Hormonal regulation of glucose clearance in lactating northern elephant seals (Mirounga angustirostris)
Hormonal regulation of glucose clearance in lactating northern elephant seals (Mirounga angustirostris)
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DOI：
10.1242/jeb.018176
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发表时间：
2008-09-15
影响因子：
2.8
通讯作者：
Crocker, Daniel E.
中科院分区：
文献类型：
--
作者：
Fowler, Melinda A.;Champagne, Cory D.;Crocker, Daniel E.
北方象海豹表现出罕见的禁食和哺乳的策略。我们通过在哺乳早期和断奶前进行的葡萄糖耐量测试(GTT)来研究北部象海豹葡萄糖清除的激素调节。为了进行比较，在蜕皮禁食后期对不同的雌性进行了相同的测量。连续采血测定葡萄糖注射后3h的葡萄糖清除率和激素反应。在采样期结束时，所有组的血糖都保持在较高水平。各试验组之间的葡萄糖清除率没有显著差异。在哺乳早期观察到显著的胰岛素反应，在哺乳期后期没有观察到显著的反应，在蜕皮禁食后期观察到中期的反应。胰岛素对葡萄糖负荷的反应随着脂肪组织比例的增加而降低。在哺乳早期和晚期，血浆胰高血糖素在GTT后显著下降，尽管与其他物种相比下降的幅度较小。低血糖可能是促进哺乳期晚期净脂肪分解的关键因素。试验组之间持续的低葡萄糖清除提示外周组织对胰岛素不敏感。不依赖于胰岛素释放的高血糖素抑制提示典型的胰岛素-高血糖素反调节机制的改变。这些发现表明，糖尿病样疾病的代谢特征可能适用于长期禁食的情况。
Northern elephant seals exhibit the rare strategy of fasting and lactating concomitantly. We investigated hormonal regulation of glucose clearance in northern elephant seals using glucose tolerance tests (GTT) performed early in lactation and again just prior to weaning. For comparison, identical measurements were made on separate females late in the molt fast. Serial blood samples were used to assess glucose clearance and hormone responses for 3 h post glucose injection. Plasma glucose remained elevated at the end of the sampling period in all groups. Glucose clearance rates were not significantly different among test groups. A significant insulin response was observed in early lactation, no significant response was observed late in lactation and an intermediate response was observed late in the molt fast. The insulin response to a glucose load decreased with adipose tissue proportions. Plasma glucagon decreased significantly following GTT in early and late lactation, although the magnitude of the depression was small in comparison to other species. Hypoinsulemia may be critical to facilitate net lipolysis late in lactation. Consistently low glucose clearance among test groups suggests insulin insensitivity within peripheral tissues. Glucagon suppression independent of insulin release suggests modification of the typical insulin-glucagon counter-regulation. These findings suggest that metabolic features of diabetic- like conditions may be adaptive in the context of long-term fasting.