Relationship between abnormal sperm morphology induced by dietary zinc deficiency and lipid composition in testes of growing rats

Effects of Dietary Zinc Deficiency and Supplementation on Prepubertal Rat Testes: Sulfhydryl and Antioxidant Status

The study was designed to investigate the effects of dietary zinc deficiency and supplementation on antioxidant system viz. superoxide-dismutase, glutathione reductase, glutathione peroxidase, glutathione- S-transferase, catalase and sulfhydryls levels (GSH, TSH, NPSH and PBSH) in testes of Wistar rats. Pre-pubertal rats were divided into two groups with 6 sub-groups each viz. zinc control (ZC), pair fed (PF), zinc deficient (ZD), zinc control supplementation (ZCS), pair-fed supplementation (PFS) and zinc deficient supplementation (ZDS). Experiments were set for 2- and 4-weeks followed by 4 weeks of zinc supplementation. The zinc deficient group animals exhibited significant decrease in gonado-somatic index (2- and 4- weeks), sulfhydryls levels, GSH, GPx, GR (2 and 4-weeks) and GST concentration (2-weeks). However, after zinc supplementation significant improvement in gonadosomatic index, SH, GSH, antioxidant enzyme levels (GR, GPx, and GST) in deficient groups has been observed. Zinc deficiency during pre-pubertal period affected growth and caused dysregulation of the glutathione antioxidant system. The significant alterations in the levels of antioxidant enzymes and non-enzymatic antioxidant system (GSH and SH) in zinc deficient groups could be due to alleviated generation of free radicals, causative factor for increased oxidative stress which may lead to infertility as oxidative stress is a common pathology seen during infertility. Altered antioxidant system and sulfhydryls levels in testes due to dietary zinc deficiency reflect the significance of optimum zinc for maintaining homeostatic balance in gonadal physiology. Supplementing zinc for 4 weeks could reduce the redox imbalance which may help in alleviating oxidative stress induced alterations in testes.

Zinc Supplementation Reduces Testicular Cell Apoptosis in Mice and Improves Spermatogenic Dysfunction Caused by Marginal Zinc Deficiency

Zinc (Zn) is an important trace element in the human body and plays an important role in growth, development, and male reproductive functions. Marginal zinc deficiency (MZD) is common in the human population and can cause spermatogenic dysfunction in males. Therefore, the aim of this study was to investigate methods to improve spermatogenic dysfunction caused by MZD and to further explore its mechanism of action. A total of 75 4-week-old male SPF ICR mice were randomly divided into five groups (control, MZD, MZD + ZnY2, MZD + ZnY4, and MZD + ZnY8, 15 mice per group). The dietary Zn content was 30 mg/kg in the control group and 10 mg/kg in the other groups. From low to high, the Zn supplementation doses administered to the three groups were 2, 4, and 8 mg/kg·bw. After 35 days, the zinc content, sperm quality, activity of spermatogenic enzymes, oxidative stress level, and apoptosis level of the testes in mice were determined. The results showed that MZD decreased the level of Zn in the serum, sperm quality, and activity of spermatogenic enzymes in mice. After Zn supplementation, the Zn level in the serum increased, sperm quality was significantly improved, and spermatogenic enzyme activity was restored. In addition, MZD reduced the content of antioxidants (copper-zinc superoxide dismutase (Cu-Zn SOD), metallothionein (MT), and glutathione (GSH) and promoted malondialdehyde (MDA) production. The apoptosis index of the testis also increased significantly in the MZD group. After Zn supplementation, the level of oxidative stress decreased, and the apoptosis index in the testis was reduced. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) showed that the expression of B-cell lymphoma-2 (Bcl-2) mRNA and Bcl-2/BCL2-associated X (Bax) in the control group decreased in testicular cells, and their expression was restored after Zn supplementation. The results of this study indicated that Zn supplementation can reduce the level of oxidative stress and increase the ability of testicular cells to resist apoptosis, thereby improving spermatogenic dysfunction caused by MZD in mice.

