The rats had unlimited access to two bottles of water between the sucrose-access-periods.
Thus, GH32 genes have been documented in several pathogenic fungal biotrophs and appear to be expressed in order to enhance C metabolism and access sucrose at infection sites.
52 As shown in Figure 1, while lean outbred Sprague Dawley rats exhibit a near linear concentration-response curve in their brief-access sucrose- and corn oil licking behavior, their obese counterparts show a right shift with less responding to the lowest concentrations but more responding to the highest concentrations.
Long Evans rats (Harlan, Indianapolis, IN, USA), were used for the intermittent access 20% sucrose two-bottle-choice drinking paradigm, operant sucrose self-administration procedures as well as the 5% sucrose two-bottle-choice drinking paradigm, since such studies are well-documented in this strain [31], [32], [33].
Unlimited access to sucrose early in life reduced sucrose-seeking when work was required to obtain it.
Thus, unlimited access to sucrose early in life reduced motivation for sucrose rewards and preferentially enhanced consumption of freely-available food over more palatable food that required work to obtain.
Taken together, these behavior results indicate that mice given unlimited access to sucrose in early life exhibit reduced sucrose-seeking behavior in adulthood as indicated by a lower breakpoint.
We show that unlimited access to sucrose early in life reduces motivation to acquire sucrose, but only when work is required to obtain it.
We gave mice unlimited or no access to sucrose for a short period post-weaning and measured sucrose-seeking, food consumption, and weight gain in adulthood.
These findings are consistent with a recent publication by Frazier et al. [12] reporting that 3-week old mice having unlimited access to sucrose pellets for 4 to 7 weeks display decreased motivation for sucrose in adulthood.
