Hepatic glucose utilization and lipogenesis of hybrid striped bass (Morone chrysops × Morone saxatilis) in response to dietary carbohydrate level and complexity
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The influence of carbohydrate level and complexity on in vitro hepatic glucose utilization and lipogenesis were determined in hybrid striped bass, Morone chrysops ♀ × Morone saxatilis ♂. Six isocaloric, isonitrogenous diets containing glucose, maltose, or dextrin at two different levels (200 or 400 g kg-1 diet) were fed to adult fish for 15 weeks. Liver explants were obtained at near-maximum postprandial glycaemic response and incubated with radioactive labelled substrates. Glycogen synthesis from [ 14C]glucose was not different among treatments and was less than 14CO2 formation. 14CO2 production increased as a function of carbohydrate level but was unrelated to carbohydrate complexity. There was no detectable conversion of [14C]glucose to lactate for any treatment. Rates of de novo lipogenesis from [1- 14C]acetate were high in comparison to [U-14C]glucose or [9,10-3H]palmitate incorporation into liver lipids and differed in response to carbohydrate level and complexity. [9,10-3H]palmitate esterification was an order of magnitude less than glycogen and CO2 production but 4-10 times greater than [14C]glucose incorporation into liver lipids. Palmitate incorporation did not differ among treatments. Incorporation of [14C]glucose into liver lipids was higher in fish fed diets containing 400 g kg-1 carbohydrate. These data support the idea that glucose is not a major oxidative substrate in hybrid striped bass and indicate that the level of soluble carbohydrate should be limited to 200 g kg-1 diet or less for hybrid striped bass. © 2008 Blackwell Publishing Ltd.
author list (cited authors)
RAWLES, S. D., SMITH, S. B., & GATLIN, D. M.