MT-I mRNA Research Articles

Effects of water-borne copper on the survival, antioxidant status, metallothionein-I mRNA expression and physiological responses of the Chinese mitten crab, <em>Eriocheir sinensis</em> (Decapoda: Brachyura) larvae

The lethal concentration of water-borne copper in Chinese mitten crab Eriocheir sinensis larvae was tested by exposing the animals to 0, 0.1, 0.2, 0.3, 0.5 and 0.8 mg Cu L -1 at 20°C for 96 h. The 96-h median lethal concentration (LC50) and its corresponding 95% confident interval was estimated on zoea 1 larvae and megalopa larvae, respectively. Acute dissolved copper toxicity was higher for zoea 1 larvae (0.16 mg L -1 ) than for megalopa larvae (0.21 mg L -1 ). The antioxidant status, metallothionein-I mRNA expression and physiological response of the crab to copper toxicity was further investigated by exposing the megalopa larvae to 0, 0.08 and 0.16 mg Cu L -1 for 96 h. The superoxide dismutase activity, catalase activity, glutathione S-transferase (GST) activity and lipid peroxidation content of megalopa larvae increased concomitantly with the exposure time and copper concentration. MT-I mRNA expression levels were positively correlated with both the concentration and duration of copper exposure. The oxygen consumption and respiratory quotient of megalopa larvae in response to 0.16 mg L -1 copper were significantly higher than those in the control group after 96 h of exposure (P E. sinensis larvae. MT-I and GST appear to be suitable biomarkers of environmental copper exposure stress in E. sinensis larvae

Metallothioneins I/II Expression in Rat Strains with Genetically Different Susceptibility to Experimental Autoimmune Encephalomyelitis

Objectives: Compared to the Dark Agouti (DA), the Albino Oxford (AO) rat strain exhibits lower susceptibility to the induction of experimental autoimmune encephalomyelitis (EAE). Here, we investigated the potential contribution of the heavy metal-binding proteins metallothioneins (MTs) I/II to these effects. Methods: Rats were immunized with bovine brain homogenate emulsified in complete Freund's adjuvant or only with complete Freund's adjuvant. The expression patterns of MTs mRNA and proteins and tissue concentrations of Zn²⁺ and Cu²⁺ were estimated in the brain and in the liver on days 7 and 12 after immunization, by real-time PCR, immunohistochemistry and inductively coupled plasma spectrometry, respectively. Additionally, the hepatic transforming growth factor beta and nuclear factor kappa B immunoreactivities were tested. Results: Clinical signs of EAE were not induced in AO rats, but they upregulated the expression of MT I/II proteins in the brain (hippocampus and cerebellum) and in the liver, similarly as DA rats. The transcriptional activation of MT-I occurred, however, only in DA rats, which accumulated also more zinc in the brain and in the liver. In contrast, intact AO rats had greater hepatic MT-I mRNA immunoreactivity and more Cu²⁺ in the hippocampus. Besides, in immunized AO rats a high upregulation of transforming growth factor beta and nuclear factor kappa B immunoreactivities was found in several hepatic structures (vascular endothelium, Kupffer cells and hepatocytes). Conclusions: Our data show that AO and DA rats differ in constitutive and inductive MT-I gene expression in the brain and in the liver, as well as in the hepatic cytokine profile, suggesting that these mechanisms may contribute to the discrepancy in the susceptibility to EAE.

Metallothionein (MT) -I and MT-II Expression Are Induced and Cause Zinc Sequestration in the Liver after Brain Injury

Experiments with transgenic over-expressing, and null mutant mice have determined that metallothionein-I and -II (MT-I/II) are protective after brain injury. MT-I/II is primarily a zinc-binding protein and it is not known how it provides neuroprotection to the injured brain or where MT-I/II acts to have its effects. MT-I/II is often expressed in the liver under stressful conditions but to date, measurement of MT-I/II expression after brain injury has focused primarily on the injured brain itself. In the present study we measured MT-I/II expression in the liver of mice after cryolesion brain injury by quantitative reverse-transcriptase PCR (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) with the UC1MT antibody. Displacement curves constructed using MT-I/II knockout (MT-I/II−/−) mouse tissues were used to validate the ELISA. Hepatic MT-I and MT-II mRNA levels were significantly increased within 24 hours of brain injury but hepatic MT-I/II protein levels were not significantly increased until 3 days post injury (DPI) and were maximal at the end of the experimental period, 7 DPI. Hepatic zinc content was measured by atomic absorption spectroscopy and was found to decrease at 1 and 3 DPI but returned to normal by 7DPI. Zinc in the livers of MT-I/II−/− mice did not show a return to normal at 7 DPI which suggests that after brain injury, MT-I/II is responsible for sequestering elevated levels of zinc to the liver. Conclusion: MT-I/II is up-regulated in the liver after brain injury and modulates the amount of zinc that is sequestered to the liver.

