Chromium induced testicular impairment in relation to adrenocortical activities in adult albino rats

Using Bayesian and weighted regression to evaluate the association of idiopathic oligoastenoteratozoospermia with seminal plasma metal mixtures

Idiopathic oligoastenoteratozoospermia (iOAT) affects 30% of infertile men of reproductive age. However, the associations between Cr, Fe, Cu, Se or Co levels and iOAT risk have not been determined. This research aimed to assess the associations between Cr, Fe, Cu, Se and Co levels as well as their mixtures in seminal plasma and the risk of iOAT and severe iOAT. Therefore, a case‒control study including 823 participants (416 iOAT patients and 407 controls) recruited from October 2021 to August 2022 at the reproductive medicine center of the First Affiliated Hospital of Anhui Medical University was conducted in Anhui, China. The concentrations of Cr, Fe, Cu, Se and Co in seminal plasma were detected via inductively coupled plasma‒mass spectrometry. Binary logistic regression models were used to assess the associations between the levels of Cr, Fe, Cu, Se and Co and the risk of iOAT and severe iOAT; additionally, Bayesian kernel machine regression (BKMR) and weighted quantile sum (WQS) regressions were performed to evaluate the joint effect of seminal plasma levels of Cr, Fe, Cu, Se and Co on the risk of iOAT and explore which elements contributed most to the relationship. We found significant associations between the concentrations of Fe, Cu and Se in seminal plasma and iOAT risk after adjusting for covariates (Fe, lowest tertile vs. second tertile: aOR = 1.86, 95% CI = 1.31, 2.64; Cu, lowest tertile vs. second tertile: aOR = 1.95, 95% CI = 1.37, 2.76; Se, lowest tertile vs. second tertile: aOR = 1.65, 95% CI = 1.17, 2.35). A lower Se concentration in seminal plasma (lowest tertile vs. second tertile: aOR = 1.84, 95% CI = 1.10, 3.10) was positively associated with the risk of severe iOAT. Additionally, we also observed an association between the concentration of Cr in seminal plasma and the risk of iOAT before adjusting for covariates (Cr, third tertile vs. lowest tertile: OR=1.44, 95% CI: 1.03, 2.02). According to the BKMR analyses, the risk of iOAT increased when the overall concentrations were less than the 25th percentile. The results from the WQS regression indicated that a negative WQS index was significantly associated with the iOAT risk, while a positive WQS index was not. Se and Fe had significant weights in the negative direction. In conclusion, lower Cu, Fe and Se levels in seminal plasma were positively associated with iOAT risk, while higher Cr levels in seminal plasma were positively associated with iOAT risk according to the single element model, and lower levels of Se were related to a greater risk of severe iOAT; when comprehensively considering all the results from BKMR and WQS regression, Fe, Se and Cr levels contributed most to this relationship.

Impact of Chromium Picolinate on Leydig Cell Steroidogenesis and Antioxidant Balance Using an In Vitro Insulin Resistance Model

Leydig cells (LCs) play a pivotal role in male fertility, producing testosterone. Chromium (III) picolinate (CrPic3), a contentious supplement with antidiabetic and antioxidant properties, raises concerns regarding male fertility. Using a rodent LC line, we investigated the cytotoxicity of increasing CrPic3 doses. An insulin resistance (IR) model was established using palmitate (PA), and LCs were further exposed to CrPic3 to assess its antioxidant/antidiabetic activities. An exometabolome analysis was performed using 1H-NMR. Mitochondrial function and oxidative stress were evaluated via immunoblot. Steroidogenesis was assessed by quantifying androstenedione through ELISA. Our results uncover the toxic effects of CrPic3 on LCs even at low doses under IR conditions. Furthermore, even under these IR conditions, CrPic3 fails to enhance glucose consumption but restores the expression of mitochondrial complexes CII and CIII, alleviating oxidative stress in LCs. While baseline androgen production remained unaffected, CrPic3 promoted androstenedione production in LCs in the presence of PA, suggesting that it promotes cholesterol conversion into androgenic intermediates in this context. This study highlights the need for caution with CrPic3 even at lower doses. It provides valuable insights into the intricate factors influencing LCs metabolism and antioxidant defenses, shedding light on potential benefits and risks of CrPic3, particularly in IR conditions.

