Ontogeny of hyperphagia in the Zucker (fa/fa) rat.
The ontogeny of hyperphagic behavior in the Zucker fatty (fa/fa) rat was examined. Wild-type, +/fa, and fa/fa pups aged postnatal day 5 (P5), P9, P12, P15, and P18 were evaluated using a test that measured ingestive behavior independent of the dam. The independent ingestive test consisted of giving pups access to a test solution [half-and-half (cream and milk)] on a tissue on the floor of a test chamber for 20 min. The latency to ingest and the intake (weight gain and percent weight gain) were measured and normalized to +/fa littermates. Pups were tested once to eliminate any effects of test experience. fa/fa Pups ingested significantly more than lean pups (+/+ and +/fa) on P12, P15, and P18, but not on P5 or P9. The latencies of fa/fa pups did not differ significantly from the latencies of +/+ pups except on P18, when the latencies of fa/fa pups were significantly shorter. The latencies of +/fa pups were significantly longer than the latencies of fa/fa or +/+ pups on P5 and P12. These results demonstrate that hyperphagia in fa/fa rats emerges between P9 and P12 under the test conditions used.
E. W. Bourne Behavioral Research Laboratory, New York Hospital-Cornell Medical Center, White Plains, New York 10605, USA.
T J
TJ
Kowalski
A M
AM
Ster
G P
GP
Smith
D000375:Aging / Q000502:physiology*; D000818:Animals; D001835:Body Weight; D005260:Female; D005838:Genotype; D006579:Heterozygote; D006963:Hyperphagia / Q000503:physiopathology*; D008297:Male; D009765:Obesity / Q000235:genetics / Q000503:physiopathology*; D051381:Rats; D011924:Rats, Zucker; D013851:Thinness; D015430:Weight Gain