Soares-Cunha C, Coimbra B, Borges S, Carvalho M M, Rodrigues A J, Sousa N
1Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Braga, Portugal 2ICVS/3B’s–PT Government Associate Laboratory, Braga/ Guimarães, Portugal.
Transl Psychiatry. 2014;4(6):e397. doi: 10.1038/tp.2014.45.
Exposure to elevated levels of glucocorticoids (GCs) during neurodevelopment has been identified as a triggering factor for the development of reward-associated disorders in adulthood. Disturbances in the neural networks responsible for the complex processes that assign value to rewards and associated stimuli are critical for disorders such as depression, obsessive–compulsive disorders, obesity and addiction. Essential in the understanding on how cues influence behavior is the Pavlovian–instrumental transfer (PIT), a phenomenon that refers to the capacity of a Pavlovian stimulus that predicts a reward to elicit instrumental responses for that same reward. Here, we demonstrate that in utero exposure to GCs (iuGC) impairs both general and selective versions of the PIT paradigm, suggestive of deficits in motivational drive. The iuGC animals presented impaired neuronal activation pattern upon PIT performance in cortical and limbic regions, as well as morphometric changes and reduced levels of dopamine in prefrontal and orbitofrontal cortices, key regions involved in the integration of Pavlovian and instrumental stimuli. Normalization of dopamine levels rescued this behavior, a process that relied on D2/D3, but not D1, dopamine receptor activation. In summary, iuGC exposure programs the mesocorticolimbic dopaminergic circuitry, leading to a reduction in the attribution of the incentive salience to cues, in a dopamine-D2/D3-dependent manner. Ultimately, these results are important to understand how GCs bias incentive processes, a fact that is particularly relevant for disorders where differential attribution of incentive salience is critical.
在神经发育过程中暴露于高水平的糖皮质激素(GCs)已被确定为成年期奖赏相关障碍发展的触发因素。负责为奖赏和相关刺激赋予价值的复杂过程的神经网络紊乱,对于抑郁症、强迫症、肥胖症和成瘾等疾病至关重要。巴甫洛夫式-工具性转移(PIT)对于理解线索如何影响行为至关重要,这是一种现象,指的是预测奖赏的巴甫洛夫式刺激引发对同一奖赏的工具性反应的能力。在这里,我们证明子宫内暴露于GCs(iuGC)会损害PIT范式的一般版本和选择性版本,提示动机驱动力存在缺陷。在PIT表现期间,iuGC动物在皮质和边缘区域的神经元激活模式受损,前额叶和眶额叶皮质(参与巴甫洛夫式和工具性刺激整合的关键区域)出现形态计量学变化和多巴胺水平降低。多巴胺水平的正常化挽救了这种行为,这一过程依赖于D2/D3而非D1多巴胺受体的激活。总之,iuGC暴露对中脑皮质边缘多巴胺能神经回路进行了编程,导致线索的激励显著性归因以多巴胺-D2/D3依赖的方式减少。最终,这些结果对于理解GCs如何影响激励过程很重要,这一事实对于激励显著性差异归因至关重要的疾病尤为相关。