Distribution and possible origin of galanin-like immunoreactive nerve fibers in the mammalian dental pulp.

Human, dog, cat and rat dental pulps were investigated for the presence and distribution of galanin-like immunoreactive (-IR) nerve fibers, and the possible origin of pulpal galanin-IR nerve fibers in the rat was examined. Galanin-IR nerve fibers were present in the dental pulps of all species examined. Two types of galanin-IR nerve fibers were distinguished with regard to morphology; thin varicose nerve fibers and thick smooth-surfaced nerve fibers. Thin varicose galanin-IR nerve fibers were seen to run along the blood vessel in the human, dog and cat root pulp. In the coronal pulp, galanin-IR nerve fibers ran toward the odontoblastic layer but they did not form the subodontoblastic nerve plexus. In rat molar pulp, few galanin-IR nerve fibers were observed; the distribution of these nerve fibers was similar to those in human, dog and cat pulp. In contrast, many thick smooth-surfaced galanin-IR nerve fibers were observed near the blood vessels in incisor pulp of the rat; occasionally a few varicose galanin-IR nerve fibers were also observed. Transection of the inferior alveolar nerve or mandibular nerve caused complete disappearance of galanin-IR nerve fibers in rat dental pulp, while surgical sympathectomy of the superior cervical ganglion did not affect their distribution. The present results indicate that galanin-IR nerve fibers are present in the mammalian dental pulp, and that the intrapulpal galanin-IR nerve fibers in the rat originate from the trigeminal ganglion and are primary afferents.

Appearance of dynorphin in the spinal trigeminal nucleus complex following experimental tooth movement in the rat.

Changes in the expression of dynorphin were investigated immunohistochemically. Cells showing dynorphin immunoreactivity first appeared 2 days and disappeared 15 days after the unilateral insertion of separating elastics between the upper molars. These immunopositive cells were localized in the superficial layers in the medial third of the subnucleus caudalis on the ipsilateral side, except at 1 and 15 days. On the contralateral side, a few immunoreactive cells only were observed in the subnucleus caudalis of the 3- to 8-day groups. No immunoreactivity was observed in the subnucleus interpolaris, subnucleus oralis spinal trigeminal nucleus complex (STNC), principal trigeminal nucleus and mesencephalic trigeminal nucleus of the experimental rats and all the trigeminal nuclei of control animals. The findings indicate that experimental tooth movement induced the expression of dynorphin in the superficial layers of the subnucleus caudalis STNC. The subnucleus caudalis may play an important part in modulation of the discomfort and pain evoked by tooth movement.

Appearance of neuropeptide Y-like immunoreactive cells in the rat trigeminal ganglion following dental injuries.

The effects of these injuries on the presence and distribution of neuropeptide Y (NPY)-immunoreactive (-IR) neurones were examined immunohistochemically. In the normal trigeminal ganglion: some perivascular nerves displayed NPY-IR but there were no NPY-IR ganglionic cells. Fourteen days after extraction or pulp exposure of the upper first molar, NPY-IR cells appeared in the maxillary region of the trigeminal ganglion. About 90% of the injury-evoked NPY-IR cells had medium to large diameters (more than 300 microns2 in cross-sectional area). Shallow cavity preparation, however, did not induce the appearance of NPY-IR cells in the trigeminal ganglion. These results indicate the dental injuries alter the primary sensory neurones in the trigeminal ganglion.

[Immunohistochemical studies on the peptidergic nerve distribution in hard palate mucosa and gingiva of the rat. 2. Responses of calcitonin gene-related peptide (CGRP)-containing nerve fibers on wound healing of the mucosa].