A Comprehensive Review of the Impact of Chromium Picolinate on Testicular Steroidogenesis and Antioxidant Balance

Low testosterone (T) levels are a major cause of male infertility, as this hormone is crucial for several processes throughout the entire male reproductive tract. Leydig cells (LC) produce T through testicular steroidogenesis. Disrupted LC function can hinder steroid production and fertility. Among the factors that affect steroidogenesis, endocrine-disrupting chemicals (EDCs) raise concerns, as they disturb hormonal signaling. Chromium is classified as an EDC, and its main forms are hexavalent (Cr(VI)) and trivalent chromium (Cr(III)). While Cr(III) is controversially regarded as an essential metal, its compound Cr(III) picolinate (CrPic3) is used as a nutritional supplement due to its antidiabetic and antioxidant properties. This review aims to identify the possible effects of CrPic3 on testicular steroidogenesis and thus, on male fertility. The detriments caused by CrPic3 in LC include the inhibition of enzymes involved in steroidogenesis, and, as in other cells, the induction of mutagenesis and apoptosis. Remarkably, CrPic3 impacts male fertility through the alteration of reactive oxygen species (ROS), T levels, and sperm parameters (sperm motility and abnormal sperm count). However, gaps and inconsistencies exist in the literature concerning its effects on male fertility. Thus, further research is imperative to comprehend the underlying mechanisms of CrPic3 in the physiological processes relevant to male fertility, ensuring the supplement's safety for use by men.

Bone marrow mesenchymal stem cells repair hexavalent chromium-induced testicular injury by regulating autophagy and ferroptosis mediated by the AKT/mTOR pathway in rats

There is no ideal therapy for testicular damage induced by Cr(VI); however, bone marrow mesenchymal stem cells (BMSCs) transplantation may be a promising therapy. A Cr(VI) solution was administered to rats by intraperitoneal injection for 30 days, then BMSCs from donor rats were transplanted. Two weeks later, decreased activity and appetite, along with other pathological changes, were improved in the BMSCs group. The location of BMSCs in damaged testes was observed via laser confocal microscopy. Chromium content in the Cr(VI) and BMSCs groups significantly increased compared with that in the control group, but there was no significant difference between the two groups, as revealed by atomic absorption spectrometry. The ferrous iron and the total iron content of testes in the BMSCs group were significantly lower than those in the Cr(VI) group, as observed by Lillie staining and a tissue iron assay kit. Western blotting and immunohistochemical analyses revealed that the expression of Beclin 1, LC3B, 4-hydroxynonenal, and transferrin receptor 1 was decreased in the BMSCs group, compared with the Cr(VI) group. The expression of glutathione peroxidase 4 (GPX4), SLC7A11, p-AKT, mammalian target of rapamycin (mTOR), and p-mTOR in the BMSCs group was higher than that in the Cr(VI) group. Taken together, we propose that BMSCs repair Cr(VI)-damaged testes by alleviating ferroptosis and downregulating autophagy-associated proteins through the upregulation of AKT and mTOR phosphorylation.

A review of the endocrine disrupting effects of micro and nano plastic and their associated chemicals in mammals

Over the years, the vaste expansion of plastic manufacturing has dramatically increased the environmental impact of microplastics [MPs] and nanoplastics [NPs], making them a threat to marine and terrestrial biota because they contain endocrine disrupting chemicals [EDCs] and other harmful compounds. MPs and NPs have deleteriouse impacts on mammalian endocrine components such as hypothalamus, pituitary, thyroid, adrenal, testes, and ovaries. MPs and NPs absorb and act as a transport medium for harmful chemicals such as bisphenols, phthalates, polybrominated diphenyl ether, polychlorinated biphenyl ether, organotin, perfluorinated compounds, dioxins, polycyclic aromatic hydrocarbons, organic contaminants, and heavy metals, which are commonly used as additives in plastic production. As the EDCs are not covalently bonded to plastics, they can easily leach into milk, water, and other liquids affecting the endocrine system of mammals upon exposure. The toxicity induced by MPs and NPs is size-dependent, as smaller particles have better absorption capacity and larger surface area, releasing more EDC and toxic chemicals. Various EDCs contained or carried by MPs and NPs share structural similarities with specific hormone receptors; hence they interfere with normal hormone receptors, altering the hormonal action of the endocrine glands. This review demonstrates size-dependent MPs' bioaccumulation, distribution, and translocation with potential hazards to the endocrine gland. We reviewed that MPs and NPs disrupt hypothalamic-pituitary axes, including the hypothalamic-pituitary-thyroid/adrenal/testicular/ovarian axis leading to oxidative stress, reproductive toxicity, neurotoxicity, cytotoxicity, developmental abnormalities, decreased sperm quality, and immunotoxicity. The direct consequences of MPs and NPs on the thyroid, testis, and ovaries are documented. Still, studies need to be carried out to identify the direct effects of MPs and NPs on the hypothalamus, pituitary, and adrenal glands.

