The corticotropin-releasing hormone family of peptides is involved in regulating the neuroendocrine stress response. Also, the vagus nerve plays an important role in the transmission of immune system-related signals to brain structures, thereby orchestrating the neuroendocrine stress response. Therefore, we investigated gene expression of urocortin 2 (Ucn2) and c-fos, a markers of neuronal activity, within the hypothalamic paraventricular nucleus (PVN), a brain structure involved in neuroendocrine and neuroimmune responses, as well as in the adrenal medulla and spleen in vagotomized rats exposed to immune challenge. In addition, markers of neuroendocrine stress response activity were investigated in the adrenal medulla, spleen, and plasma. Intraperitoneal administration of lipopolysaccharide (LPS) induced a significant increase of c-fos and Ucn2 gene expression in the PVN, and adrenal medulla as well as increases of plasma corticosterone levels. In addition, LPS administration induced a significant increase in the gene expression of tyrosine hydroxylase (TH) and phenylethanolamine N-methyltransferase (PNMT) in the adrenal medulla. In the spleen, LPS administration increased gene expression of c-fos, while gene expression of TH and PNMT was significantly reduced, and gene expression of Ucn2 was not affected. Subdiaphragmatic vagotomy significantly attenuated the LPS-induced increases of gene expression of c-fos and Ucn2 in the PVN and Ucn2 in the adrenal medulla. Our data has shown that Ucn2 may be involved in regulation of the HPA axis in response to immune challenge. In addition, our findings indicate that the effect of immune challenge on gene expression of Ucn2 is mediated by vagal pathways.

促肾上腺皮质激素释放激素肽家族参与调节神经内分泌应激反应。此外，迷走神经在将免疫系统相关信号传递到大脑结构方面发挥着重要作用，从而协调神经内分泌应激反应。因此，我们研究了下丘脑室旁核 (PVN) 内尿皮质素 2 (Ucn2) 和 c-fos（神经元活动标志物）的基因表达，PVN 是一种参与神经内分泌和神经免疫反应的大脑结构，以及肾上腺髓质和暴露于免疫攻击的迷走神经切断大鼠的脾脏。此外，还研究了肾上腺髓质、脾脏和血浆中神经内分泌应激反应活性的标志物。腹腔内给予脂多糖（LPS）可诱导PVN和肾上腺髓质中c-fos和Ucn2基因表达的显着增加以及血浆皮质酮水平的增加。此外，LPS 诱导肾上腺髓质中酪氨酸羟化酶 (TH) 和苯乙醇胺 N-甲基转移酶 (PNMT) 基因表达显着增加。在脾脏中，LPS给药增加了c-fos的基因表达，而TH和PNMT的基因表达显着降低，并且Ucn2的基因表达不受影响。膈下迷走神经切断术显着减弱了 LPS 诱导的 PVN 中 c-fos 和 Ucn2 以及肾上腺髓质中 Ucn2 基因表达的增加。我们的数据表明 Ucn2 可能参与调节 HPA 轴以应对免疫挑战。此外，我们的研究结果表明，免疫攻击对 Ucn2 基因表达的影响是由迷走神经途径介导的。