The vascular endothelium as a target tissue in acute cadmium toxicity

Cadmium Induces Vascular Endothelial Cell Detachment by Downregulating Claudin-5 and ZO-1 Levels

Cadmium is a contributing factor to cardiovascular diseases and highly toxic to vascular endothelial cells. It has a distinct mode of injury, causing the de-endothelialization of regions in the monolayer structure of endothelial cells in a concentration-dependent manner. However, the specific molecules involved in the cadmium toxicity of endothelial cells remain unclear. The purpose of this study was to identify the specific molecular mechanisms through which cadmium affects endothelial detachment. Cadmium inhibited the expression of claudin-5 and zonula occludens (ZO)-1, which are components of tight junctions (strongest contributors to intercellular adhesion), in a concentration- and time-dependent manner. Compared to arsenite, zinc, and manganese, only cadmium suppressed the expression of both claudin-5 and ZO-1 molecules. Moreover, the knockdown of claudin-5 and ZO-1 exacerbated cadmium-induced endothelial cell injury and expansion of the detachment area, whereas their overexpression reversed these effects. CRE-binding protein inhibition reduced cadmium toxicity, suggesting that CRE-binding protein activation is involved in the cadmium-induced inhibition of claudin-5 and ZO-1 expression and endothelial detachment. These findings provide new insights into the toxicological mechanisms of cadmium-induced endothelial injury and risk of cardiovascular disease.

Evidence of the protective role of D-Aspartate in counteracting/preventing cadmium-induced oxidative stress in the rat testis

Cadmium (Cd), by producing oxidative stress and acting as an endocrine disruptor, is known to cause severe testicular injury, documented by histological and biomolecular alterations, such as decreased serum testosterone (T) level and impairment of spermatogenesis. This is the first report on the potential counteractive/preventive action of D-Aspartate (D-Asp), a well-known stimulator of T biosynthesis and spermatogenesis progression by affecting hypothalamic-pituitary-gonadal axis, in alleviating Cd effects in the rat testis. Our results confirmed that Cd affects testicular activity, as documented by the reduction of serum T concentration and of the protein levels of steroidogenesis (StAR, 3β-HSD, and 17β-HSD) and spermatogenesis (PCNA, p-H3, and SYCP3) markers. Moreover, higher protein levels of cytochrome C and caspase 3, together with the number of cells positive to TUNEL assay, indicated the intensification of the apoptotic process. D-Asp administered either simultaneously to Cd, or for 15 days before the Cd-treatment, reduced the oxidative stress induced by the metal, alleviating the consequent harmful effects. Interestingly, the preventive action of D-Asp was more effective than its counteractive effect. A possible explanation is that giving D-Asp for 15 days induces its significant uptake in the testes, reaching the concentrations necessary for optimum function. In summary, this report highlights, for the first time, the beneficial role played by D-Asp in both counteracting/preventing the adverse Cd effects in the rat testis, strongly encouraging further investigations to consider the potential value of D-Asp also in improving human testicular health and male fertility.

Ocular and Systemic Factors Associated with Glaucoma

Glaucoma is one of the leading causes of irreversible blindness in the world. Although numerous factors have been implicated in the pathogenesis of glaucoma, the main focus of management still remains lowering the intraocular pressure (IOP) by medical or surgical therapy. However, a major challenge is that many glaucoma patients continue to progress despite good control of IOP. In this regard, the importance of other coexisting factors that may contribute to disease progression needs to be explored. Ophthalmologists need to be aware of ocular risk factors and the impact of systemic diseases and their medications, along with lifestyle modifications on the course of glaucomatous optic neuropathy and adopt a holistic approach in treating the eye as well as the patient to alleviate the suffering from glaucoma in a comprehensive manner.

How to cite this article

Dada T, Verma S, Gagrani M, et al. Ocular and Systemic Factors associated with Glaucoma. J Curr Glaucoma Pract 2022;16(3):179-191.

Effects of Cadmium Exposure on Leydig Cells and Blood Vessels in Mouse Testis

Environmental exposure to cadmium (Cd) contributes to a decline in the quality of human semen. Although the testis is sensitive to Cd exposure, the mechanism underlying how cadmium affects the testis remains to be defined. In this study, male mice were treated with intraperitoneal injections of 0, 0.5, 1.5 and 2.5 mg CdCl₂/kg/day for 10 days, respectively. Both the testicular weight and the 3β-HSD activity of Leydig cells were significantly reduced with the administration of 2.5 mg CdCl₂/kg/day. The height of endothelial cells in the interstitial blood vessels significantly increased with the use of 2.5 mg CdCl₂/kg/day compared with the control. Western blot data showed that the protein levels of CD31, αSMA, caveolin and Ng2 increased with cadmium exposure, and this increase was particularly significant with the administration of 2.5 mg CdCl₂/kg/day. CD31, αSMA, caveolin and Ng2 are related to angiogenesis. Based on our data, cadmium exposure may stimulate the proliferation of the mural cells and endothelial cells of blood vessels, which may lead to abnormal function of the testis.

Cadmium-induced toxicity increases prolyl endopeptidase (PREP) expression in the rat testis

During the differentiation of the male gamete, there is a massive remodeling in the shape and architecture of all the cells of the seminiferous epithelium. The cytoskeleton, as well as many associated proteins with it, plays a pivotal role in this process. The testis is particularly susceptible to environmental pollutant, which can lead to injury and impairment of normal spermatozoa production. Cadmium (Cd) is one of the major chemical environmental toxicants in economically developed countries. Food and cigarettes are the main sources of exposure to this element. Here, the protective role of zinc (Zn) to prevent the testicular toxicity in male adult rats after prenatal and during lactation exposure to Cd has been assessed. Altered testicular histology at the interstitial and germinal levels was found, whereas Zn supply completely corrected Cd toxicity. Moreover, the effects of these metals on the testicular expression and localization of the protease prolyl endopeptidase (PREP) were evaluated. Interestingly, the results showed an increase of PREP messenger RNA and protein. Data were corroborated by immunofluorescence. This study raises the possibility of using PREP as a new fertility marker.

