Bio-imaging, University of Antwerp, Antwerp, Belgium.
Centre for Psychiatric Research, Aarhus University Hospital, Risskov, Denmark.
PLoS One. 2014 Apr 16;9(4):e95077. doi: 10.1371/journal.pone.0095077. eCollection 2014.
The pathophysiology of major depressive disorder (MDD) and other stress related disorders has been associated with aberrations in the hippocampus and the frontal brain areas. More recently, other brain regions, such as the caudate nucleus, the putamen and the amygdala have also been suggested to play a role in the development of mood disorders. By exposing rats to a variety of stressors over a period of eight weeks, different phenotypes, i.e. stress susceptible (anhedonic-like) and stress resilient animals, can be discriminated based on the sucrose consumption test. The anhedonic-like animals are a well validated model for MDD. Previously, we reported that in vivo diffusion kurtosis imaging (DKI) of the hippocampus shows altered diffusion properties in chronically stressed rats independent of the hedonic state and that the shape of the right hippocampus is differing among the three groups, including unchallenged controls. In this study we evaluated diffusion properties in the prefrontal cortex, caudate putamen (CPu) and amygdala of anhedonic-like and resilient phenotypes and found that mean kurtosis in the CPu was significantly different between the anhedonic-like and resilient animals. In addition, axial diffusion and radial diffusion were increased in the stressed animal groups in the CPu and the amygdala, respectively. Furthermore, we found that the CPu/brain volume ratio was increased significantly in anhedonic-like animals as compared with control animals. Concurrently, our results indicate that the effects of chronic stress on the brain are not lateralized in these regions. These findings confirm the involvement of the CPu and the amygdala in stress related disorders and MDD. Additionally, we also show that DKI is a potentially important tool to promote the objective assessment of psychiatric disorders.
重性抑郁障碍（MDD）和其他应激相关障碍的病理生理学与海马体和额叶大脑区域的异常有关。最近，其他大脑区域，如尾状核、壳核和杏仁核，也被认为在情绪障碍的发展中发挥作用。通过在八周的时间内使大鼠暴露于各种应激源，可以根据蔗糖消耗测试区分不同的表型，即应激易感（快感缺失样）和应激耐受动物。快感缺失样动物是 MDD 的一种经过充分验证的模型。以前，我们报道了海马体的体内扩散峰度成像（DKI）显示慢性应激大鼠的扩散特性发生改变，与快感缺失状态无关，并且右海马体的形状在包括未受挑战的对照组在内的三组之间存在差异。在这项研究中，我们评估了快感缺失样和应激耐受表型的前额叶皮质、尾状核壳核（CPu）和杏仁核的扩散特性，发现 CPu 中的平均峰度在快感缺失样和应激耐受动物之间存在显著差异。此外，在 CPu 和杏仁核中，轴向扩散和径向扩散在应激动物组中分别增加。此外，我们发现 CPu/脑体积比在快感缺失样动物中显著增加，与对照组动物相比。同时，我们的结果表明，慢性应激对这些区域的大脑没有偏侧化影响。这些发现证实了 CPu 和杏仁核在应激相关障碍和 MDD 中的参与。此外，我们还表明，DKI 是一种促进精神疾病客观评估的潜在重要工具。
