Extrinsic and intrinsic sources of calcitonin gene-related peptide immunoreactivity in the lamb ileum: a morphometric and neurochemical investigation
Extrinsic and intrinsic sources of calcitonin gene-related peptide immunoreactivity in the lamb ileum: a morphometric and neurochemical investigation
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DOI：
10.1007/s00441-005-0075-2
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发表时间：
2006-02-01
影响因子：
3.6
通讯作者：
Furness, JB
中科院分区：
文献类型：
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作者：
Chiocchetti, R;Grandis, A;Furness, JB
为探讨绵羊回肠降钙素基因相关肽免疫反应(CGRP-IR)神经纤维的外源性来源，将逆行荧光示踪剂Fast Blue(FB)注入回肠壁。胸腰背根神经节(DRG)和迷走神经节远端(结节)显示FB标记神经元的切片进行CGRP免疫组织化学处理。本文还研究了CGRP-IR在回肠纤维和神经细胞体中的分布。对2~4月龄羔羊的肌间神经丛(MP)和粘膜下神经丛(SMP)内的CGRP免疫反应阳性肠神经元进行了形态计量学分析。FB逆行标记的感觉神经元散在分布于T5-L4背根节内，但多数位于上腰椎节段(L1-L3)，回肠的外源性传入神经仅有一小部分来自结状神经节。在背根节内，57%的逆行标记神经元也是CGRP-IR。在冷冻切片中，在上皮下的固有层、乳房和淋巴滤泡(Peyer‘s Plats)周围以及肠血管沿线和周围可见致密的CGRP-IR纤维网络。罕见的CGRP-IR纤维也存在于两个肌层。在CGRP阴性的胞体周围可观察到致密的CGRP-IR纤维细胞周围篮。仅有的CGRP-IR神经细胞是定位于MP以及SMP的外部和内部成分的明确的Dogiel II型神经元。肌间神经节的CGRP免疫反应阳性神经元明显大于粘膜下神经节(平均面积：肌间神经元约1400微米(2)，粘膜下神经元约750微米(2))。约6%的肌间神经元和25%的粘膜下神经元为CGRP-IR Dogiel II型神经元。在这两个神经丛中，CGRP-IR神经元的比例分别为9%(MP)和42%(SMP)，而CGRP-IR神经元均未显示血管活性肠肽、一氧化氮合酶或酪氨酸羟基酶的免疫反应。因此，CGRP免疫反应在绵羊回肠的肠神经系统(如人的小肠和猪回肠的MP)中仅存在于一种形态上确定的神经元类型，即Dogiel II型细胞。这些可能是固有的初级传入神经元。
To investigate extrinsic origins of calcitonin gene-related peptide immunoreactive (CGRP-IR) nerve fibres in the sheep ileum, the retrograde fluorescent tracer Fast Blue (FB) was injected into the ileum wall. Sections of thoraco-lumbar dorsal root ganglia (DRG) and distal (nodose) vagal ganglia showing FB-labelled neurons were processed for CGRP immunohistochemistry. The distribution of CGRP-IR in fibres and nerve cell bodies in the ileum was also studied. CGRP-IR enteric neurons were morphometrically analysed in myenteric (MP) and submucosal plexuses (SMP) of lambs (2-4 months). Sensory neurons retrogradely labelled with FB were scattered in T5-L4 DRG but most were located at the upper lumbar levels (L1-L3); only a minor component of the extrinsic afferent innervation of the ileum was derived from nodose ganglia. In the DRG, 57% of retrogradely labelled neurons were also CGRP-IR. In cryostat sections, a dense network of CGRP-IR fibres was observed in the lamina propria beneath the epithelium, around the lacteals and lymphatic follicles (Peyer's platches), and along and around enteric blood vessels. Rare CGRP-IR fibres were also present in both muscle layers. Dense pericellular baskets of CGRP-IR fibres were observed around CGRP-negative somata. The only CGRP-IR nerve cells were well-defined Dogiel type II neurons localised in the MP and in the external and internal components of the SMP. CGRP-IR neurons in the myenteric ganglia were significantly larger than those in the submucosal ganglia (mean profile areas: about 1,400 mu m(2) stop for myenteric neurons, 750 mu m(2) stop for submucosal neurons). About 6% of myenteric neurons and 25% of submucosal neurons were CGRP-IR Dogiel type II neurons. The percentages of CGRP-IR neurons that were also tachykinin-IR were about 9% (MP) and 42% (SMP), whereas no CGRP-IR neurons exhibited immunoreactivity for vasoactive intestinal peptide, nitric oxide synthase or tyrosine hydroxylase in either plexus. Thus, CGRP immunoreactivity occurs in the enteric nervous system of the sheep ileum (as in human small intestine and MP of pig ileum) in only one morphologically defined type of neuron, Dogiel type II cells. These are probably intrinsic primary afferent neurons.