Specificity of the sodium chloride appetite of adrenalectomized rats; substitution of lithium chloride for sodium chloride.

Abstract

A cafeteria or choice experiment was performed to determine the specificity of the NaCl appetite of adrenalectomized rats. In this experiment fluid intakes of male adrenalectomized rats were compared with those of male controls. All animals were allowed to choose freely between distilled water and a salt solution as drinking fluids. Nine different salt solutions were used with at least three separate concentrations of each salt being given. The salts used were: NaCl, LiCl, KCl, CaCl2, Na2SO4, Na citrate, Na oxalate, NaI and NaHCO3. Adrenalectomized rats showed a specific appetite for NaCl and gained weight only when this salt was given. Though greater volumes of Na2SO4, NaHCO3 and and Na citrate solutions were ingested than water, adrenalectomized rats lost weight on all of these. Normal rats failed to manifest an appetite for any of the salts offered. Particular attention was given to LiCl since this salt has been reported by others to stimulate chemoreceptors of the tongue of the anesthetized rat to produce electrical responses which are similar in amplitude to those initiated by the same concentration of NaCl. Both normal and adrenalectomized rats were given choice between NaCl solutions and water and later, between LiCl solutions and water. In equimolar concentrations, LiCl could not be substituted for NaCl; these two salts did not appear to ‘taste’ the same to either unanesthetized normal or adrenalectomized rats. Other experiments revealed that it was not possible to mask the ‘taste’ of LiCl in solution by mixing varying amounts of NaCl with it. However, a possibility exists that LiCl and NaCl taste the same to adrenalectomized rats and that LiCl is rejected because its toxic effects are manifested when small amounts are ingested.