Carter R R, Grovum W L
Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Canada.
Br J Nutr. 1990 Jul;64(1):285-99. doi: 10.1079/bjn19900029.
The site where osmotically active substances act to depress food intake was determined in sheep. After 5.5 h of food deprivation, solutions of sodium chloride or polyethylene glycol-200 (PEG-200) were added to either the reticulo-rumen or the abomasum. The sheep were then immediately offered pelleted lucerne (Medicago sativa). Water was withheld during the first 60 min of feeding but was available from 60 to 90 min. There was a linear inhibition in food intake in the first 10 min after loading 2.37, 6.25, 12.5, 25.0 or 50.0 g NaCl into the rumen according to a 5 x 5 Latin square design (P = 0.0001). The intake reduction was 3.49 g food/g NaCl. An osmotic load of PEG-200 equivalent to 50 g NaCl also significantly inhibited food intake in the first 10 min of the meal compared with a control treatment. The inhibition of food intake after loading 55 g NaCl into the rumen was not affected by injecting lidocaine hydrochloride into the reticulum immediately before NaCl loading. NaCl injected into the abomasum did not significantly affect food intake in the first 10 min of feeding even though the tonicity of abomasal digesta was increased to unphysiological levels. There was no consistent relationship between food intake and the change in the tonicity of jugular plasma following solute loading and drinking. The sensing site of hypertonicity was localized to the wall of the reticulo-rumen where neuronal receptors appear to be capable of detecting osmotic pressure within the physiological range to depress food intake. These receptors should be identified and characterized because of their possible significance in limiting food intake by ruminants.
在绵羊身上确定了渗透活性物质抑制食物摄入的作用部位。禁食5.5小时后，将氯化钠溶液或聚乙二醇-200（PEG-200）添加到瘤胃或皱胃中。然后立即给绵羊提供苜蓿颗粒（紫花苜蓿）。在喂食的前60分钟不提供水，但在60至90分钟时可以饮水。根据5×5拉丁方设计，向瘤胃中装入2.37、6.25、12.5、25.0或50.0克氯化钠后的前10分钟内，食物摄入量呈线性抑制（P = 0.0001）。摄入量减少为每克氯化钠减少3.49克食物。与对照处理相比，相当于50克氯化钠的PEG-200渗透负荷在进食的前10分钟也显著抑制了食物摄入。在向瘤胃中装入55克氯化钠之前立即向网胃注射盐酸利多卡因，并未影响装入氯化钠后对食物摄入的抑制作用。即使皱胃消化物的张力增加到非生理水平，注入皱胃的氯化钠在喂食的前10分钟也未显著影响食物摄入。溶质负荷和饮水后，食物摄入量与颈静脉血浆张力的变化之间没有一致的关系。高渗的传感部位定位于瘤胃壁，那里的神经元受体似乎能够检测生理范围内的渗透压以抑制食物摄入。由于这些受体在限制反刍动物食物摄入方面可能具有重要意义，因此应该对其进行鉴定和表征。
