High-affinity GABA uptake in a subpopulation of somatostatin cells in rat pancreas.

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Abstract
The aim of this study was to localize the high-affinity uptake of [3H]-GABA in Langerhans islets of rats aged 2.5, 7.5, and 75 days. On high-resolution autoradiography, cells presenting characteristic somatostatin granules were labeled, whereas others containing similar granules appeared nearly devoid of silver grains. Immunogold detection with antisomatostatin antibodies and high-resolution autoradiography suggested that uptake of GABA is indeed performed by somatostatin cells. To test the heterogeneity of uptake frequency in somatostatin cells, a second approach, coupling immunohistochemistry with anti-somatostatin, anti-PP, anti-glucagon, anti-glicentin, and anti-CCK antibodies, and low-resolution autoradiography, was applied on paraffin sections. It demonstrated that the uptake ability is not characteristic of all the somatostatin cells but of only a subpopulation of them. A few cells not immunoreactive to the anti-somatostatin antiserum also appeared to be able to take up GABA. Moreover, except for a rare few, the PP-glucagon-, glicentin-, and CCK-39-immunoreactive cells were not labeled by autoradiography.