Bauer A J, Sarr M G, Szurszewski J H
Department of Physiology and Biophysics, Mayo Medical School, Rochester, Minnesota.
Gastroenterology. 1991 Oct;101(4):970-6. doi: 10.1016/0016-5085(91)90723-x.
Intracellular recording techniques were used to study the effects of methionine enkephalin and dynorphin(1-13) on normal circular smooth muscle of human and baboon jejunum. Tetrodotoxin-sensitive inhibitory junction potentials had a mean (+/- SEM) amplitude of 21 +/- 3.3 mV in human jejunum and 24.1 +/- 1.3 mV in baboon jejunum. In both species, exogenously added methionine enkephalin and dynorphin (1-13) decreased inhibitory junction potentials amplitude in a dose-dependent manner with methionine enkephalin being more potent. Both opioid peptides acted on receptors located on axons of intrinsic inhibitory nerves. The effects of both methionine enkephalin and dynorphin(1-13) were blocked by ICI-174,864, a selective delta-receptor antagonist. The selective delta agonist, cyclic [D-penicillamine2, D-penicillamine5]enkephalin, and the selective mu agonist, Try-Pro-NMePhe-D-Pro-NH2, (each 10 mumol/L) decreased inhibitory junction potential amplitude by 79% +/- 6.9% and 61% +/- 4.8%, respectively. The selective kappa agonist, [trans-3,4-dichloro-N-methyl-N-(2-91-pyrolidinyl)-cyclohexyl]- benzeneacetamide methanesulfonate, (10 mumol/L) had no effect. Although direct postsynaptic opioid receptor blockade of the inhibitory neurotransmitter on the smooth muscle cell has not been ruled out, the authors believe these data suggest that delta and mu receptors were present on inhibitory motor nerves innervating the circular muscle and that methionine enkephalin and dynorphin(1-13) decreased release of inhibitory neurotransmitter(s) by acting on delta receptors.
采用细胞内记录技术研究甲硫氨酸脑啡肽和强啡肽（1-13）对人及狒狒空肠正常环形平滑肌的影响。河豚毒素敏感的抑制性接头电位在人空肠中的平均（±标准误）幅度为21±3.3mV，在狒狒空肠中为24.1±1.3mV。在这两个物种中，外源性添加的甲硫氨酸脑啡肽和强啡肽（1-13）均以剂量依赖性方式降低抑制性接头电位幅度，且甲硫氨酸脑啡肽的作用更强。两种阿片肽均作用于内在抑制性神经轴突上的受体。甲硫氨酸脑啡肽和强啡肽（1-13）的作用均被选择性δ受体拮抗剂ICI-174,864阻断。选择性δ激动剂环[D-青霉胺2，D-青霉胺5]脑啡肽和选择性μ激动剂酪氨酰-脯氨酰-N-甲基苯丙氨酰-D-脯氨酰胺（均为10μmol/L）分别使抑制性接头电位幅度降低79%±6.9%和61%±4.8%。选择性κ激动剂[反式-3,4-二氯-N-甲基-N-(2-吡咯烷基)-环己基]-苯乙酰胺甲磺酸盐（10μmol/L）无作用。虽然尚未排除抑制性神经递质在平滑肌细胞上的直接突触后阿片受体阻断作用，但作者认为这些数据表明，在支配环形肌的抑制性运动神经上存在δ和μ受体，且甲硫氨酸脑啡肽和强啡肽（1-13）通过作用于δ受体减少抑制性神经递质的释放。
