Renal and skeletal lesions in experimental cadmium poisoning: histological and biochemical approaches

Evidence of chronic cadmium exposure identified in the critically endangered Christmas Island flying-fox (Pteropus natalis)

The Christmas Island flying-fox (Pteropus natalis) is the last native mammal on Christmas Island and its population is in decline. Phosphate mining occurs across much of the eastern side of Christmas Island. The phosphate deposits are naturally rich in cadmium, and potentially other metals, which may be threatening the Christmas Island flying-fox population. To test this, concentrations of metals (cadmium, copper, iron, mercury, lead, and zinc) were measured in fur and urine collected from Christmas Island flying-foxes and interpreted concurrently with urinalysis and serum biochemistry data. In addition, metal concentrations in liver and kidney samples from two Christmas Island flying-foxes and associated histological findings from one of these individuals are reported. Fur cadmium concentrations were significantly higher in the Christmas Island flying-fox compared to concentrations found in flying-foxes in mainland Australia. Additionally, 30% of Christmas Island flying-foxes had urine cadmium concentrations exceeding maximum concentrations previously reported in flying-foxes in mainland Australia. Glucosuria and proteinuria were identified in two Christmas Island flying-foxes, suggestive of renal dysfunction. In one aged flying-fox, kidney cadmium concentrations were four-fold higher than toxic thresholds reported for domestic mammals. Microscopic evaluation of this individual identified bone lesions consistent with those described in laboratory animals with chronic cadmium poisoning. These results suggest that Christmas Island flying-foxes are being exposed to cadmium and identification of these sources is recommended as a focus of future research. Unexpectedly, urine iron concentrations in Christmas Island flying-foxes were higher compared to previous studies of Australian mainland flying-foxes, which suggests that urinary excretion of iron may be an important aspect of iron homeostasis in this species whose diet is iron rich.

Groundwater quality in Ghaziabad district, Uttar Pradesh, India: Multivariate and health risk assessment

This study aimed to assess the quality of groundwater and potential health risk due to ingestion of heavy metals in the peri-urban and urban-industrial clusters of Ghaziabad district, Uttar Pradesh, India. Furthermore, the study aimed to evaluate heavy metals sources and their pollution level using multivariate analysis and fuzzy comprehensive assessment (FCA), respectively. Multivariate analysis using principle component analysis (PCA) showed mixed origin for Pb, Cd, Zn, Fe, and Ni, natural source for Cu and Mn and anthropogenic source for Cr. Among all the metals, Pb, Cd, Fe and Ni were above the safe limits of Bureau of Indian Standards (BIS) and World Health Organization (WHO) except Ni. Health risk in terms of hazard quotient (HQ) showed that the HQ values for children were higher than the safe level (HQ = 1) for Pb (2.4) and Cd (2.1) in pre-monsoon while in post-monsoon the value exceeded only for Pb (HQ = 1.23). The health risks of heavy metals for the adults were well within safe limits. The finding of this study indicates potential health risks to the children due to chronic exposure to contaminated groundwater in the region. Based on FCA, groundwater pollution could be categorized as quite high in the peri-urban region, and absolutely high in the urban region of Ghaziabad district. This study showed that different approaches are required for the integrated assessment of the groundwater pollution, and provides a scientific basis for the strategic future planning and comprehensive management.

Human renal tubular cells contain CD24/CD133 progenitor cell populations: Implications for tubular regeneration after toxicant induced damage using cadmium as a model

The proximal tubules of the kidney are target sites of injury by various toxicants. Cadmium (Cd⁺²), an environmental nephrotoxicant can cause adverse effects and overt renal damage. To decipher the mechanisms involved in nephrotoxicity, an in vitro model system is required. Mortal cultures of human proximal tubule (HPT) cells have served, as models but are difficult to acquire and do not lend themselves to stable transfection. The immortalized human proximal tubule cell line HK-2, has served as a model but it lacks vectorial active transport and shows signs of lost epithelial features. Recently a new proximal tubule cell line was developed, the RPTEC/TERT1, and the goal of this study was to determine if this cell line could serve as a model to study nephrotoxicity. Global gene expression analysis of this cell line in comparison to the HK-2 and HPT cells showed that the RPTEC/TERT1 cells had gene expression patterns similar to HPT cells when compared to the HK-2 cells. The HPT and the RPTEC/TERT1 cell line had an increased population of stem/progenitor cells co-expressing CD24 and CD133 when compared to the HK-2 cells. The level of expression of cadherins, claudins and occludin molecules was also similar between the RPTEC/TERT1 and the HPT cells. Acute exposure to Cd⁺² resulted in necrosis of the RPTEC/TERT1 cells when compared to the HK-2 cells which died by apoptosis. Thus, the RPTEC/TERT1 cells are similar to HPT cells and can serve as a good model system to study mechanisms involved in toxicant induced renal damage.

Effects of cadmium alone and in combination with low molecular weight chitosan on metallothionein, glutathione-S-transferase, acid phosphatase, and ATPase of freshwater crab Sinopotamon yangtsekiense

Cadmium (Cd) is an environmental contaminant showing a variety of deleterious effects, including the potential threat for the ecological environment and human health via food chains. Low molecular weight chitosan (LMWC) has been demonstrated to be an effective antioxidant. Metallothionein (MT) mRNA levels and activities of glutathione-S-transferase (GST), superoxide dismutase (SOD), acid phosphatase (ACP), Na(+),K(+)-ATPase, and Ca(2+)-ATPase as well as malondialdehyde (MDA) contents in the gills of the freshwater crab Sinopotamon yangtsekiense were analyzed in vivo in order to determine the injury of Cd exposure on the gill tissues as well as the protective effect of LMWC against this injury. The results showed that there was an apparent accumulation of Cd in the gills, which was lessened by the presence of LMWC. Moreover, Cd(2+) significantly increased the gill MT mRNA levels, ACP activity and MDA content while decreasing the activities of SOD, GST, Na(+),K(+)-ATPase, and Ca(2+)-ATPase in the crabs relative to the control. Cotreatment with LMWC reduced the levels of MT mRNA and ACP but raised the activities of GST, Na(+),K(+)-ATPase, and Ca(2+)-ATPase in gill tissues compared with the crabs exposed to Cd(2+) alone. These results suggest that LMWC may exert its protective effect through chelating Cd(2+) to form LMWC-Cd(2+) complex, elevating the antioxidative activities of GST, Na(+),K(+)-ATPase, and Ca(2+)-ATPase as well as alleviating the stress pressure on MT and ACP, consequently protecting the cell from the adverse effects of Cd.

Expression of metallothionein cDNA in a freshwater crab, Sinopotamon yangtsekiense, exposed to cadmium

This paper aims at evaluating the induction of metallothionein (MT) synthesis in gills, heart and hepatopancreas of a freshwater crab, Sinopotamon yangtsekiense. Crabs were exposed to different cadmium concentrations (from 0 to 5 mg/L) from 24 to 96 h. The amount of cadmium (Cd) accumulated in gills, heart and hepatopancreas of the crab showed an increase with an increase in the treatment concentration. Furthermore, the amount of Cd accumulated in these tissues showed an increase with an increase in duration. On the other hand, MT and β-actin genes were amplified using reverse transcription PCR (RT-PCR). Metallothionein gene expression induced by Cd was analyzed using real-time quantitative polymerase chain reaction. Its expression levels were correlated to duration time and increased with cadmium concentrations in water, whilst β-actin was expressed at a relatively constant level. The MT transcript levels in gills and hepatopancreas were higher than that in heart. Furthermore, the MT mRNA expression was not time dependent, and no relationship with Cd accumulation followed the time course of treatment at the same dose Cd treatment. But the clear dose response of MT to cadmium exposure of S. yangtsekiense is a proof of the feasibility of MT as a biomarker for testing cadmium pollution.

