Jeanblanc J, Peterschmitt Y, Hoeltzel A, Louilot A
INSERM U 405 and Institute of Physiology, Louis Pasteur University, Faculty of Medicine, 11 rue Humann, 67085 Strasbourg Cedex, France.
Neuroscience. 2004;128(1):187-200. doi: 10.1016/j.neuroscience.2004.06.022.
The use of latent inhibition paradigms is one means of investigating the involvement of mesencephalic dopaminergic (DA) neurons in cognitive processes. We have shown recently that DA neurons reaching the core and the dorsomedial shell parts of the nucleus accumbens and the anterior part of the striatum are differentially involved in latent inhibition. In other respects, theoretical, behavioral and anatomo-functional data suggest that the entorhinal cortex (ENT) may control latent inhibition expression. In this study, using in vivo voltammetry in freely moving rats, we investigated the influence of the ENT on the DA responses obtained in the core and dorsomedial shell parts of the nucleus accumbens and the anterior part of the striatum. For this purpose a reversible inactivation of the left ENT was achieved by the local microinjection of tetrodotoxin, 3 h before pre-exposure to the conditional stimulus (banana odour). During the second session, animals were aversively conditioned to banana odour. Results obtained during the third session (test session), in animals submitted to the reversible blockade of the ENT before the first session were as follows: (1) pre-exposed conditioned animals displayed behavioral aversive responses; (2) where core DA responses were concerned, responses were situated between those observed in pre-exposed and non-pre-exposed conditioned animals; (3) by contrast, where the dorsomedial shell part of the nucleus accumbens and the anterior striatum were concerned, DA variations were not statistically different in pre-exposed and non-pre-exposed conditioned rats. These data suggest that the left ENT exerts a crucial influence over the latent-inhibition-related DA responses in the left dorsomedial shell part of the nucleus accumbens and the left anterior part of the striatum, whereas one or more other brain regions control DA variations in the left core part of the nucleus accumbens. These data may help us to understand the pathophysiology of schizophrenic psychoses.
使用潜伏抑制范式是研究中脑多巴胺能（DA）神经元参与认知过程的一种方法。我们最近发现，投射到伏隔核核心和背内侧壳部以及纹状体前部的DA神经元在潜伏抑制中发挥着不同的作用。在其他方面，理论、行为和解剖功能数据表明，内嗅皮层（ENT）可能控制潜伏抑制的表达。在本研究中，我们利用自由活动大鼠的体内伏安法，研究了ENT对伏隔核核心和背内侧壳部以及纹状体前部DA反应的影响。为此，在对条件刺激（香蕉气味）进行预暴露前3小时，通过局部微量注射河豚毒素实现左ENT的可逆性失活。在第二阶段，对动物进行香蕉气味厌恶条件反射。在第一阶段前接受ENT可逆性阻断的动物在第三阶段（测试阶段）获得的结果如下：（1）预暴露的条件动物表现出行为厌恶反应；（2）就核心DA反应而言，反应介于预暴露和未预暴露的条件动物中观察到的反应之间；（3）相比之下，就伏隔核背内侧壳部和前纹状体而言，预暴露和未预暴露的条件大鼠的DA变化在统计学上没有差异。这些数据表明，左ENT对伏隔核左背内侧壳部和纹状体左前部与潜伏抑制相关的DA反应具有关键影响，而一个或多个其他脑区控制伏隔核左核心部的DA变化。这些数据可能有助于我们理解精神分裂症性精神病的病理生理学。
