Thermogenesis, low-protein diets, and decreased development of AFB1-induced preneoplastic foci in rat liver.

Notes: 

Disease onset began above 12% protein.

TitleThermogenesis, low-protein diets, and decreased development of AFB1-induced preneoplastic foci in rat liver.
Publication TypeJournal Article
Year of Publication1991
AuthorsHorio F, Youngman LD, Bell RC, Campbell TC
JournalNutrition and cancer
Volume16
Issue1
Pagination31-41
Date Published1991
ISSN0163-5581
KeywordsAflatoxin B1, Animals, Body Temperature Regulation, Body Weight, Caseins, Dietary Proteins, Dopamine, Eating, gamma-Glutamyltransferase, Liver, Liver Neoplasms, Experimental, Male, Norepinephrine, Organ Size, Oxygen Consumption, Precancerous Conditions, Rats, Rats, Inbred F344
Abstract

The development of hepatocellular, putatively preneoplastic, gamma-glutamyl transpeptidase positive (GGT+) foci and tumors induced by aflatoxin B1 (AFB1) has been shown to be reduced in male F344 rats fed a diet containing 6% protein (as casein). This reduction occurs despite increased energy intake, when compared with animals fed a diet containing 22% protein. Among its many effects, low protein intake is known to increase the proportion of energy intake expended in the form of heat (thermogenesis); thus, this investigation examined the association between the development of GGT+ foci and alterations in indices of thermogenesis induced by feeding varying levels of dietary protein. Five days following the completion of AFB1 dosing, animals were assigned to groups fed 4%, 8%, 12%, 16%, or 22% dietary protein for 6 weeks. Foci development (% liver volume occupied) was markedly reduced in animals fed the low-protein diet (4%, 8%), yet calorie consumption per 100 g body wt was greater. A modest negative linear trend was observed in oxygen consumption with increasing levels of dietary protein intake. Urinary norepinephrine levels were elevated in the groups fed 4% and 8% protein; urinary dopamine and norepinephrine turnover rates in brown adipose tissue were highest in animals fed 4% protein. These results suggest that GGT+ foci development occurs when a "critical level" (approx 12%) of dietary protein intake is reached. Inhibition of foci development at lower levels of protein intake is associated with several indicators of increased thermogenesis.

Alternate JournalNutr Cancer
PubMed ID1681520
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