Male Syrian hamsters demonstrate a conditioned place preference for sexual behavior and female chemosensory stimuli

Abstract

Sexual behavior is a natural reward for many rodent species, and it often includes chemosensorydirected components. Chemosensory stimuli themselves may also be rewarding. Conditioned place preference (CPP) is one paradigm frequently used to test the rewarding properties of a range of stimuli. Males and females of several rodent species show a CPP for sexual behavior, however, it is currently unknown whether sexual behavior can induce a CPP in male Syrian hamsters. As male Syrian hamsters are an animal model commonly used for investigation of the neurobiology of sexual behavior, understanding the rewarding components of sexual stimuli will better direct future research on brain regions and neurotransmitters involved in these behaviors. Experiment 1 tested the prediction that male hamsters show a CPP for sexual behavior. Female chemosensory stimuli are essential for the display of sexual behavior in male hamsters, however, the rewarding properties of female chemosensory stimuli contained in vaginal secretions (VS) are uncertain. Therefore, Experiment 2 tested the prediction that male hamsters show a CPP for VS. This study is the first demonstration that both sexual behavior and VS induce a CPP in male hamsters. Thus, female chemosensory stimuli are a natural reward in a species that is dependent on these stimuli for reproductive fitness.

Absence of social conditioned place preference in BTBR T+tf/J mice: Relevance for social motivation testing in rodent models of autism

“…An additional limitation is that one cannot rule out aggression and sex as unconditioned stimulus in these tasks since rodents will operantly respond to contexts associated with agonistic and sexual interactions [4,17,18]. However, despite the lack of formal assessment, observers noted no instances of sexual or aggressive interactions during the manually-scored conditioning sessions.…”

The Teenage Brain

“…We found that sexually naïve adult male hamsters form a CPP to female pheromones alone, which indicates that pheromones are an unconditioned reward in adulthood (Bell, Meerts, & Sisk, 2010). In contrast, juvenile male hamsters fail to form a CPP to female pheromones, which demonstrates that pheromones are not an unconditioned reward in preadolescent males, consistent with our hypothesis that the rewarding properties of female pheromones are acquired over adolescent development (Bell, De Lorme, Figueira, Kashy, & Sisk, 2012).…”

Maturation of social reward in adult male Syrian hamsters does not depend on organizational effects of pubertal testosterone

“…The control animals were used to confirm that preference scores do not change over the period of exposure to the two different compartments in the absence of conditioning. This biased assignment approach to CPP has been used previously for both sexual and drug rewards (Paredes and Alonso, 1997, Pierman et al, 2006, Dominguez-Salazar et al, 2008, Camacho et al, 2009, Meerts and Clark, 2009, Bell et al, 2010). The CPP apparatus was cleaned thoroughly with 25% ethanol following each Test and conditioning session between animals, and 75% ethanol after each S day.…”

“…Either a clean or vaginal secretion-containing Eppendorf tube was taped to the top of the back wall of each respective compartment, out of reach of the male. The purpose of the two modes of vaginal secretions delivery was to ensure exposure to both volatile and non-volatile components, as both are important and potentially have different roles in male sexual behavior (as discussed in Bell et al, 2010). Control animals received blank oil and empty tubes on all sessions.…”

“…For example, sexually naïve adult male hamsters show an unconditioned attraction to vaginal secretions that is not seen in prepubertal males (Johnston and Coplin, 1979). In addition, sexually naïve adult male hamsters show a conditioned place preference (CPP) to both vaginal secretions alone and sexual interactions with a female, whereas prepubertal males do not show a CPP to vaginal secretions, indicating that this chemosensory stimulus is unconditionally rewarding to adult, but not prepubertal, males (Bell et al, 2010, unpublished data). Thus, neural processing of vaginal secretions changes over the course of pubertal development such that they acquire positive valence, even without sexual experience.…”