Sex differences in sucrose-induced locomotor sensitization and cross-sensitization with the D2/D3 agonist quinpirole in rats

In humans, women are known to have a greater prevalence of eating-related disorders and stronger experience of food cravings than men. Similarly, in rodents, females display a greater preference and motivation for the highly palatable sweet food, sucrose, than do males. Pre-exposure to sucrose has been shown to enhance locomotor sensitization induced by dopaminergic agonists, however, evidence of sex differences in this effect is limited. Female (n = 16) and male (n = 16) Long-Evans rats received 30 min daily access to sucrose (0.3 M) or water for nine consecutive days followed by daily administration of the D2/D3 agonist, quinpirole (0.5 mg/kg), for nine consecutive days. Automated locomotor activity assessment occurred on the first, fifth, and ninth days of the sucrose and quinpirole phases. In the sucrose phase, sex × fluid interactions were broadly observed in activity measures across and within testing days with females but not males showing an effect of sucrose-induced locomotor sensitization. In the quinpirole phase, a sex × fluid interaction was only observed in a single activity measure across days, suggesting that sucrose pre-exposure does not robustly alter quinpirole sensitization by sex. A sex difference was identified in the effect of locomotor sensitization induced by sucrose, but not for sucrose pre-exposure on quinpirole sensitization. These results suggest that differences exist between sexes in sucrose-induced sensitization in rodents, perhaps underlying sex differences in food cravings and eating-related disorder prevalence in humans.