The Effects of a Vitamin D–deficient Diet on Chronic Cadmium Exposure in Rats

Itai-itai disease (IID) of humans is one of the most severe forms of chronic cadmium (Cd) intoxication. Itai-itai disease occurs mainly in post-menopausal women and is characterized by osteoporosis with osteomalacia, renal tubular disorder, and renal anemia. Some researchers insist the major cause of IID is not Cd, but rather malnutrition, especially hypovitaminosis D. We administrated a low concentration of Cd chloride intravenously to ovariectomized female rats that were fed a vitamin D–deficient diet or a normal diet for fifty weeks. The vitamin D–deficient diet decreased serum concentration of vitamin D, but it did not affect the metabolism of the kidney or bone. Cadmium treatment alone induced a decrease in serum concentration of vitamin D, as well as renal dysfunction, renal anemia, and abnormal bone metabolism. Osteoporosis with osteomalacia, tubular nephropathy, fibrous osteodystrophy, and bone marrow hyperplasia occurred following Cd treatment. In rats treated with Cd and administered a vitamin D–deficient diet, the toxic effects of Cd on kidney, bone, and hematopoiesis were enhanced in comparison to rats treated with Cd and a normal diet. The present experiment demonstrated that hypovitaminosis D did not evoke morphologic features of IID in humans but did enhance Cd-induced toxicity in the rat model of this disease.

Effect of Chlorella vulgaris intake on cadmium detoxification in rats fed cadmium

The aim of this study was to investigate if dietary Chlorella vulgaris (chlorella) intake would be effective on cadmium (Cd) detoxification in rats fed dietary Cd. Fourteen-week old male Sprague-Dawley (SD) rats weighing 415.0 +/- 1.6 g were randomly divided into two groups and fed slightly modified American Institute of Nutrition-93 Growing (AIN-93G) diet without (n=10) or with (n=40) dietary Cd (200 ppm) for 8 weeks. To confirm alteration by dietary Cd intake, twenty rats fed AIN-93G diet without (n=10) and with (n=10) dietary Cd were sacrificed and compared. Other thirty rats were randomly blocked into three groups and fed slightly modified AIN-93G diets replacing 0 (n=10), 5 (n=10) or 10% (n=10) chlorella of total kg diet for 4 weeks. Daily food intake, body weight change, body weight gain/calorie intake, organ weight (liver, spleen, and kidney), perirenal fat pad and epididymal fat pad weights were measured. To examine Cd detoxification, urinary Cd excretion and metallothonein (MT) concentrations in kidney and intestine were measured. Food intake, calorie intake, body weight change, body weight gain/calorie intake, organ weight and fat pad weights were decreased by dietary Cd intake. Urinary Cd excretion and MT concentrations in kidney and small intestine were increased by dietary Cd. After given Cd containing diet, food intake, calorie intake, body weight change, body weight gain/calorie intake, organ weights and fat pad weights were not influenced by dietary chlorella intake. Renal MT synthesis tended to be higher in a dose-dependent manner, but not significantly. And chlorella intake did not significantly facilitate renal and intestinal MT synthesis and urinary Cd excretion. These findings suggest that, after stopping cadmium supply, chlorella supplementation, regardless of its percentage, might not improve cadmium detoxification from the body in growing rats.

[Anemia induced by cadmium intoxication]

Anemia is commonly induced by chronic cadmium (Cd) intoxication. Three main factors are involved in the development of Cd-induced anemia: hemolytic, iron-deficiency, and renal. Intravascular hemolysis can occur at the early stage of Cd exposure owing to the direct damaging effect on erythrocytes. In addition, Cd that accumulates in erythrocytes affects membrane cytoskeletons and decreases cell deformability, and these cells are then trapped and destroyed in the spleen. Iron deficiency can be detected in animals after an oral exposure to Cd, which competes with iron for absorption in the intestines, leading to anemia. However, an increase in body iron content along with anemia is often observed in cases of parenteral exposure or itai-itai disease. Therefore, it is estimated that Cd disrupts the efficient usage of iron in hemoglobin synthesis in the body. Renal anemia is observed during the very last phase of chronic, severe Cd intoxication, such as itai-itai disease, showing a decrease in the production of erythropoietin from renal tubular cells. Because the renal anemia is based on the same pathophysiology as Cd-induced osteomalacia, which is derived from the disturbance of mineral metabolism due to renal tubular dysfunction, it is reasonable to include renal anemia in the criteria for the diagnosis of itai-itai disease. Hemodilution could also contribute to the development of Cd-induced anemia. Bone marrow hypoplasia or the inhibition of heme synthesis might only be involved in Cd-induced anemia in severe cases of Cd intoxication.

Lithium Induced Toxicity in Rats: A Hematological, Biochemical and Histopathological Study

Lithium (Li(+)) salts are commonly used in treating bipolar diseases. As physicians frequently keep the patients on long-term lithium therapy, awareness of the numerous side effects and pathogenesis of this lightest alkali metal is needed for such treatments. The current study was designed to evaluate the toxic effect of small doses of lithium nitrate in rats. In the present study we showed that the oral gavage feeding of lithium nitrate (20 mg Li/kg body wt) for 7 weeks on every alternate day to male albino wistar rats elicited a significant alterations in gross hematological values owing to hypochromic anemia and leucocytosis. Erythrocyte sedimentation rate (ESR) and clotting time depicted higher values and animals exhibited icteric condition. Serum levels of hexose, cholesterol and blood urea elevated; however, proteins depleted markedly. A significant increase in serum calcium and phosphorus has also been registered in lithium salt treated animals. The enzyme activities of alkaline phosphatase (Alpase) and acid phosphatase (Acpase) diminished depicting the disturbed general physiological status while there was a marked rise in the activities of transaminases (GOT and GPT) reflecting a stimulating transamination reaction in hepatic and renal tissues. The histopathological picture of the kidney tissues revealed many deformative alterations. Necrosis, binucleated cells and Kuffer's cells are visible in renal tissue. The epithelium lining of renal tissue was damaged and there were also some marked changes in glomerular region apart from intracellular alterations in corticomedulary region. The results of present study suggest that small doses of lithium induce toxicity in rats.

