FOOD DEPRIVATION-INDUCED INCREASES IN HOARDING BY SIBERIAN HAMSTERS ARE NOT PHOTOPERIOD-DEPENDENT

Siberian hamsters increase food hoarding in response to chronic food r estriction and food deprivation, conditions that lead to a loss of bod y mass and fat. Therefore, the first purpose of the present experiment s was to test further the effects of food deprivation on food hoarding by varying the length and order of repeated fasts to address the foll owing questions: 1. Does the magnitude of the food-hoarding response i ncrease as food deprivation length increases? 2, Is the effect of food deprivation on food hoarding experience-dependent? Second, we were in terested in testing the effects of short winter-like days (SDs) on foo d hoarding. We tested this by measuring food hoarding in long days (LD s) and SDs during baseline conditions and after food deprivation to ad dress the following question: Does SD exposure increase baseline and f ood deprivation-induced hoarding due to the naturally occurring SD-ind uced decreases in body fat? During each experiment, we were interested in determining how hamsters utilize their food hoard (i.e., add to it and eat from it). Our results extended those of our previous studies in showing that: 1. Food-deprivation length and the initial food-hoard size were not related to one another; 2. The maintenance of food-hoar d size was proportional to the length of the fast; 3. The effects of a bout of food deprivation on food hoarding were dependent upon the len gths of previous fasts; 4. Baseline food hoarding was not different be tween LD- and SD-exposed hamsters: 5. The maintenance of food-hoard si ze, but not the initial fast-induced increases in food-hoard size, wer e increased in SDs; 6. Hamsters ate approximately 25-33% of their dail y food intake from the food hoard under all conditions, with the degre e of food replacement increasing as fast length was increased; and 7. The typical SD-induced decrease in food intake was reflected in the fo od eaten from the food supply found outside the burrow, but food eaten from the hoard was increased. Collectively, the results of the presen t experiments suggest that the initiation of food hoarding may be asso ciated with short-term fluctuations in energy metabolism associated wi th fasting, but that the more long-term decreases in body mass (fat) a re involved in the maintenance of food-hoard size.