Aqueous bark extract of Terminalia arjuna protects against cadmium-induced hepatic and cardiac injuries in male Wistar rats through antioxidative mechanisms

Cadmium (Cd) is one of the most ubiquitous toxic heavy metal in the environment. The present study was conducted to evaluate the protective role of aqueous bark extract of Terminalia arjuna (TA) against Cd induced oxidative damage in hepatic and cardiac tissues as the TA bark extract has folkloric medicinal use in the treatment of various hepatic and cardiac disorders. Male Wistar rats were divided into 4 groups. The control group was treated with normal saline as the vehicle; the second group orally administered with TA (20 mg/kg bw) daily for 15 days; the third group injected with Cd-acetate (0.44 mg/kg bw, s.c.) every alternate day for a period of 15 days; and the fourth group was administered with TA, 60 min prior to Cd treatment. The biomarkers of organ damage were significantly increased in the Cd treated groups. Besides, a significant alteration in the tissue levels of biomarkers of oxidative stress, the activities and the levels of antioxidant enzymes was observed following treatment with Cd. Additionally, some of the enzymes were found to be inhibited uncompetitively by Cd when tested in an in vitro system. Furthermore, evidence gathered from studies on the histological parameters and mitochondrial membrane potential in both the tissues argue in favour of the possible protective role of TA against Cd induced damage. Finally, gas chromatography-mass spectrometry revealed the presence of eight major bioactive phytochemicals in aqueous bark extract of TA having potent free radical scavenging property. The results indicate that the extract could protect hepatic and cardiac tissues against Cd-induced oxidative stress mediated damages through antioxidant mechanism(s).

The effect of repeated cadmium oral exposure on the level of sex hormones, estrous cyclicity, and endometrium morphometry in female rats

Cadmium (Cd) is regarded as a potential endocrine disruptor. However, the exact mechanism by which this metal may interfere with the reproductive system has not yet been elucidated. The present study aimed to investigate the effect of subacute Cd oral administration at daily doses of 0.09, 1.8, and 4.5 mgCd/kg b.w. and the impact of Cd on sex hormones (estradiol (E2) and progesterone (P)) in the plasma and uterus, as well as on estrous cyclicity and histopathological changes in uterine and ovary in female rats after terminating the exposure and after a prolonged observation period (3 months). Moreover, Cd bioaccumulation in the uterine and brain tissue of rats was analyzed. The study revealed that oral Cd exposure induced changes in the plasma levels of steroid hormones: decrease in E2 and increase in P after the highest dose of Cd. Probably, for the first time, it was evidenced that circulation sex hormone disturbances in Cd-exposed rats caused irregular estrous cycle, persisting for 3 months after exposure termination; no alterations in these hormone levels in uterine tissue were noted. Cd did not induce estradiol-like hyperplasia of endometrium, but resulted in endometrial edema irrespective of the dose, and caused damage of the ovaries after the highest dose. In summary, subacute oral exposure of female rats to Cd may lead to long-term disturbances in reproductive system.

Effects of cadmium exposure on medaka (Oryzias latipes) testes

Adult male medaka (Oryzias latipes) were exposed to 10 ppm of cadmium for 96 h, and the testes were examined histopathologically. Numerous apoptotic cells were found in the spermatogonia and spermatocytes at 72 and 96 h after initiation of cadmium exposure, and the pyknotic index, TUNEL-positive rate, and cleaved caspase-3-positive rate in the spermatogonia and spermatocytes of the cadmium-treated group were higher compared with the control group. No significant difference between the control and cadmium-treated groups was found in the phospho-histone H3-positive rate in the spermatogonia and spermatocytes. No edematous, hemorrhagic, or necrotic changes were observed within the testes in the cadmium-treated group. These results suggest that spermatogonia and spermatocytes in medaka testes are highly sensitive to cadmium. Exposure to 10 ppm of cadmium induced histopathologic changes in the testes that were similar to those described in rodents exposed to low doses of cadmium.

Possible antioxidant effect of Lycium barbarum polysaccharides on hepatic cadmium-induced oxidative stress in rats

The aim of this study was to investigate the potential protective effect of Lycium barbarum polysaccharides (LBP) pretreatment against cadmium (Cd)-induced hepatotoxicity in rats. Wistar rats were divided into control group, LBP group (300 mg/kg orally, once a day, for 30 days), Cd group (CdCl₂ 4 mg/kg i.p. once), and LBP + Cd group (LBP 300 mg/kg orally, once a day, for 30 days + CdCl₂ 4 mg/kg i.p. 24 h after the last treatment). Cd liver injury was examined by morphological/histological changes, transaminases, total protein concentration, and oxidative stress evaluated by MDA, 3NT, GSH, SOD, and TEAC activities. Cd intoxication caused gross morphological changes with hyperemia of the parenchyma, increased volume, and disappearance of the anatomical limits of the lobes associated with an increase of ALT, GSH, and TEAC in plasma and a decrease of MDA, GSH, and TEAC in liver, SOD, and total proteins in plasma. LBP pretreatment caused a slight improvement in the histological architecture and in the 3NT amount together with a significant improvement of hematic parameters. On the basis of the obtained results, we can affirm that LBP pretreatment can ameliorate liver conditions, but further studies are needed to better evaluate the protective antioxidant effects of LBP against Cd-induced toxicity.

The Protective Effects of Probiotic Bacteria on Cadmium Toxicity in Rats

One of the useful properties of probiotic bacteria is their capacity to bind different targets, thus eliminating them through feces. It is supposed that one of these targets could be cadmium, a widespread environmental toxicant that causes various disturbances in biological systems. This study examined the protective effects of probiotic supplementation against cadmium-induced toxicity in the rat. The experiment was conducted in the course of 5 weeks. Animals were divided into four groups: (1) controls, (2) probiotics treated, (3) cadmium treated, and (4) probiotics + cadmium treated. The cadmium concentration was measured in the blood, liver, kidney, and feces, as well as the blood alanine aminotransferase (ALT) and aspartate aminotransferase (AST) as biomarkers of the liver function. Histomorphological changes in the liver and kidney were also determined. Our results revealed that probiotics combined with cadmium increase this metal concentration in feces. As a result, blood, liver, and kidney Cd levels, as well as blood ALT and AST activities were lessened compared to the rat group treated with cadmium only. Besides, probiotics consumed simultaneously with cadmium attenuated histomorphological changes in the liver and kidney caused by cadmium. The rise in lactobacilli number in feces of rats treated simultaneously with cadmium and probiotics results in strong correlation with the increase of Cd concentration in their feces and the decrease of Cd concentration in their blood. We speculate that probiotics actively contribute to cadmium excretion through feces, probably, by its binding to their bacterial cell wall.

