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Increase in intake with sham feeding experience is concentration dependent.
J D Davis1, G P Smith, B Singh
1Department of Psychiatry, Joan and Sanford I. Weill Medical College of Cornell University, White Plains, New York 10605, USA. jddavis@med.cornell.edu
The American Journal of Physiology
|August 13, 1999
Summary
Sham feeding intake in rats depends on milk concentration. Concentrated milk requires multiple tests to reach maximum intake, while dilute milk reaches maximum intake faster due to different feedback mechanisms.
Area of Science:
- Physiology
- Animal Behavior
Background:
- Sham feeding studies typically show a progressive rise in intake over three tests.
- A previous study suggested this rise might be concentration-dependent, with dilute solutions reaching maximum intake sooner.
Purpose of the Study:
- To investigate the effect of milk concentration on sham feeding intake in rats.
- To determine if the number of sham feeding tests required to reach maximum intake is influenced by solution concentration.
Main Methods:
- Six groups of rats were used, with each group receiving five sham feeding tests.
- Each group was exposed to a different concentration of sweetened condensed milk (0.5:1 to 16:1 dilutions).
Main Results:
- Maximum sham intake was reached within three tests for the three most concentrated milk solutions.
- Maximum sham intake was reached in the first test for the three weakest milk solutions.
- This indicates that concentrated solutions are regulated by two negative feedback signals, while dilute solutions are regulated by one.
Conclusions:
- The progressive rise in sham feeding intake is concentration-dependent.
- Two negative feedback signals (gastrointestinal fluid accumulation and a labile signal) regulate intake of concentrated solutions.
- Only a nonlabile negative feedback signal regulates intake of dilute solutions.