Retraction: Exercise-induced metallothionein expression in human skeletal muscle fibres

Exercise induces free oxygen radicals that cause oxidative stress, and metallothioneins (MTs) are increased in states of oxidative stress and possess anti-apoptotic effects. We therefore studied expression of the antioxidant factors metallothionein I and II (MT-I + II) in muscle biopsies obtained in response to 3 h of bicycle exercise performed by healthy men and in resting controls. Both MT-I + II proteins and MT-II mRNA expression increased significantly in both type I and II muscle fibres after exercise. Moreover, 24 h after exercise the levels of MT-II mRNA and MT-I + II proteins were still highly increased and the MT-II mRNA expression reached a 15-fold increase. As expected, immunohistochemical detection of malondialdehyde (MDA) and nitrotyrosine (NITT) showed that formation of free radicals and oxidative stress were clearly increased in exercising muscle peaking shortly after the end of exercise in both type I and II muscle fibres. This is the first report demonstrating that MT-I + II are significantly induced in human skeletal muscle fibres following exercise. As MT-I + II are antioxidant factors that protect various tissues during pathological conditions, the MT-I + II increases post exercise may represent a mechanism whereby contracting muscle fibres are protected against cellular stress and injury.

Chromium (VI) inhibits mouse metallothionein-I gene transcription by modifying the transcription potential of the co-activator p300

The production of the heavy metal-binding proteins, the metallothioneins (MTs), is induced by heavy metals such as Zn, Cd, and Hg. MTs maintain Zn homeostasis and attenuate heavy metal-induced cytotoxicity by sequestering these metals and lowering their intracellular concentrations. Previously, we had reported that Zn induced the formation of a co-activator complex containing metal response element-binding transcription factor-1 (MTF-1) and the histone acetyltransferase (HAT), p300, which plays an essential role in the activation of MT-1 transcription. In addition, we had shown that Cr(VI) inhibits Zn-induced MT-1 transcription by preventing the Zn-dependent formation of the MTF-1-p300 complex. In the current study, we have shown that the inhibition by Cr(VI) was partially overcome by the overexpression of p300 or MTF-1 in an MT-I promoter-driven luciferase reporter assay system and have used real-time RT-PCR to determine MT-I mRNA levels. It has been reported that Cr(VI) inhibits CYP1A1 transcription by crosslinking histone deacetylase (HDAC) to the promoter. The crosslink inhibits the recruitment of p300 to the MT-1 promoter and blocks HAT-dependent transactivation by p300. However, our results demonstrate that trichostatin A, an HDAC inhibitor, could not block the inhibitory effects of Cr(VI) on MT-1 transcription and that there were no significant differences in the in vitro inhibitory effects of Cr(VI), Cr(III), and Zn on p300 HAT activity. This suggests that the inhibitory effects of Cr(VI) on MT-I transcription may be due to its effects on the HAT-independent transactivation ability rather than the HAT-dependent, HDAC release-related transactivation ability of p300.

Attenuation of cadmium-induced testicular injury in metallothionein-III null mice

