孤束核内迷走神经传入纤维与神经降压肽样神经元间的突触联系—溃变结合免疫电镜研究

THE SYNAPTIC CONNECTIONS OF THE VAGAL AFFERENT FIBERS AND NEUROTENSIN-LIKE IMMUNOREACTIVE PROFILES IN THE NUCLEUS OF SOLITARY TRACT—DEGENERATION. COMBINED WITH IMMUNO-ELECTRON MICROSCOPIC STUDY

用切断颈迷走神经的顺行溃变法结合免疫组化(PAP法)研究了孤束核内迷走神经传入纤维与NT样免疫反应(NT-LI)结构超微结构及其联系。发现溃变的迷走神经传入纤维终末多呈电子致密型,少量为电子透亮型;溃变的轴突终末少量地与NT-LI树突形成非对称性突触,较多的与未标记的树突或胞体形成对称性和非对称性突触;NT-LI结构可作为突触前成分或突触后成分与未标记的细胞构成对称性或非对称性突触,NT-LI结构间各存在对称性的轴-体、轴-树和树-树突触。结果表明迷走神经传入纤维可与孤束核内NT-LI细胞构成突触,但数量较少,孤束核内的NT-LI细胞可能作为迷走神经传入纤维与迷走神经背核中节前神经元或高位脑部之间联系的中间神经元的一部分,从而参与内脏、心血管活动的调节。

The ultrastructhre and intranuclear connections of the vagat afferent fibers and neurotensin-like immunoreactive (NT-LI) p roofiles in the nucleus of solitary tract have been studied electron microscopically by the anterograde, degeneration method combined with immanocytochemistry (PAP technique), Vagal afferents are allowed to degenerate by cutting the cervical vagal nerve. It has been found that most vagal affenent terminals show electron-dense degeneration, a few electron-lucent degeneration. The NT-LI profiles include NT-LI perikarya, dendrites and axons. The degenerated axonal terminals form asymmetrical synapses with NT-LI dendrites and also establish symmetrical or asymmetrical synapses with unlabeled dendrites or perikarya. The NT-LI profiles may be pre-or post-synaptic elements and form synapses with the unlabeled cells, which are symmetrical or asymmetrical ones. Tile symmetrical axodendritic, axo-somatic and dendrodendritic synapses also exist between the NT-LI profiles. The results indicate that in the nucleus of solitary tract, the vagal afferent fibers connect with NT-LI cells. But the number of these synapses is small. It is suggested that NT-LI cells in the nucleus of solitary tract may act as a part of intermediate neurons connecting the vagal afferent fibers with parasympathetic preganglionic neurons in the dorsal vagal nucleus or with the high level brain areas to play roles invisceral and cardrovascular activity regulation.