![]() ![]() ![]() For example, glucose enters the cells mainly via the GLUT family of facilitative transporters (although δ-cells recently were reported to also be equipped with Na +-dependent glucose transporters ). The glucose sensing machinery of δ-cells shares many features with that of β-cells. (2019) from the Rorsman laboratory present an extensive experimental effort that provides new insights into the mechanisms by which glucose stimulates somatostatin secretion from δ-cells. In this issue of the Journal of General Physiology, Denwood et al. The secretion of somatostatin is stimulated by glucose and other nutrients ( Rorsman and Huising, 2018), as well as paracrine factors ( van der Meulen et al., 2015 Adriaenssens et al., 2016 Vergari et al., 2019), but because of the scarcity of δ-cells and difficulties of accessing them for physiological investigations the understanding of the control mechanisms for somatostatin secretion is still rather limited (see Rorsman and Huising for a review of δ-cell physiology). Somatostatin potently inhibits the release of both glucagon and insulin and likely controls the phase relationship of the normal, pulsatile release pattern of the islet hormones, in which glucagon pulses occur in opposite phases to those of insulin and somatostatin ( Gylfe and Tengholm, 2014). The δ-cells have neurite-like extensions that enable contacts with many other cells and are, despite their low number, efficient paracrine regulators of islet function ( Cejvan et al., 2003 Hauge-Evans et al., 2009 Brereton et al., 2015 Li et al., 2017). Somatostatin is released from pancreatic δ-cells, which constitute ∼5–10% of the islet cell population ( Brissova et al., 2005). Pancreatic islets are key regulators of energy homeostasis, primarily because they secrete the blood glucose–lowering hormone insulin from β-cells and glucose-elevating glucagon from α-cells. By activating specific G protein–coupled receptors, somatostatin suppresses electrical activity, secretion and proliferation of the target cells ( Patel, 1999). Somatostatin is an inhibitory peptide produced by neuroendocrine cells in the nervous system, gastrointestinal tract and pancreatic islets. ![]()
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