Stricker E M
J Comp Physiol Psychol. 1981 Feb;95(1):1-25. doi: 10.1037/h0077764.
Subcutaneous injection of polyethylene glycol (PEG) solution produced a progressive sequestration of extracellular fluid at the injection site. Appropriately, PEG-treated rats showed both thirst and sodium appetite. However, water intake began within 1 to 2 hr after the injections, whereas consumption of NaCl solution did not start until 3-4 hr later. Then rats ingested both fluids alternately until plasma volumes were restored, whereupon saline intake became even more prominent while water was consumed due to induced osmoregulatory needs. These three phases were seen regardless of the dose of PEG that was administered or the concentration of saline that was available. In contrast, after maintenance on a sodium-deficient diet for 2-4 days, or after bilateral adrenalectomy, rats increased their intake of saline immediately after PEG treatment. These and other findings suggest that the delayed onset of sodium appetite after PEG treatment that occurs when rats are maintained on standard sodium-rich chow results from the buffer provided by surplus extracellular fluid in those animals. They further suggest that sodium appetite is not directly associated with decreases in plasma volume or sodium concentration but instead may be stimulated by decreased availability of sodium in the brain.
皮下注射聚乙二醇（PEG）溶液会在注射部位导致细胞外液逐渐潴留。相应地，经PEG处理的大鼠表现出口渴和对钠的食欲。然而，注射后1至2小时内开始饮水，而直到3 - 4小时后才开始饮用氯化钠溶液。然后大鼠交替摄入两种液体，直到血浆容量恢复，此时由于诱导的渗透调节需求，盐水摄入变得更加显著，而水的消耗仍在继续。无论给予的PEG剂量或可用盐水的浓度如何，都会出现这三个阶段。相比之下，在缺钠饮食维持2 - 4天或双侧肾上腺切除术后，大鼠在PEG处理后立即增加了盐水摄入量。这些以及其他发现表明，当大鼠以富含钠的标准食物饲养时，PEG处理后钠食欲延迟出现是由于这些动物体内多余细胞外液提供的缓冲作用。它们进一步表明，钠食欲并非直接与血浆容量或钠浓度的降低相关，而是可能由大脑中钠可用性的降低所刺激。
