Microcanalization in the epididymis to overcome ductal obstruction caused by chronic exposure to chromium – a study in the mature bonnet monkey (Macaca radiata Geoffroy)

Quantitative assessment of Nigella sativa and conjugated silver nanoparticles against hexavalent chromium toxic effects on sperm function

BACKGROUND

Infertility has been observed as one of the major issues in humans, one known risk factor is heavy metals.

METHODS

The main focus of the present research was to assess the toxic effect of hexavalent chromium (Cr (VI)) on sperm and its mitigation by Nigella sativa seed extract (NS) and its conjugated silver nanoparticles (NS + NP). In the present study, we administered 1.5 mg/kg body of Cr (VI) orally in mice for 60 days routinely, to induce toxicity in testes and effect on sperm production and motility in male mice. NS and NS + NP (50 mg/kg body weight) were administered to evaluate protective action against Cr (VI). The sperm were analyzed by computer-assisted semen analysis (CASA) and chromium concentration in testicular tissue was measured via the atomic absorption spectrophotometer.

RESULTS

The CASA analysis showed that Cr (VI) was directly linked with a decline in sperm concentration, motility, distance, velocity, straightness, and head beat frequency attributes. However, the administration of Nigella sativa seed extract and its green synthesized silver nanoparticles improved sperm concentration, motility, distance, velocity, straightness, and head beat frequency. The chromium content in the testes of Cr-exposed animals significantly increased, which negatively affected sperm parameters. However, Nigella sativa and Nigella sativa conjugated silver nanoparticles appeared to help in the removal of Cr content from testes hence improving the sperm parameters in exposed mice.

CONCLUSION

The decrease in Cr concentration improved sperm quality and quantity, hence, improve male fertility.

Unraveling Hypothalamus-Pituitary dysregulation: Hypergonadotropism in F1 progeny due to prenatal exposure to hexavalent chromium

The endocrine disruptor hexavalent chromium [Cr(VI)] is a proven reproductive toxicant. We recently demonstrated that prenatal Cr(VI) exposure causes testicular resistance to gonadotropins, resulting in hypergonadotropic hypoandrogenism in F1 rats. However, the mechanism driving hypergonadotropism in F1 rats exposed to Cr(VI) prenatally remains an enigma. Therefore, we hypothesized that 'Prenatal Cr(VI) exposure may disrupt steroid hormones-mediated negative feedback regulation of the hypothalamic GnRH, and its receptor in the pituitary of F1 rats, leading to hypergonadotropism.' We administered potassium dichromate (50, 100, or 200 mg/L) to pregnant rats through drinking water between days 9 and 14, and their male F1 offspring were euthanized at 60 days of age. Prenatal Cr(VI) exposure in F1 rats resulted in the accumulation of Cr in the hypothalamus and pituitary. Western blot detected decreased hypothalamic GnRH, Kisspeptin1, and its receptor GPR54, along with diminished ERα, AR, aromatase, and 5α reductase, and GnRH regulatory transcription factors Pit-1 and GATA-4 proteins. Immunohistochemical studies revealed increased immunopositivity of GnRH receptor, AR, 5α reductase, ERα, ERβ, and aromatase proteins in the pituitary, whereas decreased Kisspeptin1, GPR54, and inhibin β. Our findings imply that Cr(VI) exposure during the prenatal period disrupts the hypothalamic Kisspeptin-GPR54-Pit-1/GATA4-GnRH network, boosting the pituitary GnRH receptor. We conclude that prenatal exposure to Cr(VI) alters GnRH expression in the hypothalamus and its receptor in the pituitary of F1 progeny through interfering with the negative feedback effect of androgens and estrogens.

