Mathieu A M, Caboche J, Besson M J
Laboratoire de Neurochimie-Anatomie, Centre National de la Recherche Scientifique URA 1488, Université Pierre et Marie Curie, Paris, France.
Synapse. 1996 Jun;23(2):94-106. doi: 10.1002/(SICI)1098-2396(199606)23:2<94::AID-SYN5>3.0.CO;2-B.
The effects of a repeated treatment with nicotine on the expression of mRNAs encoding preproenkephalin (PPE), preprotachykinin-A (PPT-A), and preprodynorphin (PPDYN) were examined by in situ hybridization histochemistry in various subregions of the nucleus accumbens (Acb). In saline-treated rats, optical density measurements on autoradiographic films showed marked anteroposterior decreasing gradients for PPE and PPT-A mRNAs in the rostral pole and the core, in the cone, and in the ventral shell of the Acb, whereas a lower anteroposterior gradient was observed for PPDYN mRNA signals. The intensity of the three mRNA signals also varied according to Acb subregion. However, analysis of percentages of prepropeptide mRNA-containing neurons as compared to total neurons showed, in the rostral pole, the core, and the cone, a similar percentage of PPE mRNA (around 45%)- and PPT-A mRNA (around 40%)-expressing neurons. The ventral shell can be distinguished from the other subregions by a lower percentage of PPE mRNA (35.8%)- and PPT-A mRNA (30.6%)-expressing neurons. The percentage of PPDYN mRNA-containing neurons, by contrast, was similar (around 37%) in the core, the cone, and the ventral shell. Repeated nicotine administration increases the PPE mRNA level in the rostral pole and the anterior third of the core without any change in PPT-A and PPDYN mRNA levels in the various Acb subregions examined. The PPE mRNA increase does not support an effect mediated through an interaction of nicotine with DA neurons. The effect could be linked to a nicotine activation of other afferents to the anterior Acb and/or to a direct nicotine stimulation of PPE mRNA neurons.
通过原位杂交组织化学技术，研究了尼古丁重复给药对伏隔核（Acb）各个亚区中编码前脑啡肽原（PPE）、前速激肽原 -A（PPT-A）和前强啡肽原（PPDYN）的mRNA表达的影响。在生理盐水处理的大鼠中，对放射自显影片的光密度测量显示，在Acb的吻端极、核心、锥体和腹侧壳中，PPE和PPT-A mRNA呈现明显的前后递减梯度，而PPDYN mRNA信号的前后梯度较低。三种mRNA信号的强度也因Acb亚区而异。然而，与总神经元相比，对含前体肽mRNA的神经元百分比分析显示，在吻端极、核心和锥体中，表达PPE mRNA（约45%）和PPT-A mRNA（约40%）的神经元百分比相似。腹侧壳与其他亚区的区别在于，表达PPE mRNA（35.8%）和PPT-A mRNA（30.6%）的神经元百分比较低。相比之下，在核心、锥体和腹侧壳中，含PPDYN mRNA的神经元百分比相似（约37%）。重复给予尼古丁可增加吻端极和核心前三分之一区域的PPE mRNA水平，而在所检测的Acb各个亚区中，PPT-A和PPDYN mRNA水平没有任何变化。PPE mRNA的增加不支持尼古丁与多巴胺能神经元相互作用介导的效应。这种效应可能与尼古丁对Acb前部其他传入神经的激活和/或尼古丁对PPE mRNA神经元的直接刺激有关。