Aronia melanocarpa Ameliorates Adrenal Cytoarchitecture Against the Hexavalent Chromium-Induced Injury

Hexavalent chromium is a toxin that penetrates the cell, triggering reactive oxygen species (ROS) production. Aronia melanocarpa, due to its proanthocyanidins, anthocyanins, and phenolic acid contents, is a valuable antioxidant. The aim was to observe the influence of hexavalent chromium Cr(VI) on the adrenal gland, and if this impact can be recovered by the administration of A. melanocarpa. Accordingly, 36 rats were divided into six groups: control; Aronia; Cr receiving Cr(VI) in distilled water for 3 months; CrA receiving a mix of Cr(VI) and A. melanocarpa at 2.5% aqueous extract for 3 months; Cr2 receiving, for 3 months, Cr(VI) in distilled water, and next, for 1 month, only distilled water; and respectively, CrA2 receiving, for 3 months, Cr(VI) in distilled water, followed by 1 month of Aronia at 2.5% extract administration. The adrenal gland samples were examined toward histological and molecular assessment, and results were statistically analyzed (ANOVA). Hexavalent chromium induced changes in the adrenal cortex expressed by focal or diffuse hypertrophies, cytoplasmic vacuolization (due to lipidic accumulation), and cells' shape and size alteration, including necrosis. These structural alterations were carried by Bax and Bcl2 gene expression: the Bax gene expression levels, increased significantly (p < 0.001) in all experimental groups, except the Aronia group, compared with control. In the Cr2, CrA, and CrA2 groups, notable reduction of Bax gene expression (p < 0.001) was reported compared with the Cr group. Regarding the Bcl2 gene expression (p < 0.001), a significant increase was observed in the experimental groups, compared with the control. The Bcl2 expression level had a similar pattern to Bax gene, consequently trying to compensate its overexpression. Aronia administered concomitantly, or after Cr(VI), diminished structural changes and expression of the studied genes, thus reducing the Bax/Bcl2 ratio and suggesting that the active ingredients from Aronia are capable of blocking apoptotic cascade induced by the pathway of Bax and Bcl2 proteins.

The association between metal exposure and semen quality in Chinese males: The mediating effect of androgens

As a crucial factor in male reproduction, androgens may represent an intermediate biological mechanism linking metal exposure with effects on semen quality. This study aimed to investigate the association between metal exposure and semen quality, and to assess the mediating role of seminal androgens between metal exposure and semen quality. We investigated the presence of 10 metals in semen and assessed their effect on semen quality in 1136 men recruited from a hospital in Shenzhen, China. Of these, 464 subjects were randomly selected for 4 androgens detection in semen. Cross-sectional associations between single/multiple metals, androgen levels and semen quality were explored by multivariable linear regressions. Mediation analysis was performed to detect the role of seminal androgens on the association between metal exposure and semen quality. Seminal selenium and iron were positively associated with both sperm concentration and total sperm count. Negative associations were observed between both manganese and zinc and sperm concentration, molybdenum and total sperm count, copper and sperm motility. Furthermore, we found significant dose-dependent relationships between both iron and selenium levels and dihydrotestosterone (DHT), arsenic levels and testosterone, as well as zinc and dehydroepiandrosterone. Mediation analysis indicated that higher seminal iron and selenium were associated with an increasing sperm concentration after controlling for DHT, with 10.32% and 12.89% of these associations were mediated by DHT, respectively. A similar mediation effect of DHT was observed in the associations between iron and selenium levels and total sperm count (13.39% and 21.57% mediation, respectively). Our findings suggested that the presence of selenium and iron in semen was beneficial to sperm concentration and total count. Seminal manganese, zinc, molybdenum and copper may be associated with reduced semen quality. The associations between seminal selenium and iron and sperm concentration and total count were partially explained by the concomitant variation of seminal DHT.

Correlation between urinary chromium level and semen quality in men attending an andrology laboratory

Chromium is an essential element that is required for the normal physiology but can be toxic to humans above a certain level. In spite of growing interest in research on chromium exposure to human health consensus about its effect on human, semen quality has not been achieved. The aim of the present study is to evaluate the impact of chromium exposure on semen parameters. A total of 760 males attending andrology laboratory of Tongji Hospital, Wuhan, for routine semen analysis were enrolled and requested to provide semen and urine samples. The urine level of chromium was evaluated using inductively coupled plasma mass spectrometry (ICP-MS), and computer-assisted semen analysis (CASA) was applied to examine semen parameters. Associations between semen parameters and urinary chromium were analyzed by means of multivariate linear regression analysis. Multivariate analysis showed a negative association between the urinary concentrations of chromium and progressive motility (β = - 0.014, p = 0.040) and total motility (β = - 1.077, p = 0.048), while other semen parameters did not show any statistically significant changes. Urinary chromium could influence semen quality parameters and impair male fecundity.