Perspectives of nanomaterials in microbial remediation of heavy metals and their environmental consequences: A review

Nanomaterials (NMs) have diverse applications in various sectors, such as decontaminating heavy metals from drinking water, wastewater, and soil. Their degradation efficiency can be enhanced through the application of microbes. As microbial strain releases enzymes, which leads to the degradation of HMs. Therefore, nanotechnology and microbial-assisted remediation-based methods help us develop a remediation process with practical utility, speed, and less environmental toxicity. This review focuses on the success achieved for the bioremediation of heavy metals by nanoparticles and microbial strains and in their integrated approach. Still, the use of NMs and heavy metals (HMs) can negatively affect the health of living organisms. This review describes various aspects of the bioremediation of heavy materials using microbial nanotechnology. Their safe and specific use supported by bio-based technology paves the way for their better remediation. We discuss the utility of nanomaterials for removing heavy metals from wastewater, toxicity studies and issues to the environment with their practical implications. Nanomaterial assisted heavy metal degradation coupled with microbial technology and disposal issues are described along with detection methods. Environmental impact of nanomaterials is also discussed based on the recent work conducted by the researchers. Therefore, this review opens new avenues for future research with an impact on the environment and toxicity issues. Also, applying new biotechnological tools will help us develop better heavy metal degradation routes.

HBM4EU Chromates Study: Urinary Metabolomics Study of Workers Exposed to Hexavalent Chromium

Exposure to hexavalent chromium Cr(VI) may occur in several occupational activities, placing workers in many industries at risk for potential related health outcomes. Untargeted metabolomics was applied to investigate changes in metabolic pathways in response to Cr(VI) exposure. We obtained our data from a study population of 220 male workers with exposure to Cr(VI) and 102 male controls from Belgium, Finland, Poland, Portugal and the Netherlands within the HBM4EU Chromates Study. Urinary metabolite profiles were determined using liquid chromatography mass spectrometry, and differences between post-shift exposed workers and controls were analyzed using principal component analysis. Based on the first two principal components, we observed clustering by industrial chromate application, such as welding, chrome plating, and surface treatment, distinct from controls and not explained by smoking status or alcohol use. The changes in the abundancy of excreted metabolites observed in workers reflect fatty acid and monoamine neurotransmitter metabolism, oxidative modifications of amino acid residues, the excessive formation of abnormal amino acid metabolites and changes in steroid and thyrotropin-releasing hormones. The observed responses could also have resulted from work-related factors other than Cr(VI). Further targeted metabolomics studies are needed to better understand the observed modifications and further explore the suitability of urinary metabolites as early indicators of adverse effects associated with exposure to Cr(VI).

Impact of Environmental and Lifestyle Use of Chromium on Male Fertility: Focus on Antioxidant Activity and Oxidative Stress

Male reproductive tissues are strongly susceptible to several environmental and lifestyle stressors. In general, male reproductive health is highly sensitive to oxidative stress, which results in reversible and/or irreversible changes in testosterone-producing cells, spermatogenesis, and sperm quality. Chromium compounds are widely used in the +3 and +6 valence states, as food supplements, and in the industrial field, respectively. Chromium (III) compounds, i.e., Cr(III)-tris-picolinate, [Cr(pic)₃], known as chromium picolinate, are used as nutritional supplements for the control of diabetes, body weight, and muscular growth. However, previous studies showed that animal models exposed to chromium picolinate experienced degenerative changes in spermatogenesis. Contradictory results are documented in the literature and deserve discussion. Furthermore, the long-term effects of chromium picolinate on the antioxidant system of treated subjects have not been properly studied. Comprehensive studies on the role of this compound will help to establish the safe and useful use of chromium supplementation. On the other hand, chromium (VI) compounds are widely used in several industries, despite being well-known environmental pollutants (i.e., welding fumes). Chromium (VI) is known for its deleterious effects on male reproductive health as toxic, carcinogenic, and mutagenic. Previous studies have demonstrated severe lesions to mouse spermatogenesis after exposure to chromium (VI). However, workers worldwide are still exposed to hexavalent chromium, particularly in electronics and military industries. Data from the literature pinpoints mechanisms of oxidative stress induced by chromium compounds in somatic and germ cells that lead to apoptosis, thus underlining the impairment of fertility potential. In this review, we analyze the benefits and risks of chromium compounds on male fertility, as well as the mechanisms underlying (in)fertility outcomes. Although supplements with antioxidant properties may maximize male fertility, adverse effects need to be investigated and discussed.