Aims In order to evaluate the role of metallothionein (MT)-III in cadmium (Cd)-induced testicular toxicity, we examined the sensitivity of MT-III null mice to severe testicular injury caused by Cd. Main methods Male MT-III null mice, MT-I/II null mice and wild-type mice were given a subcutaneous injection of CdCl 2 (15 μmol/kg). The testis was collected from each mouse at 6, 12 and 24 h after Cd administration. Key findings Testicular hemorrhages by evaluating morphology, hemoglobin content and histological parameters in the 3 types of mice were elevated by Cd injection in a time-dependent manner. The degree of hemorrhage in Cd-injected MT-I/II null mice was similar to that in the wild-type mice. In contrast, hemorrhage in the MT-III null mice was attenuated compared with that in wild-type mice and MT-I/II null mice. Cd levels, MT-I and MT-II mRNA levels and Cd-binding molecules in the testis were similar between MT-III null mice and wild-type mice. In microarray analysis, high expression of purine-nucleoside phosphorylase 2 (Pnp2), retinal degeneration 3 (Rd3), and cadherin-like 24 (Cdh24) was revealed in the testis of MT-III null mice under normal or Cd-treated conditions. Significance MT-III null mice were found to show attenuation of Cd-induced severe testicular toxicity. These results suggest the lack of MT-III contributes to protection of testis from Cd. In addition, regulation of Pnp2, Rd3, and Cdh24 mRNA levels may involve the sensitivity of MT-III null mice to Cd.

Dichotomous Effects of Lead Acetate on the Expression of Metallothionein in the Liver and Kidney of Mice

Metallothionein (MT) is a low-molecular-weight cysteine-rich protein which has a high affinity for metals and plays important roles in the protection against metal toxicity. As little information is available concerning the mechanism of MT induction by lead (Pb) compounds, we investigated the induction of MT by Pb acetate both at mRNA and protein levels in mice. Administration of Pb increased the levels of MT-I mRNA in the liver and kidney in six strains of mice. However, MT protein was detected only in the liver, and little or no increases in MT protein were detected in the kidney of any strains of mice. Speciation of metals in the liver cytosol showed that the major metal bound to MT was zinc but not Pb. The increases in plasma concentrations of interleukin-6 suggest that the production of interleukin-6 by Pb administration is involved in the induction of MT in the liver. Treatment of renal cells with Pb in vitro also resulted in the increase in MT mRNA but little increase in MT protein. These data suggest that Pb exerts a dual effect on MT expression; enhancement of MT gene transcription both in the liver and kidney and suppression of MT mRNA translation in the kidney.

A Real-Time PCR Method for the Quantification of the Two Isoforms of Metallothionein in Lake Trout (Salvelinus namaycush)

Metallothioneins (MTs) are low-molecular-weight proteins whose physiologic roles are the regulation of essential metals Cu and Zn, sequestration of heavy metals, and free radical scavenging. Induced production of MTs in a wide variety of organisms exposed to heavy metals has made them popular exposure indicators. While it has been postulated that the three different isoforms of MT play different physiologic roles, methods to discern induction separately have not been available. The development of real-time polymerase chain reaction (real-time PCR) primers and TaqMan probes to measure the two MT isoforms found in salmonid fish are described. Assuming a high degree of homology between the isoforms and within different groups of salmonids, the sequences for MT-I and MT-II from rainbow trout were used to develop primers and probes for lake trout using the Primer3 program. Two sections of each isoform that varied by only a few nucleotides were targeted. SYBR Green validated the primer specificity, and melt curve analysis further ensured that only one product was amplified. Analysis of archived samples from fish captured in unmanipulated reference lakes or from lakes experimentally treated with cadmium or ethynylestradiol (EE2) afforded an examination of seasonal and contaminant influences on MT-I and MT-II mRNA expression.

Auricular Chondritis Caused by Metal Ear Tagging in C57BL/6 Mice

Although it has been shown that auricular chondritis in rats is caused by the use of metal identification ear tags, the pathogenesis remains unclear. Based on the hypothesis that the auricular chondritis is caused by metal ions released from metal identification ear tags, we investigated the pathogenesis in male C57BL/6 mice tagged with metal identification ear tags. Twenty-six weeks after the attachment of the ear tags, visible increases in the thickness of the auricle were observed, and the concentrations of copper and iron in the tagged ears were significantly increased (P < .05) in the tagged ears compared with the untagged ears. There was up-regulation of metallothionein (MT)-I and MT-II mRNA in the tagged ears, and this was confirmed by immunohistologic staining of the destroyed cartilage. Histopathologically, there were observed severe chondritis with extensive granulomatous inflammation, newly formed cartilage nodules, and osseous metaplasia accompanied by cellular infiltrates, such as CD4 T lymphocyte, macrophages, neutrophils, and mast cells, and expression of Th1 cytokines, such as interferon-gamma, tumor necrosis factor-alpha, and interleukin-2 in the tagged ear. Based on these results, we concluded that the release of copper and iron ions from the metal ear tags played a major role in the onset of auricular chondritis. Subsequent cellular interactions, such as CD4 T cells, macrophages, fibroblasts, and mast cells, mediated by cytokines, such as tumor necrosis factor-alpha and interferon-gamma, caused an autoimmune response that may have led to the progression of auricular chondritis as an autoimmune disease.

