Scalera G, Tarozzi G
Dipartimento di Scienze Biomediche, Sezione di Fisiologia, Universita' di Modena e Reggio Emilia, Via Campi, 287, 41100 Modena, Italy.
Exp Physiol. 2001 Jul;86(4):489-98. doi: 10.1113/eph8602167.
In a previous report, it has been shown that water deprivation significantly affects the two-bottle taste preferences and one-bottle taste acceptance in rats when no food was available during tests. Since no food was available, the course of drinking was never interrupted by eating. Theoretically, if a rat faces a simultaneous choice between food and fluid, and if the course of drinking is interrupted by eating, these conditions might interfere with taste preferences, total fluid intake and eating in thirsty rats. The aims of the present experiments were: to ascertain whether food intake during both two-bottle preference and one-bottle acceptance tests in thirsty rats might be influenced by the palatability of the solutions; to verify whether the availability of food during tests influences taste preference and acceptance, and total fluid intake; to detect variations induced by dehydration on body weight and some plasma and urinary parameters that might interfere with food and fluid intake, taste preference and acceptance. Using naive rats, five groups of rats showing the same taste preferences for one of four prototypical tastes and water were selected. Then, both two-bottle preference (Expt 1) and one-bottle acceptance tests (Expt 2) were performed in rats deprived of water for either 12, 24, 36 or 48 h. The results showed that in both Expt 1 and Expt 2, inhibition of feeding and decrease of body weight during dehydration was very similar in all rats. The presence of food during the tests did not affect taste preference and acceptance. During Expt 1, after severe water deprivation (36 and 48 h), food intake was related to the palatability of the solution paired with water. When rats drank either NaCl or sucrose, they ate less food than rats drinking HCl, quinine, or water. In Expt 2, rats drinking NaCl solution as the only source of fluid ate significantly less food than all other groups. The intake of sucrose and/or NaCl solutions be may explained by two different post-ingestion effects (energetic and osmotic). Since rats drinking either sucrose or NaCl ate less food but drank more fluid, they had a significantly higher fluid/food intake ratio than that of rats who drank water, quinine, or HCl, who ate more food but drank less fluid. The increase of the fluid/food intake ratio in rats drinking sucrose or NaCl was directly correlated with the length of dehydration. Self-denial of food during dehydration may be responsible for overeating and overdrinking during the recovery period after tests. After dehydration lasting for 24 and 48 h, plasma [Na(+)], [protein], osmolality and haematocrit values increased but [K(+)] decreased. Urinary volume decreased but urinary [Na(+)] increased. These results are related to food and fluid intake, taste preference and acceptance after dehydration periods. Experimental Physiology (2001) 86.4, 489-498.
在之前的一份报告中已经表明，在测试期间无食物供应的情况下，禁水会显著影响大鼠的双瓶味觉偏好和单瓶味觉接受度。由于无食物供应，饮水过程从未被进食打断。从理论上讲，如果一只大鼠面临食物和液体的同时选择，并且饮水过程被进食打断，这些情况可能会干扰口渴大鼠的味觉偏好、总液体摄入量和进食情况。本实验的目的是：确定在口渴大鼠的双瓶偏好测试和单瓶接受度测试期间，食物摄入量是否可能受到溶液适口性的影响；验证测试期间食物的可获得性是否会影响味觉偏好和接受度以及总液体摄入量；检测脱水对体重以及一些可能干扰食物和液体摄入量、味觉偏好和接受度的血浆和尿液参数所引起的变化。使用未经训练的大鼠，选择了五组对四种典型味觉之一和水具有相同味觉偏好的大鼠。然后，对禁水12、24、36或48小时的大鼠进行双瓶偏好测试（实验1）和单瓶接受度测试（实验2）。结果表明，在实验1和实验2中，所有大鼠在脱水期间的摄食抑制和体重减轻情况非常相似。测试期间食物的存在并未影响味觉偏好和接受度。在实验1中，经过严重禁水（36和48小时）后，食物摄入量与与水配对的溶液的适口性有关。当大鼠饮用氯化钠或蔗糖溶液时，它们摄入的食物比饮用盐酸、奎宁或水的大鼠少。在实验2中，将氯化钠溶液作为唯一液体来源饮用的大鼠摄入的食物明显少于所有其他组。蔗糖和/或氯化钠溶液的摄入量可能由两种不同的摄入后效应（能量和渗透）来解释。由于饮用蔗糖或氯化钠溶液的大鼠摄入的食物较少但饮用的液体较多，它们的液体/食物摄入比明显高于饮用盐酸、奎宁或水的大鼠，后者摄入的食物较多但饮用的液体较少。饮用蔗糖或氯化钠溶液的大鼠的液体/食物摄入比的增加与脱水时间直接相关。脱水期间的自我禁食可能是导致测试后恢复期暴饮暴食的原因。在持续脱水24和48小时后，血浆[Na⁺]、[蛋白质]、渗透压和血细胞比容值升高，但[K⁺]降低。尿量减少但尿[Na⁺]增加。这些结果与脱水期后的食物和液体摄入量、味觉偏好和接受度有关。《实验生理学》（2001年）86.4，489 - 498。