Prenatal exposure to hexavalent chromium disrupts testicular steroidogenic pathway in peripubertal F1 rats

We have reported sub-fertility in F1 progeny rats with gestational exposure to hexavalent chromium [Cr(VI)], which had disrupted Sertoli cell (SC) structure and function, and decreased testosterone (T). However, the underlying mechanism for reduced T remains to be understood. We tested the hypothesis "transient prenatal exposure to Cr(VI) affects testicular steroidogenesis by altering hormone receptors and steroidogenic enzyme proteins in Leydig cells (LCs)." Pregnant Wistar rats were given drinking water containing 50, 100, and 200 mg/L potassium dichromate during gestational days 9-14, encompassing fetal differentiation window of the testis from the bipotential gonad. F1 male rats were euthanized on postnatal day 60 (peripubertal rats with adult-type LCs alone). Results showed that prenatal exposure to Cr(VI): (i) increased accumulation of Cr(III) in the testis of F1 rats; (ii) increased serum levels of luteinizing and follicle stimulating hormones (LH and FSH), and 17β estradiol, and decreased prolactin and T; (iii) decreased steroidogenic acute regulatory protein, cytochrome P450 11A1, cytochrome P450 17A1, 3β- and 17β-hydroxysteroid dehydrogenases, cytochrome P450 aromatase and 5α reductase proteins, (iv) decreased specific activities of 3β and 17β hydroxysteroid dehydrogenases; (v) decreased receptors of LH, androgen and estrogen in LCs; (vi) decreased 5α reductase and receptor proteins of FSH, androgen, and estrogen in SCs. The current study concludes that prenatal exposure to Cr(VI) disrupts testicular steroidogenesis in F1 progeny by repressing hormone receptors and key proteins of the steroidogenic pathway in LCs and SCs.

Prenatal exposure to excess chromium attenuates transcription factors regulating expression of androgen and follicle stimulating hormone receptors in Sertoli cells of prepuberal rats

We have reported that gestational exposure to hexavalent chromium (CrVI) represses androgen receptor (Ar) and follicle stimulating hormone receptor (Fshr) in Sertoli cells (SCs) of adult rats, while the mechanism underlying remains obscure. We tested the hypothesis "transient gestational exposure to CrVI during the critical embryonic windows of testicular differentiation and growth may have adverse impact on transcription factors controlling the expression of Ar and Fshr in SCs of the F₁ progeny". CrVI (K₂Cr₂O₇) was given through drinking water (50 ppm, 100 ppm and 200 ppm), to pregnant rats from gestational day 9-14 (testicular differentiation) and 15 to 21 (prenatal differentiation and proliferation of SC); male progenies were sacrificed on postnatal day 30 (Completion of postnatal SC maturation). A significant increase in free radicals and decrease in enzymatic and non-enzymatic antioxidants were observed in SCs of experimental rats. Real time PCR and western blot data showed decreased expression of Ar, Fshr, Inhibin B, Transferrin, Androgen binding protein, Claudin 11 and Occludin in SCs of experimental rats; concentrations of lactate, pyruvate and retinoic acid also decreased. Serum FSH, luteinizing hormone and estradiol increased, whereas testosterone and prolactin decreased in experimental rats. Western blot detection revealed decreased levels of transcription factors regulating Fshr viz., USF-1, USF-2, SF-1, c-fos, c-jun and GATA 1, and those of Ar viz., Sp-1, ARA54, SRC-1 and CBP in experimental rats, whereas the levels of cyclinD1 and p53, repressors of Ar increased. ChIP assay detected decreased USF-1 and USF-2 binding to Fshr promoter, and binding of Sp-1 to Ar promoter. We conclude that gestational exposure to CrVI affects SC structure and function in F₁ progeny by inducing oxidative stress and diminishing the expression of Ar and Fshr through attenuation of their specific transcriptional regulators and their interaction with the respective promoter.

Seminal fluid metabolome and epididymal changes after antibiotic treatment in mice