Metallothionein-I and -III expression in animal models of Alzheimer disease

Previous studies have described altered expression of metallothioneins (MTs) in neurodegenerative diseases like multiple sclerosis (MS), Down syndrome, and Alzheimer’s disease (AD). In order to gain insight into the possible role of MTs in neurodegenerative processes and especially in human diseases, the use of animal models is a valuable tool. Several transgenic mouse models of AD amyloid deposits are currently available. These models express human β-amyloid precursor protein (AβPP) carrying different mutations that subsequently result in a varied pattern of β-amyloid (Aβ) deposition within the brain. We have evaluated the expression of MT-I and MT-III mRNA by in situ hybridization in three different transgenic mice models of AD: Tg2576 (carrying AβPP harboring the Swedish K670N/M671L mutations), TgCRND8 (Swedish and the Indiana V717F mutations), and Tg-SwDI (Swedish and Dutch/Iowa E693Q/D694N mutations). MT-I mRNA levels were induced in all transgenic lines studied, although the pattern of induction differed between the models. In the Tg2576 mice MT-I was weakly upregulated in cells surrounding Congo Red-positive plaques in the cortex and hippocampus. A more potent induction of MT-I was observed in the cortex and hippocampus of the TgCRND8 mice, likely reflecting their higher amyloid plaques content. MT-I upregulation was also more significant in Tg-SwDI mice, especially in the subiculum and hippocampus CA1 area. Immunofluorescence stainings demonstrate that astrocytes and microglia/macrophages surrounding the plaques express MT-I&II. In general, MT-I regulation follows a similar but less potent response than glial fibrillary acidic protein (GFAP) expression. In contrast to MT-I, MT-III mRNA expression was not significantly altered in any of the models examined suggesting that the various MT isoforms may have different roles in these experimental systems, and perhaps also in human AD.

Nitric oxide induces metallothionein-I gene expression in mesangial cells

In various forms of injury involving the renal glomerulus, mesangial cells are exposed to potentially toxic concentrations of nitric oxide (NO) caused by activation of the inducible isoform of nitric oxide synthase (NOS). Whether mesangial cells possess systems that can defend against NO mediated oxidative injury is unknown. One putative system is Metallothionein (MT). Metallothioneins constitute a family of cysteine proteins and play a significant role as anti-oxidants. The authors assessed whether NO upregulates MT-I expression in cultured glomerular mesangial cells. Northern blot analysis revealed that steady state MT-I mRNA levels were increased by three different NO donors: sodium nitroprusside (SNP), S-nitroso-N-acetyl-DL-penicillamine (SNAP), and Spermine-NONOate (Sper/NO). The increase in MT-I mRNA levels induced by SNAP-derived NO was attenuated by the antioxidant N-acetylcysteine (NAC), a glutathione (GSH) precursor, which indicates that the mechanism of NO-mediated MT-I expression may involve an oxidative stress response. These observations identify MT-I as a putative antioxidant system in NO-mediated mesangial cell injury.

Metallothionein, an Endogenous Antioxidant, Protects against Retinal Neuron Damage in Mice