Silver nanoparticles testicular toxicity in rat

To evaluate the potential testicular toxicity induced by silver nanoparticles (AgNPs) in Sprague Dawley rate. The protocol study was designed as follows: G1: 30 adult male rats were kept as control. G2: 30 adult male rats were administered 5.36 mg/kg of AgNPs orally, twice weekly for six months. G3: 30 adult male rats were administered 13.4 mg/kg of AgNPs orally, twice weekly for six months. The results of hormonal assay revealed that a significant decrease in testosterone level while a significant increase in LH level was obtained. The testicular homogenate showed a significant decrease in SOD activity accompanied by a significant increase in MDA level in both G2 and G3 in comparison with the control in a dose-response relationship. Sperm viability indicates a significant decrease in rats in G2 and G3 groups. A significant decrease in DNA chromatin integrity % was obtained in rats of G3 in comparison with G2 and control. The semithin and TEM sections of the testis of G2 and G3 groups showed Sertoli cells have vacuolations with a disturbance in the arrangement and the staining affinity of spermatogenic cells. The spermatogonia appeared with a moderate electron density of the nucleus and cytoplasm. The acrosome and its cap become oval and light electron dens of spermatid cells.

Modulatory effect of Turnera diffusa against testicular toxicity induced by fenitrothion and/or hexavalent chromium in rats

Oxidative stress and increased production of reactive oxygen species have been implicated in pesticides and heavy metals toxicity. The objective of this study was to investigate the efficacy of Turnera diffusa Willd (damiana) on counteracting fenitrothion (FNT) and/or potassium dichromate (CrVI)-induced testicular toxicity and oxidative injury in rats. FNT and/or CrVI intoxicated animals revealed a significant increase in thiobarbituric acid reactive substances and hydrogen peroxide levels. While, reduced glutathione and protein content, as well as antioxidant enzymes, phosphatases, and aminotransferases activities, were significantly decreased. In addition, significant changes in testosterone and follicle-stimulating hormone levels were detected. Furthermore, histological and immunohistochemical alterations were observed in rat testes and this supported the observed biochemical changes. On the other hand, rats treated with damiana alone decreased lipid peroxidation and increased most of the examined parameters. Moreover, damiana pretreatment to FNT and/or CrVI-intoxicated rats showed significant improvement in lipid peroxidation, enzyme activities, and hormones as compared with their respective treated groups. Conclusively, rats treated with both FNT and/or CrVI showed pronounced hazardous effect especially in their combination group in addition, Turnera diffusa had a potential protective role against FNT and/or CrVI induced testicular toxicity.

Vitamin B12-induced spermatogenesis recovery in cimetidine-treated rats: effect on the spermatogonia number and sperm concentration

The H₂-receptor antagonist cimetidine is an antiulcer drug also used for the treatment of cancer due to its antiangiogenic effect. However, this drug has caused structural changes in the seminiferous tubules. Vitamin B₁₂ has been used as a therapeutic agent for the treatment of male infertility. The supplementation of rats with vitamin B₁₂ during cimetidine treatment has recovered the damaged seminiferous tubules, but how this vitamin restores the seminiferous epithelium has not been clarified. In this study, we evaluated whether vitamin B₁₂ improves the number of spermatogonia, spermatocytes, and sperm concentration in cimetidine-treated rats. Adult male rats were treated for 50 days as follows: cimetidine group received 100 mg kg⁻¹ b.w. of cimetidine, cimetidine-B₁₂ group received cimetidine and 3 μg of vitamin B₁₂-hydroxocobalamin, B₁₂ group received only 3 μg of vitamin, and control group received saline. Sperm concentration was calculated and historesin-embedded testes sections were used for the quantitative analyses of spermatogonia (A; In/B) and spermatocytes. TUNEL method and PCNA immunofluorescence were performed. Cimetidine caused a significant reduction in sperm concentration. TUNEL-positive spermatogonia and spermatocytes were correlated to a significant reduction in the number of these cells. In cimetidine-B₁₂ group, sperm concentration was higher than cimetidine group and a significant increase in the number of spermatogonia (stages II–VI) was correlated to a high incidence of PCNA-immunolabeled spermatogonia and spermatocytes. The results show that the supplementation of rats with vitamin B₁₂ during cimetidine treatment increases sperm concentration and exerts a potential effect in the recovery of spermatogonia and spermatocytes.

Testicular Oxidative Stress and Cellular Deformities in Clarias gariepinus (Burchell) from River Yamuna in Delhi Region, India

River Yamuna is under constant menace due to pollution levels beyond limit, ensuing chronic poisoning of aquatic biota. Induction of oxidative stress and cellular deformities is a common effect in fish. The present study aimed in assessing impact of environmental pollutants on gonad (testis) of Clarias gariepinus from Wazirabad barrage (entry site) and Okhla barrage (exit site) of river Yamuna in Delhi segment. Antioxidant enzymes assays viz. Super oxide dismutase (SOD), catalase (CAT) and ferric reducing antioxidant power (FRAP); thiobarbituric acid reactive substance assay (TBARS) for determining level of lipid peroxidation and histology for analysis of degenerative changes were employed as biomarkers. The results depicted signs of environmental contamination, hallmarked by significant increase (p < 0.001) in TBARs level (µmol/g wet tissue); significant decrease (p < 0.001) in SOD, CAT (U/mg protein) and FRAP value (U/mg tissue) in response to greater pollution at Okhla barrage as compared to Wazirabad barrage. Degenerative changes viz. unorganized seminiferous tubules, extensive vacuolization in germ cells, inflammatory lesions, greater vacant spaces and condensation of tubular cells prevailed in 75%, 85%, 80%, 80%, and 65% specimens respectively from Okhla barrage. Hence, the selected biomarkers highlighted the existence of greater prooxidative compounds at the exit site resulting in stressful condition for fish in river basin.

