Acute intravenous glucose load impairs early insulin secretion and insulin content in islet β cells in mice

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• 作者：DiEn Yan ; YiNan Zhao ; XiuYing Gao ; YingSheng Zhou ; ^{yszhou@ccmu.edu.cn" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Acute hyperglycemia ; IPGTT ; GSIS ; Insulin granules
• 刊名：Life Sciences
• 出版年：2016
• 出版时间：1 January 2016
• 年：2016
• 卷：144
• 期：Complete
• 页码：148-155
• 全文大小：1293 K

文摘

To investigate insulin secretion and content in islet β cells after intravenous glucose load in mice.

Materials and methods

Acute hyperglycemia (≥ 16.7 mmol/L) in C57BL/J6 mice was achieved by hyperglycemic clamp. Mice were divided into four groups: a 2-hour and a 4-hour high glucose-infusion (2 h-HG and 4 h-HG) with 25% dextrose groups and control groups with saline infusion of the same duration. Insulin levels and response were measured using intraperitoneal glucose tolerance test (IPGTT) in mice and glucose-stimulated insulin secretion (GSIS) for isolated islets after overnight culture. Immunohistochemistry and electron microscopy (EM) for islet β cells were used after the hyperglycemic clamp to study morphologic changes of insulin granules and to assess the impact of acute glucose load on islet histology.

Key findings

Blood glucose at 15, 30, 60 and 120 min was significantly higher in 4 h-HG compared with the other groups. Serum plasma insulin significantly decreased only at 15 min as a first-phase insulin response (FPIR). Insulin secretion at 2.8 and 16.7 mmol/L glucose stimulus in 4 h-HG group decreased 77% and 64% more than those in 2 h-HG, respectively (P < 0.05). Similarly, residual insulin content in islet β cells after 2.8 and 16.7 mmol/L glucose challenge decreased 30% and 43% more than those in 2 h-HG, respectively (P < 0.05). EM showed decreased insulin granules in islet cells and swollen mitochondria only in 4 h-HG.

Significance

Short time intravenous glucose load blunted FPIRs and decreased insulin content of islet β cells.