Sex differences in sucrose reinforcement in Long-Evans rats

Abstract

Background There are sex differences in addiction behaviors. To develop a pre-clinical animal model to investigate this, the present study examined sex differences in sucrose taking and seeking using Long-Evans rats. Methods Five experiments were conducted using separate groups of subjects. The first two examined sucrose or saccharin preference in two-bottle home cage choice tests. Experiment three assessed sucrose intake in a binge model with sucrose available in home cage bottles. Experiments four and five utilized operant-based procedures. In experiment four rats responded for sucrose on fixed and progressive ratio (FR, PR) schedules of reinforcement over a range of concentrations of sucrose. A final component of experiment four was measuring seeking in the absence of sucrose challenged with the dopamine D1 receptor antagonist SCH23390. Experiment five assessed responding for water on FR and PR schedules of reinforcement. Results When accounting for body weight, female rats consumed more sucrose than water; but there was no sex difference in saccharin preference over a range of saccharin concentrations. When accounting for body weight, females consumed more sucrose than males in the binge model, and only females increased binge intake over 14 days of the study. Females responded at higher rates for sucrose under both FR and PR schedules of reinforcement. Females responded at higher rates in extinction (seeking); SCH23390 reduced sucrose seeking of both females and males. Females responded at higher rates for water on FR and PR schedules than males, although rates of responding were low and decreased over sessions. Conclusions Across bottle-choice, binge intake, and operant procedures, female Long-Evans rats consumed more sucrose and responded at higher rates for sucrose. Although females also responded more for water, the vigor of responding did not explain the consistent sex difference in sucrose taking and seeking. The sex difference in sucrose taking was also not explained by sweet preference, as there was no sex difference in saccharin preference. These data provide a pre-clinical model to further evaluate sex differences in addiction behaviors and manipulations designed to reduce them.

Sex Differences in Behavior and Learning Abilities in Adult Rats

“…The volume of consumed 2% sucrose solution per body weight was also the same in females and males. These findings did not support the hypothesis that females had a stronger sucrose preference than males [ 6 ]. This disagreement might relate to methodological differences in test conduction.…”

“…As early as in 1967, Elliott Valenstein and coauthors demonstrated that female rats of Charles River CD and Holtzman strains consumed larger quantities of a mildly sweet 3% glucose solution and a 0.25% saccharin solution (judged to be very sweet by humans) [ 2 , 3 ]. Since that time, the sucrose preference test has been widely used in rodents in many variations [ 4 , 5 , 6 ]. Recently, Tapia et al in 2019 [ 5 ] found that female rats worked harder in order to obtain a sucrose pellet and consumed more sucrose pellets than males.…”

“…Recently, Tapia et al in 2019 [ 5 ] found that female rats worked harder in order to obtain a sucrose pellet and consumed more sucrose pellets than males. Grimm et al in 2020 [ 6 ] showed that female Long-Evans rats consumed more sucrose than males and showed no sex difference in saccharin preference. Furthermore, Laura Buczek et al in 2020 [ 7 ] demonstrated in Sprague Dawley rats that females showed an increased susceptibility to overeat palatable food in comparison to males.…”

Ketogenic diet prevents sucrose withdrawal-induced anxiety-like behaviour in male mice

“…Sex differences are observed in preference, reinforcement and motivation toward sucrose. In operant procedures, female Long-Evans rats consume more sucrose and respond at higher rates for sucrose as compared to males 22 . In another study, female rats consume more sucrose pellets and work harder to obtain a sucrose pellet than males 23 .…”

Assessing the Beclin-1 Knockout: Autophagy, Neurogenesis, and the TUNL Task

“…Sbisa et al (2017) showed that estrous cycle does not affect female rat's performance on the TUNL task, so I may be able to rule that out, though Sbisa did not test for differences in response latency. I was not able to find any consistent information in the literature pertaining to sex differences in motivation or response time in mice, let alone in connection to autophagy, but female Long-Evans (Grimm et al, 2022) and Sprague Dawley (Reichelt et al, 2016) rats show increased response to sugars compared to males. The reward in this study (Milk2Go strawberry milk) was highly sweet, which may explain the finding.…”