Pawlak Cornelius R, Schwarting Rainer K W, Bauhofer Artur
Experimental and Physiological Psychology, Philipps-University of Marburg, Gutenbergstr. 18, 35032 Marburg, Germany.
Brain Res Mol Brain Res. 2005 Jun 13;137(1-2):159-65. doi: 10.1016/j.molbrainres.2005.03.002. Epub 2005 Apr 12.
There is evidence that interleukin (IL)-2 may be related to anxiety as measured in the elevated plus-maze. Recently, we showed that normal adult male Wistar rats can differ systematically in this test of avoidance behavior, that is, time spent on the open arms of the elevated plus-maze. Rats with low open arm time had higher striatal levels of IL-2 mRNA than those with high open arm time, but did not differ significantly in expression of other striatal cytokine mRNA. Here, we investigated whether these expression effects are anatomically specific to the striatum. Therefore, we asked in this double-blind study whether elevated plus-maze behavior may also be related to endogenous levels of cytokine mRNA in other brain regions, which play a role for anxiety, namely the amygdala, hippocampus, and the prefrontal cortex. Additionally, and as peripheral controls, immuno-neuro-endocrine relevant tissues (adrenal glands, spleen) were analyzed. Based on open arm time in the elevated plus-maze, male Wistar rats were divided into sub-groups with either low or high open arm time behavior. Then, IL-1beta, IL-2, IL-6, and tumor necrosis factor (TNF)-alpha cDNA levels were measured post-mortem using semi-quantitative, competitive, reverse transcription polymerase chain reaction. First, we found that cytokine expressions differed considerably between and within these central and peripheral tissues. Secondly, rats with high compared to low open arm time behavior showed higher IL-2 mRNA levels in the prefrontal cortex, which is an inverse pattern to what we recently found in the striatum. These results provide new evidence indicating that cytokine mRNA in the brain can be related to elevated plus-maze behavior and that this relationship is site (prefrontal cortex, striatum)- and cytokine mRNA-specific (IL-2).
有证据表明，白细胞介素（IL）-2可能与高架十字迷宫实验中所测量的焦虑有关。最近，我们发现正常成年雄性Wistar大鼠在这种回避行为测试中存在系统性差异，即高架十字迷宫开放臂上所花费的时间。开放臂时间短的大鼠纹状体中IL-2 mRNA水平高于开放臂时间长的大鼠，但在其他纹状体细胞因子mRNA的表达上无显著差异。在此，我们研究了这些表达效应在纹状体中是否具有解剖学特异性。因此，在这项双盲研究中，我们探讨了高架十字迷宫行为是否也与其他对焦虑起作用的脑区（即杏仁核、海马体和前额叶皮质）中细胞因子mRNA的内源性水平有关。此外，作为外周对照，对免疫神经内分泌相关组织（肾上腺、脾脏）进行了分析。根据高架十字迷宫中的开放臂时间，将雄性Wistar大鼠分为开放臂时间行为低或高的亚组。然后，使用半定量、竞争性逆转录聚合酶链反应在死后测量IL-1β、IL-2、IL-6和肿瘤坏死因子（TNF）-α cDNA水平。首先，我们发现这些中枢和外周组织之间以及组织内部的细胞因子表达存在很大差异。其次，与开放臂时间行为低的大鼠相比，开放臂时间行为高的大鼠前额叶皮质中IL-2 mRNA水平更高，这与我们最近在纹状体中发现的模式相反。这些结果提供了新的证据，表明脑中的细胞因子mRNA可能与高架十字迷宫行为有关，并且这种关系具有部位（前额叶皮质、纹状体）和细胞因子mRNA特异性（IL-2）。
