized ultrastructurally, with colloidal gold, in the B cells and absent in the A cells and D cells. Quantitative analysis of the colloidal gold particle distribution in the B cell revealed 29.5±5.2 gold particles/μm2 in the nuclei, 29.3±6.9 gold particles/μm2 in the mitochondria and 4.9±1.0gold particles/μrn2 in the secretion granules. Particle density in the remainder of the cytoplasm was 41.9±4.1 particles/μm2. The paucity of gamma amino butyric acid in the B cell secretion granules differs from observations on gamma amino butyric acidergic neurons, where there is an accumulation of gamma amino butyric acid within the neurosecretory vesicles. These findings indicate that if gamma amino butyric acid is released from the islet, then it is by a nongranular mechanism. In addition, the results are compatible with the hypotheses that gamma amino butyric acid within the B cell functions in the regulation of insulin biosynthesis, and/or functions as an alternative energy source for the B cell through the gamma amino butyric acid shunt.

Original languageEnglish (US)
Pages (from-to)115-119
Number of pages5
JournalDiabetologia
Volume30
Issue number2
DOIs
StatePublished - Feb 1 1987

Keywords

  • GABA
  • Lowicryl K4M
  • electron microscopy
  • immunohistochemistry
  • insulin
  • islet of Langerhans

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