(L-458) Effects of reproductive experience on cost-benefit decision making in females

Introduction:: After decades of neglect, a growing body of preclinical behavioral neuroscience research is including female subjects, with significant findings that underscore the importance of this inclusion. These efforts have largely neglected the variable of reproductive experience, however, in that almost all studies employ reproductively naïve animals. In contrast, the majority of women undergo reproductive/maternal experience at some point in their lives, and pregnancy and childbirth are associated with alterations in risks of multiple psychiatric disorders. Research in rodents shows that maternal experience affects spatial learning, memory and other aspects of hippocampal function. Yet, there has been little investigation of how reproductive experience (RE) affects cost-benefit decision making, despite the relevance of this aspect of cognition for psychiatric disorders. To address this issue, we investigated the long-term effects of reproductive experience on risky and impulsive decision making, as well as behavioral flexibility and reward motivation.


Materials and Methods:: Female (nulliparous, n=16; parous, n=14) Long-Evans rats were evaluated in tests of impulsive and risky decision making in standard operant chambers. Female rats in the parous group were mated, gave birth, and nursed for 21 days until pup weaning, whereas rats in the nulliparous group were unmated. One week after pups were weaned (or at the equivalent time point in nulliparous rats), rats began behavioral testing. Rats were initially tested in an intertemporal (impulsive) choice task, in which they made discrete choices between a small immediate food reward and a large food reward delivered after a variable delay period ranging from 0 to 60 s. Next, in a risky decision-making task, rats made discrete choices between a small, “safe” food reward and a large food reward accompanied by variable probabilities of mild footshock punishment. Rats’ behavioral flexibility was tested in a reversal learning task in which they had to learn the advantageous choice between two options dispensing food that switched during the course of experiment. To investigate effects of reproductive experience on food motivation, rats were tested on a progressive ratio schedule of reinforcement. Data from the decision-making tasks were analyzed via two-factor, repeated measures ANOVA (group x delay, group x probability of shock, group x session).


Results, Conclusions, and Discussions:: On the delay discounting task, there was a main effect of RE (F(1,28)=6.59, p= .02) and an interaction between delay and RE (F(4,112)=3.52, p< .01). Specifically, parous rats chose the large reward less frequently than the nulliparous (greater impulsive choice). On the risky decision-making task, there was a main effect of shock (F (2.32, 63.26) = 36.71, p< .01), such that preference for the large reward declined as probability of shock increased, but no main effect of RE (F (1, 28) = 1.91, p=0.18). There was, however, a significant interaction between shock and RE (F (4, 109) = 3.64, p< .01), such that parous females chose the large reward more frequently than nulliparous females at higher shock probabilities, suggestive of greater risk taking in this group. Both groups showed comparable behavioral flexibility in the reversal learning task. Data from the progressive ratio task revealed no differences between groups. Subsequent tests on shock reactivity threshold showed no effect of RE on reactivity threshold.

Together, these results show distinct effects of reproductive experience on different forms of cost-benefit decision making in females. Complementary experiments show that greater risk-taking behavior and impulsive choice in parous females are not due to reduced cognitive flexibility, altered food motivation, or reduced shock reactivity. This study highlights reproductive status as a variable that may influence aspects of cognition relevant for psychiatric disorders. Future research is needed to elucidate the neural basis of alterations in decision making induced by reproductive experience.

The plasticity of the female brain during pregnancy and postpartum is widely recognized, but literature on long term effects of reproductive experience on cognition is relatively scarce. Given the prevalence of reproductive experience in humans, our results suggest that preclinical research should include reproductive status as a variable, in order to better model the human condition and maximize the likelihood that therapeutic development will result in benefits for all individuals.


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