降钙素基因相关肽、甘丙肽免疫反应在大鼠臂旁外侧核分布的超微结构特征分析

AN ELECTRON MICROSCOPIC OBSERVATION ON CGRP-IR, GAL-IR STRUCTURES IN THE LATERAL PARABRACHIAL NUCLEUS IN THE RAT

应用免疫电镜包埋前染色技术对降钙素基因相关肽、甘丙肽免疫反应在大鼠臂旁外侧核分布的超微结构特征进行了研究。在臂旁外侧核腹外侧区中,常见降钙素基因相关肽阳性轴突终末与阴性树突及树突棘形成轴-树或轴-棘突触,大多为非对称型,少数为对称型;也可见阳性树突或阳性胞体与阴性轴突终末形成的轴-树或轴-体突触。阳性轴突终末含清亮小泡和致密核心小泡。臂旁外侧孩腹外侧部中甘丙肽阳性结构大多为阳性轴突终末,部分为阳性树突及阳性胞体。阳性树突常呈丛状分布于血管附近,阳性轴突常与阴性树突,阳性树突常与阴性轴突形成轴-树突触,大多为非对称型。臂旁外侧核腹外侧亚核的甘丙肽阳性结构分布基本与前者相似,但轴-树突触大多为对称型,而且一些阳性轴突与血管基膜紧贴。

The ultrastructural characteristics of CGRP-ir, GAL-ir structures in the lateral parabrachial nucleus (LPBN) were observed by employing pre-embedding immuno-electron microscopy. The results showed that in the ventrolateral part of the LPBN it was quite common to see that the CGRP-ir axonal terminals formed axo-dendritic or possible axo-spine synapses with the nonimmunoreactive dendrites or dendritic spines. Most of them were asymmetric. The non-immunoreactive dendrites receiving one immunoreactive axonal terminal might also be postsynaptic to other non-immunoreactive axons within the same section. The axodendritic or axo-somatic synapses formed by immunoreactive dendrites with non-immunoreactive axonal terminals or immunoreactive soma with non-immunoreactive axonal terminals could also be seen. The immunoreactive axonal terminals contained small clear vesicles and large dense-core vesicles of various sizes.The GAL-ir structures in the ventrolaterall part of the LPBN were mostly immunoreactive axonal terminals, some were immunoreactive dendrites. The latter often appeared in clusters near blood vessels. Most of the immunoreactive axonal terminals formed synapses with unlabeled dendrites and the immunoreactive dendrites were postsynaptic to the unlabeled axonal terminals. The majority of the synapses were asymmetric. The GAL-ir structures in the ventrolateral nucleus bore strong resemblance to those in the ventrolateral part of the LPBN. But most of the axo-dendritic synapses were symmetric, and some were found in close proximity to the unlabeled external glial sheath and basal membrane of blood vessels.