Possible antioxidant effect of Lycium barbarum polysaccharides on hepatic cadmium-induced oxidative stress in rats

The aim of this study was to investigate the potential protective effect of Lycium barbarum polysaccharides (LBP) pretreatment against cadmium (Cd)-induced hepatotoxicity in rats. Wistar rats were divided into control group, LBP group (300 mg/kg orally, once a day, for 30 days), Cd group (CdCl₂ 4 mg/kg i.p. once), and LBP + Cd group (LBP 300 mg/kg orally, once a day, for 30 days + CdCl₂ 4 mg/kg i.p. 24 h after the last treatment). Cd liver injury was examined by morphological/histological changes, transaminases, total protein concentration, and oxidative stress evaluated by MDA, 3NT, GSH, SOD, and TEAC activities. Cd intoxication caused gross morphological changes with hyperemia of the parenchyma, increased volume, and disappearance of the anatomical limits of the lobes associated with an increase of ALT, GSH, and TEAC in plasma and a decrease of MDA, GSH, and TEAC in liver, SOD, and total proteins in plasma. LBP pretreatment caused a slight improvement in the histological architecture and in the 3NT amount together with a significant improvement of hematic parameters. On the basis of the obtained results, we can affirm that LBP pretreatment can ameliorate liver conditions, but further studies are needed to better evaluate the protective antioxidant effects of LBP against Cd-induced toxicity.

Zinc-regulating Proteins, ZnT-1, and Metallothionein I/II Are Present in Different Cell Populations in the Mouse Testis

Zinc ions play an important role in testis development and spermatogenesis. Thus, nutritional zinc deficiency leads to aberrant testicular development, reduced spermatogenesis, and male sterility. The precise actions of zinc in mediating these functions and the mechanisms by which zinc is itself regulated in the testis, however, have not been adequately elucidated. We have assessed the distribution of the zinc-regulating proteins ZnT-1 and metallothionein I/II (MT I/II) in the mouse seminiferous tubule. Colabeling for ZnT-1 and MT I/II demonstrated unique patterns of distribution for these proteins, with ZnT-1 present in Sertoli cells in addition to luminal spermatozoa and MT I/II restricted to spermatocytes. These findings were confirmed by dual-label immunofluorescence for ZnT-1 and the Sertoli cell marker, vimentin, and by immunoelectron microscopy. The differential expression patterns of ZnT-1 and MTs support the hypothesis that ZnT-1 and MTs play different roles in the regulation of intracellular zinc in this organ. The specific expression of ZnT-1 in the Sertoli cells, moreover, is consistent with their role in maintaining a nurturing, closely regulated environment for spermatogenesis.

The Far Side of Vascular Injury

Substances historically thought to cause direct vascular injury in laboratory animals are a heterogeneous group of toxic agents with varied mechanisms of action. Morphologically, the reviewed agents can be broadly categorized into those targeting endothelial cell (ECs) and those targeting smooth muscle cells (SMCs). Anticancer drugs, immunosuppressants, and heavy metals are targeting primarily ECs while allylamine, β-aminopropionitrile, and mitogen-activated protein kinase kinase inhibitors affect mainly SMCs. It is now recognized that the pathogenicity of some of these agents is often mediated through intermediary events, particularly vasoconstriction. There are clear similarities in the clinical and microscopic findings associated with many of these agents in animals and man, allowing the use of animal models to investigate mechanisms and pathogenesis. The molecular pathogenic mechanisms and comparative morphology in animals and humans will be reviewed.

Toxic effects of cadmium on testis of birds and mammals: a review

In humans and other mammals, cadmium (Cd) causes various damages to different organs and tissues of the body. This review presents a comprehensive overview on the effect of Cd on the structure of seminiferous tubules, Leydig cells and blood vessels in the testis. The main observation of the effect of Cd is destruction of the seminiferous tubules with severe necrotic areas. Damage is to all stages of developing germ cells by inducing their structural changes and the apoptotic cell death. Sertoli supporting cells are considered the most vulnerable cells. Their damage results in cytoplasmic rearrangement and disruption of inter-Sertoli tight junctions resulting in increased permeability of the blood-testis barrier, structural changes in the Leydig cells and decreased testosterone secretion. After long time of Cd exposure an increase of the amount of interstitial connective tissue occurs. In blood vessels Cd exposure causes various morphological and physiological changes in vascular endothelial cells and smooth muscle cells. In humans and other mammals, the range of effect depends on the dose, route, ways, and duration of exposure. After necrosis of the sensitive cells Cd produced lesions in surrounding tissue and activate free cells. Atrophy of the seminiferous tubules is followed by Leydig cell regeneration and interstitial revascularization. In birds, spermatogenic cells underwent irreversible degeneration or atrophy of seminiferous tubules in the absence of significant vascular lesions.

Cadmium exposure induces vascular injury due to endothelial oxidative stress: the role of local angiotensin II and COX-2

Cadmium is an environmental pollutant that is closely linked with cardiovascular diseases, such as atherosclerosis and hypertension. Moreover, cadmium can induce an increase in oxidative stress. One of the main sites affected by oxidative stress is the aorta, which consequently develops atherosclerosis. However, there are few reports demonstrating aortic effects induced by small concentrations of cadmium that are similar to those found in the blood resulting from occupational exposure. Furthermore, several studies have reported on chronic cadmium exposure, and the results of these studies may have been influenced by the secondary effects induced by this metal, such as hypertension. Therefore, we investigated the effects of acute cadmium exposure on the vascular reactivity to phenylephrine of aortic rings isolated from male Wistar rats. Cadmium increased phenylephrine reactivity without changing the vasorelaxation induced by acetylcholine and sodium nitroprusside. Endothelial damage or incubation with L-NAME shifted the phenylephrine concentration-response curves leftward in arteries incubated with or without cadmium, but the curves were shifted to a lesser degree after cadmium incubation. Enalapril, losartan, the nonselective COX inhibitor indomethacin, the TXA(2) synthase inhibitor furegrelate, the selective COX-2 inhibitor NS 398, the TP receptor antagonist SQ 29.548, the EP1 receptor antagonist SC 19.220, superoxide dismutase, and the NADPH oxidase inhibitor apocynin partially reverted the cadmium-induced effects on the reactivity to phenylephrine. Cadmium exposure increased vasoconstrictor activity by reducing NO bioavailability owing to the increased production of ROS by NADPH oxidase. The results of the tested cadmium concentration, which is below the reference values, suggest that acute cadmium exposure may induce vascular injury through endothelial oxidative stress. These data contribute to the evidence indicating that cadmium is a high risk to public health.

