P2.115 Thursday, Jan. 5 Dietary carbohydrate and biomarkers of sustained glycemia in rainbow trout SANTIN, A.E.*; POWELL, M.S.; HARDY, R.W.; RODNICK, K.J.; Idaho State University, Pocatello; University of Idaho, Hagerman; University of Idaho, Hagerman; Idaho State University, Pocatello firstname.lastname@example.org
Rainbow trout (Oncorhynchus mykiss) are carnivorous fish intolerant of dietary carbohydrate. Our recent work showed low glycated hemoglobin (0.5%) that is not indicative of chronic glycemia. This is probably due to low glucose permeability into erythrocytes. Extracellular biomarkers may reflect variations in glucose concentrations over time. Plasma glucose (PG) changes immediately in the presence of dietary carbohydrate. Fructosamine (SeFa) are plasma proteins with glucose non-enzymatically bound, reflecting glucose levels over two to three weeks in humans. We examined the effects of low (15%) and high (35%) carbohydrate diets on PG and SeFa in female rainbow trout (10 and 100 g) fed to satiety over ten weeks. At two weeks, postprandial PG increased from ~5 mM in small fish on the low carbohydrate diet to 15 mM for fish on the high carbohydrate diet. Conversely, PG was similar (10-15 mM) for larger fish on both diets. After ten weeks, both sizes of fish on both diets had similar PG (5-10 mM), suggesting adaptation to carbohydrate supplementation. At two weeks, SeFa showed little difference between both diets despite significant differences in PG. Surprisingly, after ten weeks, larger fish on the low carbohydrate diet had a 3-fold higher concentration of SeFa over the high carbohydrate diet (~300 vs 100 µmol/L). Possible reasons for lower SeFa in response to the high carbohydrate diet are 1) excess glucose lost via urinary excretion, 2) increased activation of fructosamine 3-kinase promoting protein deglycation, or 3) increased protein turnover. Overall, both small and large rainbow trout can adapt to increased dietary carbohydrate and reduce protein glycation relative to a low carbohydrate diet.