Impact of latent toxoplasmosis on the fertility indices of male rats

Infertility is a prevalent condition affecting approximately 70 million people worldwide and male factor contributes to about fifty percent of the issues. Studies on infectious agents as a possible cause of infertility has become prominent in the past decade. Toxoplasma gondii has emerged as a prime candidate as it has been found in the reproductive organs and semen of males of many animal species and humans. The aim of this study is to assess the effect of latent toxoplasmosis on experimental rat fertility. Ninety Toxoplasma infected rat were used as the experimental group besides, thirty control naïve ones. Both groups were observed clinically. Weekly assessment of fertility indices starting from the 7th week post infection till the 12th week were done by recording rat body weight, weight of testes, semen analysis and histo-morphometric analysis of the testes. Toxoplasma infected rats exhibited significant gradual loss of body weight and the absolute weight of the testes. The sperm characteristic parameters including percentage of motile sperm, percentage of viable sperm and sperm concentration in Toxoplasma infected rats showed highly significant decrease throughout the observation period in comparison to the control group with recording highly significant increase in the percentage of abnormal sperm forms. Pathological insults in tests of the infected rat group were denoted. Our findings demonstrated that Toxoplasma gondii is accused for affecting male rat main reproductive parameters and is implicated in the male reproductive disorders.

Regulation of semen quality by fatty acids in diets, extender, and semen

Fatty acids (FAs) are classified into different types according to the degree of hydrocarbon chain saturation, including saturated fatty acids (SFAs), monounsaturated fatty acids (MUFAs), omega-3 polyunsaturated fatty acids (omega-3 PUFAs) and omega-6 polyunsaturated fatty acids (omega-6 PUFAs), which play an important role in maintaining semen quality. This review focuses on the regulation of FAs in semen, diet and extender on semen quality, and expounds its effects on sperm motility, plasma membrane integrity, DNA integrity, hormone content, and antioxidant capacity. It can be concluded that there are species differences in the FAs profile and requirements in sperm, and their ability to regulate semen quality is also affected by the addition methods or dosages. Future research directions should focus on analyzing the FAs profiles of different species or different periods of the same species and exploring suitable addition methods, doses and mechanism of regulating semen quality.

Zinc-Enriched Yeast May Improve Spermatogenesis by Regulating Steroid Production and Antioxidant Levels in Mice

Zinc (Zn) is an essential nutrient for the human body. This nutrient is involved in numerous physiological functions and plays an important role in spermatogenesis. Zn-enriched yeast (ZnY) is considered a Zn supplement with high bioavailability and is widely used as a functional food. However, the effect of ZnY on male reproductive function remains unclear. This study aimed to investigate the beneficial effects of ZnY on the treatment of male spermatogenesis disorders. The spermatogenic dysfunctional mice were established by using cyclophosphamide (CP). CP was administered in saline at a dose of 50 mg/kg bw/day for 5 days by intraperitoneal injection (i.p.). Then, ZnY was orally supplemented at the dose levels of 2, 4, and 8 mg Zn/kg bw/day for 30 days. CP significantly decreased the sperm density and viability, testicular marker enzymes, serum testosterone, follicular stimulating hormone (FSH), and luteinizing hormone (LH). ZnY supplementation significantly improved these sperm parameters and hormone levels. Additionally, ZnY decreased the CP-induced lipid peroxidation and increased the glutathione levels. Moreover, ZnY increased the gene expression of anti-apoptotic proteins and steroid synthetase in mouse testes. The low-dose ZnY supplementation has a better effect on improving spermatogenesis, while the other two groups are less beneficial roles possibly due to excessive Zn intake. The present results suggest that appropriate ZnY can act as an accessory factor to improve steroid production and antioxidant levels in spermatogenic dysfunction mice.

