Protective effects of antioxidants against cadmium-induced oxidative damage in rat testes

Cadmium as a male reproductive toxicant and natural and non-natural ways to tackle it: a review

Cadmium (Cd) is a naturally occurring environmental pollutant, a toxic substance that causes oxidative stress. According to epidemiological studies, the data suggested that environmental and occupational Cd exposure may be related to several diseases and severe testicular damage. However, studies are going on to explore the mechanism of Cd-induced male reproductive toxicity and its treatment strategies. Currently, researchers are focusing on naturally occurring bioactive compounds, plant extracts, and biochemical, which have better efficacy, less toxicity, and high bioavailability. This review focuses on the mechanistic effect of Cd on testicular toxicity and different categories of compounds having a beneficial impact on Cd-induced male reproductive toxicity. Some potent bioactive antioxidants are quercetin, caffeic acid phenethyl ester, cyanidin-3-O-glucoside, curcumin, and silymarin. In comparison, plant extracts are Costus afer leaf methanol extract, methanol root extract of Carpolobia lutea, red carrot methanolic extract, Panax ginseng extract, and biochemicals including melatonin, progesterone, glutamine, L-carnitine, and selenium. Advanced and more detailed studies are needed on these compounds to explore their mechanism in attenuating Cd-induced testicular toxicity and can be potential therapeutics in the future.

Protective effects of melatonin against the toxic effects of environmental pollutants and heavy metals on testicular tissue: A systematic review and meta-analysis of animal studies

BACKGROUND

Environmental pollution and infertility are two modern global challenges that agonize personal and public health. The causal relationship between these two deserves scientific efforts to intervene. It is believed that melatonin maintains antioxidant properties and may be utilized to protect the testicular tissue from oxidant effects caused by toxic materials.

METHODS

A systematic literature search was conducted in PubMed, Scopus, and Web of Science to identify the animal trial studies that evaluated melatonin therapy's effects on rodents' testicular tissue against oxidative stress caused by heavy metal and non-heavy metal environmental pollutants. Data were pooled, and standardized mean difference and 95% confidence intervals were estimated using the random-effect model. Also, the risk of bias was assessed using the Systematic Review Centre for Laboratory animal Experimentation (SYRCLE) tool. (PROSPERO: CRD42022369872).

RESULTS

Out of 10039 records, 38 studies were eligible for the review, of which 31 were included in the meta-analysis. Most of them showed beneficial effects of melatonin therapy on testicular tissue histopathology. [20 toxic materials were evaluated in this review, including arsenic, lead, hexavalent chromium, cadmium, potassium dichromate, sodium fluoride, cigarette smoke, formaldehyde, carbon tetrachloride (CCl4), 2-Bromopropane, bisphenol A, thioacetamide, bisphenol S, ochratoxin A, nicotine, diazinon, Bis(2-ethylhexyl) phthalate (DEHP), Chlorpyrifos (CPF), nonylphenol, and acetamiprid.] The pooled results showed that melatonin therapy increased sperm count, motility, viability and body and testicular weights, germinal epithelial height, Johnsen's biopsy score, epididymis weight, seminiferous tubular diameter, serum testosterone, and luteinizing hormone levels, testicular tissue Malondialdehyde, glutathione peroxidase, superoxide dismutase, and glutathione levels. On the other hand, abnormal sperm morphology, apoptotic index, and testicular tissue nitric oxide were lower in the melatonin therapy arms. The included studies presented a high risk of bias in most SYRCLE domains.

CONCLUSION

In conclusion, our study demonstrated amelioration of testicular histopathological characteristics, reproductive hormonal panel, and tissue markers of oxidative stress. Melatonin deserves scientific attention as a potential therapeutic agent for male infertility.

SYSTEMATIC REVIEW REGISTRATION

https://www.crd.york.ac.uk/PROSPERO, identifier CRD42022369872.

Melatonin modulates Nrf2 activity to protect porcine pre-pubertal Sertoli cells from the abnormal H2 O2 generation and reductive stress effects of cadmium

Melatonin (MLT) is a cytoprotective agent holding potential to prevent cadmium (Cd) toxicity and its impact in testicular function and fertility. In this study, we explored such potential in porcine pre-pubertal Sertoli cells (SCs). Cd toxicity resulted in impaired SC viability and function, abnormal cellular H₂ O₂ generation and efflux, and induction of reductive stress by the upregulation of Nrf2 expression and activity, cystine uptake and glutathione biosynthesis, glutathione-S-transferase P (GSTP) expression, and protein glutathionylation inhibition. Cd toxicity also stimulated the activity of cellular kinases (MAPK-ERK1/2 and Akt) and NFkB transcription factor, and cJun expression was increased. MLT produced a potent cytoprotective effect when co-administered with Cd to SCs; its efficacy and the molecular mechanism behind its cytoprotective function varied according to Cd concentrations. However, a significant restoration of cell viability and function, and of H₂ O₂ levels, was observed both at 5 and 10 μM Cd. Mechanistically, these effects of MLT were associated with a significant reduction of the Cd-induced activation of Nrf2 and GSTP expression at all Cd concentrations. CAT and MAPK-ERK1/2 activity upregulation was associated with these effects at 5 μM Cd, whereas glutathione biosynthesis and efflux were involved at 10 μM Cd together with an increased expression of the cystine transporter xCT, of cJun and Akt and NFkB activity. MLT protects SCs from Cd toxicity reducing its H₂ O₂ generation and reductive stress effects. A reduced activity of Nrf2 and the modulation of other molecular players of MLT signaling, provide a mechanistic rational for the cytoprotective effect of this molecule in SCs.

