Figure 1.
Mean fluid intake in two-bottle and one-bottle salt intake tests in naïve rats.
Intakes of IS (A) and HS (B) compared to water in 24 h two-bottle choice tests in naïve rats. C, mean preference scores for IS and HS solutions in 24 h two-bottle salt choice tests with water. One-bottle intake tests with IS (D) and HS (E) in naïve rats. Error bars +SEM, n = 6–10 animals per group. *p<0.05, **p<0.01, ***p<0.001. HS, hypertonic saline; IS, isotonic saline; W, water.
Figure 2.
A dramatic and lasting switch in salt preference after 24 h one-bottle tests with IS and HS solutions.
Ai, Mean fluid intake following 5 different 24 h one-bottle treatments, control, IS, HS, DH and 4% HSD. Aii, water intake measures for the proceeding 24 h after treatment. B, mean intakes of water and IS solution in two-bottle choice tests performed 7 d after one-bottle tests. C, mean salt preference scores for all groups calculated from the total fluid intake data in B. D, the two-bottle choice tests were repeated 35 d after one-bottle tests for control WEx, ISEx and HSEx groups. Values are means +SEM of n = 6–10 animals per group. E, mean salt preference scores for all groups calculated from the total fluid intake data in D. *p<0.05, **p<0.01, ***p<0.001. DH, dehydrated; HS, hypertonic saline; HSD, high salt diet; HSEx, hypertonic saline exposed; IS, isotonic saline ISEx isotonic saline exposed; W, water; WEx, water exposed.
Figure 3.
A significantly reduced appetite for salt solutions following a single 24 h one-bottle test with HS.
A, Mean preference scores have been calculated from 24 h measures of water and salt intake at the percentage shown for WEx and HSEx rats. B, mean preference score for IS on day 9 (before tests) and day 30 (after tests). C, mean intakes of 1% sucrose solution compared to water in 24 h two-bottle choice test. D, mean intakes of 1% sucrose prepared in IS in 24 h two-bottle choice test with water. E, mean preference scores calculated from the fluid intake data in C and D. Values are means +SEM of n = 8 animals per group. *p<0.05, **p<0.01, ***p<0.001. HS, hypertonic saline. HSEx, hypertonic saline exposed; IS, isotonic saline; Suc, sucrose; WEx, water exposed.
Figure 4.
The effect of AngII on IS and water intake.
Ai, total fluid intakes in WEx and HSEx rats in 1 h two-bottle choice tests with water and IS after AngII administration. Water intake (Aii) and IS intake (Aiii) in WEx and HSEx rats after AngII administration. B, salt preference score in WEx and HSEx rats after AngII administration. One-bottle tests with IS (C) and water (D) following AngII administration. Values are means +SEM of n = 10 animals per group. *p<0.05. HSEx, hypertonic saline exposed; IS, isotonic saline; WEx, water exposed.
Figure 5.
The effects of 1 d DH and 1 d HS exposure on gene expression in rat SON and PVN.
Relative mRNA expression of hnAVP, hnOT, AVP, OT, hnCRH, CRH, c-Fos, Nr4a1 and Arc was investigated by qPCR in the SON and PVN of control, 1 d DH and 1 d HS rats. Values are means +SEM of n = 5–6 animals per group. *p<0.05, **p<0.01, ***p<0.001. 1 d DH, 1 day dehydrated; 1 d HS, 1 day hypertonic saline.
Figure 6.
Gene expression changes in rat SON and PVN 1 d and 7 d after DHEx or HSEx compared to control animals.
Relative mRNA expression of hnAVP, hnOT, AVP, OT, hnCRH, CRH, c-Fos, Nr4a1 and Arc was investigated by qPCR in the SON and PVN of rats RH (1 d and 7 d) after DHEx and HSEx. Values are means +SEM of n = 6 animals per group. *p<0.05, **p<0.01, ***p<0.001. DH, dehydrated; DHEx dehydrated exposed; HS, hypertonic saline; HSEx, hypertonic saline exposed; RH, Rehydration.