To clarify the functional role of metallothionein (MT) in retinal damage in mice deficient in both MT-I and -II (MT-I/-II-deficient mice [C57BL/6J background]) and wild-type (C57BL/6J) mice and MT induction (zinc sulfate [ZnSO4] and 1alpha, 25-dihydroxyvitamin D3 [Vit. D3]). Retinal, cell damage was induced by intravitreous injection of N-methyl-D-aspartate (NMDA; 40 nmol/eye). Retinal MT-I, -II, and -III mRNA expression was monitored by real-time reverse-transcription-PCR of total retinal RNA from eyes injected or not injected with NMDA. In wild-type mice, MT-I and -II immunohistochemistry was performed (with antibody that recognizes both proteins) 12 and 24 hours after intravitreous NMDA injection. To examine the involvement of induced retinal MT, ZnSO4 (10 nmol/eye) or Vit. D3 (0.2 or 2 ng/eye) was intravitreously injected 24 hours before NMDA injection in wild-type or MT-I/-II-deficient mice, and ganglion cell layer (GCL) cell loss and inner plexiform layer (IPL) thinning were evaluated 7 days after the NMDA injection. The protective effect of Vit. D3 was assessed against the RGC-5 cell death induced by oxidative stress (using buthionine sulfoximine [BSO] to deplete glutathione in combination with glutamate to inhibit cystine uptake). In wild-type mice, MT-II mRNA expression was time-dependently elevated by NMDA (5.9 and 7.4 times versus the nontreated control at 4 and 12 hours, respectively, after injection), with the normal level being regained within 24 hours. In contrast, MT-I and -III showed persistent decreases (to <50% control) from 4 to 24 hours. In wild-type mice, MT-like immunoreactivity was increased in the inner retina (GCL and IPL) 12 and 24 hours after NMDA injection. At 7 days after NMDA injection in MT-I/-II-deficient mice (versus wild-type mice), GCL cell loss was increased, but IPL thickness was not different. Pretreatment with ZnSO4 or Vit. D3 increased inner retinal MT-like immunoreactivity 24 hours after NMDA injection and significantly attenuated NMDA-induced GCL cell loss in wild-type mice, but ZnSO4 pretreatment did not protect against such cell loss in MT-I/-II-deficient mice. In vitro, Vit. D3 pretreatment (100 nM) reduced BSO+glutamate-induced RGC-5 cell death. These findings suggest that MT, especially MT-II, protects against retinal neuron damage, by acting as an endogenous antioxidant.

Upregulation of Metallothionein-I mRNA Expression in a Rodent Model for Amyotrophic Lateral Sclerosis

Metallothionein (MT) mRNA expression was investigated in a rodent model (G93A SOD1 transgenic mouse) for a lethal motor neuron disease, amyotrophic lateral sclerosis (ALS). In 8-wk-old mice that did not yet exhibit motor paralysis, MT-I mRNA expression was already significantly upregulated in the region of the spinal cord responsible for motor paralysis. The expression of another isoform, MT-III, was not changed. In the cerebellum, which is not responsible for motor paralysis in ALS, neither the expression profiles of MT-I nor MT-III were altered. In 16-wk-old mice exhibiting motor paralysis, the expression of MT-I mRNA remained upregulated and the MT-III level tended to be elevated. Although no significant differences were found in the levels of both isoforms in the liver or kidney of 8-wk-old mice, the MT-I mRNA expression level was significantly upregulated in the kidney and liver of 16-wk-old mice. These results indicated that the MT-I isoform, but not the MT-III isoform, is associated with motor neuron death in ALS and suggested that the disease might be a systemic disorder to which the spinal cord is particularly susceptible.

Metallothionein Expression and Tissue Metal Kinetics After Partial Hepatectomy in Mice

To better elucidate previous results showing that partial hepatectomy noticeably changes the tissue content of zinc, calcium, magnesium, and iron(II) ions in regenerating the liver, thymus, and spleen, we report on the correlation of these metal tissue kinetics in these organs with the expression of metallothionein-I+II (MT-I+II) proteins and MT-I mRNA in early postoperative period (1, 2, 6, 12, and 24 h) after one-third hepatectomy (pHx). The results showed that 2 h after pHx the regenerating liver accumulated Zn2+, Ca2+, Mg2+, and Fe2+ ions while decreasing the concentration of all these metals in the spleen and of Zn2+ in the thymus. On the 24th h, a new high accumulation of Zn2+ and Ca2+ was seen in the regenerating liver and of Zn2+, Ca2+, and Fe2+ in the spleen. Simultaneously, MT-I mRNA increased in the liver and spleen. In hepatocytes and on several spleen and thymus mononuclear lymphatic cells, the increased expression of MT proteins was found mainly in the cytoplasm and nuclei. The areas expressing MTs in regenerating liver inversely correlated with those containing apoptotic cells, suggesting that these proteins participate in tissue restoration through reduction or increase of metal ions after injury to the liver.