Paternal environment can induce detrimental developmental origins of health and disease (DOHaD) effects in resulting offspring and even future descendants. Such paternal-induced DOHaD effects might originate from alterations in a possible seminal fluid microbiome (SFM) and composite metabolome. Seminal vesicles secrete a slightly basic product enriched with fructose and other carbohydrates, providing an ideal habitat for microorganisms. Past studies confirm the existence of a SFM that is influenced by genetic and nutritional status. Herein, we sought to determine whether treatment of male mice with a combination of antibiotics designed to target SFM induces metabolic alterations in seminal vesicle gland secretions (seminal fluid) and histopathological changes in testes and epididymides. Adult (10- to 12-week-old) National Institutes of Health (NIH) Swiss males (n = 10 per group) were treated with Clindamycin 0.06 mg/kg day, Unasyn (ampicillin/sulbactam) 40 mg/kg day and Baytril (enrofloxacin) 50 mg/kg day designed to target the primary bacteria within the SFM or saline vehicle alone. Fourteen-day antibiotic treatment of males induced metabolomic changes in seminal vesicles with inosine, xanthine and l-glutamic acid decreased but d-fructose increased in glandular secretions. While spermatogenesis was not affected in treated males, increased number of epididymal tubules showed cribriform growth in this group (7 antibiotic-treated males: 3 saline control males; P = 0.01). Antibiotic-treated males showed more severe cribriform cysts. Current findings suggest antibiotic treatment of male mice results in seminal fluid metabolome and epididymal histopathological alterations. It remains to be determined whether such changes compromise male reproductive function or lead to DOHaD effects in resulting offspring.

Male reproductive toxicity of CrVI: In-utero exposure to CrVI at the critical window of testis differentiation represses the expression of Sertoli cell tight junction proteins and hormone receptors in adult F1 progeny rats

The effect of gestational exposure to CrVI (occupational/environmental pollutant and target to Sertoli cells(SC)) was tested in a rat model during the testicular differentiation from the bipotential gonad may interrupt spermatogenesis by disrupting SC tight junctions(TJ) and it's proteins and hormone receptors. Pregnant Wistar rats were exposed to 50/100/200ppm CrVI through drinking water during embryonic days 9-14. On Postnatal day 120, testes were subjected to ion exchange chromatographic analysis and revealed increased level of CrIII in SCs and germ cells, serum and testicular interstitial fluid(TIF). Microscopic analyses showed seminiferous tubules atrophy and disruption of SC TJ, which also recorded decreased testosterone in TIF. mRNA and Protein expression analyses attested decreased level of Fshr, Ar, occludin and claudin-11 in SCs. Immunofluorescent detection revealed weak signal of TJ proteins. Taken together, we concluded that gestational exposure to CrVI interferes with the expression of SC TJ proteins due to attenuated expression of hormone receptors.

Toxic and genotoxic effects of hexavalent chromium in environment and its bioremediation strategies

Chromium is one of the major inorganic environmental pollutants, which is added in the environment through various natural and anthropogenic activities and exists mainly in two forms: Cr(III) and Cr(VI). Cr(VI) is considered to be more toxic than Cr(III) due to its high solubility and mobility. It is a well-reported occupational carcinogen associated with lung, nasal, and sinus cancers. Thus, this review article provides the detailed information on the occurrence, sources of chromium contamination in the environment and their toxicological effects in human, animal, plants as well as in microorganisms, and bioremediation strategies to minimize the toxic effects.

Hexavalent chromium affects sperm motility by influencing protein tyrosine phosphorylation in the midpiece of boar spermatozoa

Hexavalent chromium reportedly induces reproductive toxicity and further inhibits male fertility in mammals. In this study, we investigated the molecular mechanism by which hexavalent chromium affects motility signaling in boar spermatozoa in vitro. The results indicated that Cr(VI) decreased sperm motility, protein phosphorylation, mitochondrial membrane potential (ΔΨm) and metabolic enzyme activity starting at 4μmol/mL following incubation for 1.5h. Notably, all parameters were potently inhibited by 10μmol/mL Cr, while supplementation with the dibutyryl-cAMP (dbcAMP) and the 3-isobutyl-1-methylxanthine (IBMX) prevented the inhibition of protein phosphorylation. Interestingly, high concentrations of Cr (>10μmol/mL) increased the tyrosine phosphorylation of some high-molecular-weight proteins in the principle piece but decreased that in the middle piece associated with an extreme reduction of sperm motility. These results suggest that chromium affects boar sperm motility by impairing tyrosine phosphorylation in the midpiece of sperm by blocking the cAMP/PKA pathway in boar sperm in vitro.

