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KMID : 1141520170320040475
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Endocrinology and Metabolism
2017 Volume.32 No. 4 p.475 ~ p.484
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Rebound Feeding in the Wake of Short-Term Suspension of Food Intake Differs in the Presence of Estrous Cycle Peak versus Nadir Levels of Estradiol
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Shakya Manita
Briski Karen P.
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Abstract
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Background: Short-term interruption of feeding is ordinary in modern life but negatively impacts appetite control and body weight. Estradiol (E) imposes long-term inhibitory tonus on food consumption; however, E influence on energy repletion secondary to food deprivation (FD) is unclear. This study investigated the hypothesis that E signal strength regulates hyperphagic responses to FD of varying duration.
Methods: Ovariectomized female rats were implanted with E-containing silastic capsules (30 [E-30] or 300 μg [E-300]/mL) to replicate plasma concentrations at cycle nadir versus peak levels.
Results: Data show that food intake was increased equally in E-30 and E-300 rats after 12 hours of food deprivation (FD-12); yet, FD of 18 hours (FD-18) amplified refeeding by E-300 versus E-30. Caudal fourth ventricular administration of the 5′-monophosphate-activated protein kinase (AMPK) inhibitor compound C (Cc) did not modify FD-induced hyperphagia in E-30 (regardless of FD interval) or E-300 animals exposed to FD-12, but diminished refeeding after FD-18 in E-300 rats. Cc-reversible hyperglycemia occurred in refed FD-18 groups. Serum insulin was resistant to FD-12 plus refeeding, but was elevated by AMPK-dependent mechanisms in refed E-300 FD-18 rats; equivalent Cc-insensitive decrements in circulating leptin occurred in all FD groups.
Conclusion: Current results show that estrous cycle peak, but not baseline, E levels engage hindbrain AMPK signaling to intensify hyperphagia in response to prolongation of FD. Observations of hindbrain AMPK-dependent hyperglycemia, alongside elevated insulin secretion, in refed rats exposed to FD-18 implicate this sensor in insulin resistance mechanisms of glucose partitioning in response to this metabolic imbalance.
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KEYWORD
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Refeeding, Food deprivation, AMP-activated protein kinases, Compound C, Estradiol, Insulin
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