Letrozole protects against cadmium-induced inhibition of spermatogenesis via LHCGR and Hsd3b6 to activate testosterone synthesis in mice

The heavy metal cadmium is proposed to be one of the environmental endocrine disruptors of spermatogenesis. Cadmium-induced inhibition of spermatogenesis is associated with a hormone secretion disorder. Letrozole is an aromatase inhibitor that increases peripheral androgen levels and stimulates spermatogenesis. However, the potential protective effects of letrozole on cadmium-induced reproductive toxicity remain to be elucidated. In this study, male mice were administered CdCl2 (4 mg/kg BW) orally by gavage alone or in combination with letrozole (0.25 mg/kg BW) for 30 days. Cd exposure caused a significant decreases in body weight, sperm count, motility, vitality, and plasma testosterone levels. Histopathological changes revealed extensive vacuolization and decreased spermatozoa in the lumen. However, in the Cd + letrozole group, letrozole treatment compensated for deficits in sperm parameters (count, motility, and vitality) induced by Cd. Letrozole treatment significantly increased serum testosterone levels, which were reduced by Cd. Histopathological studies revealed a systematic array of all germ cells, a preserved basement membrane and relatively less vacuolization. For a mechanistic examination, RNA-seq was used to profile alterations in gene expression in response to letrozole. Compared with that in the Cd-treated group, RNA-Seq analysis showed that 214 genes were differentially expressed in the presence of letrozole. Gene ontology (GO) enrichment analysis and KEGG signaling pathway analysis showed that steroid biosynthetic processes were the processes most affected by letrozole treatment. Furthermore, we found that the expression of the testosterone synthesis-related genes LHCGR (luteinizing hormone/choriogonadotropin receptor) and Hsd3b6 (3 beta- and steroid delta-isomerase 6) was significantly downregulated in Cd-treated testes, but these genes maintained similar expression levels in letrozole-treated testes as those in the control group. However, the transcription levels of inflammatory cytokines, such as IL-1β and IL-6, and oxidative stress-related genes (Nrf2, Nqo1, and Ho-1) showed no changes. The present study suggests that the potential protective effect of letrozole on Cd-induced reproductive toxicity might be mediated by the upregulation of LHCGR and Hsd3b6, which would beneficially increase testosterone synthesis to achieve optimum protection of sperm quality and spermatogenesis.

Evidence of melatonin ameliorative effects on the blood-testis barrier and sperm quality alterations induced by cadmium in the rat testis

Herein, we further document the protective action of melatonin (MLT) in mitigating cadmium (Cd) effects on adult rat testis. Cd treatment provoked testicular injury, that was documented by histological and biomolecular alterations, i.e., decrease of serum and testicular testosterone concentration and modified sperm parameters. Mainly, both the cytoarchitecture of the blood-testis barrier (BTB) and germ cell morphology were perturbed, as highlighted by impairment in structural (OCN, VANGL, Cx43) and regulative (Src and FAK) protein levels and/or activation. The study focused on the involvement of the autophagy pathway, that was enhanced especially in the Sertoli cells, probably in response to the disorganization of the BTB. Results obtained with the MLT co-treatment demonstrated that its administration decreased the level of oxidative damage caused by Cd, with reversal of all the observed changes. Moreover, the beneficial effects of MLT alone were evidenced by an increase of sperm quality, in term of motility and DNA integrity. The combined results, obtained in rat, strongly encourage to consider a role for MLT in improving also human testicular health, not only in men exposed to Cd, but also in those having fertility disorders, to ameliorate sperm quality and, consequently, reproductive success.

Altered Expression of DAAM1 and PREP Induced by Cadmium Toxicity Is Counteracted by Melatonin in the Rat Testis

Cadmium (Cd) is one of the most toxic pollutants for health due to its accumulation in several tissues, including testis. This report confirms that Cd increased oxidative stress and apoptosis of germ and somatic cells and provoked testicular injury, as documented by biomolecular and histological alterations, i.e., CAT and SOD activity, the protein level of steroidogenic enzymes (StAR and 3β-HSD), and morphometric parameters. Additionally, it further documents the melatonin (MLT) coadministration produces affects in mitigating Cd-induced toxicity on adult rat testis, as demonstrated by the reduction of oxidative stress and apoptosis, with reversal of the observed histological changes; moreover, a role of MLT in partially restoring steroidogenic enzymes expression was evidenced. Importantly, the cytoarchitecture of testicular cells was perturbed by Cd exposure, as highlighted by impairment of the expression and localization of two cytoskeleton-associated proteins DAAM1 and PREP, which are involved in the germ cells' differentiation into spermatozoa, altering the normal spermatogenesis. Here, for the first time, we found that the co-treatment with MLT attenuated the Cd-induced toxicity on the testicular DAAM1 and PREP expression. The combined findings provide additional clues about a protective effect of MLT against Cd-induced testicular toxicity by acting on DAAM1 and PREP expression, encouraging further studies to prove its effectiveness in human health.

Aqueous extract of Adansonia digitata prevents Cadmium Chloride-induced testicular damage in Wistar Rats

OBJECTIVES

The role of aqueous extract of Adansonia digitata was investigated against cadmium chloride-induced testicular damage in Wistar Rats.

METHODS

Thirty (30) male Wistar Rats weighing (150-170) were divided into six groups (n=5). Group A served as control and received oral administration of phosphate buffer saline; group B received 800 mg/kg A. digitata only; group C were injected intraperitoneally with single dose 2 mg/kg b.w cadmium chloride; group D were injected intraperitoneally with single dose 2 mg/kg b.w cadmium chloride and treated with 800 mg/kg aqueous extract of A. digitata; group E received 300 mg/kg vitamin E only; group F were injected intraperitoneally with single dose 2 mg/kg b.w cadmium chloride and treated with 300 mg/kg vitamin E. After 21 days, the animals were sacrificed by cervical dislocation, the testes were excised fixed in Bouins fluids for histological analysis and the other homogenized in 5% sucrose solution for determination of tissue malondialdehyde (MDA) and antioxidant enzyme activity, biochemical assay.

RESULTS

The group treated with cadmium chloride plus A. digitata caused significant decrease in MDA levels with significant increase (p<0.05) in antioxidant activities and biochemical enzymes when compared to cadmium chloride only group.

CONCLUSIONS

Aqueous extract of A. digitata appears to have ameliorative effect against cadmium chloride-induced testicular damage. This could be attributed to the presence of polyphenolic compound.

Cardamine hupingshanensis aqueous extract improves intestinal redox status and gut microbiota in Se-deficient rats

BACKGROUND

As an essential trace element for mammalian species, selenium (Se) possesses powerful antioxidant properties and is a potential regulator of intestinal microbiota. However, effects of Cardamine hupingshanensis aqueous extract (CE), rich in Se, on balancing the intestinal redox status and regulating gut microbiota have been neglected.

RESULTS

An Se-deficient rat model was established by feeding a low-Se diet (LD) for 5 weeks and CE was then supplemented to LD or normal-Se-diet (ND) rats. Antioxidant enzyme activities and short-chain fatty acids (SCFA) concentration were increased by CE in both LD and ND rats. CE improved the intestinal morphology of LD rats impaired by deficient Se. Intestinal microbiota demonstrated various changes; for example, Butyrivibrio was increased in LD rats, while Bacteroides, Christensenellaceae, Clostridiaceae and Blautia were enhanced in ND rats.