Effect of sulforaphane on metallothionein expression and induction of apoptosis in human hepatoma HepG2 cells

The molecular mechanism of sulforaphane on the induction of metallothionein (MT) genes in HepG2 cells and the antiproliferative effects of sulforaphane were investigated in this study. Treatment of the cells with sulforaphane at non-toxicity concentration (0-20 microM) resulted in coordinate increases in the induction of MT-I and MT-II mRNA, followed by corresponding increases in MT protein expression. Western blot analysis revealed the increased level of the transcription factor, Nrf2 in a time-dependent manner from sulforaphane-treated cells. Furthermore, sulforaphane activated the extracellular signal-regulated protein kinase (ERK), p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK) pathways. SB203580, a specific inhibitor of p38 and PD98059, a specific inhibitor of ERK, abolished sulforaphane-induced MT protein expression, whereas SP600125, a specific inhibitor of JNK, had no significant effect. At relatively high concentration (30-100 microM), sulforaphane is a cell growth modulator, as it induced apoptotic cell death characterized by internucleosomal DNA fragmentation and caused a rapid induction of caspase 3 activity, according to the appearance of the caspase 3 fragments and stimulated proteolytic cleavage of poly (ADP-ribose) polymerase in a time-dependent manner. Moreover, sulforaphane-induced apoptotic cell death was accompanied by upregulation of Bax and downregulation of Bcl-2 and Bcl-X(l) protein. Sulforaphane-induced DNA fragmentation was blocked by the N-acetyl-L-cysteine and catalase, suggesting that the death signaling was triggered by oxidative stress. Taken together these results strongly suggest that at low concentrations of sulforaphane, activation of MAPKs, such as ERK and p38 pathway, lead to Nrf2-mediated MT gene expression. Whereas at a higher concentration, sulforaphane is an effective apoptosis inducer in HepG(2) cells through regulation of Bcl-2 family molecular and activation of ICE/Ced-3 protease (caspase 3) cascade. The results from this study may provide more evidence for its chemopreventive function.

Exercise‐induced metallothionein expression in human skeletal muscle fibres

Exercise induces free oxygen radicals that cause oxidative stress, and metallothioneins (MTs) are increased in states of oxidative stress and possess anti-apoptotic effects. We therefore studied expression of the antioxidant factors metallothionein I and II (MT-I + II) in muscle biopsies obtained in response to 3 h of bicycle exercise performed by healthy men and in resting controls. Both MT-I + II proteins and MT-II mRNA expression increased significantly in both type I and II muscle fibres after exercise. Moreover, 24 h after exercise the levels of MT-II mRNA and MT-I + II proteins were still highly increased and the MT-II mRNA expression reached a 15-fold increase. As expected, immunohistochemical detection of malondialdehyde (MDA) and nitrotyrosine (NITT) showed that formation of free radicals and oxidative stress were clearly increased in exercising muscle peaking shortly after the end of exercise in both type I and II muscle fibres. This is the first report demonstrating that MT-I + II are significantly induced in human skeletal muscle fibres following exercise. As MT-I + II are antioxidant factors that protect various tissues during pathological conditions, the MT-I + II increases post exercise may represent a mechanism whereby contracting muscle fibres are protected against cellular stress and injury.

Interferon-Alpha-Induced Changes in Metallothionein Expression in Liver Biopsies from Patients with Chronic Hepatitis C

An association between reactive oxygen species and liver damage has been postulated in the course of hepatitis C virus (HCV) infection. Metallothionein (MT), induced by HCV core protein and interferon (IFN), plays a role in scavenging free radicals. MT expression in liver biopsies obtained from 21 patients with chronic HCV infection before and after IFN-alpha therapy was investigated. Changes in Knodell histological activity index (HAI) scores, MT protein levels (immunohistochemistry), MT-I and MT-II messenger (m)RNA expression levels (in situ hybridization) and proliferating cell nuclear antigen (PCNA) labelling index were determined and compared in serial liver specimens. MT staining was clustered around the portal tracts with inflammatory cells and fibrosis. The pattern of MT protein before IFN-alpha therapy was similar in all patients, but was higher in IFN-sustained responders than in nonresponders after IFN-alpha therapy. HAI scores and PCNA labelling indexes were significantly reduced after IFN-alpha therapy. MT-II mRNA expression correlated positively with PCNA index before therapy and with HAI scores after therapy (P<0.05). No correlation was found between MT-I mRNA and HAI scores or PCNA index. The findings indicate that IFN-alpha-induced hepatic MT may participate in the therapeutic effects of IFN-alpha for HCV. In addition, MT-II mRNA expression may be involved in cell proliferation in the livers of patients with chronic HCV infection.