Long-lasting morphofunctional remodelling of liver parenchyma and stroma after a single exposure to low and moderate doses of cadmium in rats

Frequent exposure to cadmium (Cd) in low doses is common; however, the long-lasting effects of this exposure are still poorly understood. Therefore in this study we have evaluated long-lasting hepatic morphofunctional adaptations in rats exposed to low and moderate doses of Cd. Five experimental groups were tested: control (0.9% saline) and other four receiving single intraperitoneal doses of 0.67, 0.74, 0.86 and 1.1 mg of Cd/kg. The animals were killed after eight weeks and the following parameters were analysed: biometrics, oedema, Cd bio-accumulation, collagen, glycogen, lipid droplets, superoxide dismutase (SOD) and catalase (CAT), serum transaminases, liver histopathology and stereology. In all groups exposed to Cd there was significant increase in SOD and CAT activities, ALP levels, proportion of binucleated hepatocytes, nuclei/cytoplasm ratio, macrophages (Kupffer cells) and collagen fibres. In these groups, glycogen accumulation by hepatocytes and the proportion of sinusoidal capillaries were significantly reduced compared with controls. The liver somatic index was increased, and liver oedema was evident in animals exposed to higher dose of Cd. Areas of necrosis were found in animals exposed to the three highest doses. These results indicate that Cd is an extremely toxic bioactive heavy metal, which even at low doses is able to disrupt liver homeostasis. At low and moderate doses, Cd exposure induces morphofunctional pathological remodelling of the hepatic stroma and parenchyma, which remain active after eight weeks. In response to injury, the liver tissue triggers a reactive process by enhancing activation of antioxidant enzymes and collagenogenesis.

Nitric oxide protects endothelium from cadmium mediated leakiness

Cadmium targets the vascular endothelium causing endothelial dysfunction and leakiness of endothelial barrier. Nitric oxide plays a major role in mediating endothelial functions including angiogenesis, migration and permeability. The present study investigates the nitric oxide effects on cadmium induced endothelial leakiness. Results of ex vivo and in vitro permeability assays showed that even a sub-lethal dose of cadmium chloride (1 µM) was sufficient to induce leakiness of endothelial cells. Cadmium drastically altered the actin polymerisation pattern and membrane tension of these cells compared to controls. Addition of nitric oxide donor Spermine NONOate (SP) significantly blunted cadmium-mediated effects and recover endothelial cells integrity. Cadmium-induced cytoskeletal rearrangements and membrane leakiness are associated with the low nitric oxide availability and high reactive oxygen species generation. In brief, we show the protective role of nitric oxide against cadmium-mediated endothelial leakiness.

Bismuth protects against arsenite-induced inhibition of proteoglycan synthesis in cultured vascular endothelial cells

Chronic ingestion of arsenic is associated with an increased risk of vascular disease such as atherosclerosis. Previously, we showed that arsenite inhibits the synthesis of general proteoglycans (PGs), which are key molecules in the progression of atherosclerosis, in vascular endothelial cells. In the present study, we investigated the effect of several metals on arsenite-induced inhibitory effect in endothelial cells. The results indicate that, after 24-hr incubation, the inhibition of PG synthesis caused by sodium arsenite was protected by bismuth nitrate but not zinc sulfate, manganese chloride, nickel chloride or cobalt chloride. The accumulation of arsenic in the cell layer was significantly decreased by bismuth after 12-hr incubation and that of bismuth was also decreased by arsenite. It was therefore suggested that the protective effect of bismuth against the inhibitory effect of arsenite on PG synthesis in vascular endothelial cells may be due, at least in part, to the decrease in cellular arsenic accumulation.

Barriers in the developing brain and Neurotoxicology

The brain develops and grows within a well-controlled internal environment that is provided by cellular exchange mechanisms in the interfaces between blood, cerebrospinal fluid and brain. These are generally referred to by the term "brain barriers": blood-brain barrier across the cerebral endothelial cells and blood-CSF barrier across the choroid plexus epithelial cells. An essential component of barrier mechanisms is the presence of tight junctions between the endothelial and epithelial cells of these interfaces. This review outlines historical evidence for the presence of effective barrier mechanisms in the embryo and newborn and provides an up to date description of recent morphological, biochemical and molecular data for the functional effectiveness of these barriers. Intercellular tight junctions between cerebral endothelial cells and between choroid plexus epithelial cells are functionally effective as soon as they differentiate. Many of the influx and efflux mechanisms are not only present from early in development, but the genes for some are expressed at much higher levels in the embryo than in the adult and there is physiological evidence that these transport systems are functionally more active in the developing brain. This substantial body of evidence supporting the concept of well developed barrier mechanisms in the developing brain is contrasted with the widespread belief amongst neurotoxicologists that "the" blood-brain barrier is immature or even absent in the embryo and newborn. A proper understanding of the functional capacity of the barrier mechanisms to restrict the entry of harmful substances or administered therapeutics into the developing brain is critical. This knowledge would assist the clinical management of pregnant mothers and newborn infants and development of protocols for evaluation of risks of drugs used in pregnancy and the neonatal period prior to their introduction into clinical practice.

Gadolinium chloride pretreatment ameliorates acute cadmium-induced hepatotoxicity

Cadmium is a known industrial and environmental pollutant. It causes hepatotoxicity upon acute administration. Features of cadmium-induced acute hepatoxicity encompass necrosis, apoptosis, peliosis and inflammatory infiltration. Gadolinium chloride (GdCl3) may prevent cadmium-induced hepatotoxicity by suppressing Kupffer cells. The effect of GdCl3 pretreatment on a model of acute cadmium-induced liver injury was investigated. Male Wistar rats 4–5 months old were injected intraperitoneally with normal saline followed by cadmium chloride (CdCl2; 6.5 mg/kg) or GdCl3 (10 mg/kg) followed by CdCl2 (6.5 mg/kg; groups I and II, respectively). Rats of both the groups were killed at 9, 12, 16, 24, 48 and 60 h after cadmium intoxication. Liver sections were analyzed for necrosis, apoptosis, peliosis and mitoses. Liver regeneration was also evaluated by tritiated thymidine incorporation into hepatic DNA. Serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were also determined. Hepatic necrosis, hepatocyte and nonparenchymal cell apoptosis and macroscopic and microscopic types of peliosis hepatis were minimized by gadolinium pretreatment. Serum levels of AST and ALT were also greatly diminished in rats of group II. Tritiated thymidine incorporation into hepatic DNA was increased in gadolinium pretreatment rats. Kupffer cell activation was minimal in both the groups of rats. Gadolinium pretreatment attenuates acute cadmium-induced liver injury in young Wistar rats, with mechanisms other than Kupffer cell elimination.