CONCLUSION

Our findings provide evidence that CE shows potential in improving intestinal redox status and regulating gut microbiota. © 2020 Society of Chemical Industry.

Amelioration of cadmium-induced testes' damage in rats by the bone marrow mesenchymal stem cells

Cadmium (Cd) and its compounds are highly toxic to virtually all organ systems of the mammals. Cd-induced testicular injuries have been reported in various animal species, using different protocols. The self-renewal capacity and the ability to generate different specialized cell types make the mesenchymal stem cells (MSCs) one of the ideal choices for restoring tissue damages of various etiologies. The use of bone marrow-derived MSCs (BM-MSCs) is among the most recent strategies to repair the Cd-induced testicular damage, but empirical studies in this regard are largely missing. Keeping in view the CD-induced testicular damage and the suggested restorative functions of BM-MSCs, the objectives of the current study were twofold: to induce testicular injury in Sprague-Dawley (SD) rats by a single intraperitoneal (i.p.) 2mg/kg Cd injection; and to study the reparative potential of BM-MSCs in Cd-induced testicular damage in adult male rats. The SD rats were randomly divided into three groups (n = 10 each): control (untreated), Cd-group (i.p. 2mg/kg Cd), and Cd+SC group (i.p. 2mg/kg Cd plus two intravenous doses of 1 × 106 BM-MSCs via penile vein). After four weeks, Cd-group showed a significantly lower (p < 0.05) weight-gain, sperm count, and sperm viability, as well as led to testicular atrophy, necrosis, fibrosis, calcification, and marked perivascular lymphocytic infiltration, as compared to the untreated controls. As hypothesized, the rats exposed to Cd, but treated with BM-MSCs (Cd+SC group), showed a lesser degree of Cd-induced damage. In conclusion, the findings of current investigation indicate a reversal of Cd-induced testicular injury by BM-MSCs. The study supports the previously suggested notion that BM-MSCs can repair the Cd-induced testes' damage in rats.

Protective Effect of Selenium on Aflatoxin B1-Induced Testicular Toxicity in Mice

Aflatoxins have been considered as one of the major risk factors of male infertility, and aflatoxin B1 (AFB1) is the most highly toxic and prevalent member of the aflatoxins family. Selenium (Se), an essential nutritional trace mineral for normal testicular development and male fertility, has received extensive intensive on protective effects of male reproductive system due to its potential antioxidant and activating testosterone synthesis. To investigate the protective effect of Se on AFB1-induced testicular toxicity, the mice were orally administered with AFB1 (0.75 mg/kg) and Se (0.2 mg/kg or 0.4 mg/kg) for 45 days. We found that that Se elevated testes index, sperm functional parameters (concentration, malformation, and motility), and the level of serum testosterone in AFB1-exposed mice. Moreover, our results showed that Se attenuated the AFB1-induced oxidative stress and the reduction of testicular testosterone synthesis enzyme protein expression such as steroidogenic acute regulatory protein (StAR), P450 side-chain cleavage (P450scc), and 17β-hydroxysteroid dehydrogenase (17β-HSD) in AFB1-exposed mice. These results demonstrated that Se conferred protection against AFB1-induced testicular toxicity and can be attributed to its antioxidant and increased testosterone level by stimulating protein expression of StAR and testosterone synthetic enzymes.

Effect of selenium on testicular damage induced by varicocele in adult male Wistar rats

PROJECT

Varicocele is an abnormal tortuosity and distension of the veins of the pampiniform plexus in the spermatic cord. It is the most common surgically correctable cause of male infertility. Several studies have revealed the effects of increased oxidative stress on serum, semen, and testicular tissues in patients with varicocele or in animal models. The aim of this study was to investigate the effects of sodium selenite on testicular damage induced by experimental left varicocele in male Wistar rats.

PROCEDURE

In the present study, the effects of oral administration of sodium selenite (at doses of 0.05, 0.1, 0.2, and 0.4mg/kg bw) were assessed in normal and varicocelized rats.

RESULTS

The varicocelized control rats showed decrease in sperm quality parameters, decreased activity of testes CAT, GPX and SOD, increased levels of MDA, and damage in testicular architecture. Administration of sodium selenite significantly reduced these changes to nearly normal levels, but did not change these parameters in normal rats. Histopathological studies further confirmed the protective effects of sodium selenite on varicocele-induced testicular damage in rats. Administrations of sodium selenite did not change these parameters in normal rats.

CONCLUSIONS

Taken together, the results of this study suggest that sodium selenite treatment may have beneficial effect on the testes of varicocelized rats.

Protective effect of Lycium barbarum polysaccharides against cadmium-induced testicular toxicity in male mice

The present study was performed to determine whether Lycium barbarum polysaccharides (LBPs) would protect mice against cadmium (Cd)-induced testicular toxicity. Seventy-two male mice were randomly divided into six groups with twelve mice per group. Four groups were administered orally with cadmium chloride (5.0 mg per kg body weight) for 35 days and treated in combination with LBPs (0, 10.0, 33.3 or 100 mg kg^-1) from one week before exposure to Cd until the end of the experiment. The other two groups were administered orally with vehicle or LBP (100 mg kg^-1) only. Pretreatment with LBP ameliorated the Cd-induced reduction in the body weights, sperm motility as well as the level of testosterone in serum. Moreover, Cd-induced increase in the abnormal sperms was reduced and effects of Cd on the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were reversed. Histopathological examination further confirmed that the LBPs effectively attenuated Cd-induced degeneration of seminiferous tubules. Thus, LBPs attenuated Cd-induced testicular injury by improving the activity of antioxidant enzymatic activity and lowering the oxidative stress, so it could be a potential auxiliary therapeutic agent for Cd-induced testicular toxicity.

Protective effect of selenium against cisplatin-induced nasopharyngeal cancer in male albino rats

The present study evaluated the protective effect of selenium against cisplatin-induced nasopharyngeal cancer in the cardiac tissue of adult rats. Male Wistar rats were divided into 4 groups of 6 rats each. Different combinations of selenium and cisplatin were administered for 45 days, following which the animals were sacrificed and the nasopharyngeal tissue was surgically removed. Lipid peroxidation, reduced glutathione, and the antioxidant enzymes superoxide dismutase (SOD), catalase and lactate dehydrogenase (LDH) were measured. Apoptotic-related gene (p53, bax and caspase 3) mRNA expression was determined using quantitative polymerase chain reaction. Caspase 3 activity was also measured in all the groups. The results demonstrated that selenium significantly reduced the levels of malondialdehyde. The levels of glutathione, SOD, LDH and catalase significantly increased following selenium treatment. Relative mRNA expression (p53, bax and caspase 3) was significantly reduced in the cisplatin-treated rats, but it significantly increased following selenium treatment. The anticancer activity of selenium was also investigated in HK1cells. Fluorescence and confocal microscopy were used to analyze apoptosis and reactive oxygen species. The protective effect of selenium was also evident through caspase 3 activity, which significantly increased following selenium treatment. Taken together, these results indicate that selenium may be beneficial against cisplatin-induced nasopharyngeal cancer.