Effects of chromium picolinate on fat deposition, activity and genetic expression of lipid metabolism-related enzymes in 21 day old Ross broilers

Objective

This experiment was conducted to investigate the effects of chromium picolinate (CrP) on fat deposition, genetic expression and enzymatic activity of lipid metabolism-related enzymes.

Methods

Two hundred forty one-day-old Ross broilers were randomly divided into 5 groups with 4 replicates per group and 12 Ross broiler chicks per replicate. The normal control group was fed a basal diet, and the other groups fed the same basal diet supplemented with 0.1, 0.2, 0.4, and 0.8 mg/kg CrP respectively. The experiment lasted for 21 days.

Results

Added CrP in the basal diet decreased the abdominal fat, had no effects on subcutaneous fat thickness and inter-muscular fat width; 0.2 mg/kg CrP significantly decreased the fatty acid synthase (FAS) enzymatic (p<0.05); acetyl-CoA carboxylase (ACC) enzymatic activity decreased in all CrP groups (p<0.05); hormone-sensitive lipase (HSL) enzymatic activity also decreased, but the change was not significant (p>0.05); 0.4 mg/kg CrP group significantly decreased the lipoprotein lipase (LPL) enzymatic activity. FAS mRNA expression increased in all experimental groups, and the LPL mRNA expression significantly increased in all experimental groups (p<0.05), but not 0.2 mg/kg CrP group.

Conclusion

The results indicated that adding CrP in basal diet decreased the abdominal fat percentage, had no effects on subcutaneous fat thickness and inter-muscular fat width, decreased the enzymatic activity of FAS, ACC, LPL and HSL and increased the genetic expression levels of FAS and LPL.

Relationships between seminal plasma metals/metalloids and semen quality, sperm apoptosis and DNA integrity

This study aimed to investigate the relationships between environmental exposure to metals/metalloids and semen quality, sperm apoptosis and DNA integrity using the metal/metalloids levels in seminal plasma as biomarkers. We determined 18 metals/metalloids in seminal plasma using an inductively coupled plasma-mass spectrometry among 746 men recruited from a reproductive medicine center. Associations of these metals/metalloids with semen quality (n = 746), sperm apoptosis (n = 331) and DNA integrity (n = 404) were evaluated using multivariate linear and logistic regression models. After accounting for multiple comparisons and confounders, seminal plasma arsenic (As) quartiles were negatively associated with progressive and total sperm motility using multivariable linear regression analysis, which were in accordance with the trends for increased odds ratios (ORs) for below-reference semen quality parameters in the logistic models. We also found inverse correlations between cadmium (Cd) quartiles and progressive and total sperm motility, whereas positive correlations between zinc (Zn) quartiles and sperm concentration, between copper (Cu) and As quartiles and the percentage of tail DNA, between As and selenium (Se) quartiles and tail extent and tail distributed moment, and between tin (Sn) categories and the percentage of necrotic spermatozoa (all P_trend<0.05). These relationships remained after the simultaneous consideration of various elements. Our results indicate that environmental exposure to As, Cd, Cu, Se and Sn may impair male reproductive health, whereas Zn may be beneficial to sperm concentration.

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.