Long-term cadmium exposure accelerates age-related mitochondrial changes in renal epithelial cells

Long-term cadmium exposure leads to mitochondrial dysfunction in the proximal tubular epithelial cells. Mitochondrial DNA deletion may contribute to the pathogenesis of cadmium-induced nephropathy. The aim of our study is to clarify the accumulation of mitochondrial DNA deletion and mitochondrial dysfunction in the renal cortex of rats injected three times/week with 1 ml of 1 mM CdCl2 or saline for 80 weeks. After 40-week cadmium injection, mitochondrial number diminished, and cadmium in the renal cortex reached a saturation level. At this time interval, nearly 30% of cadmium in the whole cell fraction was found in the mitochondria. Cytochrome c oxidase (COX) activity in the proximal tubular epithelial cells decreased after 40-week exposure of cadmium. Oxidized phosphatidylcholine (oxPC) started to accumulate in the cytochrome c-positive mitochondria in some tubular epithelial cells after 80-week exposure. After 40 weeks, accumulation of the 4834-bp deletion in mitochondrial DNA was evident in both control and cadmium-treated groups. However, the amount of accumulated mitochondrial DNA deletion tended to increase after 40-week exposure, and was significantly greater after 80 weeks of exposure, compared to the control. Our results indicate that long-term cadmium exposure in rats accelerates accumulation of 4834-bp mitochondrial DNA deletions and impairment of mitochondrial function associated with accumulation of oxidized product.

Environmental cadmium induces histopathological changes in kidneys of roe deer

Kidney samples of 224 roe deer (113 males, 111 females) aged three months to approximately nine years were collected in eastern Austria. Cadmium contents were examined and histological examinations were performed considering 11 different pathomorphological parameters. Cadmium burden was relatively high (range: 0.010-22.076 ppm) and increased with age. Females aged one to two years had higher contents than males of the same age. The culling site had no influence on cadmium load. The relation between the occurrence of histopathological changes and age, sex, origin, and cadmium concentration in 208 roe deer was tested. The frequency of vacuolic degeneration, pycnotic nuclei, caryolysis, and necrosis was related to increased cadmium levels. Increasing age correlated with lymphohistiocytic infiltration, interstitial fibrosis, and swelling of glomeruli. Pigment deposits and thickening of Bowman's capsule could be related to both cadmium and age. Furthermore, roe deer from an industrialized region showed alterations more frequently than animals from rural areas. We found no relation between morphological changes and sex. Though it remains to be established whether environmental cadmium exposure is the sole cause for the histopathological alterations observed, the results of this study indicate that chronic cadmium poisoning may be an important cofactor in the pathogenic mechanisms of renal damage in roe deer and that cadmium intoxication may be more widespread among wildlife than previously known.

Effects of cadmium intake on bone metabolism of mothers during pregnancy and lactation

Cadmium (Cd) is a heavy metal that exists ubiquitously in the environment, and it interacts with essential elements such as zinc, copper, iron, and calcium (Ca). Particularly, Cd interferes with Ca and vitamin D metabolism in bone kidney and intestine. The interaction between Cd and Ca in bone, intestine, and kidney may result in the disorder of bone metabolism. On the other hand, pregnancy and lactation are also important physiological factors affecting bone metabolism in the mother. Ca absorption is decreased by competition with Cd in the intestine, and more Ca is released from maternal bone and transferred to neonate by lactation. In the intestine, Cd uptake competes with Ca uptake. Cd causes a marked decrease in bone density compared to the normal decrease in bone mineral density during lactation. Lactation is an important factor contributing to the decrease in bone mineral density and Cd has an additive effect of decreasing bone metabolism of mother animal, although the Cd intake level is relatively low (approximately 3-14 microgCd/kg/day). The relationship among maternal Cd intake, renal function and bone metabolism and the interaction between Cd and Ca during lactation are reviewed herein, together with additional data obtained recently in our laboratory.

Cadmium distribution and toxicity in tissues of small rodents

The aim of the present paper is to discuss the accumulation and distribution of cadmium (Cd) in the various tissues of animals, the interactions of cadmium with other elements, and the damage to tissues caused by this metal. Cadmium is not physiologically or biochemically essential to an organism. It is absorbed via the gastrointestinal tract and lungs and accumulated in various tissues, mainly the kidneys and liver. The distribution of cadmium between various tissues depends on many endogenous and exogenous factors. Cadmium is bound to a low-molecular-weight protein, metallothionein (MT), and to high-molecular-weight proteins. This metal has a great affinity to thiol groups. Cadmium binds also to O- and N-containing ligands. The distribution of cadmium between organs differs markedly depending on the chemical form of administered Cd and the duration of exposure. Acute exposure results in a different distribution pattern throughout the body than does chronic exposure. Long-term exposure to high doses of cadmium may cause biochemical and functional changes in some critical organs. Cadmium can influence the absorption and distribution of essential elements and can replace them in enzymes. Metallothionein and glutathione play important roles in the transport of metals and in detoxification processes. Reported findings are mainly the results of experiments on laboratory animals. The lack of data concerning the localization of cadmium in various tissues of wild species is noticeable and there is a great need for such data.

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.

Long-term oral intake of low-dose cadmium exacerbates age-related impairment of renal functional reserve in rats

Our study was designed to clarify whether renal functional reserve (RFR) was impaired in rats chronically treated with oral low-dose cadmium (Cd). Rats (n = 15) were treated with 1 ppm of cadmium chloride added to drinking water. We measured RFR (representing the ability to increase glomerular filtration rate [GFR] and renal plasma flow [RPF] in response to infusion of glycine) at 2 and 10 months after initiation of exposure to Cd. Urinary excretion of Cd was significantly higher in 10-month Cd-treated rats than in age-matched control rats (provided with distilled water only). Weight gain was noted in Cd-treated rats, which was identical to that in age-matched control rats. Urinary volume and urinary excretions of sodium, protein, and glucose were similar in the two groups. There were no differences in the basal mean arterial pressure (MAP) and renal hemodynamics between 2-month Cd-treated and age-matched control rats. Infusion of glycine resulted in significant increases in GFR and RPF and a significant reduction in renal vascular resistance (RVR) in both 2-month Cd-treated and age-matched control rats (control, GFR: 133 +/- 10%, RPF: 148 +/- 8%; 2-month Cd-treated rats, GFR: 152 +/- 12% and RPF: 154 +/- 7%). The basal MAP and renal hemodynamics in 10-month Cd-treated rats were also identical to those in age-matched control rats. Infusion of glycine significantly increased GFR in 10-month control rats (132 +/- 15%), but not in 10-month Cd-treated rats (98 +/- 11%), but did not change MAP, RPF, and RVR in both groups. In addition to age-related pathological changes, mild renal interstitial edema and degenerative mitochondria with diminished matrix density and loss of the cristae in the proximal tubular cells were more frequent in 10-month Cd-treated rats. Our results suggest that long-term oral intake of low-dose Cd in rats exacerbate age-related impairment of renal functional reserve and degeneration of the proximal tubular epithelial cells.

