Persisting adiposity following chronic consumption of 10% sucrose solution: Strain differences and behavioural effects

- Consuming 10% sucrose solution increased weight gain in Albino but not Hooded Wistar rats.
- Both strains showed sucrose-induced insulin resistance and glucose intolerance.
- Sucrose-fed rats had more retroperitoneal and epididymal fat after 6-week caloric restriction.
- Operant responding by sucrose-fed Albino rats was less sensitive to satiety.
- Sucrose and control rats did not differ in reversal learning.

The metabolic consequences of providing rats with extended access to sugar solutions have varied across studies. The two experiments in this study examined the effects of 8 weeks of 24-h access to 10% sucrose solution on adult Wistar rats. This was followed by 6 weeks of food restriction with no access to sucrose during which the behavioural effects of prior sucrose consumption on reward-oriented behaviour (Experiment 1) and reversal learning (Experiment 2) were assessed. In a comparison between rat strains, Experiment 1 found that sucrose accelerated weight gain in Albino but not Hooded Wistar rats, while sucrose-fed rats of both strains exhibited elevated fasting blood glucose and resistance to insulin. Importantly, at cull retroperitoneal fat deposits were elevated in sucrose-fed rats, at which point glucose and insulin had resolved to control levels and liver triglyceride content did not differ between groups. Experiment 2 also found that retroperitoneal fat content was higher in sucrose-fed rats at cull, after 6 weeks of behavioural testing without sucrose and with restricted access to food, and found a similar effect for epididymal fat. Behavioural testing in Experiment 1 found that sucrose exposure had no effect on habit formation assessed using an outcome devaluation paradigm. However, instrumental responding by sucrose-fed Albino rats was the least affected by pre-feeding, indicating a relationship between sucrose-induced obesity and food-seeking behaviour. In Experiment 2, sucrose-fed and control rats did not differ on a discrimination reversal task. In conclusion, this study demonstrates that the behavioural and metabolic effects of sucrose consumption vary with strain. Further, results indicate that sucrose consumption can lead to lasting increases in adipose tissue stores, a finding which has significant implications for human diets.