Protective effect of pretreatment with cilostazol on cytotoxicity of cadmium and arsenite in cultured vascular endothelial cells

Cilostazol, an antiplatelet drug, exhibits antiatherogenic effects. The purpose of the present study was to determine the effect of cilostazol on the cytotoxicity of cadmium (Cd) and arsenite (iAs(III)), which involved in the pathogenesis of vascular disorders such as atherosclerosis, in cultured vascular endothelial cells. Cytotoxicity was evaluated by the lactate dehydrogenase leakage assay and morphological observation. Cd (10 µM) -induced cytotoxicity was prevented by pretreatment with cilostazol (30 and 100 µM) and simultaneous treatment with cilostazol (100 µM). On the other hand, iAs(III)-induced cytotoxicity was blocked by pretreatment with cilostazol (30 and 100 µM) but not simultaneous treatment with cilostazol. The mRNA level and the protein level of metallothionein (MT) were significantly increased by cilostazol in the cells. These results suggested, therefore, that pretreatment with cilostazol effectively prevents the cytotoxicity of Cd and iAs(III) in cultured vascular endothelial cells, at least in part through the induction of MT synthesis.

Responses to cadmium intoxication in the liver of the wall lizard Podarcis sicula

This study examined the cytological and molecular effects of cadmium, a toxic heavy metal, in the liver of the Italian wall lizard Podarcis sicula. Cadmium was administered in single dose, by diet, to induce a concentration comparable with that measured in animals living in contaminated sites. For comparison, cadmium was also administered in multiple doses by food (chronic) or in a single dose intraperitoneally (i.p.); the effects were followed at regular time intervals up to 30 days post treatments. Atomic absorption spectrometry analysis demonstrated cadmium ion uptake and accumulation in the parenchyma with an estimated half-life of approximately 8 days. Cytological analyses revealed that the metal induced oedema, activated metallothionein expression in Kupffer cells and extracellular matrix production in fat storing cells. It also caused swelling and alteration in lipid and sugar metabolism in hepatocytes. In conclusion, in the wall lizard cadmium is toxic to the liver even at very low concentrations, the response is not strictly dose and time dependent and almost no recovery occurs in short (30 days) time periods.

Cadmium attenuates bradykinin-driven nitric oxide production by interplaying with the localization pattern of endothelial nitric oxide synthase

Cadmium, a ubiquitous heavy metal, interferes with endothelial functions and angiogenesis. Bradykinin is a Ca-mobilizing soluble peptide that acts via nitric oxide to promote vasodilation and capillary permeability. The objective of the present study was to explore the Cd implications in bradykinin-dependent endothelial functions. An egg yolk angiogenesis model was employed to evaluate the effect of Cd on bradykinin-induced angiogenesis. The results demonstrate that 100 nmol/L Cd attenuated bradykinin-dependent angiogenesis. The results of the in vitro wound healing and tube formation assays by using EAhy 926, a transformed endothelial cell line, suggest that Cd blocked bradykinin-mediated endothelial migration and tube formation by 38% and 67%, respectively, while nitric oxide supplementation could reverse the effect of Cd on bradykinin-induced endothelial migration by 94%. The detection of nitric oxide by using a DAF-2DA fluorescent probe, Griess assay, and ultrasensitive electrode suggests that Cd blocked bradykinin-induced nitric oxide production. Fluorescence imaging of eNOS-GFP transfected endothelial cells, immunofluorescence, and Western blot studies of Cd and bradykinin-treated cells show that Cd interfered with the localization pattern of eNOS, which possibly attenuates nitric oxide production in part. Additionally, Ca imaging of Cd- and bradykinin-treated cells suggests that Cd blocked bradykinin-dependent Ca influx into the cells, thus partially blocking Ca-dependent nitric oxide production in endothelial cells. The results of this study conclude that Cd blunted the effect of bradykinin by interfering with the Ca-associated NOS activity specifically by impeding subcellular trafficking of eNOS.

Cadmium concentrations in blood and seminal plasma: correlations with sperm number and motility in three male populations (infertility patients, artificial insemination donors, and unselected volunteers)

To investigate a possible common environmental exposure that may partially explain the observed decrease in human semen quality, we correlated seminal plasma and blood cadmium levels with sperm concentration and sperm motility. We studied three separate human populations: group 1, infertility patients (Long Island, NY, USA); group 2, artificial insemination donors (AID) (Rochester, NY, USA); and group 3, general population volunteers (Rochester, NY, USA). Information about confounding factors was collected by questionnaire. Seminal plasma cadmium did not correlate with blood cadmium (Spearman correlation, n = 91, r = -0.092, P = 0.386, NS). Both blood and seminal plasma cadmium were significantly higher among infertility patients than the other subjects studied (for example, median seminal plasma cadmium was 0.282 microg/L in infertility patients versus 0.091 microg/L in AID and 0.092 microg/L in general population volunteers; Kruskal-Wallis test, P < 0.001). The percentage of motile sperm and sperm concentration correlated inversely with seminal plasma cadmium among the infertility patients (r = -0.201, P < 0.036 and r = -0.189, P < 0.05, respectively), but not in the other two groups. Age (among infertility patients) was the only positive confounder correlating with seminal plasma cadmium. To validate our human findings in an animal model, we chronically exposed adolescent male Wistar rats to low-moderate cadmium in drinking water. Though otherwise healthy, the rats exhibited decreases in epididymal sperm count and sperm motility associated with cadmium dose and time of exposure. Our human and rat study results are consistent with the hypothesis that environmental cadmium exposures may contribute significantly to reduced human male sperm concentration and sperm motility.

Adrenomedullin reduces antioxidant defense system and enhances kidney tissue damage in cadmium and lead exposed rats

Adrenomedullin (AdM) is synthesized and secreted by a number of cells and tissue. AdM is a potent vasodilator but it is also considered a neuromodulator, an angiogenic factor, and a hormone regulator. AdM possess antiapoptotic, antioxidant, and antimicrobial properties. Heavy metals such as cadmium and lead are found widely in the environment and they have important biological functions. Lead (Pb) and cadmium (Cd) can accumulate in the lungs, liver, bone, and kidneys and cause serious organ damage. In the present study, we investigated the effect of AdM, Pb + AdM, and Cd + AdM treatments on superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) activities as well as the level of malondialdehyde (MDA) in the kidney. Heavy metal accumulation was determined in kidney with and without AdM infusion and kidney damage was evaluated by light and electron microscopy. Increased heavy metal accumulation was observed in the heavy metal and AdM treated groups. SOD, CAT, GSH-Px activities, and MDA levels were significantly different in the treatment groups when compared with the control group. Tubular degeneration, necrosis, cell swelling, mononuclear cell infiltration, and degenerated organelles were observed in the kidney following treatment. Therefore, AdM infusion has no beneficial and/or compensatory role in cadmium and lead toxicity in the kidney. We conclude that heavy metal accumulation in the kidney in conjunction with AdM infusion is cytotoxic despite the known beneficial effects of adrenomedullin.

