Daytime food restriction alters liver glycogen, triacylglycerols, and cell size. A histochemical, morphometric, and ultrastructural study

RFS promoted a decrease in the liver/body weight ratio prior to food access, a reduction of hepatic water content, an increase in cross-sectional area of the hepatocytes, a moderate reduction in glycogen content, and a striking decrease in triacylglyceride levels. Although these adaptation effects were also observed when the animal displayed FAA, they were reversed upon feeding. Mitochondria observed by electron microscopy showed a notorious opacity in the hepatocytes from rats during FAA (11:00 h). Twenty four hour fasting rats did not show any of the modifications observed in the animals expressing the FEO.Our results demonstrate that FEO expression is associated with modified liver handling of glycogen and triacylglycerides accompanied by morphometric and ultrastructural adaptations in the hepatocytes. Because the cellular changes detected in the liver cannot be attributed to a simple alternation between feeding and fasting conditions, they also strengthen the notion that RFS promotes a rheostatic adjustment in liver physiology during FEO expression.From an evolutionary perspective, circadian systems have conferred a survival advantage by optimizing behavioral and physiological adaptations to periodic events that occur approximately each 24 h. An ultimate goal of this adaptation is to enhance the reproductive success and life span by allowing more effective access to nutritional resources [1,2]. The vertebrate circadian system results from the coordinated action of a light-entrained master pacemaker located in the suprachiasmatic nucleus (SCN) of the hypothalamus, and a set of subordinated clocks in peripheral organs [3]. The 24-h programs of the central and peripheral oscillators are based on similar, but not identical, molecular transcription-translation feedback loops [4]. The normal timing between the principal and the peripheral clocks can be disrupted when activity, sleep, or feeding patterns are altered [5]. An example of this situation happens when feedin