Volcanogenic pollution and testicular damage in wild mice

Many evidences have surfaced the adverse effects of environmental pollutants on male reproduction. Volcanogenic pollution is understudied, although it is a well-known source of hazardous contaminants. This study aims to assess the effects of chronic exposure to volcanogenic pollution on wild mice testes by studying: (i) diameter of seminiferous tubules; (ii) relative volumetric density of different spermatogenic cells and interstitial space; (iii) damage in the seminiferous tubules and (iv) apoptotic level in the germinal epithelium. The mice from the polluted site showed higher levels of the selected heavy metals than those from the reference site. The mean diameter of seminiferous tubules and the relative volume occupied by spermatozoa and lumen in exposed mice were significantly lower than in the unexposed group. Contrarily, exposed mice showed a significantly higher relative volume occupied by interstitium, as well as, a higher degree of damage and a significantly higher number of apoptotic cells in the germinal epithelium. Results show that secondary manifestations of volcanic activity can pose a serious risk of testicular injury and therefore for male reproduction.

Disruption of estrogen receptor signaling and similar pathways in the efferent ductules and initial segment of the epididymis

Seminiferous tubular atrophy may involve indirectly the disruption of estrogen receptor-α (ESR1) function in efferent ductules of the testis. ESR1 helps to maintain fluid resorption by the ductal epithelium and the inhibition or stimulation of this activity in rodent species will lead to fluid accumulation in the lumen. If not resolved, the abnormal buildup of fluid in the head of the epididymis and efferent ductules becomes a serious problem for the testis, as it leads to an increase in testis weight, tubular dilation and seminiferous epithelial degeneration, as well as testicular atrophy. The same sequence of pathogenesis occurs if the efferent ductule lumen becomes occluded. This review provides an introduction to the role of estrogen in the male reproductive tract but focuses on the various overlapping mechanisms that could induce efferent ductule dysfunction and fluid backpressure histopathology. Although efferent ductules are difficult to find, their inclusion in routine histological evaluations is recommended, as morphological images of these delicate tubules may be essential for understanding the mechanism of testicular injury, especially if dilations are observed in the rete testis and/or seminiferous tubules.

Signature Lesion:

The rete testis and efferent ductules can appear dilated, as if the lumens were greatly expanded with excess fluid or the accumulation of sperm. Because the efferent ductules resorb most of the fluid arriving from the rete testis lumen, one of two mechanisms is likely to be involved: a) reduced fluid uptake, which has been caused by the disruption in estrogen receptor signaling or associated pathways; or b) an increased rate of fluid resorption, which results in luminal occlusion. Both mechanisms can lead to a temporary increase in testicular weight, tubular dilation and atrophy of the seminiferous tubules.

Histological and ultrastructural studies on the toxic effect of pan masala and its amelioration by Elettaria cardamomum

AIM

To investigate the histological and ultrastructural changes observed in pan masala intoxicated mammalian testes under the effect of cardamom.

METHODS

Male Swiss mice were given pan masala orally at a dose of 2% of the feed and cardamom at a dose of 0.2% of the feed. They were divided into three groups, control (Group I), pan masala-treated (Group II), and a combination of pan masala and cardamom-treated group (Group III). Histologically, the testes of Group II mice displayed degeneration of tubular epithelium, disruption of spermatogenesis, and a marked reduction in germ cells.

RESULTS

When cardamom was given, damage was less with fewer distorted cells and also improvement with normal tubules and spermatid differentiation in Group III. Ultrastructurally, pan masala-treated testes showed cytoplasmic vacuolation, shrinkage and pyknotic nuclei of spermatogonia, and abnormal acrosomal granules.

CONCLUSION

When cardamom was given, the amelioration process was more evident showing a comparable morphology with control.

The "filarial dance" is not characteristic of filariasis: observations of "dancing megasperm" on high-resolution sonography in patients from nonendemic areas mimicking the filarial dance and a proposed mechanism for this phenomenon

