Effects of capsaicin in temporomandibular joint arthritis in rats

Temporomandibular joint (TMJ) arthritis was induced in female Lewis rats by unilateral injection of a suspension of heat-killed Mycobacterium butyricum in paraffin oil into the TMJ. Control rats received paraffin oil by the same route. Arthritic and control rats were pretreated either with capsaicin or denervation of the mandibular branch of the trigeminal nerve. Tissues were collected for neuropeptide extraction and analysed by radioimmunoassay and reverse-phase high-performance liquid chromatography. In all groups, the levels of substance P- (SP), calcitonin gene-related peptide- (CGRP) and neuropeptide Y- (NPY) like immunoreactivity (LI) were higher in the trigeminal ganglia than in the TMJs. In control rats, capsaicin significantly lowered the levels of SP-LI in the trigeminal ganglia and TMJ, but not CGRP-LI and NPY-LI. In the arthritic rats, capsaicin pretreatment significantly lowered the SP-LI and CGRP-LI in the trigeminal ganglia and TMJ, but not the NPY-LI. In the trigeminal ganglia the unilateral denervation significantly lowered SP-LI in control rats, and in arthritic rats SP-LI and CGRP-LI. On the denervated side of the arthritic TMJ, NPY-LI, SP-LI and CGRP- LI were significantly lowered as compared to the arthritic control rats and to the contralateral side. In this rat model, pretreatment with capsaicin and surgical denervation decreased the neuropeptide content in the trigeminal ganglia and the TMJ. The results clearly demonstrate a close interaction between increased neuropeptide release from sensory and sympathetic neurones after induction of arthritis in the rat.     

Trigeminal amyloidoma: case report and review of the literature.

The authors present a case of amyloid infiltration involving the trigeminal nerve that mimicked a malignant cavernous sinus tumor with perineural tumor infiltration. A 64-year-old man presented with trigeminal nerve numbness. Imaging revealed a plaque-like enhancing lesion along the right lateral cavernous sinus extending anteriorly into Meckel's cave and involving the proximal V2 and V3 branches of the trigeminal nerve. The patient underwent an extradural frontotemporal craniotomy with middle fossa exposure of the cavernous sinus to diagnose and treat the presumed malignant cavernous sinus tumor. A reddish mass involving the lateral dural wall of the cavernous sinus was resected. The gasserian ganglion, V2, and V3, the latter of which was biopsied, were enlarged. Permanent histopathological studies showed microscopic eosinophilic, amorphous material, which stained positive for Congo red, and an absence of neoplastic cells. The final diagnosis was amyloidoma. Thus, amyloidomas can involve the trigeminal nerve or ganglia and should be considered in the differential diagnosis of a cavernous sinus lesion mimicking a tumor. Patients may have symptomatic improvement of trigeminal neuropathy with resection of the amyloidoma outside the nerve capsule that is compressing the nerve, while resection of the lesion from within the capsule may result in permanent trigeminal nerve dysfunction.     

Somatosensory nuclei in the brainstem of the rat: independent projections to the thalamus and cerebellum

The dorsal column nuclei and the sensory trigeminal nuclei project not only to the ventrobasal thalamus but also to the cerebellum. In this study the numbers and distribution of neurones projecting to these two regions were examined for the following nuclei: the rostral part of the main cuneate nucleus, the external cuneate nucleus, nucleus x, the principal sensory nucleus of the trigeminal nerve, and the oral, interpolar, and caudal subnuclei of the spinal nucleus of the trigeminal nerve. A thalamic projection from nucleus x and from the external cuneate nucleus was confirmed, and a distinct group of neurones projecting to the ventroposteromedial thalamus was distinguished near the ventromedial aspect of the principal sensory nucleus. Of the 165,000 neurones examined, only one was found to be double labelled. It was concluded that the populations of neurones that project to the ventrobasal thalamus and to the cerebellum are separate, and that somatosensory neurones in the brainstem do not send axon collaterals to both regions.     