Ameliorative effect of propolis on the cadmium-induced reproductive toxicity in male albino rats

Propolis is a potent antioxidant and a free radical scavenger. The present study aimed to investigate protective effects of propolis extract on cadmium-induced testicular damage, apoptosis, HIF-1α expression and toxicity in rat's testis tissue. A total of 32 male rats were equally divided into four study groups namely, control, Cd (1mg/kg/day), Cd+propolis (50mg/kg/day) and propolis. The rats were decapitated under ketamine anesthesia and their testes tissues were removed. Serum testosterone, tissue malondialdehyde and HIF-1α levels, HIF-1α expression, apoptosis and histopathological damage scores were then compared. In the Cd group, the diameters of seminiferous tubules, tubular biopsy score of Johnsen and serum testosterone levels were decreased compared control group, but tissue HIF-1α and tissue MDA levels was higher than control group. The immunoreactivity of HIF-1α and the number of apoptotic cells were increased in Cd group. Furthermore, the propolis treated group showed an improved histological appearance in the Cd group. Thus, the results suggest that propolis acts as a potent protective agent against Cd-induced testicular toxicity in rats.

Efficacy of Crocus sativus L. on reduction of cadmium-induced toxicity on spermatogenesis in adult rats

Cadmium is a toxic heavy metal element, which probably cause infertility by impairment in spermatogenesis. The present work aimed (i) to study the toxic effect of cadmium on spermatogenesis in rat, as well as (ii) the protective effect of Crocus sativus L. on cadmium-intoxicated rats. Cadmium chloride was administered intraperitoneally during 16 days at intervals of 48 h between subsequent treatments. Crocus sativus L. was pre-treated in both of control and cadmium-injected rats. Animals were sacrificed on day 17 after the first treatment. The left cauda epididymis was removed and immediately immersed into Hank's balanced salt solution for the evaluation of sperm count and viability, and left testis was fixed in 10% formalin for histological evaluation. Following contamination with cadmium, a decrease was observed in the number and viability of cauda epididymis sperm, which were increased by Crocus sativus L. pre-treatment (P < 0.05). In addition, cadmium decreased both cell proliferation and Johnsen Scores in the seminiferous tubules, which were reversed by Crocus sativus pre-treatment (P < 0.05). Furthermore, cadmium-induced decrease in the amount of free serum testosterone as well as an increase in lipid peroxidation activity in the testicular tissue was reversed by Crocus sativus L. (P < 0.05). These findings may support the concept that Crocus sativus L. can improve the cadmium toxicity on spermatogenesis.

Oxidative stress and spermatogenesis suppression in the testis of cadmium-treated Bombyx mori larvae

Bombyx mori L. (B. mori) were exposed to cadmium chloride (CdCl2) incorporated in an artificial diet (0, 6.25, 12.5, 25, and 50 mg kg(-1)) throughout the larval stage. Changes in malondialdehyde (MDA) and reduced glutathione (GSH) contents and activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), as well as their corresponding messenger RNA (mRNA) levels in the testes of the fifth instar larvae were evaluated. Additionally, spermatozoon deformation in the testes was examined. Upon Cd treatment, the MDA content in the testes was significantly increased in a concentration-dependent manner. Cd-exposed larvae had increased levels of glutathione. Pearson's correlation analysis revealed that SOD and CAT activities were positively correlated (R (2) = 0.605, P = 0.017). The changing trends in the mRNA levels of these enzymes were not always consistent with those of enzymatic activities. Alterations in GSH-Px activities and mRNA levels were positively correlated (R (2) = 0.771, P < 0.01). Morphological analysis revealed that Cd deformed and affected the maturation of spermatozoa. Our results collectively support a relationship between Cd and alterations in the levels of antioxidant enzymes in B. mori testes.

Improvement of Heart Redox States Contributes to the Beneficial Effects of Selenium Against Penconazole-Induced Cardiotoxicity in Adult Rats

The present study was performed to evaluate the protective effect of selenium (Se) against penconazole (PEN)-induced oxidative stress in the cardiac tissue of adult rats. Male Wistar rats were divided into four groups of six each. The first group represented the controls. For the second group (PEN), no treatment was performed during the first 6 days, and then, the rats received intraperitoneally 67 mg/kg body weight (bw) of PEN every 2 days from day 7 until day 15, the sacrifice day. For the third group (Se + PEN), Se was administered daily through the diet at a dose of 0.5 mg/kg of diet for 15 days. Rats of this group received also every 2 days PEN (67 mg/kg bw) from day 7 until day 15. The fourth group (Se) received daily, through the diet, Se (0.5 mg/Kg of diet) during 15 days. Our results showed that Se reduced significantly the elevated cardiac levels of malondialdehyde and protein carbonyl following PEN treatment, and attenuated DNA fragmentation induced by this fungicide. In addition, Se modulated the alterations of antioxidant status: enzymatic (superoxide dismutase, glutathione peroxidase, and catalase) and nonenzymatic (glutathione and vitamin C) antioxidants in the heart of PEN-treated rats. This trace element was also able to alleviate perturbations of lipid profile. The protective effect of selenium was further evident through the histopathological changes produced by PEN in the heart tissue. Taken together, our results indicated that Se might be beneficial against PEN-induced cardiac oxidative damage in rats.

Effect of chronic exposure to cadmium on serum lipid, lipoprotein and oxidative stress indices in male rats

Cadmium (Cd) is an environmental toxic metal implicated in lipid abnormalities. The present study was designed to elucidate the possible association between chronic exposure to Cd concentration and alterations in plasma lipid, lipoprotein, and oxidative stress indices in rats. Sixteen male rats were assigned to 2 groups of 8 rats each (test and control). The Cd-exposed group obtained drinking water containing cadmium chloride (CdCl2) in the concentration of 2.0 mg Cd/L in drinking water for 3 months. At the end of the experimental period, blood samples were obtained to determine the changes of serum triglycerides (TG), total cholesterol (TC), highdensity lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), reduced glutathione (GSH), malondialdehyde (MDA) and also serum Cd contents. The results of the present study indicated that Cd administration significantly increased the serum levels of TG, TC, LDL-C, MDA and Cd with reduction in the HDL-C and GSH levels. In conclusion, evidence is presented that chronic exposure to low Cd concentration can adversely affect the lipid and lipoprotein profile via lipid peroxidation.

