Water regulation in the rat: III. The artificial control of thirst with stomach loads of water and sodium chloride

Although the study of motivational variables in relation to other behavioral phenomena has become a matter of increasing interest, the actual number of ways in which motivation can be controlled is indeed small. In animal experiments under hunger or thirst motivation, procedures have been limited almost exclusively to variations in the techniques of deprivation. A brief description of some of the variants of the "natural" procedure will serve to clarify the need for additional methods of controlling motivational variables. The purpose of this monograph is (a) to describe a procedure for "artificially" manipulating the thirst drive of rats by the placement of stomach loads of varying volume and composition, and (b) to present a series of standardizing, parametric studies of some of the principle variables involved. The subjects were 52 male albino rats of the Holtzman strain, 120-160 days of age at the beginning of the experiment. They had previously been used in other experiments, but had no prior experience with either runways or water deprivation. The present experiment controlled as much as possible the spacing of trials on test day and the delay between running and loading. The starting scores in this experiment were indicative of motivational effects induced by our loading, but the highly massed trials precluded precise information. The results we have reported on facilitation of drinking by loads of hypertonic saline, when considered together with our findings of drinking inhibition by water loads varying in volume indicate the possibility of arranging load conditions in such a fashion as to produce a linear change in water consumption over a very wide range. It is also concluded that with loading, one can control the water ingestion drinking of thirsty rats over a range from complete inhibition to an intake maximum unobtainable with deprivation. The volume of a hypertonic NaCl stomach load plays a relatively small role in comparison with the amount of sodium chloride in the load. (PsycINFO Database Record (c) 2016 APA, all rights reserved)