Uncoupling between bone formation and resorption in ovariectomized rats with chronic cadmium exposure

Osteoporosis, osteomalacia, and pathological fractures are characteristic features of Itai-Itai disease. The mechanisms of bone damage caused by cadmium (Cd) exposure have not been fully clarified. We investigated skeletal changes in ovariectomized rats with chronic Cd exposure, using bone histomorphometry and mechanical tests. Female Sprague-Dawley rats at the age of 8 weeks were ovariectomized. Eight weeks after ovariectomy, the rats were divided into two groups: Cd-OVX group (n = 15), ovariectomized rats given cadmium chloride (CdCl(2), 0.18 mg/rat) ip three times a week for 28 weeks; Cont-OVX group (n = 10), ovariectomized rats given distilled water alone for 28 weeks. Cd-OVX rats had a significant increase in serum concentration of intact osteocalcine and showed numerical but not significant increase in urinary excretion of deoxypyridinoline despite a significant decrease in glomerular filtration rate to 40% of the value in Cont-OVX rats. Bone mineral content (BMC) and density were significantly decreased in both the lumbar vertebral body and femur of Cd-OVX rats. Ultimate compressive load in the lumbar body and bending load in the midfemur were significantly lower in Cd-OVX rats than in Cont-OVX rats but the differences were not demonstrated when the values were corrected for BMC. Structural moduli in the lumbar vertebral body and the midfemur were not different between the two groups. Cd-OVX rats showed significant decreases in the trabecular bone volume and trabecular number with increased values in the indices of bone formation and resorption in the lumbar vertebral body cancellous bone in comparison with Cont-OVX rats. In the midfemur, Cd-OVX rats had significantly smaller cortical bone area than Cont-OVX rats but the moment of inertia was identical between the two groups. The indices of bone formation and resorption at endocortical surface of the midfemur were significantly increased in Cd-OVX rats over those in Cont-OVX rats, whereas the indices of bone formation at the periosteal surface were not different between the two groups. These data suggested that chronic Cd exposure exacerbated the uncoupling between bone formation and resorption in ovariectomized rats, which resulted in the osteopenia, structural changes of the bone, and decreased mechanical strength in ovariectomized rats with chronic Cd exposure.

Immunohistochemical localization of metallothionein in the developing teeth of cadmium-injected rats

The ability of cadmium (Cd) to induce the synthesis of metallothionein (MT) in the developing teeth of the rat was investigated. Rats were given daily intraperitoneal injections of cadmium chloride (1.5 mg Cd/kg) for 7 days. The induction of MT synthesis in incisor teeth after Cd treatment was investigated immunohistochemically using a polyclonal antibody to MT. Immunoreactivity to MT was observed in the papillary layer of epithelial cells of the secretory zone, in one layer of epithelial cells of the presecretory zone and within ameloblasts of the postsecretory zone. Normal control rats did not exhibit MT staining. These results indicate that Cd induces MT synthesis within specific epithelial cells of the enamel organ of the rat. It is proposed that these findings demonstrate an adaptive cellular mechanism that protects these cells from cadmium toxicity.

Kidney changes in multiparous, nulliparous and ovariectomized mice fed either a nutrient-sufficient or -deficient diet containing cadmium

As a simulation of the etiological factors known for Itai-Itai disease, a syndrome characterized by renal dysfunction and osteomalacia in its Japanese victims, female mice were subjected to the individual and combined stresses of dietary Cd, nutrient-deficient diet, multiparity and ovariectomy. Renal function as affected by the etiological factors was periodically evaluated by determination of protein, amino acid, glucose and Cd concentrations in urine; periodic changes in skeletal Ca status were assessed relative to current renal function. Renal metabolism of Cd, Zn and Cu was also examined. At age 68 days, female mice were given nutrient-sufficient (+) or -deficient (-), purified diets containing either 0.25 (environmental), 5, or 50 ppm Cd as CdCl(2); the nutritional composition of (-) diet simulated that of food consumed by Japanese victims of Itai-Itai disease. At age 70 days, half of the females began a breeding regimen of six consecutive, 42-day rounds of pregnancy/lactation (PL mice); the remainder were maintained as virgin, non-pregnant controls (NP mice). Limited numbers of PL and NP mice were sacrificed at the end of each reproductive round. PL( + ) mice taken in a given round had successively borne litters in that round and all preceding ones. PL(-) females taken at the end of round (R)-1, -2 and -3 had successively borne litters through those rounds; those taken at the end of R-5 or R-6 had nonsuccessively borne litters in four of five or three of six rounds, respectively. At the conclusion of the 252-day reproductive period, remaining females entered the 392-day, post-reproductive phase of the experiment. At age 546 days (mid-R-12), PL females having successfully borne at least three litters were ovariectomized (OV) to mimic human menopause; at the same time, NP females were either ovariectomized or sham-operated (SO). After surgery, all females were maintained to age 714 days (mid-R-16), then sacrificed. Spot urine samples were taken from individual mice at the end of most reproductive rounds (R-2-->6), prior to surgery (mid-R-10), and prior to final sacrifice (late-R-15); samples were also collected via metabolism cages at the end of R-10. Food consumption, monitored on a weekly basis over the first nine rounds, was generally not significantly affected by dietary Cd level or nutrient deficiencies in females of the same reproductive status; consumption was increased about 2.5-fold in PL versus NP groups during the reproductive period and about 1.4-fold during the post-reproductive period. At each of the three dietary Cd levels and after all reproductive rounds, mean renal Cd concentrations were 1.2- to 5.6-fold higher in PL than NP mice. After six reproductive rounds, renal Cd concentrations in PL(+) and (-) groups exposed to 50 ppm Cd had reached 155 and 179 microg Cd/g kidney, respectively. Although these levels fell within a concentration range (145-200 microg Cd/g) where cadmium-induced renal dysfunction could be anticipated, no significant, Cd-dependent changes in mean urinary amino acid or protein concentrations were found. Moreover, among the same population, a 12% incidence of elevated urinary Cd (> or = 250 ng/ml) was noted, however none of the affected individuals exhibited depressed total calcium content (TCa) or calcium:dry weight ratios (Ca:DW) for femur. Such results suggested that the Cd-induced, skeletal demineralization observed in mice during the reproductive period (Bhattacharyya et al., Toxicology 1988a; 50: 193-204; Whelton et al., Toxicology 1994: 91: 235-251) likely occurred in the general absence of cadmium-induced renal dysfunction. By the end of the post-reproductive period, the incidence of elevated urinary Cd increased to 26% among ovariectomized females: of these, 89% with urinary Cd > or = 345 ng/ml exhibited decreases in TCa and/or Ca:DW values for femur or lumbar vertebrae that exceeded one S.D. of their group mean. Such results suggested that skeletal demineralization observed at

Hepatic levels of cadmium, zinc and copper in multiparous, nulliparous and ovariectomized mice fed either a nutrient-sufficient or -deficient diet containing cadmium