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

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

Protective effects of grape seed extract on cadmium-induced testicular damage, apoptosis, and endothelial nitric oxide synthases expression in rats

This study aims to evaluate the protective effect of grape seed proanthocyanidin extract (GSPE) on cadmium (Cd)-induced testicular apoptosis, endothelial nitric oxide synthases (eNOS) expression, and toxicity in rats. A total of 24 male Wistar rats were divided into four groups, namely, control, Cd (2.5 mg/kg), Cd + GSPE (100 mg/kg/day), and GSPE. Spermatogenesis and mean seminiferous tubule diameter were significantly decreased in the Cd groups. Furthermore, the GSPE-treated animals showed an improved histological appearance in the Cd group. The immunoreactivity of eNOS and the number of apoptotic cells were increased in Cd group. Our data indicate a significant reduction of terminal deoxynucleotide transferase-mediated 2'-deoxyuridine 5'-triphosphate nick end-labeling staining and a decrease in the expression of eNOS in the testes tissue of the Cd group treated with GSPE therapy. Therefore, our results suggest that GSPE acts as a potent protective agent against Cd-induced testicular toxicity in rats.

The protective effect of Physalis peruviana L. against cadmium-induced neurotoxicity in rats

The present study was carried out to investigate the protective effect of Physalis peruviana L. (family Solanaceae) against cadmium-induced neurotoxicity in rats. Adult male Wistar rats were randomly divided into four groups. Group 1 was used as control. Group 2 was intraperitoneally injected with 6.5 mg/kg bwt of cadmium chloride for 5 days. Group 3 was treated with 200 mg/kg bwt of methanolic extract of Physalis (MEPh). Group 4 was pretreated with MEPh 1 h before cadmium for 5 days. Cadmium treatment induced marked disturbances in neurochemical parameters as indicating by significant (p < 0.05) reduction in dopamine (DA), serotonin (5-HT), and 5-hydroxyindoleacetic acid (5-HIAA) in cerebellum, hippocampus, and cerebral cortex and enhanced significantly (p < 0.05) the levels of lipid peroxidation and nitric oxide in the brain. Cadmium treatment also decreased the amount of nonenzymatic and enzymatic antioxidants significantly (p < 0.05). Pretreatment with MEPh resulted in significant (p < 0.05) decreases in lipid peroxidation and nitric oxide levels and restored the amount of glutathione successfully. Although, preadministration of MEPh also brought the activities of cellular antioxidant enzymes, namely superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase significantly (p < 0.05) to the control levels, as well as the levels of Ca(2+), Cl(-), DA, 5-HT, and serotonin metabolite, 5-HIAA. These data indicated that Physalis has a beneficial effect in ameliorating the cadmium-induced oxidative neurotoxicity in the brain of rats.

Biochemical and histopathological evaluations of ghrelin effects following cadmium toxicity in the rat testis

Numerous reports demonstrate that cadmium (Cd) induces oxidative stress by increasing lipid peroxidation and altering antioxidative enzymes status. Thirty male rats were subdivided into control-saline, Cd-saline and Cd-ghrelin groups. A single dose of Cd was injected to induce testicular injury and also ghrelin for 10 consecutive days to group 3. SOD activity decreased and lipid peroxidation increased by Cd administration. The mean activities of GPx and CAT as well as GSH content were lower in the Cd-saline rats; however, they did not statistically differ compared with the controls. Exposure to Cd resulted in complete degeneration of seminiferous tubules with severe depletion of germ cells and arrest in spermatogenesis. Notably, ghrelin treatment not only prevented reduction in SOD, GPx, CAT and GSH level, but also increased enzyme activities form their normal values. Moreover, TBARS concentration was significantly reduced by ghrelin administration. Furthermore, ghrelin pre-treatment resulted in partial but not significant prevention in testicular histopathological features damaged by Cd. In conclusion, the obtained results indicate for the first time the novel evidences of ghrelin ability in promotion of antioxidant enzyme activities and reduction of lipid peroxidation following Cd-induced oxidative stress in the rat testis. These observations also demonstrate that ghrelin may be considered as promising antioxidant agent in prevention and attenuation of testicular injury upon Cd toxicity.

A review of metal-catalyzed molecular damage: protection by melatonin

Metal exposure is associated with several toxic effects; herein, we review the toxicity mechanisms of cadmium, mercury, arsenic, lead, aluminum, chromium, iron, copper, nickel, cobalt, vanadium, and molybdenum as these processes relate to free radical generation. Free radicals can be generated in cells due to a wide variety of exogenous and endogenous processes, causing modifications in DNA bases, enhancing lipid peroxidation, and altering calcium and sulfhydryl homeostasis. Melatonin, an ubiquitous and pleiotropic molecule, exerts efficient protection against oxidative stress and ameliorates oxidative/nitrosative damage by a variety of mechanisms. Also, melatonin has a chelating property which may contribute in reducing metal-induced toxicity as we postulate here. The aim of this review was to highlight the protective role of melatonin in counteracting metal-induced free radical generation. Understanding the physicochemical insights of melatonin related to the free radical scavenging activity and the stimulation of antioxidative enzymes is of critical importance for the development of novel therapeutic strategies against the toxic action of these metals.

Saffron improves epididymal sperm parameters in rats exposed to cadmium

Background:

Cadmium (Cd) is known to cause various disorders in the testis. The general population may be exposed to Cd through ingestion of food and drinking water, inhalation of particulates from ambient air, tobacco smoke and ingestion of contaminated soil and dust. Saffron (Crocus sativus L.) is widely used as a food flavour, and has well known medicinal effects.

Objectives:

The aim of this study was to determine the effects of saffron on the results of semen parameters (sperm concentration, motility and viability in cauda of epididymis) in rats exposed to cadmium.

Materials and Methods:

Thirty Wistar male rats were divided into four groups. Cadmium chloride (1 mg/kg body weight) was injected intraperitoneally during 16 days at intervals of 48 hours between subsequent treatments. Crocus sativus L. (100 mg/kg b.w., IP) was pretreated in both control and cadmium-injected rats. Both control and cadmium-injected rats were pretreated with Crocus sativus L. (100 mg/kg b.w., IP). The animals were killed and their sperm count, motility, and vitality were evaluated.

