Syed Ali Gilani, Joseph Fr O Hare, Mark Williams.
Ghrelin, leptin and plasma free fatty acid (FFA) levels are modulated in adaptation to fasting.
J Pak Med Students Jan ;1(3):68-74.

BACKGROUND: The hormones ghrelin and leptin play central roles in the regulation of appetite, energy expenditure and body weight. Changes in ghrelin and leptin, at least to some degree, are thought to underpin metabolic diseases such as the metabolic syndrome. This regulation is particularly highlighted in the response of a small mammal to a state of starvation in which ghrelin and leptin are modulated in order to increase survivability. The aim of this study was to examine the relationship between ghrelin, leptin, and plasma FFAs after fasting in mice. METHODS: Ten male mice were subjected to a controlled 18-hour fast. After 18 hours, a terminal blood sample was obtained for the analysis of hormone and plasma FFA levels. These levels were compared to control mice that received a normal diet and to baseline levels prior to fast. RESULTS: We found that the plasma ghrelin levels in the fasting mice were significantly higher than in control (1106 ± 72.57 vs. 282.3 ± 28.07 pg/ml; P<0.0001, STD err). In an antagonist manner, plasma leptin was significantly lower in fasting mice (3.2 [IQR 2.66-4.653] vs. 0.64 [IQR 0.458-1.105] ng/ml; P<0.0001). Plasma FFA doubled from control values of 4.438 ± 0.094 to a fasting average of 7.276 ± 0.413 μEq/L. CONCLUSION: The levels of plasma ghrelin, which is an appetite inducer, are significantly increased during a fast. Plasma leptin, which produces satiety, is reduced. Plasma FFAs are increased approximately two-fold, probably as a result of mobilization of fat stores. These changes may help to prolong survival of the animal under harsh conditions.

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