As a simulation of etiological factors known for Itai-Itai disease, female mice were subjected to the individual and combined stresses of dietary cadmium, nutrient-deficient diet, multiparity and ovariectomy. From age 68 days, female mice were maintained on either nutrient-sufficient (+) or -deficient (-), purified diets containing either 0.25 (environmental), 5, or 50 ppm Cd as CdCl(2); the nutritional composition of (-) diet simulated that of food consumed by Japanese women who contracted Itai-Itai disease. At age 70 days, half of the mice began a breeding regimen of six consecutive, 42-day rounds of pregnancy/lactation (PL mice); the remainder were maintained as virgin, non-pregnant controls (NP mice). Limited numbers of PL and NP mice were sacrificed at the end of each reproductive round. PL(+) mice taken in a given round had successively borne litters in that round and all preceding ones. PL(-) females taken at the end of round (R)-1, -2 and -3 had successively borne litters through those rounds; those taken at the end of R-5 or -6 had nonsuccessively borne litters in four of five or three of six rounds, respectively. At the end of the 252-day reproductive period, remaining females entered the 392-day, post-reproductive phase of the experiment. At age 546 days (mid-R-12), PL females having successfully borne at least three litters were ovariectomized (OV) to mimic human menopause, while NP females were either ovariectomized or sham-operated (SO). After surgery, all females were maintained to age 714 days (mid-R-16), then sacrificed. Food consumption, monitored on a weekly basis over the first nine rounds, was in general not significantly affected by dietary Cd level or nutrient deficiencies for females of the same reproductive status; consumption was increased about 2.5-fold in PL versus NP groups during the reproductive period and about 1.4-fold during the post-reproductive period. Over the reproductive period, small increases in liver concentrations of Zn and Cu were observed (ca. 3.1- and 2.5-fold, respectively) with far larger increases for Cd (ca. 22200-fold). Threshold hepatic Cd concentrations below which the concentrations of Zn and Cu were relatively constant and independent of Cd concentration were identified; they were 2.7 microg Cd/g liver for Zn and 3.3 microg Cd/g liver for Cu for females consuming (+) diet, and 4.9 microg Cd/g liver for Zn and 4.5 microg Cd/g liver for Cu for females consuming (-) diet. Regardless of Cd exposure level, round-by-round hepatic concentrations of Cd were generally 2- to 6-fold higher in PL than NP mice, while Zn or Cu levels were generally only 1.1- to 2.5-fold higher. For each reproductive round, hepatic concentrations of Cd in NP females were consistently about 10-fold greater in mice exposed to 50 than 5 ppm dietary Cd: corresponding Zn levels were essentially equivalent. For PL females. Cd levels were about 7-fold greater in 50 than 5 ppm Cd-exposed groups, however Zn concentrations were about 45% decreased. The pattern of Cd, Zn and Cu sequestration established during the reproductive period clearly differed from that of the post-reproductive period. Between R-6 and -16, hepatic concentrations of Cd, Zn and Cu appreciably decreased (14-69%) in 5 ppm Cd-exposed NPOV and PLOV females regardless of diet-type consumed. At the 50 ppm Cd level, Cd and Zn concencentrations dramatically rose with increases in Cd (37-129%) exceeding those of Zn (12-21%).

Skeletal changes in multiparous, nulliparous and ovariectomized mice fed either a nutrient-sufficient or -deficient diet containing cadmium

As a simulation of the etiological factors known for Itai-Itai disease, a syndrome characterized by osteomalacia and renal dysfunction in its Japanese victims, female mice were subjected to the individual and combined stresses of dietary cadmium, nutrient-deficient diet, multiparity and ovariectomy; the calcium-depleting effect of each factor was evaluated by determining Ca levels in femur and lumbar vertebrae. At age 68 days, female mice were given nutrient-sufficient (+) or -deficient (-), purified diets containing either 0.25 (environmental), 5, or 50 ppm Cd as CdCl2; the nutritional composition of (-) diet simulated that of food consumed by Japanese victims of Itai-Itai disease. At age 70 days, half of the females began a breeding regimen of six consecutive, 42-day rounds of pregnancy/lactation (PL mice); the remainder were maintained as virgin, non-pregnant controls (NP mice). Limited numbers of PL and NP mice were sacrificed at the end of each reproductive round. PL(+) mice taken at the end of round (R)-6 had successively borne litters in all six rounds, while PL(-) counterparts had nonsuccessively borne only three. At the conclusion of the 252-day reproductive period, remaining females entered the 392-day, post-reproductive phase of the experiment. At age 546 days (mid-R-12), PL females having successfully borne at least three litters were ovariectomized (OV) to mimic human menopause; at the same time, NP females were either ovariectomized or sham-operated (SO). After surgery, all females were maintained to age 714 days (mid-R-16), then sacrificed. During the post-reproductive period, food consumption by females of the same reproductive status was unaffected by elevated levels of Cd or nutrient-deficiencies in diet. However by R-16, Cd at 50 vs. 0.25 ppm had reduced body mass by 11% in both NP and PLOV females, femur and lumbar vertebral calcium content (TCa) by 20 and 25% in the respective groups, and femur and vertebral calcium/dry weight ratios (Ca/DW) by 12 and 11%. Alternative R-16 comparisons indicated that (-) diet also diminished skeletal Ca, but that the additional factors of (prior) multiparity and ovariectomy generated only small and non-significant effects. Comparison of skeletal status between the ends of the reproductive and post-reproductive periods indicated that (1) individual NP groups, regardless of Cd exposure, generally sustained small decreases in TCa and CaDW over time (consistent with aging), but PL groups without exception secured significant gains (consistent with cessation of multiparous activity), (2) skeletal integrity of PL groups was significantly more compromised by the combination of Itai etiological factors at the end of R-6 than R-16, and (3) among those factors, the most demineralizing over lifetime were chronic exposure to Cd followed by ingestion of (-) diet. Despite these findings, skeletal degeneration characteristic of the Itai-Itai syndrome was ultimately not duplicated in this mouse model suggesting that the full-blown disease required primary and profound skeletal demineralization secondarily supported and enhanced by renal dysfunction.

Iron deposition at mineralization fronts and osteoid formation following chronic cadmium exposure in ovariectomized rats

To investigate whether chronic exposure of cadmium (Cd) chloride induces osteomalacic lesions similar to Itai-itai disease (IID), ovariectomized rats were injected intravenously with the cadmium at doses of 0.05 and 0.5 mg/kg/day, 5 days per week, for 50 weeks. In six rats in the 0.5 mg/kg group, the administration was continued for up to 70 weeks. In the 0.5 mg/kg group, the plasma concentration of calcium was similar in the treatment and control groups throughout the treatment period. The urinary excretion of calcium increased from 20 weeks and the increase became marked from 40 weeks. Histopathologically, osteoid seams in the femur, tibia, and humerus were increased from 50 weeks, and these changes became prominent at 70 weeks. Hypertrophy and hyperplasia of chief cells in the parathyroid were also observed from 50 weeks. The osteoid morphometry of the trabecular bone of the femur and sternum revealed a dose-dependent increase in osteoid/bone volumes. Roentgenographs of the antebrachial and metacarpal bones taken at 70 weeks showed so-called paper bone. The bone Cd content markedly increased until 25 weeks, but thereafter decreased linearly for up to 70 weeks. In contrast to the Cd content, the iron content decreased until 25 weeks, but thereafter increased until 70 weeks. Undecalcified section of the humerus showed the deposition of iron and formation of osteoid at mineralization fronts. Our data suggest that osteomalacic lesions were caused by chronic Cd intoxication, and that iron, as well as Cd, was involved in osteoid formation.

Low-level cadmium exposure of lactating rats causes alterations in brain serotonin levels in the offspring

Effects on monoaminergic and cholinergic transmitter systems as well as neurotrophins were characterized in developing Sprague-Dawley rats directly exposed to 5 ppm cadmium in the drinking water or indirectly via exposed dams. Cadmium was given to dams during the lactation period, from parturition to postnatal day 17, and/or to the offspring until postnatal day 42. Cresyl violet staining and glial fibrillary acidic protein immunohistochemistry did not reveal any obvious neuropathology after cadmium exposure. Following high-power microwave fixation, concentrations of acetylcholine (ACh) and monoamines were determined in cerebral cortex, striatum, and hippocampus using HPLC with electro-chemical detection. ACh, dopamine, and noradrenaline levels were not significantly affected after the different cadmium exposures. Cortical levels of serotonin were significantly reduced in rats exposed to cadmium during lactation as well as in rats exposed to cadmium during both lactation and postweaning. A major decrease in 5-hydroxyindoleacetic acid was found in cortex and hippocampus in rats exposed to cadmium during lactation. The regional characteristics of cadmium toxicity as reflected in changes of neurotrophins were studied using in situ hybridization histochemistry with oligonucleotide probes and phosphoimaging evaluation. No significant changes in the mRNA expression of brain-derived neurotrophic factor (BDNF), neurotrophin-3, and the high-affinity tyrosine kinase receptor of BDNF, trkB, were detected. The present results demonstrate that exposure to levels of cadmium as low as 5 ppm in the drinking water leads to neurochemical disturbances of the serotonergic system in the offspring during the lactational period.