Results:

Sperm parameters did not differ significantly between control and sham groups. Following contamination with cadmium, sperm count, motility and vitality were significantly decreased in comparison to control group (P < 0.05). In pretreated (saffron) group, the sperm parameters improved significantly in comparison with cadmium group (P ≤ 0.05). A significant decrease in sperm motility was observed in Cd-treated rats compared to the control rats. However, no significant changes were recorded by comparison of the control and saffron treated groups except for the sperm motility parameter.

Conclusions:

Saffron, as an antioxidant, is positively effective on sperm parameters in rats exposed with cadmium.

Comparative analysis of antioxidants against cadmium induced reproductive toxicity in adult male rats

The present study was conducted to compare and evaluate the potential benefits of three different antioxidants in reversing cadmium (Cd)-induced reproductive toxicity in adult male rats. Rats (n = 5) weighing 180 +/- 20 gm were divided into five groups (control, Cd, Cd + sulforaphane, Cd + vitamin E, and Cd + plant extract). Treated groups received CdCl2 (0.2 mg/kg), sulforaphane (25 µg/rat), vitamin E (75 mg/kg), and plant extract (100 mg/kg) for 15 days. Blood samples and testicular tissues were obtained for estimation of testosterone, Zn, and Cd concentration and daily sperm production/efficiency of sperm production. Cadmium exposure caused a significant decrease in final body weight (p < 0.0001). The plasma concentrations of Cd were significantly increased and Zn concentration decreased (p < 0.0001) in the Cd group as compared to the control group. The testicular concentrations of Cd were significantly increased and Zn concentration decreased (p < 0.0001) in the Cd group as compared to the control group. Cadmium exposure caused a significant decrease (p < 0.0001) in plasma testosterone concentrations and daily sperm production as compared to the control group. More significant effects were observed with Cd+sulforaphane, Cd + vitamin E, and Cd + plant extract treated groups in slashing Cd-induced toxicity. Present findings suggest that Ficus religiosa and sulforaphane are more powerful antioxidants as compared to vitamin E in reversing the oxidative stress and can have a protective role against Cd induced reproductive toxicity in adult male rats. Part of the mechanism involved in this protective role seems to be associated with the antioxidant properties of these agents in reducing reproductive damage.

Rutin- and Selenium-attenuated cadmium-induced testicular pathophysiology in rats

Cadmium (Cd) is known to cause oxidative damage in the testes of rats. The aim of this study was to investigate the protective role of rutin (RUT, 30 mg/kg) and selenium (Se, 0.15 ppm) alone or in combination against Cd (200 ppm)-induced lipid peroxidation, steroidogenesis and changes in antioxidant defence system in the rat testes. The obtained results showed that Cd increased lipid peroxidation and abnormal sperm count and decreased plasma testosterone, lactate dehydrogenase, acid phosphatase, alkaline phosphatase and testicular steroidogenic enzymes: 3β-hydroxysteroid dehydrogenase (HSD), 17β-HSD activities as well as epididymal sperm counts and motility, while RUT and Se treatment reversed this change to control values. Acute intoxication with Cd was also followed by significantly decreased activity of the antioxidant defence system (superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), glutathione (GSH), and glutathione-S-transferase (GST)). Treatment with RUT and Se reversed Cd-induced alterations of antioxidant defence system and significantly prevented Cd-induced testes damage and depletion of plasma and testicular Se levels. RUT and Se appear not to have more profound effects than their separate effects against Cd-induced testicular toxicity, although Se was more potent than RUT in the recovery of testosterone levels. These results suggest that both RUT and Se do not have synergistic role against Cd-induced testicular injury.

Selenium-vitamin E combination modulates endometrial lipid peroxidation and antioxidant enzymes in streptozotocin-induced diabetic rat

Diabetes mellitus is associated with diabetic impairment of uterine function, ultimately leading to reduced fertility. Its etiology may involve oxidative damage by reactive oxygen substances, and protection against this damage can be offered by antioxidant supplementation. In the present study, the effects of a vitamin E-plus-selenium (VESe) combination on lipid peroxidation (MDA) and the scavenging enzyme activity in the uterine endometrium of streptozotocin (STZ)-induced diabetic rats were investigated. Twenty-four female rats were equally divided into three groups as follows: group I (control); group II (diabetic); group III (diabetic + VESe), STZ + vitamin E (60 mg/kg over 1 day) + selenium-treated (Na2SeO3, 1 mg/kg over 1 day). After 4 weeks of receiving the VESe treatment, endometrium samples were taken from the uterus. Although the VESe treatment decreased the MDA and blood glucose levels in the STZ group, the observed values remained significantly higher than in the controls. Catalase, superoxide dismutase, and glutathione peroxidase activities and body weight gain were significantly (p < 0.01) lower in STZ groups as compared to control group, whereas their activities were (p < 0.01) increased by VESe treatment. However, there was no significant difference on body weight gain and uterine weights between control and STZ + VESe groups. In conclusion, the endometrial complications caused by oxidative stress, and the abnormal blood glucose levels in diabetic of rats, can be alleviated by strengthening the physiological antioxidative defense through the administration of vitamin E and Se.

Ovarian toxicity induced by dietary cadmium in hen

To investigate the toxicity of cadmium (Cd) on female reproduction in birds, this study was conducted to determine the changes in biochemical parameters of serum and ovary tissue caused by dietary cadmium in hens. Ninety 50-day-old hyline white hens were randomly divided into three groups (30 hens per group): a control group was fed with basal diet, a low dose group was fed with basal diet containing 140 mg/kg CdCl(2) and a high dose group was fed with basal diet containing 210 mg/kg CdCl2. After being treated with Cd for 20, 40 and 60 days, ovary and serum samples were collected and examined for Cd content, histological evaluations, malondialdehyde (MDA) content, glutathione peroxidase (GPx) content, activities of superoxide dismutase (SOD), nitric oxide (NO) content, nitric oxide synthase (NOS) activity, and serum estradiol and progestogen levels. The results showed that the content of Cd, MDA, NO and the activity of NOS in ovary and serum were increased (P < 0.05), while the level of GPx and the activity of SOD were decreased (P < 0.05) in low dose and high dose groups. A time- and dose-dependent correlation was observed between serum and ovary tissue cadmium levels. The number of apoptotic cells in the ovary was increased in the Cd treatment group (P < 0.05). Extensive damage was observed in the ovary. The level of estradiol and progestogen in the serum of low dose and high dose groups was decreased significantly (P < 0.05). It indicated that Cd exposure resulted in oxidative damage of hens' ovary tissue by altering antioxidant defense enzyme systems, lipid peroxidation, apoptosis and endocrine disturbance which may be possible underlying reproductive toxicity mechanisms induced by Cd.

