Metabolism in starvation

The entire process of ketosis reversed by restoring an adequate level of carbohydrate metabolism. In starvation, restoration consists of adequate carbohydrate ingestion in diabetes melhtus, ketosis can be reversed by insulin administration, which permits circulating blood glucose to be taken up by the cells. With production of oxaioacetate, the... 

Cahill GE. Enel metabolism in starvation. Annu Rev Nutr. 2006 26 1-22. 

Brain Coordination of the nervous system Glycolysis, amino acid metabolism Glucose, amino acid, ketone bodies (in starvation) Polyunsaturated fatty acids in neonate Lactate ... 

The major role of skeletal muscle is movement, which is described and discussed in Chapter 13). Nevertheless, since muscle comprises 40% of the body it is large enough to play a part in control of the blood concentrations of the major fuels glucose, fatty acids, triacylglycerol and some amino acids. Skeletal muscle contains the largest quantity of protein in the body, which is used as a source of amino acids under various conditions (e.g. starvation, trauma, cancer see above). It plays an important part in the metabolism, in particular, of branched-chain amino acids, glutamine and alanine, which are important in the overall metabolism of amino acids in the body (discussed below). 

A detailed account of the metabolic changes that occur in starvation and the role they play in ensuring survival, from even a prolonged period of starvation, is presented in Chapter 16. 

The amino acids that are made available as a result of protein degradation in starvation are nsed as precursors of glucose, which is required for the brain. The decline in starvation-induced protein degradation is a result of the decreased requirement for glucose by the brain due to the increase in utilisation of ketone bodies. The qnestion arises, therefore, as to the mechanism by which the protein breakdown in muscle is reduced. Two answers, which are interdependent, have been put forward (i) decreased metabolic activity in tissues, and (ii) a decrease in the plasma level of thyroxine and hence triiodothyronine. 

The anorexia suffered by cancer patients is likely to arise from a combination of psychological stress, altered senses of taste and smell and increased levels of cytokines, which influence the appetite and satiety centres in the hypothalamus. There are several consequences micronutrient intake will be diminished and this may contribute to the signs and symptoms of the disease. Plasma amino acid levels will fall, as in starvation (Chapter 16). Synthesis of glutamine (by muscle, adipose and lung), aspartate (by liver), glutathione (by the intestine) and arginine (by the kidney) will all be compromised. The metabolic significance of all of these is discussed in Chapter 18. 

Action through delignification that commences at the onset of the secondary metabolic (nitrogen starvation) phase in most fungi. 

Since the presumed cytosolic pathway interfaces directly with the network of secondary metabolism, the observed induction of DS-Co and CM-2 isozymes in response to wounding was expected. However, the even greater response of plastidic isozymes was unexpected. Perhaps the increased pull on carbohydrate metabolism in the cytosol affects the balance of substrates feeding into the aromatic pathway of the plastid. If so, a tendency to starvation for pathway endproducts may trigger derepression of the plastidic-pathway isozymes. 

In addition to the effects of a low insulin/glucagon ratio, long-term changes in metabolism during starvation are induced by the corticosteroid, cortisol. 

Goldstein, A.H., Baertlein, D.A. McDaniel, R.G. (1988a). Phosphate starvation inducible metabolism in L. esculentum I. Plant Physiology 87, 711-15. 

Gerald, V.M. (1976). The effect of starvation on energy turnover and protein metabolism in Ophiocephalus punctatus. Hydrobiologia 49,131-201. 

Maksimovich, A. A. (1988). The characteristics of carbohydrate metabolism in Pacific salmon under total starvation (In Russian). Izvestiya Akademii Nauk SSSR, Seriya Biologiya 1988 (4), 500-508. 

L. Sicko-Goad and T. Jensen (1976). Phosphate metabolism in blue-green algae. II. Changes in phosphate distribution during starvation and the phosphate overplus phenomenon in Plectonema... 

Michael MD, Kulkami RN, Postic C et al. (2000) Loss of insulin signaling in hepatocytes leads to severe insulin resistance and progressive hepatic dysfunction. Mol Cell 6 87-97 Neumann-Haefelin C, Beha A, Kuhlmann J et al. (2004) Muscle-type specific intramyocellular and hepatic lipid metabolism during starvation in Wistar rats. Diabetes 53 528-534... 

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