Central but not peripheral oxytocin administration reduces risk-based decision-making in male rats

The hormone oxytocin has long been associated with social behaviors, but recent evidence suggests that it may also affect reward processing in non-social contexts. Decisions are an integral component of many social and reward-based behavioral paradigms. Thus, a broad role for oxytocin in decision-making may explain the wide variety of effects that have been previously observed and resolve controversies in the literature about its role. To determine if oxytocin can selectively modulate decision-making in male rats, we assessed the dose-dependent effects of central (intracerebroventricular) or peripheral (intraperitoneal) administration of oxytocin on probability and delay discounting, two commonly used decision-making tasks that are free of social contexts. Our results showed that central administration of oxytocin dose-dependently reduced preference for risky outcomes in the probability discounting task, but had no impact on delay discounting or reward sensitivity. This effect was blocked by the co-administration of an oxytocin antagonist. Additionally, we found no effect of peripheral oxytocin administration on any task. To identify potential cognitive mechanisms of central oxytocin's effect on decision-making, we determined if central or peripheral oxytocin affects reward sensitivity using an intracranial self-stimulation task, and motivation using a progressive ratio task. These results showed that at the dosage that affects decision-making, central oxytocin had a mild and short-lasting effect on motivation, but no observable effect on reward sensitivity. This pattern of results suggests that oxytocin may selectively reduce risky decisions in male rats, even at dosages that have no major effects on reward processing and motivation. These findings highlight a potentially novel role for oxytocin in non-social cognitive processes and expand our understanding of the mechanism by which oxytocin may regulate social behavior.