Biphasic action of iodine in excess at different doses on ovary in adult rats

Iodine consumption in excess of its recommended levels over a prolonged period of time is well known to cause thyroid disorders. The thyroid hormones on the other hand are responsible in maintenance of the physiology of the reproductive system. Excess iodine intake affects male reproductive physiology. However, the effects of excess iodine on the ovarian structure and function is yet to be established. The present study has thus been undertaken to investigate the effect of excess iodine on the ovarian physiology. Excess iodine was administered through oral gavage in the form of potassium iodide (KI) for duration of 60days, at two different doses. The doses used were 100 EI, i.e., 100 times more than the recommended level but tolerable to the thyroid gland and 500 EI, i.e., 500 times more than the recommended level that altered thyroid physiology. The animals were divided into three groups, one control group, and the other two receiving two separate doses (100 EI and 500 EI) of excess KI. Estrous cyclical changes, ovarian morphological changes, ovarian iodine accumulation and ovarian steroidogenic enzyme activities were analysed. The thyroid functional status was studied from the serum thyroid hormones levels. The overall results revealed a biphasic action of excess iodine that depends on its dose. At 100 EI, excess iodine did not alter thyroid physiology but lead to the development of a hypoestrogenic state. There was an increased accumulation of iodine in the ovary with decreased activity of ovarian steroidogenic enzymes and lowered serum estradiol levels. However, at 500 EI, excess iodine developed a hyperthyroid condition, which further leads to a hyperestrogenic state. There was an increased activity of serum steroidogenic enzymes as well as elevated serum estradiol levels. Fertility index was zero in both the 100 EI and 500 EI treated groups of experimental animals. Thus excess iodine (100 EI) ingestion within tolerable range though maintained a euthyroid condition yet developed a state of hypofunctioning ovary. Conversely, excessive iodine (500 EI) is intolerable to thyroid, develops a hyperthyroid condition that leads to a hyperfunctioning ovary. Therefore prolonged exposure of iodine in excess exerts biphasic mode of action depending on the dose in female reproductive physiology and both the doses used in this study affected fertility equally.

Associations of urinary metal levels with serum hormones, spermatozoa apoptosis and sperm DNA damage in a Chinese population

BACKGROUND

Exposure to metals, including essential and nonessential elements, is widespread and may be associated with male reproductive health.

OBJECTIVE

To examine whether environmental exposure to metals contributes to reproductive hormone changes, spermatozoa apoptosis and sperm DNA damage in a Chinese population.

METHODS

Eighteen metals (aluminum, arsenic, antimony, chromium, cobalt, copper, cadmium, iron, lead, manganese, molybdenum, nickel, selenium, tin, tungsten, thallium, uranium and zinc) were analyzed in two urine samples collected a few hours apart from male partners of couples attending an infertility clinic. Multivariable linear regression models were used to assess the cross-sectional associations of average urinary metal levels with serum hormones (n=511), spermatozoa apoptosis measures (n=460) and sperm DNA damage parameters (n=516).

RESULTS

We found significant inverse dose-dependent trends of urinary tin quartiles with total testosterone (T), and tin, nickel, zinc and molybdenum with the ratio of total T to luteinizing hormone (total T/LH ratio) (all Ptrend<0.05). Additionally, we found significantly dose-dependent trends of increasing urinary manganese quartiles with increasing percentage of Annexin V+/PI- spermatozoa and increasing iron with decreasing percentage of PI+ spermatozoa (both Ptrend<0.05). These dose-dependent trends remained suggestive or significant after controlling for multiple testing and other metals, and they persisted when the metals were modeled as continuous variables in a cubic spline analysis. There were no significant associations between urinary metals and sperm DNA damage after adjustment for multiple testing.

CONCLUSION

Environmental exposure to tin, nickel, zinc and molybdenum may be associated decreased total T or total T/LH ratio; manganese may induce spermatozoa apoptosis, while iron may be important for living spermatozoa. However, additional prospective research is needed to corroborate these findings in the general population.

Effect of Excess Iodine on Oxidative Stress Markers, Steroidogenic-Enzyme Activities, Testicular Morphology, and Functions in Adult Male Rats

Improper iodine intake is a major concern in public health. Chronic intake of low iodine affects gonadal functions of man and animals; however, such effects of excess iodine in male reproduction, specially on testicular morphology, testicular steroidogenic enzyme activities, sperm morphology, sperm viability, and sperm count including male hormonal profiles in reference to iodine status and thyroid hormone profiles are yet to be explored. With this background, adult male rats of 120 ± 10 gm Bw of 90 ± 5 days were divided broadly in two groups depending on the duration of the treatment for 30 and 60 days, respectively. Both the groups consisted of control animals. Excess iodine (100EI), i.e., 100 times more than its recommended level but within its tolerable ranges, was administered through gavage regularly to the first group of experimental animals for 30 and 60 days, respectively, and excessive iodine (500EI), i.e., 500 times more than its recommended level and above tolerable range in the same way and for the same durations, was administered to the other group of experimental animals. Overall results revealed that regular consumption of iodine in excess impairs reproductive functions in adult male rats depending on the dose and duration of its exposure through different mechanisms. Excess iodine accumulates in the testis which results in generation of reactive oxygen species (ROS) as evidenced by higher lipid peroxidation level as well as an imbalance in the pro-/antioxidant status inhibiting the activity of ∆(5) 3β- hydroxysteroid dehydrogenase (HSD) and 17β-HSD resulting to reduced synthesis of testosterone that causes structural and functional changes of the testis. Secondly, persistent generation of ROS in testis as a result of prolonged excess iodine exposure affects hypothalamo-pituitary-adrenal axis that stimulates synthesis and secretion of corticosterone which inhibits LH release that downregulates testosterone synthesis causing further testicular disruption. Thirdly, excess iodine when administered above its tolerable ranges for prolonged duration acts on thyroid itself developing a state of biochemical hypothyroidism (as evident by low T3) which further potentiate the disrupting effect of excess iodine on male gonads by reducing circulating testosterone level.