脑干、三叉神经及大脑动脉环的可视化研究

目的 建立人体脑干、三叉神经及大脑动脉环的可视化数字模型。方法 采用首例中国数字化可视人体数据集，在SGI工作站上对脑干及其周围毗邻结构进行计算机三维重建并立体显示。结果 获得人体脑干、三叉神经及大脑动脉环等器官组织的三维重建结构，可对其进行任意径线和角度的适时三维测量。结论 首例中国数字化可视人体数据集能够提供完整而精确的解剖断面数据，脑干及其毗邻的三叉神经、大脑动脉环的可视化模型准确反映出该区域复杂的解剖学结构特点及其相邻器官间的空间毗邻关系，可为该区域的疾病的影像诊断和外科治疗提供形态学依据。     

Timecourse of development of the wallaby trigeminal pathway. I. Periphery to brainstem

The development of the vibrissae and their innervation and the maturation of the brainstem trigeminal sensory nuclei have been studied in the wallaby, Macropus eugenii, from birth to adulthood. At birth, developing vibrissal follicles consist of solid epidermal pegs surrounded by dermal condensations. The developing follicles and adjacent skin are innervated by trigeminal afferents. Ten days after birth the follicle contains a dermal papilla and the deep vibrissal nerve can be recognised. A hair cone is present at postnatal day (P) 30 and hairs are apparent on the skin surface by P35. By P63 the deep vibrissal nerve can be seen innervating Merkel cells in the outer root sheath; in addition, the first signs of the blood sinus can be recognised. Innervation of the inner conical body and lanceolate and lamellated receptors supplying the mesenchymal sheath and waist region are not seen until P119, when the follicle resembles that seen in the adult. At birth, central processes of the trigeminal ganglion cells have entered the trigeminal tract and extend from the rostral pons to the upper cervical cord. Labelling with a carbocyanine dye at P0 shows afferents extending medially from the tract into the trigeminal subnuclei at all levels. At this stage the trigeminal nuclei appear as areas of increased cell density in the lateral brainstem. By P30–40 the four subnuclei can be distinguished on the basis of shape, cytoarchitecture, and succinic dehydrogenase reactivity. Adult morphology is not fully established until P210. In mature animals, nucleus principalis contains closely packed, polymorphic cells, frequently aligned parallel to thick fibre bundles that traverse the nucleus obliquely. Subnuclei oralis and interpolaris contain sparsely distributed, medium to large cells, randomly oriented, as well as prominent rostrocaudally directed fibre bundles. Subnucleus caudalis consists of the marginal layer, substantia gelatinosa, and magnocellular layers as described in other species. Patches of increased succinic dehydrogenase or cytochrome oxidase reactivity, presumably corresponding to the vibrissae, are present in subnuclei principalis, interpolaris, and caudalis in developing and adult animals, although the pattern is less clear than in rats. The brainstem patches are first seen at P40, approximately 6 weeks before the corresponding vibrissal-related pattern develops in the cortex. This suggests that the onset of patch formation may be regulated independently at different levels of the pathway. © 1994 Wiley-Liss, Inc.     

hNa_v1.8mRNA在三叉神经痛患者痛支神经中的表达

目的：观察河脉毒素不敏感型钠通道Navl．8 mRNA在三叉神经痛(trigeminal neuralgia,TN)患者痛支神经中的表达。方法：利用RT—PCR技术，以β—actin为内参照，检测5例原发性TN保守治疗无效患者的痛支神经、2例行舌颌颈联合根治术患者正常耳大神经和肌肉组织中hNavl．8 mRNA的表达。结泉：hNavl．8 mRNA在TN患者痛支神经中有明显表达，而在正常耳大神经及肌肉组织中均无表达。结论：hNavl．8 mRNA在三叉神经痛支中的异常表达可能与TN的发病机制有关。     

Changes in the microcirculation in rats with experimental trigeminal neuralgia

Laboratory of Pathophysiology of Pain and Laboratory of General Pathology of the Microcirculation, Research Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 111, No. 1, pp. 9–11, January, 1991.     

The influence of muscle-conditioned media on chick embryo brainstem neurons in culture

Brainstem pieces from the trigeminal region of the metencephalic basal plate of 10-day chick embryos were dissociated and cultured in control conditions or in the presence of muscle-conditioned medium (MCM). The MCM was derived from age-matched target tissue relevant to this neuronal region (jaw musculature), from relevant target tissue of an age at which innervation would initially be taking place (4 days), and from nonrelevant target tissue also of an early stage (4-day limb bud). Neuronal survival and differentiation was assessed daily, for 7 days. Survival and differentiation were significantly enhanced by the 4-day jaw MCM compared to both the controls and the cultures grown with 10-day jaw MCM and 4-day limb MCM. These measures in the presence of 10-day jaw MCM and 4-day limb MCM did not differ, but surpassed that seen in control cultures. The results are compared to the more specific responsiveness seen in earlier (2-day) neural tube cultures, and their relationship to in vivo regenerative nerve fiber outgrowth is considered.