Center for Behavioral Neuroscience, Neuroscience Institute, Georgia State University, Atlanta, GA, USA.
Neuropsychopharmacology. 2019 Mar;44(4):785-792. doi: 10.1038/s41386-018-0262-y. Epub 2018 Nov 6.
Social reward is critical for social relationships, and yet we know little about the characteristics of social interactions that are rewarding or the neural mechanisms underlying that reward. Here, we investigate the sex-dependent role of oxytocin receptors within the ventral tegmental area (VTA) in mediating the magnitude and valence of social reward. Operant and classical conditioning tests were used to measure social reward associated with same-sex social interactions. The effects of oxytocin, selective oxytocin receptor agonists, antagonists, and vehicle injected into the VTA on social reward was determined in male and female Syrian hamsters. The colocalization of FOS and oxytocin in sites that project to the VTA following social interaction was also determined. Females find same-sex social interactions more rewarding than males and activation of oxytocin receptors in the VTA is critical for social reward in females, as well as males. These studies provide support for the hypothesis that there is an inverted U relationship between the duration of social interaction and social reward, mediated by oxytocin; and that in females the dose-response relationship is initiated at lower doses compared with males. Same-sex social interaction is more rewarding in females than in males, and an inverted U relationship mediated by oxytocin may have a critical role in assigning positive and negative valence to social stimuli. Understanding these sex differences in social reward processing may be essential for understanding the sex differences in the prevalence of many psychiatric disorders and the development of gender-specific treatments of neuropsychiatric disorders.
社会奖励对于社会关系至关重要，但我们对具有奖励性的社会互动特征以及该奖励的神经机制知之甚少。在这里，我们研究了腹侧被盖区（VTA）中催产素受体在介导社会奖励的大小和效价方面的性别依赖性作用。我们使用操作性和经典条件反射测试来测量与同性社会互动相关的社会奖励。我们还确定了在 VTA 中注射催产素、选择性催产素受体激动剂、拮抗剂和载体对雄性和雌性叙利亚仓鼠的社会奖励的影响。在进行社交互动后，还确定了 FOS 和催产素在投射到 VTA 的部位的共定位。雌性比雄性更喜欢同性社交互动，而 VTA 中的催产素受体的激活对于雌性和雄性的社会奖励都是至关重要的。这些研究支持了这样一种假设，即社会互动的持续时间和社会奖励之间存在着倒 U 关系，这种关系是由催产素介导的；而且在雌性中，与雄性相比，起始剂量较低。同性社交互动对雌性比雄性更有奖励性，而催产素介导的倒 U 关系可能在给社会刺激赋予积极和消极的效价方面起着关键作用。了解社会奖励处理中的这些性别差异可能对于理解许多精神障碍的性别差异以及神经精神障碍的性别特异性治疗的发展至关重要。