Mechanisms of chromium hexavalent-induced apoptosis in rat testes

Hexavalent chromium (CrVI)-containing compounds, present in industrial settings and in the environment, are known as carcinogens and mutagens. The present study is designed to test the hypothesis that oxidative stress mediates CrVI-induced apoptosis in testis. Male Wistar rats received an intraperitoneal injection of potassium dichromate at doses of 1 and 2 mg kg^-1. Superoxide anion production was assessed by the determination of the reduction of cytochrome c and iodonitrotetrazolium, lipid peroxidation (LPO), metallothioneins (MTs), and catalase (CAT) activity. Apoptosis was evaluated by DNA fragmentation detected by agarose gel electrophoresis. Germinal cells apoptosis was detected by toluidine blue staining. The expression of Bax and Bcl-2 proteins (Pts) was also investigated. After 15 days of treatment, an increase of LPO and MT levels occurred, while CAT activity was decreased. Testicular tissues of treated rats showed pronounced degradation of the DNA into oligonucleotides as seen in the typical electrophoretic DNA ladder pattern. Intense apoptosis was observed in germinal cells of Cr-exposed rats. Bax Pt expression was induced in spermatogonia and spermatocytes cells of CrVI-treated rats. In contrast, Bcl-2 Pt was occasionally observed in germ cells of CrVI-exposed rats. These results clearly suggest that CrVI subacute treatment causes oxidative stress in rat testis leading to apoptosis.

Association of urinary metal levels with human semen quality: A cross-sectional study in China

BACKGROUND

Exposure to metals, including essential and nonessential elements, has been linked to male reproductive health in animals. However, findings from human studies are inconsistent.

OBJECTIVE

To examine the associations between metal exposure at environmental levels and semen quality in a Chinese population by performing repeated measurements of urinary metals to estimate individual-level exposure.

METHODS

From March to June 2013, 1052 men seeking semen evaluation were recruited from the Reproductive Center of Tongji Hospital in Wuhan, China. Each man provided one semen sample and two urine sample. Semen quality parameters and urinary levels of 18 metals were determined. Associations between the urinary metal levels and semen quality parameters were assessed using confounder adjusted linear and logistic regressions. Restricted cubic spline analysis was performed to assess dose-response relationships between continuous metal measurements and outcomes.

RESULTS

Urinary levels of cadmium were significantly inversely associated with progressive sperm motility and total motility (both P<0.02) based on multivariable linear regression models, consistent with the trends of increased odds ratios for below-reference semen quality parameters observed in the logistic models (both P<0.05). Additionally, we found significant inverse associations of urinary molybdenum and lead with percentages of normal sperm morphology (both P<0.05). These associations remained suggestive or significant after adjustment for multiple testing. They were also robust to the simultaneous consideration of multiple metals, and curves of restricted cubic spline showed clear dose-response relationships.

CONCLUSION

Our findings suggest that environmental exposure to cadmium, molybdenum and lead may contribute to a decline in human semen quality.

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.

Evaluation of the Reproductive Toxicity, Glycometabolism, Glycometabolism-Related Enzyme Levels and Lipid Metabolism of Chromium Malate Supplementation in Sprague-Dawley Rats

Our previous study showed that chromium malate improved the regulation of blood glucose in mice with alloxan-induced diabetes. The present study was designed to evaluate the reproductive toxicity of chromium malate in Sprague-Dawley rats and then inspected the effect of chromium malate on glycometabolism, glycometabolism-related enzymes, and lipid metabolism. The results showed that no pathological, toxic feces and urine changes were observed in clinical signs of parental and fetal rats in chromium malate groups. The fasting blood glucose, serum insulin, insulin resistance index, C-peptide, hepatic glycogen, glucose-6-phosphate dehydrogenase, glucokinase, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and triglyceride levels of chromium malate groups have no significant change compared with control group and chromium picolinate group. The serum and organ contents of Cr in chromium malate groups have no significant change when compared with control group. No measurable damage on liver, brain, kidney, and testis/uterus of chromium malate groups was found. No significant change in body mass, absolute and relative organ weights, and hematological and biochemical changes of rats were observed compared with the control and chromium picolinate groups. The results indicated that supplements with chromium malate does not cause obvious damage and has no obvious effect on glycometabolism, glycometabolism-related enzyme, and lipid metabolism on female and male rats. The results of this study suggested that chromium malate is safe for human consumption and has the potential for application as a functional food ingredient and dietary supplement.