Characterisation of the effects of cadmium on the release of calcium and on the activity of some enzymes from neonatal mouse calvaria in culture

Exposure to cadmium (Cd) causes skeletal impairments, such as osteoporosis and osteomalacia, in many mammalian species, including humans. There is, however, some controversy about the mechanism of action of these Cd-induced skeletal effects, although both a direct influence on bone cells and effects that are secondary to renal damage caused by the metal have been demonstrated. In the present study, we cultured calvarial bones from neonatal mice and exposed them to Cd to study the effects of the metal on calcium release and on the activity of some enzymes of importance for bone resorption and bone formation. Cd dose-dependently stimulated calcium release from the bones. Maximal release was noted at Cd concentrations of 0.4-0.8 microM, which was similar to the level of release in the presence of maximal stimulatory concentrations of parathyroid hormone (10 nM) and prostaglandin E2 (10 microM). Cykloheximide (1 microM) inhibited calcium release elicited by Cd, prostaglandin E2 and parathyroid hormone. Cd-induced calcium release was linearly increased from 24 to 72 hr of culture. Production of prostaglandin E2 by the bone specimens was dose-dependently stimulated by Cd and inhibited by 1 microM indomethacin. Cd-induced calcium release was inhibited by acetazolamide (100 microM), indomethacin (1 microM) and ibuprofen (10 microM). Prostaglandin E2-stimulated calcium release was not inhibited by indomethacin. Exposure to 32 microM Cd, present during a 48-hr incubation period, significantly decreased prostaglandin E2-stimulated calcium release from 38.9% to 29.8%. Calcium release induced by parathyroid hormone was more sensitive to inhibition by the metal (i.e., Cd concentrations of 0.2 and 32 microM decreased the release from 37.7% to 31% and 19%, respectively). Cd present in the culture medium during a 48-hr incubation dose-dependently inhibited the activity of alkaline phosphatase and tartrate-resistant acid phosphatase in the bones but did not influence the activity of carbonic anhydrase. We conclude that Cd has a direct stimulatory effect on bone resorption, and this effect is dependent on prostaglandin production and also on protein synthesis. On the other hand, Cd also has an inhibitory effect on bone resorption (i.e., resorption is inhibited by higher concentrations of the metal). Moreover, Cd may impair bone formation by impeding the activity of alkaline phosphatase.

Histomorphometric study of ribs with looser zones in Itai-itai disease

Twelve Looser zones and 17 healing bands of the ribs obtained from autopsy cases of Itai-itai disease were analyzed by bone histomorphometry. Furthermore, proper cancellous tissue of the ribs from 24 autopsy cases of Itai-itai disease with Looser zones or with the healing bands, 27 autopsy cases of Itai-itai disease without such lesions, and 29 control cases were studied by the same method to pursue the histogenesis of Looser zones. In translucent zones of Looser zones, 94% of the cancellous bone was occupied by thick woven bone in which 72% was woven osteoid and 22% was woven mineralized bone. In adjacent scleroses, 71% of the cancellous bone was occupied by woven bone in which 37% was woven mineralized bone, and 34% was woven osteoid; 53% of the cancellous bone consisted of mineralized bone. As compared with those in translucent zones, woven osteoid was decreased, and mineralized bone was increased significantly in the cancellous bone of adjacent scleroses. A significant increase of lamellar mineralized bone and a decrease of woven bone in healing bands were observed as compared with those in Looser zones. These findings suggest that the healing starts from the edge of the Looser zone, and slowly proceeds toward the center. In the cancellous bone of the ribs, the volume, thickness, and surface of osteoid and woven bone were significantly increased in patients with Itai-itai disease, with Looser zones as compared with those without Looser zones. It was concluded that Looser zones seem to occur in severe osteomalacic bones that contain abundant woven bone in the patients of Itai-itai disease.

Skeletal changes in multiparous and nulliparous mice fed a nutrient-deficient diet containing cadmium

Female mice were given nutrient-deficient, purified diets containing either 0.25 (environmental), 5, or 50 ppm Cd; the nutrient quality of each was patterned after deficiencies known to be present in food consumed by Japanese women who contracted Itai-Itai disease. One-half of the mice were bred for six consecutive, 42-day rounds of pregnancy/lactation (PL mice); remaining females were non-pregnant, virgin controls (NP mice). PL and NP mice were sacrificed at the end of rounds 1, 2, 3, 5, or 6. PL mice taken during the first three rounds were successively pregnant; those taken in later rounds experienced gestation/lactation either four (round 5) or three (round 6) non-successive times. No consistent round-by-round decreases in diet consumption or body weight occurred among NP mice during the 252 days of cadmium exposure, however a significant decrease in femur calcium content (11-17%) was observed in virgin groups exposed to 50 vs. 0.25 ppm Cd. Similar femur decalcification (14-20%) was observed in PL mice, however calcium loss at 50 ppm Cd paralleled decreases in food consumption (24%) and body weight (9-17%). Significant but smaller decreases in the calcium/dry weight (Ca/DW) ratio were found for NP and PL groups consuming 50 ppm dietary Cd. Over the 6-round experiment, exposure to cadmium was found to effect smaller decreases in both femur Ca content and Ca/DW ratio than either consumption of nutrient-deficient diet or multiparous experience. Demineralization results for PL mice provide evidence that the combination of chronic ingestion of cadmium in a nutrient-deficient diet and multiparous activity likely played a role in the etiology of Itai-Itai disease; results for NP mice additionally suggest that decalcification may have been initiated in human females at a time prior to the multiparous and menopausal stages of life.

Cadmium-109 metabolism in mice. II. Organ retention in mice fed a nutritionally deficient diet during successive rounds of gestation and lactation

Organ retention of 109Cd was studied in multiparous and virgin female mice provided trace amounts of 109Cd in drinking water and stable Cd as well as certain nutrient minerals, vitamins, and fat all apportioned in solid diet in amounts appropriate for the itai-itai experience. Breeder females maximally experienced 4 nonconsecutive rounds of gestation/lactation in a total of 5 such 42-d periods. On a round-by-round basis, breeder organ 109Cd content and concentration values were compared with those from their time-matched virgin controls. By the end of round 5, most organ 109Cd content values in breeders were still increasing. Relative to control values at that point, the following increases were observed: whole body (minus gastrointestinal tract), 4.7-fold; mammary tissue, 12.5-fold; liver, 4.7-fold; and kidney, 4.8-fold. Analogous increases in 109Cd concentration values were mammary tissue, 9.8-fold; liver, 2.8-fold; and kidney, 2.9-fold. Through the five rounds, a temporal shift in fractional Cd distribution was noted for breeder tissues where transfer occurred from those of the mammaries and remaining carcass to kidneys. Although by the end of the period 109Cd content in the liver still exceeded that in the kidneys, 109Cd concentration was 4.7-fold greater in renal tissues--an increase not matched by other breeder females consuming nutrient-replete rather than nutrient-deficient (itai-itai) diet. For virgin female mice over the same period, a shift of similar magnitude was observed from remaining carcass to kidneys. Not unlike the breeders, hepatic 109Cd content again exceeded that in renal tissues, while 109Cd concentration was 4.5-fold greater in the kidneys. With respect to renal 109Cd increases, the greater portion of these shifts had occurred by the end of round 3 for both breeder and virgin mice. Comparison of both content and concentration measures for a single, time-matched, virgin male group with those from a virgin female one at the end of round 3 showed only those for mammary tissues to be distinguishable, and by either measure were about fourfold higher in the female group.