The Role of Metallothionein in Hard Tissue

We studied the metallothionein (MT) induction by cadmium (Cd) in the dental pulp and bone in rats. In order to clarify the cell response to Cd in the hard tissue, the isoform-specific expression of MT mRNAs (MT-I and MT-II) was examined by reverse transcriptase-polymerase chain reaction (RT-PCR) method, and the localization of MT was confirmed by immunohistochemical studies. Both MT-I and MT-II mRNA levels were increased within 3 hours by Cd administration in both the dental pulp and bone. In the dental pulp, MT protein was localized in the specific cell type of odontoblasts (secretory odontoblasts and resting odontoblasts). In the bone, 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 the hard tissue injury in vivo.

Morphological changes and oxidative stress in rat prostate exposed to a non-carcinogenic dose of cadmium

Cadmium chloride is an environmental toxicant implicated in human prostate carcinogenesis. The mechanism of its toxicity is far from fully understood. This study evaluates the effect of exposure to an oral non-carcinogenic dose of cadmium (15 ppm in drinking water for three months) on different parameters of the ventral prostatic lobe of normal and exposed rats. We analyzed the histology by optic light microscopy, activities of antioxidant enzymes (CAT, SOD, GPx and G-6-PDH), expression of iNOS and COX-2 by Western blot, expression of MT-I, MT-II, IGF-I, IGF-BP5 and rtert by RT-PCR. Histological changes were found: the height of the cells decreased, acinar lumen were enlarged and they lost the typical invaginations. Lipoperoxidation was increased in the Cd group and the antioxidant enzymes changed their activities: SOD increased, CAT and G-6-PDH decreased and GPx did not show variations. iNOS and COX-2 did not change their expressions. MT-I and IGF-BP5 mRNA increased while MT-II, IGF-I and rtert did not show variations. Cd exposure induces important morphological changes in the prostate, which could be a consequence of lipoperoxidation and oxidative stress, which are not related to iNOS and COX-2. The histology suggests an involution state of the gland, confirmed by the expression of IGF-I, IGF-BP5 and rtert.

Neuropeptide Y alters stress‐induced changes in trace element concentrations of brain in chronically immobilized rats

AbstractCentral administration of neuropeptide Y (NPY) produces anxiolytic‐like behavioral responses in the conflict test, elevated plus maze, fear‐potentiated startle paradigm, and in the chronic immobilization stress. Exogenously administrated NPY also protects against the anxiogenic effects of corticotropin‐releasing factor. In the present study, we aimed to determine the effects of centrally administered NPY on the trace element disturbances in brain tissues (frontal and temporal lobes and brain stem) and the other major organs including liver, spleen (zinc [Zn]‐, copper [Cu]‐, and iron‐rich tissues), kidney, and stomach in chronically immobilized rats. The immobilization stress was performed in special cages in which the animals were not able to move. The rats in chronic stress and chronic stress + NPY groups were kept in the cages daily for 7 min for 15 consecutive days. Intracerebroventricular (ICV) cannulas were placed to the right lateral ventricles of the rats by using stereotaxic method. In the control and chronic stress groups, 5 μL of saline (NaCl 0.9%), and in the chronic stress + NPY group, 8 μg NPY/5 μL saline solutions, were administered into the brain via ICV cannula, respectively. Controls and immobilized rats were decapitated 30 min after the injections were over and samples of tissue were taken. Zn, Cu, and iron levels of the frontal lobe, temporal lobe, brain stem, liver, spleen, kidney, and stomach were determined by flame atomic absorption spectrophotometer. Zn and Cu levels were significantly increased in the frontal lobe, temporal lobe, and brain stem in response to chronic immobilization stress daily for 7 min for 15 consecutive days. The administration of NPY inhibited the elevation of Zn in these three parts of brain but did not affect the elevation of Cu in the frontal lobe and brain stem. Increases in Zn and Cu levels of frontal, temporal lobes, and brain stem may be related to induction of MT‐I mRNA expression by chronic immobilization stress, and NPY may affect this induction of MT‐I, altering corticotropin‐releasing factor release in the stress conditions. J. Trace Elem. Exp. Med. 17:283–290, 2004. © 2004 Wiley‐Liss, Inc.