Urinary metal concentrations in relation to semen quality: a cross-sectional study in China

Exposure to metals, including essential and nonessential elements, is widespread and may be associated with altered semen quality. This study aimed to examine the association between urinary metal concentrations and semen quality in a Chinese population. We measured semen quality parameters (sperm concentration, count, motility, normal morphology, and abnormal head) and 13 metals [arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), molybdenum (Mo), mercury (Hg), nickel (Ni), selenium (Se), and zinc (Zn)] in the urine of 394 men from an infertility clinic. Multivariable logistic and linear regressions were used to assess the relationship between the creatinine-adjusted urinary metal concentrations and semen quality parameters. We found a significant trend for decreased odds ratios (ORs) for below-reference sperm count with increasing Se quartiles (p for trend = 0.04) and a significant trend for increased sperm percent abnormal head with increasing Ni quartiles (p for trend = 0.03). These associations persisted, even when considering multiple metals. Our results suggest that Ni exposure may be associated with deteriorated sperm morphology and that Se exposure may be associated with better semen quality. However, our findings warrant further studies in a larger and general population.

Inhibition of key markers linked with spermatogenesis and cellular ATP by subchronic exposure to leachate in a rat model

Few or no studies have measured the toxic effects of subchronic exposure to leachate using key markers linked with spermatogenesis and cellular adenosine triphosphate (ATP) in an experimental rat model. This study was undertaken to evaluate the toxic effects of leachate obtained from the Elewi Odo municipal battery-recycling site (EOMABRL) on male reproductive function using testicular hormones and biomarker of cellular ATP. EOMABRL was administered at 0, 20, 40, 60, 80, and 100% concentrations to adult male rats for 60 days. After exposure, serum was collected for hormonal biochemistry assays, and testes were collected to determine the activity of xanthine oxidase (XO) and lactate dehydrogenase (LDH). Exposure of animals to EOMABRL resulted in a 519.7, 285.7, 569.1, 606.1, and 1,793.2% increase in XO activity with a sequential decrease in LDH activity (marker of cellular ATP) by 44.1, 55.9, 61.4, 69.3, and 89.7%, respectively, compared with the control. Furthermore, EOMABRL caused a significant inhibitory effect on serum luteinizing hormone, follicle-stimulating hormone, and testosterone levels. We conclude that some possible mechanisms by which EOMABRL elicits toxicity in male rat testes could be through inhibition of LDH activity and depletion of serum hormone levels.

Protective role of cactus cladodes extract on sodium dichromate-induced testicular injury and oxidative stress in rats

Cactus (Opuntia ficus-indica) is a xerophyte plant that belongs to the Cactaceae family. The present study was designed to investigate the possible protective effects of cactus cladodes extract (CCE) on sodium dichromate-induced testis damage in adult male Wistar rats. For this purpose, CCE at a dose of 100 mg/kg was orally administrated, followed by 10 mg/kg sodium dichromate (intraperitoneal injection). After 40 days of treatment, the rats were sacrificed, and the testes were excised for histological, lipid peroxidation (LPO), and antioxidant enzyme analyses. Sodium dichromate treatment significantly (P<0.01) decreased the body, testis, and accessory sex organ weights, sperm count and motility, and serum testosterone level. In addition, histological analysis revealed pronounced morphological alterations with tubular necrosis and reduction in the number of gametes in the lumen of the seminiferous tubules of sodium dichromate-intoxicated rats. Furthermore, exposure to sodium dichromate significantly (P<0.01) increased LPO level and decreased superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities in testis. Interestingly, pretreatment with CCE significantly (P<0.01) restored the serum testosterone level, sperm count, and motility to the levels of the control group. Moreover, CCE administration was capable of reducing the elevated level of LPO and significantly (P<0.01) increased SOD, CAT, and GPx activities in testis. Cactus cladodes supplementation minimized oxidative damage and reversed the impairment of spermatogenesis and testosterone production induced by sodium dichromate in the rat testis.

Excessive dietary calcium in the disruption of structural and functional status of adult male reproductive system in rat with possible mechanism

Calcium is essential for functioning of different systems including male reproduction. However, it has also been reported as chemo-castrative agent. The study has been undertaken to elucidate the effect of excessive dietary calcium on male reproductive system in animals with possible action. Adult male healthy rats fed CaCl(2) at different doses (0.5, 1.0 and 1.5 g%) in diet for 13 and 26 days to investigate reproductive parameters as well as the markers of oxidative stress. Significant alteration was found (P < 0.05) in testicular and accessory sex organs weight, epididymal sperm count, testicular steroidogenic enzyme (Δ(5) 3β-HSD and 17β-HSD) activities, serum testosterone, LH, FSH, LPO, activities of antioxidant enzymes, testicular histoarchitecture along with adrenal Δ(5) 3β-HSD activity with corticosterone level in dose- and time-dependent manner. Overall observations suggest that excessive dietary calcium enhances the generation of free-radicals resulting in structural and functional disruption of male reproduction.