Dean C, Woyach V L
Department of Anesthesiology/151, Zablocki VA, Medical College of Wisconsin, WI, USA.
Brain Res. 2004 Oct 29;1025(1-2):159-68. doi: 10.1016/j.brainres.2004.07.080.
The response to a sudden, severe loss of blood volume is complex and results in a drastic fall in arterial blood pressure and sympathoinhibition. The present study examines the distribution of serotonergic neurons in the caudal raphe involved in the mediation of the response to severe hemorrhage. Hemorrhage was performed in rats anesthetised with urethane by withdrawal of blood at a rate of 1 ml/min for approximately 4 min until blood pressure fell to 50 mm Hg. Sections through the brainstem were processed immunohistochemically to identify Fos, the protein product of the proto-oncogene c-fos expressed in the nucleus of neurons activated during the hemorrhage stimulus, and double-labeled to identify serotonin (5-hydroxytryptamine; 5-HT) content of cells. In response to hemorrhage, double-labeled Fos/5-HT neurons were located in the B3 region which includes the raphe magnus (RM) and its lateral extension. Hemorrhage-induced Fos-positive neurons that were not serotonergic were located in raphe pallidus (RP), parapyramidal cell group (PP), and the B3 region. Serotonergic neurons not activated by hemorrhage were located in the nucleus raphe pallidus, the parapyramidal cell group, the raphe obscurus (RO), and the B3 region. The specific rostrocaudal distribution of activated neurons may indicate different functions of groups of neurons in the response to hemorrhage.
对血容量突然严重减少的反应是复杂的，会导致动脉血压急剧下降和交感神经抑制。本研究考察了参与介导严重出血反应的尾侧中缝核中5-羟色胺能神经元的分布。对用乌拉坦麻醉的大鼠进行出血操作，以1 ml/分钟的速度抽血约4分钟，直到血压降至50 mmHg。对脑干切片进行免疫组织化学处理，以识别Fos，即原癌基因c-fos的蛋白质产物，其在出血刺激期间被激活的神经元细胞核中表达，并进行双重标记以识别细胞中的5-羟色胺（5-羟色胺；5-HT）含量。对出血的反应中，双重标记的Fos/5-HT神经元位于B3区域，该区域包括中缝大核（RM）及其外侧延伸部分。出血诱导的非5-羟色胺能Fos阳性神经元位于中缝苍白核（RP）、锥体旁细胞群（PP）和B3区域。未被出血激活的5-羟色胺能神经元位于中缝苍白核、锥体旁细胞群、中缝隐核（RO）和B3区域。激活神经元的特定头尾分布可能表明神经元群在出血反应中的不同功能。
