Lam W, Gundlach A L, Verberne A J
University of Melbourne, Department of Medicine, Austin and Repatriation Medical Centre, Heidelberg, Victoria, Australia.
Neuroscience. 1997 Jun;78(4):1069-85. doi: 10.1016/s0306-4522(96)00527-1.
Forebrain neuronal connections associated with the cardiovascular response to unilateral, low-intensity, electrical stimulation of the mesencephalic cuneiform nucleus were examined in the halothane-anesthetized and paralysed rat by in situ hybridization histochemistry using specific 35S-labelled oligonucleotides for detection of c-fos and nerve growth factor inducible-A gene (NGFI-A) messenger RNAs. Stimulation of the cuneiform nucleus led to increases in mean arterial pressure and heart rate, whereas no cardiovascular response was observed in animals stimulated in the inferior colliculus or in sham-operated animals [see concurrent mid- and hindbrain study [Lam W. et al. (1996) Neuroscience 71, 193-211]. Cuneiform nucleus stimulation was associated with increased c-fos and NGFI-A messenger RNA levels bilaterally in the ventromedial, dorsomedial and lateroanterior hypothalamic nuclei, lateral and anterior hypothalamic areas, and ipsilaterally in the medial amygdaloid nucleus, at levels significantly greater than those in inferior colliculus-stimulated, sham-operated and naive, unoperated animals. C-fos, but not NGFI-A, messenger RNA expression was increased bilaterally in the piriform cortex and subparafascicular thalamic nucleus. These results are consistent with the existence of direct and indirect projections between the cuneiform nucleus and the aforementioned activated areas, the functions of which may include the control of reproduction and metabolism, as well as cardiovascular regulation. The ipsilateral nature of responses in certain brain areas may be explained by the absence of decussating pathways and/or the presence of multisynaptic connections which attenuate bilateral signal transmission. The existence of structures that are known to receive afferent projections from the cuneiform nucleus, but that were not activated, may be explained by synaptic depolarization not reaching the threshold for immediate early gene expression or by a net inhibitory effect on innervated neurons. Characterization of these activated forebrain regions using other compatible labelling techniques should further elucidate the mechanisms by which these central nervous system structures are integrated in the response to stimulation of the cuneiform nucleus.
采用原位杂交组织化学技术，使用特异性的35S标记寡核苷酸来检测c-fos和神经生长因子诱导A基因（NGFI-A）信使核糖核酸，在氟烷麻醉并麻痹的大鼠中，研究了与中脑楔形核单侧、低强度电刺激引起的心血管反应相关的前脑神经元连接。刺激楔形核会导致平均动脉压和心率升高，而在下丘刺激的动物或假手术动物中未观察到心血管反应[见同期中脑和后脑研究[Lam W.等人（1996年）《神经科学》71卷，193 - 211页]。楔形核刺激与双侧腹内侧、背内侧和下丘脑外侧前核、下丘脑外侧和前区以及同侧杏仁内侧核中c-fos和NGFI-A信使核糖核酸水平升高有关，其水平显著高于在下丘刺激、假手术和未手术的未处理动物。梨状皮质和束旁丘脑核双侧c-fos信使核糖核酸表达增加，但NGFI-A未增加。这些结果与楔形核和上述激活区域之间存在直接和间接投射相一致，其功能可能包括生殖和代谢控制以及心血管调节。某些脑区反应的同侧性质可能是由于缺乏交叉通路和/或存在减弱双侧信号传递的多突触连接来解释。已知接受楔形核传入投射但未被激活的结构的存在，可能是由于突触去极化未达到立即早期基因表达的阈值或对受支配神经元存在净抑制作用来解释。使用其他兼容标记技术对这些激活的前脑区域进行表征，应能进一步阐明这些中枢神经系统结构在对楔形核刺激的反应中整合的机制。
