Glucose homeostasis

Maintenance of blood glucose within a narrow concentration range is critical to 

Glucose is required as the sole fuel for certain tissues, especially the hrain. 

The liver and kidney are the main organs involved in regulating blood glucose, both directly in response to blood glucose rise and fall as well as in response to hormones. 

Regulation of blood glucose concentration occurs initially through changes in its 

Glucose uptake is mediated by the glucose transporters GLUTl or GLUT4 

All except liver. Muscle and adipose tissue at diminished rate 

Brain at a diminished rate, red blood cells, renal medulla 

1 The preferred fuel of the brain is glucose. If the blood glucose concentration falls (hypoglycaemia), the brain is deprived of fuel (neuroglycopenia) which progressively results in unconsciousness, coma, brain damage and inevitably death. 

2 The immediate reserve of glucose is liver glycogen. This is mobilised by glucagon within a few hours of fasting to maintain the normal blood glucose concentration. (NB Muscle reserves glycogen for its own use.) 

3 The brain cannot nse fatty acids as a fuel. This is because they 

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Rosen ED, Spiegelman BM (2006) Adipocytes as regulators of energy balance and glucose homeostasis. Nature 444 847-853... 

Central control of glucose homeostasis critically depends on the brain s ability to sense extracellular [glucose]. Within hypothalamus at least two types of neurons were identified which are presumably involved in this process. They are either glucose excited or glucose inhibited. Both types of neurons appear to be involved in the control of feeding, hepatic gluconeogenesis,... 

Taken together, these data emphasize the importance of insulin action in the liver for glucose homeostasis, in the regulation of insulin secretion from (3-cells and indicate that the INSR plays an important role in the central regulation of body weight and reproduction [4, 5]. 

Insulin Receptor. Table 1 The effect of insulin on energy and glucose homeostasis... 

Scheuner, D., Song, B., McEwen, E., Liu, C., Laybutt, R., Gillespie, P., Saunders, T., Bonner-Weir, S., and Kaufman, R. J. (2001). Translational control is required for the unfolded protein response and in vivo glucose homeostasis. Mol. Cell 7, 1165—1176. 

Cazarolli LH, Zanatta L, Alberton EH, Figueredo MS, Folador P, Damazio RG, Pizzolatti MG and Silva FR. 2008. Flavonoids cellular and molecular mechanisms of action in glucose homeostasis. Mini Rev Med Chem 8(10) 1032-1038. 

The liver not only extracts glucose from the blood in the postprandial state and stores it as glycogen, but is also able to synthesize glucose from non-carbohydrate sources via gluconeogenesis, therefore the liver is crucial in regulating glucose homeostasis. 

Leptin is not the only player in regulation of food intake. There are several other players, including insulin and a number of hormones secreted by the gut. Insulin plays a key role. The blood levels of insulin are proportional to the amount of body fat. Insulin acts in the brain to decrease food intake. Therefore, insulin also acts to maintain body weight constant in addition to its multiple effects on glucose homeostasis. 

Bergman RN, Ader M. Atypical antipsychotics and glucose homeostasis. J Clin Psychiatry 2005 66 504-514. 

Rodgers, J.T, Lerin, C., Haas, W., Gygi, S.P., Spiegelman, B.M. and Puigserver, P. (2005) Nutrient control of glucose homeostasis through a complex of PGC-lalpha and SlRTl. Nature, 434, 113-118. 

Insulin sensitivity Glucose homeostasis Vascular integrity... 

GLUT 2 Beta cells of pancreas liver, kidney gut 15-20 Regulation of insulin release, other aspects of glucose homeostasis... 

The effect of garlic on glucose homeostasis does not appear to be significant in persons with diabetes. Certain organosulfur constituents in garlic, however, have demonstrated hypoglycemic effects in nondiabetic animal models. 

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