Direct antiangiogenic actions of cadmium on human vascular endothelial cells

The vascular endothelium is a primary target of cadmium (Cd) toxicity, but little is known regarding a potential mechanism whereby Cd may inhibit angiogenesis. Recent findings showing that Cd can disrupt cadherin-mediated cell-cell adhesion suggested that Cd might inhibit angiogenesis by altering the function of VE-cadherin, a molecule that is essential for angiogenesis. To address this issue, endothelial cells (ECs) were exposed to Cd in the presence of serum and subjected to angiogenesis-related cell migration and tube formation assays. Initial examination of cytotoxicity showed that ECs are rather resistant to the acute cytotoxic effects of Cd even at concentrations up to 1 mM. However, 10 microM Cd decreased migration of ECs. Cd concentrations of 500 nM and greater significantly reduced organization of microvascular ECs into tubes. These antiangiogenic effects were evident even when ECs were preincubated with Cd and then washed to remove free Cd, indicating that Cd acted directly on the cells rather than on the extracellular matrix. Immunolocalization studies showed that Cd caused the redistribution of VE-cadherin from cell to cell contacts. These findings indicate that Cd acts in an angiostatic manner on ECs, and that this effect may involve alterations in the localization and function of VE-cadherin.

Acute effect of cadmium treatment on the kidney of rats: biochemical and ultrastructural studies

The present study was designed to explore the nephrotoxic effect of intraperitoneal acute administration of CdCl2 (2.5 and 5 mg kg(-1) b.w.) in rats. A number of toxicological parameters in kidney were examined including malondialdehyde (MDA) and endogenous antioxidants, e.g., catalase (CAT), superoxide dismutase (SOD) and Glutathione Peroxidase (GPx). The parameters that indicate tissue damage such as serum urea and creatinine were also determined, along with the ultrastructural changes of kidneys. A correlation was found between the dose and the intensity of changes. The results demonstrated that cadmium administration increased renal MDA but decreased CAT, SOD and GPx activities. In parallel, serum creatinine and urea elevated. The glomerular ultrastructural changes observed in cadmium-treated rats included narrowing of the capillary lumen and swelling of the capillary endothelium with occasional loss of fenestrae. The mesangium was wide with increased mesangial matrix. Loss of homogenous appearance of basement membrane displaying ondulation and thickening in many areas and deterioration of the slit membrane structures formed by the podocytes were also noted. The effects of cadmium on proximal cell ultrastructure were focal loss of brush border, nuclear membrane damage, chromatin condensation, swelling of the mitochondria with regression of mitochondrial cristae, degranulation and disintegration of protein-synthesizing structures such as rough endoplasmic reticulum, increased number of lysosomes and ultimately cell death.

Cadmium neurotoxicity

The Cd has been recognized as one of the most toxic environmental and industrial pollutants due to its ability to induce disturbances in several organs and tissues following either acute or chronic exposure. This review accounts for the recent evidence on its mechanisms to induce neurotoxicity, the role of the blood-brain barrier, oxidative stress, interference with calcium, and zinc-dependent processes and apoptosis induction as well as the modulatory effect of metallothionein. Discussion about cadmium neurotoxicity is centered on mechanisms of induction of cellular disfunctions. Future investigations must address those neuronal mechanisms in detail in order to understand cadmium-induced neurotoxicity.

The changes of heavy metal and metallothionein distribution in testis induced by cadmium exposure

Cadmium (Cd) is known to cause various disorders in the testis, and metallothionein (MT) is known as a protein, which has a detoxification function for heavy metals. However, the changes of Fe, Cu, and Zn distribution in the testis induced by Cd exposure have not been well examined. Moreover, only a few studies have been reported on the localization of MT after Cd exposure. In this study, we have investigated the changes of Fe, Cu, and Zn distribution in Cd-exposed testis by a newly developed in air micro-Particle Induced X-ray Emission (PIXE) method. Also, we examined the distribution of MT expression in testis. In the testis of Cd-treated rats with significant increases of lipid peroxidation, the sertoli cell tight junction was damaged by Cd exposure, resulting from disintegration of the blood testis barrier (BTB). Evaluation by in air micro-PIXE method revealed that Cd and Fe distribution were increased in the interstitial tissues and seminiferous tubules. The histological findings indicated that the testicular tissue damage was advanced, which may have been caused by Fe flowing into seminiferous tubules followed by disintegration of the BTB. As a result, Fe was considered to enhance the tissue damage caused by Cd exposure. MT was detected in spermatogonia, spermatocytes, and Sertoli's cells in the testis of Cd-treated rats, but was not detected in interstitial tissues. These results suggested that MT was induced by Cd in spermatogonia, spermatocytes, and Sertoli's cells, and was involved in the resistance to tissue damage induced by Cd.

Cell adhesion molecules in chemically-induced renal injury

Cell adhesion molecules are integral cell-membrane proteins that maintain cell-cell and cell-substrate adhesion and in some cases act as regulators of intracellular signaling cascades. In the kidney, cell adhesion molecules, such as the cadherins, the catenins, the zonula occludens protein-1 (ZO-1), occludin and the claudins are essential for maintaining the epithelial polarity and barrier integrity that are necessary for the normal absorption/excretion of fluid and solutes. A growing volume of evidence indicates that these cell adhesion molecules are important early targets for a variety of nephrotoxic substances including metals, drugs, and venom components. In addition, it is now widely appreciated that molecules, such as intracellular adhesion molecule-1 (ICAM-1), integrins, and selectins play important roles in the recruitment of leukocytes and inflammatory responses that are associated with nephrotoxic injury. This review summarizes the results of recent in vitro and in vivo studies indicating that these cell adhesion molecules may be primary molecular targets in many types of chemically-induced renal injury. Some of the specific agents that are discussed include cadmium (Cd), mercury (Hg), bismuth (Bi), cisplatin, aminoglycoside antibiotics, S-(1,2-dichlorovinyl)-l-cysteine (DCVC), and various venom toxins. This review also includes a discussion of the various mechanisms, by which these substances can affect cell adhesion molecules in the kidney.