Decrease in bone strength of cadmium-treated young and old rats

A decrease in mechanical strength of bones was observed both in young and old rats for long periods of administration of cadmium. Young (3-week-old) female rats were given 0 (control), 5 and 10 ppm cadmium in drinking water, respectively, for 20 weeks. Old (18-month-old) female rats were given 0 (control) and 40 ppm cadmium in drinking water, respectively, for 7 months. The compression strengths of bones of young rats which were given 10 ppm cadmium, and those of old rats which were given 40 ppm cadmium, significantly decreased at the distal end portion of femur. Cadmium contents in bones in the 10 ppm and 40 ppm groups were about 110 and 210 ng/g dry weight, respectively. The present result confirmed that cadmium has a lesional effect on the mechanical strength of bone at the concentration of 100-200 ng/g in dry weight of bone, for both young and old rats.

Pathological study on beagles after long-term oral administration of cadmium

Histopathological, histochemical, and electron microscopic examinations were performed on beagles after a long-term oral cadmium (Cd) administration of greater than 8 years. Although renal atrophy was remarkable in groups receiving doses of 50 and 100 mg/kg body weight/day, bone lesions could not be demonstrated by roentgenological and histopathologic examination. It was noticed that concomitant regeneration or recovery and cell death of the epithelium occurred in the proximal convoluted tubules. The cell death was consistent with apoptosis, a special feature of cell death, which was shown to play a major part in the tubular damage of cadmium by electron microscopic examination. Fatty degeneration of the pars recta tubules was seen to show dose-dependence. The intrarenal cadmium was localized predominantly in the cytoplasm of the proximal tubular epithelium by histochemical and ultracentrifugal cell fractionation examinations. Although no remarkable changes were found in the other organs, aggregates of siderophages in the liver and focal hemorrhage in the spleen, known as spontaneous lesions, might be related to Cd intoxication. In conclusion, the present study revealed that no bone lesions occur with Cd administration in adult beagles in spite of long-term administration. An excessive cell death to regeneration or recovery in the proximal tubules might result in the renal cortical atrophy. No remarkable changes were seen in the glomeruli and distal nephrons, which were in good agreement with Cd distribution.

A quantitative study of iliac bone histopathology on 62 cases with itai-itai disease

Sixty-two autopsy cases with "itai-itai" or "ouch-ouch" (in English) disease and 50 control subjects were examined by static quantitative bone histopathology. Decalcified sections after cyanuric chloride treatment (Yoshiki's method) were used. The small observer variances of the decalcified sections guaranteed the accuracy and precision of this method. In the static measurement analyses, significant increases in formation parameters and decreases in structural parameters were observed (P less than 0.05-0.000001), suggesting the presence of a marked osteoid accumulation accompanied by a bone mass reduction. Discriminant analysis clearly separated the patients from the control subjects. Two-thirds of the patients showed an increase in resorption surface prior to osteoid deposition and a decrease in osteoblast surface. Double tetracycline labeling in 4 patients showed an impaired osteoid maturation and mineralization. An impaired osteoblastic function was suggested by the results of the static and dynamic histomorphometry. The bone cadmium contents were measured in 46 patients by an atomic absorption spectrophotometer and found to be increased significantly (P less than 0.01). In Aluminon (an ammonium salt of aurine tricarboxytic acid) staining, a clear, reddish line was located in an osteoid-bone interface, suggesting a reaction of Aluminon with tissue aluminium and/or cadmium. These results suggested that an impairment of osteoblastic function and mineralization occurred in itai-itai disease and that cadmium is a possible etiological factor.

Teratogenicity of metals to chick embryos

The present study examines the effects of heavy metals on chick embryogenesis. The metals included were cadmium, arsenic, cobalt, copper, indium, iron, manganese, and molybdenum. Salts of each of the metals were dissolved in saline and injected into the air sacs on d 2 of incubation. Dose levels varied with the metal to be tested. Control eggs were injected with an equivalent volume of saline (0.1 ml/egg). On d 14, the live embryos were removed from the eggs and examined for gross malformations. From the LD50 values, the toxicity relationship between the metals is cadmium greater than arsenic greater than cobalt greater than copper greater than indium greater than molybdenum greater than manganese greater than iron. The LD50 values were 3, 9, 38, 58, 121, 333, 765, and 1185 micrograms/egg, respectively. The gross malformations observed were reduced body size, micromelia, twisted neck, hemorrhage, everted viscera, and microphthalmia. Arsenic and cobalt were observed to be more teratogenic than other metals. This study showed that the metals tested were both toxic and teratogenic to varying degrees in chick embryogenesis.

Behavioral deficits due to prenatal exposure to cadmium chloride in CFY rat pups

The postnatal behavioral effects of 0.20, 0.62 and 2.0 mg/kg cadmium chloride administered to pregnant CFY rats on gestational days 7 through 15 were evaluated. Offspring were tested starting on postnatal day 23 on a rotorod for motor coordination, in an open field device for motor activity and emotionality, in a water-filled tube for stress responses, in the acquisition and extinction of an instrumental shock-escape response and in a social interaction situation. All behavioral measures showed significant alterations at the medium and high dose of cadmium exposure. The results suggest that doses of cadmium chloride that produce no overt toxicity in the dam can have long-lasting behavioral alterations in the offspring.

The effect of chronic parenteral administration of cadmium on isoenzyme levels of alkaline phosphate in intestinal mucosa

Chronic administration of cadmium chloride to rats (13.3 mumol/kg body wt per dose subcutaneously) produced a decrease in the activity of alkaline phosphatase in the intestinal mucosa to less than half that in control rats by the time cumulative doses of between 30 and 48 mumol had been administered. The reduced level of activity remained approximately steady following further dosing. Three isoenzymes of intestinal alkaline phosphatase were separated electrophoretically. Chronic cadmium treatment markedly decreased the proportion of the 2 isoenzymes with lower electrophoretic mobility. Some analogies are drawn between the effect of cadmium administration, and magnesium deficiency on changes in intestinal alkaline phosphatase.

Osteopenia in inhabitants with renal dysfunction induced by exposure to environmental cadmium

Bone density was measured in 28 women with itai-itai disease, 92 men and 114 women with cadmium-induced renal dysfunctions and 44 men and 66 women living in the three different non-polluted areas using a microdensitometer. The values of both indices corresponding to cortical width and bone mineral content were significantly lower in itai-itai disease patients than the cadmium-exposed women with renal dysfunctions and the non-exposed subjects. The cadmium-exposed women also showed a decrease in bone density compared with the non-exposed subjects. A significant decrease in bone density was also observed between cadmium-exposed men and the non-exposed subjects, although the difference was not as clear as in the women. The present study indicates that exposure to cadmium could cause marked osteopenia, particularly in the women.

