Furukawa K, Rips R
Eur J Pharmacol. 1985 Jun 7;112(2):237-41. doi: 10.1016/0014-2999(85)90501-1.
pGlu-His-Pro-dexamphetamine (TRH-A) produced a contraction through the release of acetylcholine from postganglionic cholinergic neurons in the duodenum of the guinea-pig in the same manner as TRH. However, the affinity of TRH-A (pD2, 4.70) toward isolated duodenum was one thousandth that of TRH (pD2, 7.74). The effects of TRH-A (10(-4)M) were abolished by 10(-7) M TRH, but only partially (about 50%) inhibited by 10(-4) M d-amphetamine. D-Amphetamine showed no stimulatory effect on the myenteric nerves. However, the duodenal response to TRH (10(-6) M) was dose dependently inhibited by d-amphetamine (10(-6), 10(-5), 10(-4) M) while the phasic and tonic contractions caused by high K+ (40 mM) or the contractile responses to acetylcholine (10(-7) M) were not blocked by d-amphetamine. These results indicate that d-amphetamine may act as an antagonist to TRH without influencing the movement of calcium ions in smooth muscle or muscarinic receptors and that contractile responses to TRH-A are mediated through TRH receptors in the myenteric cholinergic nerves.
焦谷氨酸 - 组氨酸 - 脯氨酸 - 右旋苯丙胺（TRH - A）与TRH一样，通过豚鼠十二指肠节后胆碱能神经元释放乙酰胆碱产生收缩作用。然而，TRH - A（pD2，4.70）对离体十二指肠的亲和力是TRH（pD2，7.74）的千分之一。TRH - A（10⁻⁴M）的作用可被10⁻⁷M的TRH消除，但仅被10⁻⁴M的右旋苯丙胺部分抑制（约50%）。右旋苯丙胺对肠肌间神经无刺激作用。然而，右旋苯丙胺（10⁻⁶、10⁻⁵、10⁻⁴M）对TRH（10⁻⁶M）引起的十二指肠反应呈剂量依赖性抑制，而高钾（40 mM）引起的相性和紧张性收缩或对乙酰胆碱（10⁻⁷M）的收缩反应不受右旋苯丙胺的阻断。这些结果表明，右旋苯丙胺可能作为TRH的拮抗剂，而不影响平滑肌中钙离子的移动或毒蕈碱受体，并且对TRH - A的收缩反应是通过肠肌间胆碱能神经中的TRH受体介导的。