Lipid, lipoproteins, total antioxidant status and organ changes in rats administered high doses of cadmium chloride

OBJECTIVE

To determine the possible association between cadmium (Cd) exposure and alterations in plasma lipid and lipoprotein levels and total antioxidant status (TAS) in rats.

MATERIALS AND METHOD

Twenty male albino rats assigned to 2 groups of 10 rats each (test and control) were used for the study. Each test animal model was given 1.0 mg CdCl(2)/kg body weight, administered intraperitoneally for 4 weeks. Blood samples obtained from both groups at the beginning (baseline) and after 4 weeks of Cd exposure were analysed for triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol (LDLC), TAS and Cd. Kidney and liver sections from the rats were examined.

RESULTS

The plasma TG, TC and LDLC levels were significantly higher in exposed rats than controls (p < 0.0001, p < 0.0001 and p < 0.001, respectively). Plasma HDLC was reduced in the exposed rats compared to controls (0.41 ± 0.22 and 0.68 ± 0.14 mmol/l, respectively).

CONCLUSION

The observed dyslipidaemia and decrease in TAS could be due to increased free radical production causing oxidative stress. Damage to liver and kidney sections in the exposed group suggests that Cd toxicity results in detrimental histological changes and may be implicated in the aetiology of cerebrovascular diseases.

Selenium-vitamin E combination and melatonin modulates diabetes-induced blood oxidative damage and fetal outcomes in pregnant rats

Oxidative stress is considered to be the main cause of diabetic complications. In the current study, we investigated the effect of selenium-vitamin E combination and melatonin on lipid peroxidation (LPO) and scavenging enzyme activity in the blood of streptozocin (STZ)-induced diabetic pregnant rats. Forty female Wistar rats were randomly divided into five groups. The first and second groups were used as the non-pregnant control and pregnant control groups, respectively. The third group was the pregnant diabetic group. Vitamin E plus selenium and melatonin were administered to the diabetic pregnant rats consisting fourth and fifth groups, respectively. Diabetes was induced on day 0 of the study by STZ. Blood samples were taken from all animals on the 20th day of pregnancy. LPO level was higher in diabetic pregnant rats than in control, although superoxide dismutase, catalase, and glutathione peroxidase activities were lower in diabetic pregnant animals than in control. LPO levels were lower both in the two treatment groups than in the diabetic pregnant rats, whereas selenium-vitamin E combination and melatonin caused a significant increase in the activities of these antioxidant enzymes (p<0.01). In conclusion, vitamin E plus selenium seems to be a more potent antioxidant compared to melatonin in diabetic pregnant rats. Melatonin did not significantly affect the elevated glucose concentration of diabetic pregnant treated with melatonin group. Vitamin E plus selenium may play a role in preventing diabetes-related diseases of pregnant subjects.

Effect of selenium on carbimazole-induced testicular damage and oxidative stress in albino rats

Carbimazole is an antithyroid drug used in treatment of hyperthyroidism. The present investigation studied the effect of carbimazole on testicular activity in albino rats and the ameliorative role of selenium. Treating rats with carbimazole (1.35 mg/kg b.w) daily for 8 weeks caused reduction in the body and testes weight. Moreover, the diameters of the seminiferous tubules and heights of their germinal epithelium were significantly reduced. Testes of treated rats showed many histological alterations included congestion of blood vessels, hemorrhage, degeneration of interstitial tissue and degeneration of spermatogenic cells with apoptosis and necrosis. Histochemical results revealed reduction in polysaccharides, total proteins and nucleic acids contents in testicular tissue. In addition, the level of testosterone, luteinizing hormone (LH), T(3), T(4) and thyroid stimulating hormone (TSH) was significantly decreased in sera of treated animals. Moreover, a high lipid peroxidation with a decrease in the enzymatic antioxidant status, superoxide dismutase (SOD) and catalase (CAT) was recorded in testes homogenate. Treating animals with carbimazole and selenium showed an improvement in the histological structure as well as histochemical components of the testis with an increase in the number of spermatogenic cells. There was an increase in testosterone, LH, T(3), T(4) and TSH levels. Moreover, administration of selenium led to decrease in malondialdehyde and increase in catalase and superoxide dismutase activities. It is suggested that the curative effect of selenium against testicular damage induced by carbimazole may be due to its antioxidant properties.

Cadmium toxicity in spermatogenesis and protective effects of L-carnitine in adult male rats

In this study, the effects of cadmium toxicity and the protective effects of L-carnitine on spermatogenesis in Sprague-Dawley rat were evaluated. Animals were subdivided into five groups. Cadmium chloride (1-mg/kg body weight) was injected intraperitoneally during 16 days at intervals of 48 h between subsequent treatments. L-carnitine (500 mg/kg b.w., IP) was pretreated in both of control and cadmium-injected rats. Animals were killed on day 17 after the first treatment. The left cauda epididymis was removed and immediately immersed into Hank's balanced salt solution for evaluation of sperm count and viability. Following contamination with cadmium, a decrease in the number and viability of cauda epididymis sperm, the number of cell proliferation, and Johnsen Scores in the seminiferous tubules was observed. Consequently, L-carnitine treatment caused an increase in the number and viability of cauda epididymis sperm, the number of cell proliferation, and Johnsen Scores in the cadmium-induced group.

Cadmium and Selenium Interaction in Mammals

Izloženost kadmiju neizbježna je zbog njegove sveprisutnosti u okolišu kao prirodne sastavnice Zemljine kore i kao onečišćenja. Kadmij može izazvati toksične učinke u gotovo cijelom organizmu vezanjem za biološke strukture i nakupljanjem u tkivima, poticanjem stvaranja slobodnih radikala, kao i međudjelovanjem s esencijalnim elementima, često u obliku antagonizma. S druge strane, dodatnim unosom esencijalnih elemenata može se utjecati na raspodjelu i štetne učinke kadmija. Selenij je esencijalan mikroelement i antioksidans, a zbog svojstva vezanja za kadmij (kao i živu, arsen i druge toksične elemente) te uloge u detoksifikaciji, detaljnije se počelo istraživati međudjelovanje kadmija i selenija. U radu je dan pregled dosadašnjih saznanja o toksikokinetici i toksikodinamici kadmija, biokinetici i biodinamici selenija i mehanizmima njihova međudjelovanja proizašlih uglavnom iz istraživanja na životinjama i ograničenu broju istraživanja u ljudima. Različite doze i odnos doza, način i dužina izloženosti kadmiju i seleniju u pokusima na životinjama uzrok su često vrlo oprečnih rezultata istraživanja opisanih u literaturi. Buduća istraživanja međudjelovanja kadmija i selenija treba usmjeriti na osjetljive skupine stanovništva i na istraživanje mehanizama tog međudjelovanja. Doze i izloženost u pokusima na životinjama treba prilagoditi dugotrajnim i niskim razinama izloženosti koje su najčešće u ljudi.