The objective of this series was to show that the sonographic appearance described as the "filarial dance" is not characteristic of filariasis but occurs in nonendemic areas as a manifestation of epididymal obstruction. An experienced observer documented cases after initial observation of the filarial dance in routine clinical practice using high-frequency linear array transducers. The filarial dance was described as excessive to-and-fro movement of echogenic particles within a prominent epididymis and graded 1 to 4 according to the extent and distribution of the abnormality. The country of birth, exposure to filarial infection or travel to a filarial-endemic area, previous scrotal surgery including vasectomy, any previous or current scrotal inflammatory disease, and any congenital testicular abnormalities were recorded. Over a 10-year period, sonographic appearances consistent with the filarial dance were observed in 18 patients (bilateral in 6). The mean patient age was 47.7 (range, 28-91) years. The abnormality was graded in the 24 affected testes as follows: grade 1, n = 3; grade 2, n = 8; grade 3, n = 8; and grade 4, n = 5. No patient had a history of filariasis or travel to an endemic area. Six of 18 patients (33.3%) had bilateral vasectomies; 5 (27.8%) had a history of epididymo-orchitis in the ipsilateral testis; 3 (16.7%) had previous scrotal surgery; and 4 (22.2%) had no relevant urologic history. We have described a sonographic appearance identical to the filarial dance in men with no history of filarial infection. Most had previous scrotal surgery or infection, suggesting that the filarial dance may not always be due to movement of filarial worms. The unifying condition in patients with filariasis and our patients is lymphatic obstruction, likely the underlying cause of the appearance in both groups.

Lactational hexavalent chromium exposure-induced oxidative stress in rat uterus is associated with delayed puberty and impaired gonadotropin levels

Hexavalent chromium (CrVI) is a transition element utilized in many fields of modern industries. CrVI is a reproductive metal toxicant that can traverse the placental barrier and cause a wide range of fetal effects. Therefore, the present study was carried out to determine the CrVI-induced utero-toxicity. In the present study, lactating rats received drinking water containing CrVI (50 mg/L and 200 mg/L) from postnatal days (PND) 1-21. During PND 1-21, the pups received CrVI via the mother's milk. Pups from both control and treatment groups were continued on regular diet and water from PND-21 onwards and euthanized on PND-45 and -65. Specific activities antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), glutathione-S-transferase (GST) were estimated. Hydrogen peroxide (H₂O₂), lipid peroxidation (LPO) and serum gonadotropins viz. Luteinizing hormone (LH) and follicle stimulating hormone (FSH) were also assayed. Specific activities of SOD, CAT, GPX, GR and GST and serum testosterone and progesterone were significantly decreased, while H₂O₂, LPO and serum FSH was increased in 50-parts per million (ppm) and 200 ppm-treated rats in an age-dependent manner. These results suggest that lactational CrVI exposure induces oxidative stress in rat uterus by decreasing antioxidant enzymes, which were associated with delayed puberty and altered steroids and gonadotrophin levels.

Effect of curcumin on chromium-induced oxidative damage in male reproductive system

Hexavalent chromium, an environmental contaminant, undergoes redox cycling with generation of free radicals inside the biological system. Curcumin, the yellow bioactive component of turmeric has established its antioxidant activities. The present study evaluates possible ameliorating effects of curcumin on potassium dichromate (K(2)Cr(2)O(7)) (hexavalent chromium) induced reproductive toxicity in adult male Sprague-Dawley rats. Three experimental groups, each consisting of eight rats, were treated with 0.4mg K(2)Cr(2)O(7)/kg bw/day, 0.4mg K(2)Cr(2)O(7)/kg bw/day+20mg curcumin/kg bw on every alternate day and 20mg curcumin/kg bw on every alternate day, respectively, for 26 days. Altered testicular histology, reduced sperm count, low testosterone level, decreased accessory sex organs weight, enhanced lipid peroxidation along with reduced SOD and catalase activities were observed following K(2)Cr(2)O(7) exposure while curcumin supplementation along with K(2)Cr(2)O(7) exposure had shown to prevent the altered parameters. The results thus suggest that curcumin may have a protective role against chromium(VI) induced oxidative damage in male reproductive system.

In vivo spermatotoxic effect of chromium as reflected in the epididymal epithelial principal cells, basal cells, and intraepithelial macrophages of a nonhuman primate (Macaca radiata Geoffroy)

OBJECTIVE

To understand, through a simulation experiment in a nonhuman primate model, the potential in vivo spermatotoxic toxic effect of hexavalent chromium (CrVI) in men who are occupationally or environmentally exposed to it.

DESIGN

Controlled laboratory study.

SETTING

Research laboratory in a department of endocrinology in a university in India.

