Localization of metallothionein (MT) and expression of MT isoforms induced by cadmium in rat dental pulp

The relationship between oral cancer and cadmium: a review

Cadmium (Cd) has been classified as a type I carcinogen. Since it is ingested orally through food and tobacco use, Cd is likely to be closely related to oral cancers. The relationship between cadmium and oral cancer was investigated using papers on Pubmed and Web of Science. Thus a total of 11 studies from these databases were included in the review. Cd concentrations were significantly higher in both the blood and hair of oral cancer patients than in controls. Additionally, it has been reported that Cd increases the activity of reactive oxygen species. Tobacco plants contain varying levels of Cd. The presence of high Cd concentrations in patients who use tobacco products and develop oral cancer is strong evidence that Cd is directly related to oral cancer. While planning a study to determine the Cd concentrations in biological samples, it is advisable to examine the methodologies of previous studies and to avoid technical deficiencies. New cell line studies are required to explain the relationship between Cd and autophagy-apoptosis.

Historic variation of trace elements in pinnipeds with spatially segregated trophic habits reveals differences in exposure to pollution

Marine mammals and the ecological functions they provide to coastal and pelagic ecosystems are increasingly threatened by the intensification of anthropogenic impacts. The Uruguayan coastline throughout the 20th century, like other coastal environments worldwide, has been the sink of a variety of trace metals derived from the rapid urbanization and industrialization of related land areas. This coastline is inhabited by two species of pinnipeds trophically and spatially segregated. Otaria byronia feeds in coastal environments while Arctocephalus australis preys mainly offshore. The present study aimed to analyze historic changes in concentrations of trace elements in teeth of both species from 1941 to the present day. We analyzed the dentin of 94 canine teeth using stable isotope analysis (δ¹³C) and ICP-MS to determine their feeding areas and the concentration of 10 trace elements (Al, As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) respectively. The concentration of Cr was significantly higher during '70-'80s, in both species coinciding with tannery industry development. Both species of pinnipeds have been differentially exposed to trace elements depending on their feeding area. A pelagic diet, possibly based on squid, increased the concentration of Cd in A. australis, while O. byronia has been more exposed to anthropogenic Pb and Cu associated to a costal and more benthic diet. Our results highlight dentin as a reliable matrix for historic studies on the exposure to trace elements. In light of our results, the O. byronia's declining population could be the result of the synergistic effects of trace elements together with other ecological pressures faced in their environment.

Zinc and Metallothionein in the Development and Progression of Dental Caries

Chronic oxidative stress and reactive oxygen species (ROS) in oral cavity as well as acidic pH on dental enamel surface due to the metabolic activities of bacterial plaque are the major contributors in the development and progression of dental caries. Along with other factors, deposition or dissolution Ca and Mg mostly determines the re- or demineralization of dental enamel. Zn plays an important role for both Ca and Mg bioavailability in oral cavity. Metallothionein (MT), a group of small molecular weight, cysteine-rich proteins (~ 7 kDa), is commonly induced by ROS, bacterial infection, and Zn. In the current review, we evaluated MT at the junction between the progression of dental caries and its etiologies that are common in MT biosynthesis.

Antiallodynic action of 1-(3-(9H-Carbazol-9-yl)-1-propyl)-4-(2-methyoxyphenyl)-4-piperidinol (NNC05-2090), a betaine/GABA transporter inhibitor

The GABAergic system in the spinal cord has been shown to participate in neuropathic pain in various animal models. GABA transporters (GATs) play a role in controlling the synaptic clearance of GABA; however, their role in neuropathic pain remains unclear. In the present study, we compared the betaine/GABA transporter (BGT-1) with other GAT subtypes to determine its participation in neuropathic pain using a mouse model of sciatic nerve ligation. 1-(3-(9H-Carbazol-9-yl)-1-propyl)-4-(2-methyoxyphenyl)-4-piperidinol (NNC05-2090), an inhibitor that displays moderate selectivity for BGT-1, had an antiallodynic action on model mice treated through both intrathecally and intravenous administration routes. On the other hand, SKF89976A, a selective GAT-1 inhibitor, had a weak antiallodynic action, and (S)-SNAP5114, an inhibitor that displays selectivity for GAT-3, had no antiallodynic action. Systemic analysis of these compounds on GABA uptake in CHO cells stably expressing BGT-1 revealed that NNC05-2090 not only inhibited BGT-1, but also serotonin, noradrenaline, and dopamine transporters, using a substrate uptake assay in CHO cells stably expressing each transporter, with IC50: 5.29, 7.91, and 4.08 μM, respectively. These values were similar to the IC50 value at BGT-1 (10.6 μM). These results suggest that the antiallodynic action of NNC05-2090 is due to the inhibition of both BGT-1 and monoamine transporters.

Immunohistochemical localization of metallothionein in dental pulp after cavity preparation of rat molars

OBJECTIVE

Metallothionein (MT) is an intracellular cysteine-rich protein associated with cell proliferation and differentiation. Our objective was to examine immunohistochemically the localization of MT in the rat dental pulp after cavity preparation.

STUDY DESIGN

Cavities were prepared on the upper first molars of 9 rats. Specimens were collected at 1, 3, and 5 days after cavity preparation, and paraffin sections were made. For double-immunohistochemical staining, anti-MT monoclonal antibody (E9) and anti-proliferating cell nuclear antigen (PCNA) monoclonal antibody (PC10) were applied.

RESULTS

At 3 days after cavity preparation, some odontoblasts corresponding to the cavity, many pulp cells, and some endothelial cells in the pulp under the cavity showed both MT- and PCNA-positive immunostainings.

CONCLUSION

Metallothionein was detected in the dental pulp after pulp injury, and it is likely that MT is closely related to the proliferation of newly differentiating odontoblasts and angiogenesis during the healing process.

Metallothionein expression and localization in rat bone tissue after cadmium injection

We investigated the induction of metallothionein (MT) by cadmium (Cd) in the bone tissue of rats. To clarify the cell response to Cd in bone, the isoform-specific expression of MT mRNAs (MT-I and MT-II) was examined by reverse transcriptase-polymerase chain reaction (RT-PCR). Both MT-I and MT-II mRNA levels were increased within 3 h by Cd administration. MT (MT-I/MT-II) localization after single Cd injection were also confirmed by immunohistochemical studies. Notably, MT-positive cells were time-dependently increased, and the positive cells were mainly localized in osteocytes. The cell-specific induction of MT may be associated with Cd accumulation and Cd-induced bone injury in vivo. Furthermore, we also found that MT was consecutively expressed in some osteoclasts of control rats. This finding suggested a new role of osteoclasts in bone metabolism.