Okumura T, Taylor I L, Pappas T N
Department of Surgery, Duke University Medical Center, Durham, North Carolina, USA.
Am J Physiol. 1995 Sep;269(3 Pt 1):G328-34. doi: 10.1152/ajpgi.1995.269.3.G328.
Thyrotropin-releasing hormone (TRH) stimulates pancreatic exocrine secretion through the vagus nerve when injected into rat cerebrospinal fluid. However, little is known about the exact site of action of TRH in the brain to stimulate pancreatic secretion. Recent neuroimmunochemical and neurophysiological studies suggest that TRH could be a neurotransmitter in the dorsal vagal complex, which sends fibers to the pancreas through the vagus nerve. We therefore hypothesized that TRH may act centrally in the dorsal vagal complex to stimulate pancreatic exocrine secretion. To address this question, a TRH analogue, [1-methyl-(S)-4,5-dihydroorotyl]-L-histidyl-L-prolinamide- NH2, was microinjected into the dorsal vagal complex, and basal pancreatic fluid flow and protein secretion were measured in urethan-anesthetized rats. Microinjection of TRH analogue (0.2-2 ng/site) into the dorsal vagal complex significantly stimulated pancreatic flow and protein output in a dose-dependent manner. As a control, microinjection of the TRH analogue into the brain stem outside the vagal complex failed to stimulate pancreatic secretion. Either bilateral subdiaphragmatic vagotomy or atropine abolished the ability of the TRH analogue to stimulate pancreatic secretion. Our data suggest that TRH acts in the dorsal vagal complex to stimulate pancreatic secretion through vagus-dependent and cholinergic pathways. The dorsal vagal complex may play an important role as a central site for control of the exocrine pancreas.
当向大鼠脑脊液中注射促甲状腺激素释放激素（TRH）时，它会通过迷走神经刺激胰腺外分泌。然而，关于TRH在大脑中刺激胰腺分泌的确切作用位点知之甚少。最近的神经免疫化学和神经生理学研究表明，TRH可能是迷走神经背侧复合体中的一种神经递质，该复合体通过迷走神经向胰腺发送纤维。因此，我们假设TRH可能在迷走神经背侧复合体中发挥中枢作用，以刺激胰腺外分泌。为了解决这个问题，将一种TRH类似物[1-甲基-（S）-4,5-二氢乳清酸基]-L-组氨酰-L-脯氨酰胺-NH2微量注射到迷走神经背侧复合体中，并在乌拉坦麻醉的大鼠中测量基础胰液流量和蛋白质分泌。将TRH类似物（0.2 - 2 ng/位点）微量注射到迷走神经背侧复合体中，以剂量依赖的方式显著刺激了胰液流量和蛋白质输出。作为对照，将TRH类似物微量注射到迷走神经复合体之外的脑干中未能刺激胰腺分泌。双侧膈下迷走神经切断术或阿托品均可消除TRH类似物刺激胰腺分泌的能力。我们的数据表明，TRH在迷走神经背侧复合体中发挥作用，通过依赖迷走神经和胆碱能途径刺激胰腺分泌。迷走神经背侧复合体可能作为控制胰腺外分泌的中枢位点发挥重要作用。
