Gastrointestinal and metabolic consequences of a rat's meal on maintenance diet ad libitum

Newman, J C and Booth, D A (1981) Gastrointestinal and metabolic consequences of a rat's meal on maintenance diet ad libitum. Physiology and Behavior, 27 (5). pp. 929-939. ISSN 0031-9384

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Abstract

The gastric emptying of normally sized chow meals taken after minimal food deprivation appeared to be almost constant in rate for most of the period of emptying, although a short initial acceleration was not excluded and a slowing was generally observed late in emptying. Intestinal contents of dry matter and carbohydrate remained about constant and so under these conditions absorption rate equalled the recent gastric emptying rate. When the rat's meals are frequent, in the dark period of the 24 hour, the stomach emptied much more rapidly. When measured post mortem in groups of rats, blood concentrations of glucose did not vary markedly after a meal in the dark period, nor did blood concentrations of alanine, glycerol and other gluconeogenic precursors. An increase in rates of cerebral glucose uptake and conversion to glutamate and lactate was occasionally observed after meals, by comparisons of specific activities 5 min after subcutaneous injection of U-14C-glucose, but the increase was not regionally localised. Hepatic glycogen concentration did not vary up to the time the next meal would have been taken in the mid dark period. However, gluconeogenic capacity was reduced by 20–30% for about 90 min following the meal, as measured by conversion of a loading dose of 14C-alanine to 14C-glucose in blood. Gluconeogenesis or regulation of hepatic glucose output may protect the brain and other tissues, including even the liver, from the minor and brief variations in absorption between meals ad lib. Normal satiety and hunger may be anticipatory responses, established by the metabolic and/or hormonal consequences of occasional bursts or drops in absorption rate.

Item Type: Article
Schools and Departments: School of Psychology > Psychology
Subjects: Q Science > QD Chemistry > QD0241 Organic chemistry > QD0415 Biochemistry
Q Science > QP Physiology
Depositing User: prof. David Booth
Date Deposited: 01 Sep 2015 07:56
Last Modified: 01 Sep 2015 07:56
URI: http://sro.sussex.ac.uk/id/eprint/56425
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