ANIMAL(S)

Male bonnet monkey, Macaca radiata Geoffroy.

INTERVENTION(S)

Monkeys were exposed ad libitum to 100, 200, and 400 ppm CrVI, dissolved in drinking water, for a chronic period of 180 days.

MAIN OUTCOME MEASURE(S)

Examination of epididymis with a transmission electron microscope and assessment of the effect of CrVI in terms of accumulation of sperm-derived lipofuscin (LF) material in the principal cells, basal cells, and intraepithelial macrophages of the epithelium.

RESULT(S)

The abundance of basal cells and intraepithelial macrophages and the content of LF material in these cell types increased. The principal cells phagocytosed from the lumen the dead sperm resulting from CrVI exposure and processed them partially into LF material, which was acquired by the basal cells and intraepithelial macrophages and processed further. The LF material-laden basal cells and intraepithelial macrophages appeared to leave the epithelium, accompanied by recruitment of fresh basal cells and intraepithelial macrophages.

CONCLUSION(S)

Occupational or environmental exposure to CrVI, as would occur in the tannery, soap, and other industries in developing and underdeveloped countries, can be toxic in vivo to spermatozoa.

Reproductive toxicity of chromium in adult bonnet monkeys (Macaca radiata Geoffrey). Reversible oxidative stress in the semen

The present study was designed to test the hypothesis that oxidative stress mediates chromium-induced reproductive toxicity. Monthly semen samples were collected from adult monkeys (Macaca radiata), which were exposed to varying doses (50, 100, 200 and 400 ppm) of chromium (as potassium dichromate) for 6 months through drinking water. Chromium treatment decreased sperm count, sperm forward motility and the specific activities of antioxidant enzymes, superoxide dismutase and catalase, and the concentration of reduced glutathione in both seminal plasma and sperm in a dose- and duration-dependent manner. On the other hand, the quantum of hydrogen peroxide in the seminal plasma/sperm from monkeys exposed to chromium increased with increasing dose and duration of chromium exposure. All these changes were reversed after 6 months of chromium-free exposure period. Simultaneous supplementation of vitamin C (0.5 g/L; 1.0 g/L; 2.0 g/L) prevented the development of chromium-induced oxidative stress. Data support the hypothesis and show that chronic chromium exposure induces a reversible oxidative stress in the seminal plasma and sperm by creating an imbalance between reactive oxygen species and antioxidant system, leading to sperm death and reduced motility of live sperm.

Chronic chromium exposure-induced changes in testicular histoarchitecture are associated with oxidative stress: study in a non-human primate (Macaca radiata Geoffroy)

BACKGROUND

Reproductive toxicity of chromium is in dispute despite positive findings in rodents. Recently we reported epididymal toxicity of hexavalent chromium (CrVI) in bonnet monkeys and in this paper we report its testicular toxicity.

METHODS

Adult monkeys (Macaca radiata) were given drinking water containing CrVI (100, 200, 400 p.p.m.) for 6 months and testes were removed for ultrastructural and biochemical analyses.

RESULTS

CrVI treatment disrupted spermatogenesis, leading to accumulation of prematurely released spermatocytes, spermatids and uni- and multinucleate giant cells in the lumen of seminiferous tubules. Transmission electron microscopy revealed granulation of chromatin and vacuolation between acrosomal cap and manchette microtubules of elongated spermatids and in the Golgi area of round spermatids. Pachytene spermatocytes had fragmented chromatin and swollen mitochondria with collapsed cristae. Spermatocytes and spermatogonia in the basal compartment were unaffected. Macrophages containing phagocytosed sperm and dense inclusions in Sertoli cells were seen. Specific activities of the antioxidant enzymes superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase and glucose-6-phosphate dehydrogenase and concentrations of the non-enzymatic antioxidants glutathione, vitamins A, C and E decreased, while concentrations of H(2)O(2) and hydroxyl radicals increased in the testis of chromium-treated monkeys. Withdrawal of chromium treatment for 6 months normalized spermatogenesis and the status of pro- and antioxidants in the testis.

CONCLUSIONS

CrVI disrupts spermatogenesis by inducing free radical toxicity, and supplementation of antioxidant vitamins may be beneficial to the affected subjects.