Postprandial glycogen and lipid synthesis in prednisolone-treated rats maintained on high-protein diets with varied carbohydrate levels.
OBJECTIVE
The present experiment was designed to study the effect of a high-protein, high-carbohydrate diet versus a high-protein, low-carbohydrate diet on in vivo postprandial glycogen and lipid synthesis of rats treated with prednisolone.


METHODS
Thirty-two 6-wk-old male Sprague-Dawley rats were randomly assigned to one of four equal groups: high-protein, high-carbohydrate; high-protein, high-carbohydrate with prednisolone; high-protein, low-carbohydrate; and high-protein, low-carbohydrate with prednisolone. Rats were sham operated or subcutaneously implanted with prednisolone pellets while being maintained on their respective diets (39% of energy from protein) for 6 wk. Food intake and body weight were monitored throughout the experiment. At the end of the feeding period, overnight-fasted rats were fed a test meal and injected with 3H2O to measure in vivo rates of glycogen and lipid synthesis. Final plasma glucose, insulin, and triacylglycerol concentrations and hepatic glycogen content were also measured.


RESULTS
Results showed that hepatic glycogen content (milligrams per gram of liver) was similar across all four experimental groups. Total hepatic glycogen synthesis and its percentage synthesis via pyruvate (indirect pathway) were higher in rats maintained on the high-protein, high-carbohydrate diet compared with those on the high-protein, low-carbohydrate diet and this was not substantially affected by prednisolone administration. Hepatic and epididymal fat pad lipid syntheses were not altered by diet or prednisolone treatments.


CONCLUSIONS
Under long-term high-protein conditions, prednisolone administration does not seem to affect hepatic glycogen synthesis, which was increased with the increased carbohydrate content of the diet.
Obeid
Omar A
OA
Department of Nutrition and Food Sciences, Faculty of Agricultural and Food Sciences, American University of Beirut, Beirut, Lebanon. omar.obeid@aub.edu.lb
Boukarim
Leila K
LK
Al Awar
Rima M
RM
Hwalla
Nahla
N
D000818:Animals; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004044:Dietary Proteins / Q000008:administration & dosage*; D004435:Eating / Q000187:drug effects; D002149:Energy Intake / Q000187:drug effects; D005938:Glucocorticoids / Q000494:pharmacology; D050356:Lipid Metabolism / Q000187:drug effects; D008055:Lipids / Q000096:biosynthesis*; D008099:Liver / Q000378:metabolism*; D008112:Liver Glycogen / Q000096:biosynthesis*; D008297:Male; D019518:Postprandial Period; D011239:Prednisolone / Q000494:pharmacology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D014316:Tritium; D014867:Water; D015430:Weight Gain
D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D005938:Glucocorticoids; D008055:Lipids; D008112:Liver Glycogen; D014867:Water; D014316:Tritium; C033961:tritium oxide; D011239:Prednisolone