Cadmium accelerates bone loss in ovariectomized mice and fetal rat limb bones in culture

Loss of bone mineral after ovariectomy was studied in mice exposed to dietary cadmium at 0.25, 5, or 50 ppm. Results show that dietary cadmium at 50 ppm increased bone mineral loss to a significantly greater extent in ovariectomized mice than in sham-operated controls. These results were obtained from two studies, one in which skeletal calcium content was determined 6 months after ovariectomy and a second in which 45Ca release from 45Ca-prelabeled bones was measured immediately after the start of dietary cadmium exposure. Furthermore, experiments with 45Ca-prelabeled fetal rat limb bones in culture demonstrated that Cd at 10 nM in the medium, a concentration estimated to be in the plasma of mice exposed to 50 ppm dietary Cd, strikingly increased bone resorption, from 27 +/- 2% (mean +/- SEM) 45Ca release in cultures with no added cadmium to 68 +/- 6% release in cultures containing cadmium (n = 4). These in vitro results indicate that cadmium may enhance bone mineral loss by a direct action on bone. Results of the in vivo studies are consistent with a significant role of cadmium in the etiology of Itai-Itai disease among postmenopausal women in Japan and may in part explain the increased risk of postmenopausal osteoporosis among women who smoke.

Female reproduction and pup survival and growth for mice fed a cadmium-containing purified diet through six consecutive rounds of gestation and lactation

Female CF1 mice were bred for 6 consecutive, 42-d rounds of gestation-lactation. Their purified diets contained cadmium added at either 0.25, 5.0, or 50.0 ppm Cd; at each cadmium level, the diets were either sufficient or deficient in certain vitamins, minerals, and fat. The deficient diet at 5 ppm cadmium was designed to simulate conditions implicated in the etiology of itai-itai disease among multiparous women in Japan. Fertility, litter size, pup survival, and pup growth (weaning weight) are reported for mice on the six diets during each of the six rounds of gestation/lactation. Except for fertility, decreases in reproductive measures that occurred in response to dietary deficiencies or cadmium during round 1 of reproduction were repeated, unchanged in magnitude, in each successive round. For sufficient diet groups, 50 ppm cadmium had no effect on fertility or pup survival during lactation, but caused a 15% decrease in litter size at birth and a 25% decrease in pup growth. Dietary deficiencies alone decreased all four measures of reproductive performance: fertility by 12%, litter size by 30%, pup survival by 18%, and pup growth by 42%. In addition, dietary deficiencies strikingly decreased the incidence of consecutive pregnancies. Combined effects of 50 ppm cadmium and dietary deficiencies were additive for all reproductive measures except fertility; for fertility, cadmium caused no decrease in the fertility of sufficient-diet animals, but caused a striking 45% decrease in deficient-diet animals. Relating our results to humans, women who contracted itai-itai disease (analogous to mice on the deficient, 5 ppm cadmium diet), in addition to their characteristic bone disease, could have experienced decreases in fertility and in growth of their offspring related to their dietary deficiencies. In addition, their diet-related decreases in fertility could have been enhanced by their combined exposure to cadmium.

Interaction of cadmium ions with calcium hydroxyapatite crystals: a possible mechanism contributing to the pathogenesis of cadmium-induced bone diseases

Cadmium ions adsorb onto calcium hydroxyapatite crystals (HA) and are as effective as inorganic pyrophosphate and aluminum ions in retarding the rate of in vitro dissolution of HA. In contrast, cadmium ions have no important retarding effect on the growth of HA, but are built into the crystals, thus making them very resistant to subsequent dissolution. These effects could interfere with bone remodeling, with cadmium protecting normal sites of resorption and thus causing resorption at pathological sites.

Influence of cadmium on the chain dynamics of collagen in rat tail tendon

The molecular mobility of the chain dynamics of collagen was investigated by the thermally stimulated creep method on rat tail tendon after oral administration of cadmium (8 mg.kg-1.day-1) for six weeks. The high resolving power of the technique shows two manifestations of the pseudolathyrogen effect of cadmium: the polar side-chains of collagen, mobile in the immature specimen, which are cross-linked and so immobile in the mature specimen, remain mobile in the cadmium-treated mature specimen. There is also a subsequent decrease in the number of water molecules linked by two hydrogen atoms bound to the tropocollagen molecules. Probably these molecular modifications inhibit mineralization of the organic matrix and so osteogenesis.

Studies on heavy metals in the ground waters of the city of Aligarh U.P. (India)

A study was conducted to determine the levels of heavy metals Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn along with physico-chemical parameters in ground waters of Aligarh city, U.P. (India). Twenty seven samples of hand pump water and twenty three samples of municipal water supply were collected from different localities of the Aligarh city, five times during the period of two months at intervals of 12 days. The samples were analysed for physico-chemical characteristics (pH, electrical conductivity, chlorides, sulphates, total hardness, total alkalinity, nitrate-nitrogen, fluoride, calcium and magnesium) and heavy metal contents. The concentrations of heavy metals in the hand pump water samples were found in the ranges of Cd (ND-5.00); Cr (ND-30.00); Cu (ND-82.50); Fe (16.80-460.00); Mn (ND-425.00); Ni (ND-25.00); Pb (ND-25.00) and Zn (28.60-775.00) μg l(-1). The heavy metal concentrations in the municipal water supply samples were found to be Cd (ND-5.00); Cr (ND-25.00); Cu (ND-37.50); Fe (8.00-37.50); Mn (ND-320.00); Ni (ND-25.00); Pb (ND-25.00) and Zn (2.00-271.87) μg l(-1).It appears from the results of these studies the concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in the ground waters of the Aligarh City were found to be lower than the prescribed limits of World Health Organisation (1984), whereas the values of Fe and Mn were found above the prescribed limits in some localities. The chloride total hardness and nitrate-nitrogen were comparatively higher in the hand pump water than the municipal supply water. The reason of higher values of these parameters may be ascribed to the surface disposal of sewage wastes, wastes from metal processing industries and other house hold refuses.

Effect of long-term inhalation exposure to cadmium oxide fumes on cardiac muscle ultrastructure in rats

The ultrastructure of the cardiac muscle of rats exposed 5 h daily, 5 days a week to cadmium oxide (CdO) fumes at a concentration of 0.16 mg Cd/m3 for 3 and 6 months and at a concentration of 1 mg Cd/m3 for 3 and 4 months has been evaluated. The structure of muscle cells, arterioles and capillaries remained unchanged. There were distinct alterations of the intercalated disc structure dependent upon the level and time of exposure. The damage to intercalated discs varied from the enlargement of the fissure between membranes (within unspecialized segments) to disruption of the complex junctions.

Induction of feather malformations in chick embryos by cadmium: protection by zinc

Various doses of cadmium chloride were injected to chick embryos between the seventh and 14th day of incubation. Doses over 15 micrograms/egg produced high mortality and, when injected between the tenth and 11th day, widespread curling of the feathers in the surviving embryos. A different type of malformation, consisting of hemorrhagic atrophy of the distal part of the feathers, was observed in the embryos injected with similar doses during the 12th day. No feather malformations were observed in embryos injected before the ninth or after the 12th day of incubation. The simultaneous injection of an equimolar amount of zinc sulfate prevented the feather malformations.