Mice lacking paternal expression of imprinted Grb10 are risk-takers.

Claire L Dent,Kira D A Rienecker,Jon F Wilkins,Anthony R Isles,Trevor Humby,Andrew Ward

doi:10.1111/gbb.12679

Claire L Dent, Kira D A Rienecker + Show 4 more

Open Access

https://doi.org/10.1111/gbb.12679

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Abstract

The imprinted genes Grb10 and Nesp influence impulsive behavior on a delay discounting task in an opposite manner. A recently developed theory suggests that this pattern of behavior may be representative of predicted effects of imprinted genes on tolerance to risk. Here we examine whether mice lacking paternal expression of Grb10 show abnormal behavior across a number of measures indicative of risk‐taking. Although Grb10 +/p mice show no difference from wild type (WT) littermates in their willingness to explore a novel environment, their behavior on an explicit test of risk‐taking, namely the Predator Odor Risk‐Taking task, is indicative of an increased willingness to take risks. Follow‐up tests suggest that this risk‐taking is not simply because of a general decrease in fear, or a general increase in motivation for a food reward, but reflects a change in the trade‐off between cost and reward. These data, coupled with previous work on the impulsive behavior of Grb10 +/p mice in the delayed reinforcement task, and taken together with our work on mice lacking maternal Nesp, suggest that maternally and paternally expressed imprinted genes oppositely influence risk‐taking behavior as predicted.

Highlights

The imprinted genes Grb[10] and Nesp affect impulsive choice behavior in opposing direction.[1,2] Mice lacking paternal Grb[10] (Grb10+/p) prefer a larger, but delayed reward to a smaller, but more immediate reward in the delayed reinforcement task (DRT).[1]
Grb10+/p mice show no difference from wild type (WT) animals in their willingness to explore a novel environment, their behavior on the Predator Odor Risk-Taking (PORT) task is indicative of increased risk-taking
One suggestion is that these changes reflect a role for Grb[10] in regulating risk-taking behavior broadly.[8]

Summary

| INTRODUCTION

The imprinted genes Grb[10] and Nesp affect impulsive choice behavior in opposing direction.[1,2] Mice lacking paternal Grb[10] (Grb10+/p) prefer a larger, but delayed reward to a smaller, but more immediate reward in the delayed reinforcement task (DRT).[1]. When an allele is maternally inherited, selection more strongly favors increased mean reproductive success, even at the cost of increased reproductive variance. The idea that the choice of the more immediate, but smaller reward, displayed by Nespm/+ mice in the DRT may reflect less risktaking is supported by their behavior in other tasks. The PORT task was developed by us,[18] and has been used by others in both mice[19,20] and rats,[21] to assess “real-life” risky situations where there is a trade-off between a cost (risk of predation) and a food reward. Grb10+/p mice show no difference from wild type (WT) animals in their willingness to explore a novel environment, their behavior on the PORT task is indicative of increased risk-taking. Follow-up tests suggest that this risk-taking is not because of a general decrease in fear, or a general increase in motivation for a food reward, but reflects a change in the trade-off between cost and reward

| MATERIALS AND METHODS

| RESULTS

Findings

| DISCUSSION