Prevention of cadmium induced lipid peroxidation, depletion of some antioxidative enzymes and glutathione by a series of novel organoselenocyanates

A series of organoselenocyanate compounds 4a-d were synthesized utilizing 1,8-naphthalic anhydride as the building unit. To evaluate the preventive potential of the Se compounds against Cd induced hepatic lipid peroxidation and oxidative stress, female Swiss Albino mice were exposed to Cd (as CdCl(2)) during 20 days at a dose of 1 or 2mg/kg bw given ip and the selenium compounds were given at the dose of 3mg/kg bw orally in a pretreatment and concomitant treatment schedule. Hepatic lipid peroxidation level was increased significantly by Cd, whereas the glutathione-S-transferase (GST), superoxide dismutase(SOD), reduced glutathione(GSH) and catalase(CAT) levels were decreased. The selenium compounds effectively decreased the hepatic lipid peroxidation level of the animals treated with Cd. The compounds were also effective in restoring the GST, SOD, and GSH as well as CAT level towards normal. Cadmium induced enhanced Serum alanine aminotransferase (ALT) and aspertate aminotransferase (AST) level were also decreased by the selenium compounds. The study evidences the preventive effects of organoselenocyanates 4a-d (Scheme 1) against Cd induced lipid peroxidation and oxidative stress, 4d showing the highest activity.

Cadmium and mercury cause an oxidative stress-induced endothelial dysfunction

We investigated the ability of cadmium and mercury ions to cause endothelial dysfunction in bovine pulmonary artery endothelial cell monolayers. Exposure of monolayers for 48 h to metal concentrations greater than 3-5 microM produced profound cytotoxicity (increased lactate dehydrogenase leakage), a permeability barrier failure, depletion of glutathione and ATP and almost complete inhibition of the activity of key thiol enzymes, glucose-6-phosphate dehydrogenase (G6PDH) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH). In contrast, metal concentrations less than 1-2 microM induced increases in glutathione and thiol-enzyme activities with minimal changes in LDH leakage, barrier function and ATP content. At shorter incubation times (24 h or less), high concentrations of cadmium caused glutathione induction rather than depletion. Thus, oxidative stress and cytotoxicity induced by lower concentrations of the metal ions stimulate compensatory responses, including increased synthesis of glutathione, which presumably preserved the activity of key thiol enzymes, however these responses were not sustainable at higher metal ion concentrations. We conclude, while high concentrations of heavy metals are cytotoxic, lower concentration induce a compensatory protective response, which may explain threshold effects in metal-ion toxicity.

The vascular endothelium as a target of cadmium toxicity

Cadmium (Cd) is an important industrial and environmental pollutant that can produce a wide variety of adverse effects in humans and animals. A growing volume of evidence indicates that the vascular endothelium may be one of the primary targets of Cd toxicity in vivo. Studies over the past 20 years have shown that Cd, at relatively low, sublethal concentrations, can target vascular endothelial cells at a variety of molecular levels, including cell adhesion molecules, metal ion transporters and protein kinase signaling pathways. The purpose of this review is to summarize the results of these recent studies and to discuss the implications of these findings with regard to the mechanisms of Cd toxicity in specific organs including the lung, liver, kidney, testis and heart. In addition the possible roles of the vascular endothelium in mediating the tumor promoting and anticarcinogenic effects of Cd are discussed.

In vitro endothelial cell susceptibility to xenobiotics: Comparison of three cell types

In three different endothelial cell (EC) cultures (primary human umbilical cord vein, so-called HUVEC; and immortalized cell lines HBMEC and EA-hy-926), the effects of different xenobiotics were studied in order to standardize vascular EC models for in vitro pharmacotoxicological studies. Cell characteristics were first investigated by the production and the mRNA levels of known endothelial markers in the three EC culture models. EC secretory products, tissue plasminogen activator (tPA) and von Willebrand factor (vWF), were present in the supernatant of the immortalized cell lines. The mRNA levels of vWF, tPA, platelet endothelial cell adhesion molecule-1 (PECAM-1/CD31), and beta -integrin subunit, which are involved in the control of platelet function, coagulation, and fibrinolysis as well as in cell-matrix interactions, were investigated in all EC types. For at least three parameters, cultured cells provided marked characteristics of EC phenotype, in HUVEC and in immortalized cell lines, regardless of their origin from the macro- or microcirculation. Toxicity experiments were assessed after 24 h exposure to cadmium, cyclosporin A and cisplatin by MTT assay. These experiments show nonsignificant difference in susceptibility to cyclosporin A and cadmium on HUVEC, HBMEC, and EA-hy-926. However, HBMEC, seems to be highly susceptible to cisplatin compared to HUVEC, the latter being more sensitive than EA-hy-926. For experiments conducted with cyclosporin and cadmium, cell lines could constitute an alternative material for routine cytotoxicity studies.

[Cell biology of heavy metal toxicity in vascular tissue]

Cadmium and lead are heavy metals that have been shown to induce vascular disorders such as atherosclerosis in experimental animals. However, little is known about the mechanisms by which cadmium and lead induce vascular toxicity. The toxicity was investigated using a culture system of vascular endothelial and smooth muscle cells. Cadmium destroys the monolayer of endothelial cells and the cytotoxicity is protected by zinc and copper without metallothionein induction. On the other hand, lead does not exhibit cytotoxicity but inhibits the repair of endothelial monolayers after wounding by a lower response to endogenous basic fibroblast growth factor mediated by suppression of the synthesis of perlecan, a large heparan sulfate proteoglycan. In addition, cadmium and lead reduce endothelial fibrinolytic activity by induction of plasminogen activator inhibitor type 1 synthesis and by inhibition of tissue-type plasminogen activator, respectively. In vascular smooth muscle cells, cadmium and lead can promote their proliferation and influence proteoglycan synthesis and fibrinolysis in different manners. These results indicate that cadmium and lead have specific toxicities in the proliferation, fibrinolysis, and extracellular matrix formation of vascular endothelial and smooth muscle cells.

