Testicular hormones mediate robust sex differences in impulsive choice in rats

Abstract

Impairments in choosing optimally between immediate and delayed rewards are associated with numerous psychiatric disorders. Such ‘intertemporal’ choice is influenced by genetic and experiential factors; however, the contributions of biological sex are understudied and data to date are largely inconclusive. Rats were used to determine how sex and gonadal hormones influence choices between small, immediate and large, delayed rewards. Females showed markedly greater preference than males for small, immediate over large, delayed rewards (greater impulsive choice). This difference was neither due to differences in food motivation or reward magnitude perception, nor was it affected by estrous cycle. Ovariectomies did not affect choice in females, whereas orchiectomies increased impulsive choice in males. These data show that male rats exhibit less impulsive choice than females and that this difference is at least partly maintained by testicular hormones. These differences in impulsive choice could be linked to gender differences across multiple neuropsychiatric conditions.

Impairments in fear extinction memory and basolateral amygdala plasticity in the TgF344-AD rat model of Alzheimer’s disease are distinct from non-pathological aging

“…Collectively, these results suggest varying degrees of intact fear memory acquisition in all rats except older-aged TgAD rats. It should be notated that, in contrast to previous reports (Maren et al, 1994; Pryce et al, 1999), we found freezing time during acquisition was modestly greater in females, which is consistent with females being more sensitive to punishment (Miettunen et al, 2007; Orsini et al, 2016; Liley et al, 2019; Hernandez et al, 2020). Furthermore, female 3×TgAD and control mice have greater freezing relative to males (Stover et al, 2015).…”

Effect of Sex and Reproductive Status on Inhibitory Control and Social Cognition in the Domestic Dog (Canis familiaris)

“…In dogs, neutered males seem to be more impulsive than intact males, according to a DIAS questionnaire [ 28 ]. This is in line with results in rats, which showed that gonadectomy increased impulsive choice in males [ 33 ].…”

Effects of repeated adolescent exposure to cannabis smoke on cognitive outcomes in adulthood

“…In addition, the current study was limited to male rats. Although the null effects of cannabis smoke observed here mimicked those in our previous study that employed both sexes (Bruijnzeel et al, 2019), there are significant sex differences on several of the tasks used here (intertemporal choice, working memory, progressive ratio; Blaes et al, 2019; Hernandez et al, 2020; Orsini et al, 2016), and thus it is possible that adolescent smoke exposure would affect females differently. In addition, the current study employed only a single rat strain (Long-Evans) with a single smoke exposure regimen.…”