The effect of nutritional and thyroid state on the distribution of fatty acids between oxidation and esterification in isolated rat hepatocytes.
Small amounts of glycerol (0.25 mM) simultaneously decrease oxidation and increase esterification of fatty acids in isolated rat hepatocytes, mainly by raising the intracellular concentration of alpha-glycerophosphate. These effects were obtained in all thyroid states as well as in the fed and fasted states. In normal hepatocytes, the rate of oxidation showed a poor correlation with the content of malonyl-CoA. The effects of glycerol on fatty acid metabolism were most pronounced in hepatocytes with a high capacity for esterification and a previous low concentration of alpha-glycerophosphate (glucagon-treated hepatocytes from euthyroid fed rats). Esterification capacity was influenced by the nutritional and thyroid state (decreased in fasting and in hyperthyroidism). It was not influenced by glucagon in short-term experiments. alpha-Glycerophosphate may not regulate fatty acid metabolism in vivo, but a high esterification capacity probably traps acyl-CoA for esterification, thus preventing fatty acids from being oxidized. The metabolism of alpha-glycerophosphate seems to be accelerated by hyperthyroidism and slowed down by fasting. The effect of fasting seems not to depend on thyroid hormones for its effects on fatty acid metabolism in the liver.
D000818:Animals; D004952:Esters; D005215:Fasting; D005227:Fatty Acids / Q000378:metabolism*; D005990:Glycerol / Q000494:pharmacology*; D005994:Glycerophosphates / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008297:Male; D010084:Oxidation-Reduction; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000378:metabolism; D051381:Rats; D013961:Thyroid Gland / Q000502:physiology*
D004952:Esters; D005227:Fatty Acids; D005994:Glycerophosphates; D010169:Palmitic Acids; D019308:Palmitic Acid; D005990:Glycerol