Hope P J, Wittert G A, Horowitz M, Morley J E
Department of Medicine, University of Adelaide, Royal Adelaide Hospital, Australia.
Am J Physiol. 1997 Jan;272(1 Pt 2):R78-83. doi: 10.1152/ajpregu.1997.272.1.R78.
Little is known about feeding regulation in marsupials. Sminthopsis crassicaudata is a small nocturnal marsupial, whose tail contains approximately 25% total body fat. We have characterized the effect of gender, photoperiod, food deprivation, and tail removal (lipectomy) on food intake in S. crassicaudata. Males and females maintained in captivity on long-day (LD, 16:8-h light-dark cycle) and short-day (SD, 9:15-h light-dark cycle) light regimens were studied. Feeding patterns under LD and SD photoperiods were initially measured under conditions of ad libitum food supply and then in groups of animals exposed to 24- and 36-h periods of food deprivation. Feeding occurred predominantly in the dark. Females maintained on SD photoperiods for 5 wk ate less (P < 0.005) than females on LD or males on either SD or LD, but this reduction in food intake was not associated with a decrease either in body weight or tail width. After both 24- and 36-h fasts, total food intake in the subsequent 24 h increased (P < 0.001) up to 100% in all groups, with no gender or photoperiod effect. SD females, however, ate less (P < 0.05) than LD females in the first 6 h after refeeding. Tail width decreased (P < 0.05) in all groups of animals after the 36-h fast but only in LD animals after the 24-h fast (P < 0.05). Body weight decreased similarly in all groups of animals after fasting. The effect of tail removal was studied in LD males. The procedure, which was well tolerated, resulted in an initial decrease in body weight (P < 0.005), which recovered within 3 wk. On day 45 in the animals whose tails were removed, body fat was approximately 30% greater than body fat of controls (P < 0.02). No significant increase in food intake occurred after tail removal. These data demonstrate in Sminthopsis crassicaudata 1) a photoperiod and gender-dependent effect on food intake, 2) the ability to regulate the amount and distribution of total body fat, and 3) a dissociation between the regulation of food intake and changes in body fat stores, which suggest alterations in energy expenditure.
关于有袋类动物的进食调节，我们所知甚少。肥尾袋小鼠是一种小型夜行性有袋动物，其尾巴所含脂肪约占全身脂肪总量的25%。我们已对性别、光周期、食物剥夺和尾巴切除（脂肪切除术）对肥尾袋小鼠食物摄入量的影响进行了特征描述。研究了在长日照（LD，16:8小时明暗循环）和短日照（SD，9:15小时明暗循环）光照方案下圈养的雄性和雌性肥尾袋小鼠。最初在自由采食条件下测量LD和SD光周期下的进食模式，然后在经历24小时和36小时食物剥夺的动物组中进行测量。进食主要发生在黑暗中。在SD光周期下饲养5周的雌性比在LD光周期下的雌性或在SD或LD光周期下的雄性吃得少（P < 0.005），但这种食物摄入量的减少与体重或尾巴宽度的降低均无关。在禁食24小时和36小时后，所有组在随后24小时内的总食物摄入量均增加（P < 0.001），增加幅度高达100%，且无性别或光周期效应。然而，再喂食后的前6小时内，SD雌性比LD雌性吃得少（P < 0.05）。禁食36小时后，所有动物组的尾巴宽度均减小（P < 0.05），但禁食24小时后仅LD组的尾巴宽度减小（P < 0.05）。禁食后所有动物组的体重均有类似程度的下降。在LD雄性中研究了尾巴切除的影响。该手术耐受性良好，导致体重最初下降（P < 0.005），但在3周内恢复。在尾巴被切除的动物第45天时，其体脂比对照组高约30%（P < 0.02）。尾巴切除后食物摄入量未显著增加。这些数据表明，在肥尾袋小鼠中：1）食物摄入量存在光周期和性别依赖性效应；2）具有调节全身脂肪量和分布的能力；3）食物摄入量调节与体脂储存变化之间存在分离，这表明能量消耗发生了改变。
