A High-Throughput Method to Measure NaCl and Acid Taste Thresholds in Mice

Abstract

To develop a technique suitable for measuring NaCl taste thresholds in genetic studies, we conducted a series of experiments with outbred CD-1 mice using conditioned taste aversion (CTA) and two-bottle preference tests. In Experiment 1, we compared conditioning procedures involving either oral self-administration of LiCl or pairing NaCl intake with LiCl injections and found that thresholds were the lowest after LiCl self-administration. In Experiment 2, we compared different procedures (30-min and 48-h tests) for testing conditioned mice and found that the 48-h test is more sensitive. In Experiment 3, we examined the effects of varying strength of conditioned (NaCl or LiCl taste intensity) and unconditioned (LiCl toxicity) stimuli and concluded that 75-150 mM LiCl or its mixtures with NaCl are the optimal stimuli for conditioning by oral self-administration. In Experiment 4, we examined whether this technique is applicable for measuring taste thresholds for other taste stimuli. Results of these experiments show that conditioning by oral self-administration of LiCl solutions or its mixtures with other taste stimuli followed by 48-h two-bottle tests of concentration series of a conditioned stimulus is an efficient and sensitive method to measure taste thresholds. Thresholds measured with this technique were 2 mM for NaCl and 1 mM for citric acid. This approach is suitable for simultaneous testing of large numbers of animals, which is required for genetic studies. These data demonstrate that mice, like several other species, generalize CTA from LiCl to NaCl, suggesting that they perceive taste of NaCl and LiCl as qualitatively similar, and they also can generalize CTA of a binary mixture of taste stimuli to mixture components.

Effect of Chorda Tympani Nerve Transection on Salt Taste Perception in Mice

“…It also validates the ability of a high-throughput method of assessing taste thresholds (Ishiwatari and Bachmanov 2009) to detect changes in peripheral taste input.…”

A/J and C57BL/6J mice differ in chorda tympani responses to NaCl

“…Both the B6 and A/J strains, though, have been tested in a generalization task designed to find the threshold for sodium-specific taste (Ishiwatari and Bachmanov, 2009), with values of 5 and 30 mM, respectively (Ishiwatari and Bachmanov, 2012). Our neural data also provide a good match with these behavioral data, bearing in mind the precise nature of the task that was assigned to the animals; that is, the threshold measure did not involve discrimination of NaCl from water, but rather a conditioned taste aversion and generalizations relative to higher concentrations of NaCl that are thought to taste primarily salty to mice.…”

“…This variation includes differences in taste nerve responses (Ninomiya et al, 1989; Gannon and Contreras, 1995; Ninomiya et al, 1996, 1998; Ohkuri et al, 2006) and in two-bottle preference tests (Tordoff et al, 2007). Another behavioral test has also been developed recently in order to determine the threshold for sodium-specific taste in mice (Ishiwatari and Bachmanov, 2009). Briefly, the method involved giving mice lithium chloride to drink, and later conducting two-bottle tests with a concentration series of NaCl to find the lowest concentration of NaCl that was avoided by the mice, which was considered to be the threshold for sodium-specific taste.…”

A Behavioral and Anatomical Analysis of Conditioned Taste Aversion in C57BL/6J and DBA/2J Mice

“…A more natural classical conditioning paradigm involves the consumption, rather than injection, of the US: A study by Loy and Hall (2002) demonstrated that self-administered consumption of LiCl results in a conditioned taste aversion to salt, which generalizes to a presumably similartasting salt, NaCl (Loy, I. et al 2002;Ishiwatari, Y. et al 2009). A subsequent study by Baird and colleagues (2005) made use of this self-administration model in rats to show via a licking analysis that CTA development and generalization occur within an extremely rapid timeframe (9 min) (Baird, J. P. et al 2005).…”