The Nitric Oxide Donor, O2-Vinyl 1-(Pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (V-PYRRO/NO), Protects against Cadmium-Induced Hepatotoxicity in Mice

The nitric oxide (NO) donor, O2-vinyl 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (V-PYRRO/NO), is metabolized by P450 enzymes to release NO within the liver and is effective in protecting against hepatotoxicity of endotoxin and acetaminophen. This study examined the effects of V-PYRRO/NO on cadmium (Cd) hepatotoxicity in mice. Mice were given multiple injections of V-PYRRO/NO (10 mg/kg, s.c. at 2-h intervals) before and after a hepatotoxic dose of Cd (3.7 mg/kg Cd as CdCl2, i.p.). V-PYRRO/NO administration reduced Cd-induced hepatotoxicity as evidenced by reduced serum alanine aminotransferase activity, improved pathology, and reduced hepatic lipid peroxidation. The protection by V-PYRRO/NO was not mediated by altered Cd distribution to the liver or within hepatic subcellular fractions. Similar inductions of metallothionein, a metal-binding protein, were observed in mice receiving Cd alone or Cd plus V-PYRRO/NO. Real-time reverse transcription-polymerase chain reaction analysis revealed that V-PYRRO/NO administration suppressed the expression of inflammation-related genes such as macrophage inflammatory protein-2, CXC chemokine, thrombospondin-1, intracellular adhesion molecular-1, and interleukin-6. V-PYRRO/NO also suppressed the expression of acute phase protein genes and genes related to cell-death pathways, such as c-jun/AP-1, nuclear factor-kappaB, early response growth factor-1, heme oxygenase-1, caspase-3, growth arrest, and DNA-damaging protein-153. In summary, the liver-selective NO donor, V-PYRRO/NO, protects against Cd hepatotoxicity in mice. This protection is not mediated through altered distribution of Cd but may be related to reduced hepatic inflammation, reduced acute phase responses, and the suppression of cell-death-related components.

Comparison of acute cardiovascular effects of cadmium and captopril in relation to oxidant and angiotensin converting enzyme activity in rats

Cadmium (0.1, 0.32, 1.0 mg/kg i.v.) produced dose dependent hypertensive response in pentobarbitone anesthetized Sprague-Dawley (S-D) rats. The peak hypertensive effect was observed within 15 min of cadmium administration. This response gradually decreased over 1-h observation period. Heart rate did not change significantly. Serum malondialdehyde (MDA) levels increased with cadmium administration. The lower dose of cadmium (0.1 mg/kg i.v.) increased serum MDA to 0.14 +/- 0.02 nmol/mL as compared to 0.12 +/- 0.01 nmol/mL in the control group and was not statistically significant. However, mid (0.32 mg/kg i.v.) and high doses (1.0 mg/kg i.v.) raised serum MDA levels significantly (P < 0.01). Cadmium inhibited serum angiotensin converting enzyme (ACE) levels at all the three tested doses and was statistically significant (P < 0.01). Captopril (1.0, 3.2 mg/kg i.v.) produced a dose dependent mild hypotensive response. The peak effect was observed within 5 min. Cadmium produced inhibition of serum ACE levels, however, a dose response effect was not observed. Captopril (3.2 mg/kg i.v.) decreased serum ACE levels to 5.4 +/- 1.1 U/mL (control levels 10.7 +/- 1.4 U/mL). Serum MDA levels were decreased by captopril treatment. A correlation between serum ACE and MDA following higher dose of cadmium was found. These results indicate that acute administration of cadmium, an inorganic blocker of ACE and calcium channels cadmium produced hypertensive response while captopril produced mild hypotensive response in rats.

Effects of cadmium on E-cadherin and VE-cadherin in mouse lung

Exposure to Cd(2+) via inhalation or intratracheal instillation results in pulmonary edema, which is followed by the influx of leukocytes, the proliferation of type II pneumocytes and eventual scarring and fibrotic changes. While the general toxic effects of Cd(2+) in the lung have been well characterized, the specific molecular mechanisms underlying these effects have yet to be elucidated. Previously we have shown that Cd(2+) can disrupt the adhering junctions between various types of epithelial and endothelial cells in culture, most likely by perturbing the function of the Ca(2+) dependent cell adhesion molecules E-cadherin and VE-cadherin respectively. The objectives of this study were to determine whether respiratory exposure to Cd(2+) can alter the localization of E-cadherin and VE-cadherin in the lung, and to determine whether this effect may play a role in the acute pneumotoxic response to Cd(2+). Male CF-1 mice were exposed to CdCl(2) (0, 16.25, 32.5, 65 or 130 nmoles in 50 microl saline) via intratracheal instillation. After 24 hours, the lungs were removed and either subjected to bronchoalveolar lavage or analyzed for histopathologic changes. The results showed that Cd(2+) caused an increase in lung weight and in the protein content of the lavage fluid. These effects were accompanied by a pronounced decrease in the amount of E-cadherin in epithelial cells of the alveoli and small bronchioles and of VE-cadherin in vascular endothelial cells. Assessment of cell membrane integrity with ethidium homodimer-1 showed no evidence of severe injury or death in alveolar epithelial cells. These findings suggest that E-cadherin and VE-cadherin may be important early targets of Cd(2+) toxicity in the lung.

Experimental cadmium poisoning in sheep

Pathomorphological investigations of internal organs were made in sheep given sublethal doses of cadmium. Early histological damages in kidneys were established by renal biopsy in some experimental animals. The main histological changes were characterized by granular degeneration in proximal tubules and glomerular endothelial proliferation in kidneys, granular degeneration in hepatocytes, pericapillary oedema and activation of capillary endothelium and Kupffer cells in liver, oedematous and degenerative changes in cerebrum and in the region of Purkinje cells of cerebellum, hyperplasia and proliferation of alveolar epithelium and perivascular or peribronchial mononuclear cell infiltration in lung, and degenerative changes in the medulla and zona glomerulosa of adrenal glands.

Cadmium-induced testicular damage in a rat model of subchronic intoxication

Background: Cadmium (Cd)-induced testicular damage in relation to spermatogenesis has not been well studied. We studied the mechanism of Cd-induced testicular damage in a rat model of subchronic intoxication. Methods:  Male Sprague-Dawley rats were subcutaneously injected with 0.6 mg Cd/kg per day for 6 weeks. The concentration of Cd in urine, serum and testes was measured by using atomic absorption spectrophotometry. Testicular damage was evaluated by counting the spermatogonia (SG) and spermatocytes (SC) on one cut-surface of five seminiferous tubules in stages VII or VIII of spermatogenesis every week. The location of intratesticular cadmium was determined by using oxine-fluorescent cytochemistry. Results: There were no differences in the testes/bodyweight ratio between the study and control groups. The concentration of Cd in the testes increased more than 100-fold that in serum after week 2, suggesting active testicular Cd accumulation (1-3 mg/g tissue). Cadmium accumulation was detected in SG and SC. The number of SG and SC diminished significantly in the study group (week 2: SG 74%, SC 90%; week 4: SG 47%, SC 75%; week 6: SG 30%, SC 54% of the control, respectively). Conclusions: Cadmium accumulated in SG and SC, consequently reduced the number of these cells, and disturbed the spermatogenesis in this rat model of subchronic Cd intoxication. Therefore, the number of SG decreased in this rat model of subchronic Cd intoxication. (Reprod Med Biol 2002; 1: 59-63).