Shimosegawa T, Foda H D, Said S I
Department of Medicine, University of Illinois, Chicago.
Am Rev Respir Dis. 1989 Aug;140(2):441-8. doi: 10.1164/ajrccm/140.2.441.
Met-enkephalin (Met-Enk) and Leu-enkephalin (Leu-Enk), the opioid peptides originally isolated from the brain, are believed to act as inhibitory neuromodulators at various synaptic sites. In this immunohistochemical study, we have investigated the localization and distribution of Met- and Leu-Enk immunoreactivities in airways and pulmonary vessels of guinea pigs and rats. Immunoreactivities to both peptides were found in nerve fibers and nerve terminals distributed mainly to the trachea and major bronchi, and were especially prevalent in the smooth muscle layer, in the lamina propria, and around tracheal and bronchial glands, but not in the epithelium. Few immunoreactive nerve fibers were detected in smaller bronchi, bronchioles, and alveoli. Enkephalin-immunoreactive nerve fibers were also localized in the walls of pulmonary and bronchial vessels. Within airway microganglia, immunoreactivity was observed in a few nerve terminals, but not in ganglion cell bodies. Met- and Leu-Enk immunoreactive nerve fibers showed similar distribution patterns, though minor differences were noted between the two species: Enk-immunoreactive nerve fibers in the smooth muscle layer were more abundant in guinea pigs than in rats, whereas those in mucous glands were richer in rats than in guinea pigs. These results document the presence of Met- and Leu-Enk immunoreactivity in nerve fibers supplying guinea pig and rat airways and pulmonary vessels, and provide a morphologic basis for the view that enkephalins are likely neurotransmitters or neuromodulators in the lung.
甲硫氨酸脑啡肽（Met-Enk）和亮氨酸脑啡肽（Leu-Enk）是最初从大脑中分离出来的阿片肽，被认为在各种突触部位起抑制性神经调质的作用。在这项免疫组织化学研究中，我们调查了豚鼠和大鼠气道及肺血管中甲硫氨酸脑啡肽和亮氨酸脑啡肽免疫反应性的定位和分布。在主要分布于气管和主支气管的神经纤维和神经末梢中发现了对这两种肽的免疫反应性，尤其在平滑肌层、固有层以及气管和支气管腺周围普遍存在，但在上皮中未发现。在较小的支气管、细支气管和肺泡中检测到的免疫反应性神经纤维很少。脑啡肽免疫反应性神经纤维也定位于肺血管和支气管血管壁。在气道微神经节内，在少数神经末梢中观察到免疫反应性，但在神经节细胞体中未观察到。甲硫氨酸脑啡肽和亮氨酸脑啡肽免疫反应性神经纤维显示出相似的分布模式，尽管在这两个物种之间存在细微差异：平滑肌层中的脑啡肽免疫反应性神经纤维在豚鼠中比在大鼠中更丰富，而在黏液腺中的那些在大鼠中比在豚鼠中更丰富。这些结果证明了在豚鼠和大鼠气道及肺血管的神经纤维中存在甲硫氨酸脑啡肽和亮氨酸脑啡肽免疫反应性，并为脑啡肽可能是肺中的神经递质或神经调质这一观点提供了形态学依据。
