Cook C G, Andrews J M, Jones K L, Wittert G A, Chapman I M, Morley J E, Horowitz M
Department of Medicine, Royal Adelaide Hospital, North Terrace, Australia.
Am J Physiol. 1997 Aug;273(2 Pt 2):R755-61. doi: 10.1152/ajpregu.1997.273.2.R755.
The mechanisms responsible for the reduction in appetite and slowing of gastric emptying in older persons are unknown. The aims of this study were to evaluate the effects of aging on small intestinal regulation of appetite and pyloric motility. Eight healthy older (age 65-75 yr) and seven healthy young (age 20-34 yr) male subjects received isocaloric (2.9 kcal/min) intraduodenal infusions of lipid and glucose for 120 min, each on separate days. During the intraduodenal infusions, perceptions of hunger, desire to eat, and fullness were assessed by visual analog scales. Pyloric motility (isolated pyloric pressure waves and tonic pyloric pressure) was measured by manometry during the intraduodenal lipid infusion. On each day, after completion of the intraduodenal nutrient infusion the subject was offered a buffet meal and food intake was quantified. Before intraduodenal nutrient infusions, sensations of hunger (P < 0.01) and desire to eat (P < 0.05) were less in the older compared with the young subjects. In the young, intraduodenal lipid suppressed hunger to a greater extent than intraduodenal glucose (P < 0.05). In older persons, neither intraduodenal nutrient infusion suppressed hunger. Intraduodenal lipid and glucose increased fullness in both age groups (P < 0.05 for both), with no significant difference between the two nutrients. There was no significant difference in food intake from the buffet meal between the elderly and young subjects. Intraduodenal lipid infusion stimulated phasic pyloric pressure waves in both age groups (P < 0.01 for both), and this response was greater (P < 0.05) in older persons. There was an increase (P < 0.01) in tonic pyloric pressure during intraduodenal lipid infusion that was not significantly different between the two age groups. We conclude that the effect of small intestinal lipid infusion on hunger is attenuated, and the stimulation of phasic pyloric pressure waves increased in healthy older persons compared with healthy young males. Increased feedback from small intestinal nutrients does not appear to be responsible for the physiological anorexia of aging.
老年人食欲下降和胃排空减慢的机制尚不清楚。本研究的目的是评估衰老对小肠食欲调节和幽门运动的影响。8名健康老年人（65 - 75岁）和7名健康年轻人（20 - 34岁）男性受试者，在不同日期分别接受等热量（2.9千卡/分钟）的十二指肠内脂质和葡萄糖输注120分钟。在十二指肠内输注期间，通过视觉模拟量表评估饥饿感、进食欲望和饱腹感。在十二指肠内输注脂质期间，通过测压法测量幽门运动（孤立的幽门压力波和紧张性幽门压力）。每天，在十二指肠内营养输注完成后，为受试者提供自助餐，并对食物摄入量进行量化。在十二指肠内营养输注前，与年轻受试者相比，老年受试者的饥饿感（P < 0.01）和进食欲望（P < 0.05）较低。在年轻人中，十二指肠内脂质比十二指肠内葡萄糖更能抑制饥饿感（P < 0.05）。在老年人中，两种十二指肠内营养输注均未抑制饥饿感。十二指肠内脂质和葡萄糖在两个年龄组中均增加了饱腹感（两者均P < 0.05），两种营养素之间无显著差异。老年和年轻受试者自助餐的食物摄入量无显著差异。十二指肠内脂质输注在两个年龄组中均刺激了阶段性幽门压力波（两者均P < 0.01），且老年人的这种反应更大（P < 0.05）。在十二指肠内脂质输注期间，紧张性幽门压力增加（P < 0.01），两个年龄组之间无显著差异。我们得出结论，与健康年轻男性相比，健康老年人中十二指肠内脂质输注对饥饿的影响减弱，而阶段性幽门压力波的刺激增加。小肠营养素反馈增加似乎不是衰老生理性厌食的原因。
