Running to the taste of salt in mineralocorticoid-treated rats

In the present series of studies, the running speed of rats in a runway was used to measure appetitive motivation for different concentrations of salt solutions. We found that when rats were thirsty, they were not interested in running for concentrated salt solutions; when they were rendered salt hungry by mineralocorticoid treatment in addition to the thirst, or even without thirst, they ran vigorously for salty tasting solutions, as high as 24% NaCl. The running speed is correlated with the degree of the mineralocorticoid treatment and the salt concentration. Moreover, drinking 5 cc of a 3% NaCl solution before the runway test decreases the running speed of the mineralocorticoid-treated rat. The experiments are discussed in the context of the effects of hormonal events on the movitation to ingest salt solutions.