Involvement of selenoprotein P and GPx4 gene expression in cadmium-induced testicular pathophysiology in rat

To investigate the effect of co-exposure to cadmium (Cd) and selenium (Se) on selenoprotein P (SelP) and phospholipid hydroperoxide glutathione peroxidase (GPx4) gene expression in testis and to evaluate their possible involvement in Cd-induced testicular pathophysiology, male rats received either tap water, Cd or Cd+Se in their drinking water for 5 weeks. Cd exposure caused a down-regulation of SelP and GPx4 gene expression and a significant decrease in plasma and testicular concentrations of Se. These changes were accompanied by decreased plasma testosterone level, sperm count and motility, GSH content, protein-bound sulfhydryl concentration (PSH), enzymatic activities of catalase (CAT) and glutathione peroxidase (GSH-Px) as well as by increased glutathione-S-transferase (GST) activity, lipid peroxidation (as malondialdehyde, MDA) and proteins carbonyls (PC). The decrease of testicular SelP and GPx4 gene expression under Cd influence was significantly restored in Cd+Se group. Co-treatment with Cd and Se also totally reversed the Cd-induced depletion of Se, decrease in plasma testosterone level and partially restored Cd-induced oxidative stress and decrease in sperm count and motility. Taken together, these data suggest that down-regulation of SelP and GPx4 gene expression induces plasma and testicular Se depletion leading, at least in part, to Cd-induced testicular pathophysiology.

The changing biological roles of melatonin during evolution: from an antioxidant to signals of darkness, sexual selection and fitness

Melatonin is a molecule present in a multitude of taxa and may be ubiquitous in organisms. It has been found in bacteria, unicellular eukaryotes, macroalgae, fungi, plants and animals. A primary biological function of melatonin in primitive unicellular organisms is in antioxidant defence to protect against toxic free radical damage. During evolution, melatonin has been adopted by multicellular organisms to perform many other biological functions. These functions likely include the chemical expression of darkness in vertebrates, environmental tolerance in fungi and plants, sexual signaling in birds and fish, seasonal reproductive regulation in photoperiodic mammals, and immunomodulation and anti-inflammatory activity in all vertebrates tested. Moreover, its waning production during aging may indicate senescence in terms of a bio-clock in many organisms. Conversely, high melatonin levels can serve as a signal of vitality and health. The multiple biological functions of melatonin can partially be attributed to its unconventional metabolism which is comprised of multi-enzymatic, pseudo-enzymatic and non-enzymatic pathways. As a result, several bioactive metabolites of melatonin are formed during its metabolism and some of the presumed biological functions of melatonin reported to date may, in fact, be mediated by these metabolites. The changing biological roles of melatonin seem to have evolved from its primary function as an antioxidant.

Effects of diallyl sulfide and zinc on testicular steroidogenesis in cadmium-treated male rats

Cadmium (Cd) is one of the environmental pollutants that affect various tissues and organs including testis. Harmful effect of cadmium on testis is known to be germ cell degeneration and impairment of testicular steroidogenesis. In the present study, the effect of diallyl sulfide (DAS), a sulfur-containing volatile compound present in garlic, and zinc (Zn) was investigated on cadmium-induced testicular toxicity in rats. Male adult Wistar rats treated with cadmium (2.5 mg/kg body wt, five times a week for 4 weeks) showed decreased body weight, paired testicular weight, relative testicular weight, serum testosterone, luteinizing hormone, follicle-stimulating hormone, and testicular total antioxidant capacity (TAC) and protein levels. Testicular steroidogenic enzymes, such as 3beta-hydroxysteroid dehydrogenase (3beta-HSD) and 17beta-hydroxysteroid dehydrogenase (17beta-HSD), and marker enzymes, such as sorbitol dehydrogenase (SDH), lactate dehydrogenase (LDH), acid phosphatase (ACP), alkaline phosphatase (ALP), and glucose-6-phosphate dehydrogenase (G6PD), showed a significant decrease in activities whereas that of gamma-glutamyl transferase was significantly increased after cadmium exposure. The results have revealed that concurrent treatment with DAS or zinc restored key steroidogenic enzymes, SDH, LDH, and G6PD and increased testicular weight significantly. DAS restored the TAC level and increased testosterone level and relative testicular weight significantly. Zinc restored testicular protein level and body weight. It can be concluded that cadmium causes testicular toxicity and inhibits androgen production in adult male rats probably by affecting pituitary gonadotrophins and that concurrent administration of DAS or zinc provides protection against cadmium-induced testicular toxicity.

Cadmium-induced testicular injury

Cadmium (Cd) is an environmental toxicant and an endocrine disruptor in humans and rodents. Several organs (e.g., kidney, liver) are affected by Cd and recent studies have illustrated that the testis is exceedingly sensitive to Cd toxicity. More important, Cd and other toxicants, such as heavy metals (e.g., lead, mercury) and estrogenic-based compounds (e.g., bisphenols) may account for the recent declining fertility in men among developed countries by reducing sperm count and testis function. In this review, we critically discuss recent data in the field that have demonstrated the Cd-induced toxicity to the testis is probably the result of interactions of a complex network of causes. This is likely to involve the disruption of the blood-testis barrier (BTB) via specific signal transduction pathways and signaling molecules, such as p38 mitogen-activated protein kinase (MAPK). We also summarize current studies on factors that confer and/or regulate the testis sensitivity to Cd, such as Cd transporters and metallothioneins, the impact of Cd on the testis as an endocrine disruptor and oxidative stress inducer, and how it may disrupt the Zn(2+) and/or Ca(2+) mediated cellular events. While much work is needed before a unified mechanistic pathway of Cd-induced testicular toxicity emerges, recent studies have helped to identify some of the likely mechanisms and/or events that take place during Cd-induced testis injury. Furthermore, some of the recent studies have shed lights on potential therapeutic or preventive approaches that can be developed in future studies by blocking or minimizing the destructive effects of Cd to testicular function in men.