Abstract
The food motivated behavior of ad lib fed or calorically restricted male Zucker fatty and lean rats was compared at 12, 16, 20 and 30 weeks of age. The groups were fasted for 0, 12 and 24 hr and required to lever press for food pellets on VI 40 sec. Responding by ad lib fatties was elevated over lean controls during the rapid growth period (12 and 16 weeks of age) but was significantly reduced following the completion of growth (20 weeks). Elevated responding accompanied hyperphagia by the ad lib fatties during growth but did not accompany a second, adult onset period of hyperphagia in these fatties. In contrast, fatties calorically restricted from birth responded at elevated rates at all ages compared to lean controls. At 20 weeks restricted fatties, which were as obese on a percentage body composition basis as ad lib fatties, responded significantly more than the latter group at all fasting levels. Metabolic measurements revealed elevated fat cell size, LPL activity/cell and insulin levels in both fatty groups at 15 weeks, and elevated fat cell number in these groups at 33 weeks. The possibility is discussed that enhanced lipogenic factors present during the rapid growth period combine with the metabolic demands of growth to produce a “compensatory hyperphagia” in the fatty rat.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 565-573 |
| Number of pages | 9 |
| Journal | Physiology and Behavior |
| Volume | 25 |
| Issue number | 4 |
| DOIs | |
| State | Published - 1980 |
| Externally published | Yes |
Bibliographical note
Funding Information:All of the metabolic alterations noted above would allow more ingested energy to be packaged as triglyceride and stored in the adipocytes of developing fatties, as opposed to lean rats. The result of such a shift of energy distribution in ~The work reported in this paper was supported in part by NIH grants AM 25141, HD 0700 and a grant from the Sugar Association, and was conducted at the Institute of Human Nutrition while J. R. V., K. C. J. and M. P. C. were NIH Postdoctoral Trainees. We would like to thank Joel Grinker and Dennis Vanderweele for their invaluable comments on the manuscript, and Norra Tannenhaus, Yen Shih and Gregory Calliste for their dedicated assistance in conducting this research. Portions of these data were presented at the Eastern Psychological Assn. and FASEB Meetings, April, 1979. ZRequests for reprints should be sent to the first author who is now at the Obesity Research Center, WH-10, St. Luke's-Roosevelt Hospital, Amsterdam Ave. and ll4th St., New York, NY 10025. 3Present address: Department of Nutrition and Food Sciences, Drexel University, Philadelphia, PA 19104. 4present address: Dept. of Physiology, The University of Michigan, M4120 Med. Sci. I, Ann Arbor, MI 48109. 5Present address: Department of Biology, Vassar College, Poughkeepsie, NY 12601.
Keywords
- Caloric restriction
- Food motivated behavior
- Genetic obesity
- Lipoprotein lipase
- Zucker (fa/fa) rat
