Preference for taste solutions within 10 minutes after starting to drink in water-deprived rats

To evaluate the preference for taste solutions with palatable and aversive qualities during the initial 10 min after resuming drinking in water-deprived rats.

The effects of pre-exposure to taste solutions in eight-week-old male Wistar/ST rats and the impact of post-ingestive effects were examined by two-bottle preference tests every 2 min over a 10-min period for five days after deprived of water for 24 h. Sodium saccharin (Sacc, without post-ingestive effects) and sucrose (Suc, with post-ingestive effects) were used in the palatable solutions, and quinine hydrochloride (Q) was used in the aversive solution.

In naïve rats, a significant difference in the consumed volume of Q solution and distilled water (DW) was observed on Day 1, whereas differences for the Sacc and Suc solutions were observed on Day 4. In pre-exposed rats, differences for the Sacc, Q, and Suc solutions were observed on Day 1, Day 1, and Day 2, respectively. However, no differences were observed for the Sacc solution on Days 2, 4, and 5. The cumulative volume consumed within 10 min differed significantly among all taste solutions and DW for almost all experimental days in the naïve and pre-exposed groups.

The short-term test showed that water-deprived rats did not initially discriminate between the qualities of taste solutions when commencing drinking after deprivation. Comparisons between the naïve and pre-exposed groups revealed that drinking behavior depended on prior exposure to the solutions. The short-term tests with the Sacc and Suc solutions indicate that post-ingestive effects influence drinking behavior.