Date of Award

8-1979

Document Type

Thesis

Degree Name

Master of Arts

Department

Psychology

Abstract

In the present study, two experiments were conducted to examine the gerbil's response to acute sodium deficiency. Adult male gerbils were either exposed to a 1% b.w. subcutaneous injection of 1.5% formalin or a vehicle control injection. Within each injection level, half the animals were further assigned to either an isotonic saline or a water vehicle. Immediately following the injection, each S had access to isotonic saline and water as their drinking fluid. The formalin dissolved in water group displayed a significant increase in saline consumption, but at the same time decreased their water intake, in comparison to the water vehicle injection group. However, the formalin dissolved in isotonic saline group and the isotonic saline injection group did not differ in saline intake, but the formalin group drank significantly more water. Therefore, it was concluded that the gerbil's response to formalin is dependent upon the type of vehicle in which formalin is dissolved. It was postulated that these differences in intake between the trn formalin groups may be attributed to differences in physiological changes produced by formalin, or to differences in precedence of volume or osmoregulation. In the second experiment, adult male gerbils were exposed to a 1% b.w. subcutaneous injection of 1.5% formalin or to a vehicle injection.

Within each injection level, the animals were further divided so that equal groups had access to water and either .45%, .9%, 1.8%, or 3.6% saline solution or to water alone. The formalin group, who had access to water alone, significantly increased water consumption 12 and 24 hours after injection. Furthermore, gerbils significantly increased their intake of water 6 and 12 hours after formalin injection, when faced with a two-bottle choice situation, in comparison to a vehicle group. However, contrary to expectation, no increases in consumption of saline for the formalin group was evident. Due to these findings, no definitive conclusion can be made concerning the gerbil's ability to regulate sodium intake when various concentrations of saline solution and water are provided. It was postulated that the gerbil's drinking behavior subserves volume regulation over osmoregulation. These findings were explained in terms of the inability to take renal defense mechanisms into account and the sodium reservoir hypothesis.

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