This study investigated morphological changes of CGRP-containing nerve fibers during wound healing of the rat oral mucosa following resection of the transverse palatine ridge and gingivectomy. The tissue was immunohistochemically examined at 0, 3, 7, 14, 21, 28 and 70 days after surgical injury. The following results were obtained. 1) The Transverse Palatine Ridge. At shorter survival periods (0 and 3 days), CGRP-containing nerve fibers adjacent to the surgical defect degenerated and decreased in number. By 7 days, tissue repair had advanced and the defect had been filled with granulation tissue. Thin nerve fibers were found in and around the granulation tissue, especially nearby newly proliferating blood vessels. At 14 days, extensive regeneration of thin nerve fibers was observed in the repaired tissue. Many of them were found singularly in deeper layers of the repaired tissue, and some in bundles reaching the base of the epithelium. Some of these sprouts appeared to have existed only transiently because their number somewhat reduced by 21 days. The defect was filled with scar tissue at 28 days and mucous structure did not return to normal even at 70 days. Nerve fibers neither regenerated to regain the original density nor formed subepithelial plexuses. 2) The Gingiva. At 0 and 3 days, CGRP-containing nerve fibers near the cut surface of gingiva degenerated and their number decreased. At 7 days, a few thin regenerating fibers were found entering the epithelium on the oral side. Sprouts were also seen around small blood vessels deep in the granulation tissue. By 14 days, the nerve fibers had gradually increased with progress of tissue repair. However, rapid, transient increase in number of fibers, like that observed for the palatine ridge, was not noted. By 21 days, the junctional epithelium had regenerated, and regenerating fibers had redistributed into and beneath the sulcal epithelium. At 28 and 70 days, the repaired marginal gingiva were indistinguishable from normal (and control) marginal gingiva as regards the histology and CGRP-innervation. There were, however, a few exceptions in which junctional epithelium did not fully recover. In these animals, regeneration of CGRP-containing fibers was barely discernible in or around the sulcal epithelium.

[Immunohistochemical studies on the peptidergic nerve distribution in hard palate mucosa and gingiva of the rat].

The present study demonstrates the distribution of nerve fibers containing calcitonin gene-related peptide (CGRP), substance P (SP), neurokinin A (NKA), neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP) in the hard palate mucosa and gingiva of the rat by the use of an indirect immunofluorescence method. Nerve fibers containing CGRP, SP and NKA showed very similar distribution patterns. Numerous nerve fibers containing CGRP, SP and NKA were observed in the lamina propria of hard palate mucosa. They formed dense subepithelial plexuses in incisive papilla and transverse palatine ridges. Some of them penetrated deeply into the epithelium and terminated as free nerve endings. In gingiva, nerve fibers containing these peptides were found especially near gingival sulcus. They were abundantly distributed beneath the junctional epithelium and formed nerve plexus. In all sampling regions, these nerve fibers were seen around the large- and medium-sized blood vessels in lamina propria and submucosal layer. NPY- and VIP-containing nerve fibers were observed in close association with blood vessels of hard palate mucosa. These nerve fibers were located around the large-sized blood vessels in the submucosal layer of hard palate and a few fibers were seen running along the small blood vessels in the lamina propria of the anterior half of hard palate mucosa. Nerve fibers containing these peptides were never found in gingiva.

Leucine-enkephalin-, neurokinin A- and cholecystokinin-like immunoreactivities in the guinea pig tongue.

The occurrence of these neuropeptides was examined by immunofluorescence. Leu-Enk-like immunoreactivity was seen in nerve fibres associated with the epithelium, blood vessels and lingual salivary glands as well as in ganglionic cells within the tongue. Neuropeptide A-like immunoreactivity was found in nerve fibres associated with the epithelium, taste buds, blood vessels and lingual salivary glands. Cholecystokinin-like immunoreactivity was found in some nerve fibres around blood vessels as well as in ganglionic cells. The coexistence of these neuropeptides and substance P was also demonstrated in some nerve fibres and ganglionic cells within the tongue. Like substance P, these neuropeptides could be involved in blood flow regulation, salivation and as trophic factors for taste buds.

Cytochemical study of the Golgi apparatus and related organelles of the secretory ameloblasts of rat molar tooth germs cultured with and without colchicine.

The Golgi apparatus and Golgi-associated endoplasmic reticulum lysosome (GERL) were examined in the ameloblasts with a cytochemical marker, osmium impregnation, and two enzyme markers, thiamine pyrophosphatase (TPPase) and acid phosphatase (ACPase). In control cultured germs, osmium deposit appeared in one to two immature side cisternae of Golgi stacks; TPPase activity was restricted in a few mature side cisternae and condensing vacuoles. ACPase activity existed in the GERL and, sometimes, in the mature side-cisternae and condensing vacuoles. These findings show that Golgi stacks of ameloblasts consist of several distinct compartments. In colchicine-treated tooth germs, there were morphological and cytochemical changes in both Golgi stacks and GERL. The Golgi apparatus was fragmented and its stacks were scattered throughout the supranuclear region. In some stacks, the number of osmium-positive cisternae was greater than normal; in others they were absent. TPPase and ACPase activity was absent or diminished. These findings suggest the importance of microtubules in the organization of Golgi complex and GERL in the secretory ameloblast.