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Restriction of dietary protein leads to conditioned protein preference and elevated palatability of protein-containing food in rats

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posted on 09.01.2018, 11:25 by Michelle Murphy, Kate Z. Peters, Bethany S. Denton, Kathryn A. Lee, Heramb Chadchankar, James E. McCutcheon
The mechanisms by which intake of dietary protein is regulated are poorly understood despite their potential involvement in determining food choice and appetite. In particular, it is unclear whether protein deficiency results in a specific appetite for protein and whether influences on diet are immediate or develop over time. To determine the effects of protein restriction on consumption, preference, and palatability for protein we assessed patterns of intake for casein (protein) and maltodextrin (carbohydrate) solutions in adult rats. To induce a state of protein restriction, rats were maintained on a low protein diet (5% casein) and compared to control rats on non-restricted diet (20% casein). Under these dietary conditions, relative to control rats, protein-restricted rats exhibited hyperphagia without weight gain. After two weeks, on alternate conditioning days, rats were given access to either isocaloric casein or maltodextrin solutions that were saccharin-sweetened and distinctly flavored whilst consumption and licking patterns were recorded. This allowed rats to learn about the post-ingestive nutritional consequences of the two different solutions. Subsequently, during a preference test when rats had access to both solutions, we found that protein-restricted rats exhibited a preference for casein over carbohydrate whereas non-restricted rats did not. Analysis of lick microstructure revealed that this preference was associated with an increase in cluster size and number, reflective of an increase in palatability. In conclusion, protein-restriction induced a conditioned preference for protein, relative to carbohydrate, and this was associated with increased palatability.

Funding

Funding: This work was supported by the Biotechnology and Biological Sciences Research Council [grant # BB/M007391/1]; and the European Commission [grant # GA 631404].

History

Citation

Physiology and Behavior, 2018, 184, pp. 235-241

Author affiliation

/Organisation/COLLEGE OF LIFE SCIENCES/Biological Sciences/Neuroscience, Psychology and Behaviour

Version

VoR (Version of Record)

Published in

Physiology and Behavior

Publisher

Elsevier for International Behavioral Neuroscience Society [

issn

0031-9384

eissn

1873-507X

Acceptance date

06/12/2017

Copyright date

2017

Available date

09/01/2018

Publisher version

http://www.sciencedirect.com/science/article/pii/S003193841730433X

Notes

All raw data files will be published with this manuscript alongside the Python scripts used to perform analysis. These are deposited on Github (https://github.com/jaimemcc/murphy-2017) and Mendeley Data (doi:10.17632/wgd83v3ntb.1).

Language

en

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