Figure 1
Both diabetic and sucrose-treated rats develop polydipsia and bladder hypertrophy. (A) Fluid intake was monitored per cage every 2 weeks, by weighing water bottles over two consecutive days to calculate mean daily intake per rat. Both diabetic rats and sucrose-treated rats drank significantly more than age-matched controls at all timepoints. Diabetic rats drank more than sucrose-treated rats at the majority of time points tested (except 4 and 14 weeks, p > 0.05) * denotes diabetic group versus control and + denotes sucrose-treated group versus control; two way ANOVA and Tukey’s post hoc test: ##/**p < 0.01; ###/***p < 0.001; ####/****p < 0.0001). (B) At the final 16 week timepoint, water consumption was measured in individual rats, by separation of cagemates with a ‘buddy barrier’ in their home cage (to minimise isolation stress). Diabetic rats (n = 7) and sucrose-treated rats (n = 8) drank significantly more than controls (n = 10), and diabetic rats drank more than the sucrose-treated rats (one way ANOVA followed by Tukey’s post hoc test, ***p < 0.001****p < 0.0001). (C) Insulin levels were not significantly different in sucrose-treated rats compared to control rats in non-fasted conditions (p > 0.05), fasted serum insulin levels were increased compared with control rats (*p = 0.016, t-test). (D) However, an oral glucose tolerance test conducted at 15 weeks revealed no significant differences between control and sucrose-treated rats (p > 0.05, two-way repeated measures ANOVA followed by Tukey’s post-hoc test). Data (A–D) are expressed as mean ± SD. The empty urinary bladders of diabetic and sucrose-treated rats appeared larger (E, F) and were heavier (G) than controls with no significant difference in bladder weights between the diabetic and sucrose-treated rats. Bladder weight expressed as proportion of body weight (H) highlighted the increase in bladder size despite the diabetes-associated body weight deficit. Data are expressed as (G) median ± interquartile range, analysed by Kruskal–Wallis followed by Dunn’s multiple comparison test or (H) mean ± SD analysed by one way ANOVA followed by Tukey’s post hoc test; (*p < 0.05; **p < 0.01; ****p < 0.0001; ns p > 0.05).
