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      β-Cell Control of Insulin Production During Starvation-Refeeding in Male Rats.

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          Abstract

          Mammalian metabolism has evolved to adapt to changes in nutrient status. Insulin, the key anabolic hormone, facilitates intracellular storage of nutrient fuels and plays a pivotal role in the transition away from catabolism upon refeeding. Although circulating insulin relative to nutrient levels has been well characterized during fasting and refeeding, how pancreatic β-cell biology caters to acute changes in insulin demand has not been sufficiently addressed. Here, we examined the dynamics of (pro)insulin production and associated changes in β-cell ultrastructure during refeeding after a 72-hour fast in male rats. We found that fasted β-cells had marked degranulation, which inversely coordinated with the upregulation of autophagolysomal and lysosomal organelles. There was also expanded Golgi that correlated with enhanced (pro)insulin biosynthetic capacity but, conversely, blunted in vivo insulin secretion. Within 4 to 6 hours of refeeding, proinsulin biosynthesis, cellular ultrastructure, in vivo insulin secretion, and glucose tolerance normalized to levels near those of fed control animals, indicating a rapid replenishment of normal insulin secretory capacity. Thus, during a prolonged fast, the β-cell protects against hypoglycemia by markedly reducing insulin secretory capacity in vivo but is simultaneously poised to efficiently increase (pro)insulin production upon refeeding to effectively return normal insulin secretory capacity within hours.

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          Author and article information

          Journal
          Endocrinology
          Endocrinology
          The Endocrine Society
          1945-7170
          0013-7227
          February 01 2018
          : 159
          : 2
          Affiliations
          [1 ] Kovler Diabetes Center, Department of Medicine Section of Endocrinology, Diabetes and Metabolism, University of Chicago, Chicago, Illinois.
          [2 ] Division of Cardiovascular and Metabolic Disease, MedImmune LLC, Gaithersburg, Maryland.
          Article
          4736309
          10.1210/en.2017-03120
          5776497
          29244064

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