Improvement roles of zinc supplementation in low dose lead induced testicular damage and glycolytic inhibition in mice

Lead (Pb) is a toxic metal that affects the male reproductive system. This study aimed to investigate the effects of zinc (Zn) intake between recommended dietary allowances (RDAs) and tolerable upper intake levels (ULs) in preventing male testis damage induced by low-dose Pb. Forty-five mice were randomly divided into control, Pb, and Pb + Zn groups. They were given distilled water ad libitum with 0, 200 mg/L Pb²⁺, or 15 mg/L Zn²⁺ mixed with 200 mg/L Pb²⁺ for 90 consecutive days. The Zn levels in the blood and testis of the Pb group were significantly lower than those of the control group. The Pb levels in the blood and testis of the Pb + Zn group were significantly lower than those of the Pb group. Additionally, a significant decrease in sperm density and viability, with a significant increase in sperm abnormality rate and DNA fragmentation index, was observed in the Pb group. Zn supplementation significantly improved the above sperm parameters. Moreover, Zn supplementation decreased low-dose Pb-induced lipid peroxidation and increased glutathione, total superoxide dismutase (SOD), and copper/Zn-SOD levels. Furthermore, Zn treatment improved glycolysis products and lactate transporters in Pb-treated mouse testes. Our findings suggest that Zn intake between RDAs and UL can act as a therapeutic agent in protecting against the reproductive impairments associated with Pb exposure.

The effect of iron and/or zinc diet supplementation and termination of this practice on the antioxidant status of the reproductive tissues and sperm viability in rats

AIMS

The aim of this study was to investigate the effect of iron or/and zinc supplementation and termination of this treatment on the antioxidant defence of the male reproductive system and sperm viability in rats.

METHODS

The study consisted of 3 stages: I) 4-week adaptation to the diets (C-control or D-iron deficient); II) 4-week iron and/or zinc supplementation (10-times more than in the C diet of iron: CSFe, DSFe; zinc: CSZn, DSZn; or iron and zinc: CSFeZn, DSFeZn; and III) 2-week post-supplementation period (the same diets as during stage I). Parameters of antioxidant status (total antioxidant capacity and SOD, GPx, and CAT activiy), oxidative damage (lipid and protein peroxidation), and sperm viability were measured.

RESULTS

Simultaneous iron and zinc supplementation compared to iron supplementation (CSFeZn vs CSFe) increased SOD activity in the testes and decreased the level of malondialdehyde in the epididymis after stage II, and increased the percentage of live sperm after stage III. After discontinuation of the iron and zinc supplementation and a return to the control diet, the following was observed a decrease of SOD activity in the testes and GPx activity in the epididymis, and a increase malondialdehyde concentration in prostates. After stage III, in DSFeZn vs DSFe rats, an increase of SOD and CAT activity in the epididymis was found.

CONCLUSION

Zinc supplementation simultaneous with iron may protect the male reproductive system against oxidative damage induced by high doses of iron and may have a beneficial effect on sperm viability. The effect of this supplementation was observed even two weeks after the termination of the intervention.

Zinc Deficiency Promotes Testicular Cell Apoptosis in Mice

Zinc (Zn) plays an important role in spermatogenesis, and carbon tetrachloride (CCl₄) induces testicular oxidative damage and cell death. The objective of the present study was to define the effects of Zn deficiency in combination with CCl₄ treatment on testicular apoptosis and the associated mechanisms. Mice were fed the following diets with three different Zn levels for 6 weeks: normal zinc (ZN) diet (30 mg Zn/kg), zinc-deficient (ZD) diet (2 mg Zn/kg), and adequate zinc (ZA) diet (100 mg Zn/kg). Beginning in the third week, CCl₄ was intraperitoneally injected into half of the mice in each diet group six times over 3 weeks. We found that Zn was distributed in various tissues and organs in normal mice and that the zinc content in the testis of normal mice was high. The Zn-deficient diet reduced the zinc concentration in the testis tissue, and the testicular/body weight ratio significantly decreased. Moreover, the TUNEL results proved that CCl₄ stimulation of mice fed with a zinc-deficient diet caused marked apoptosis of testicular cells. Furthermore, the ROS levels in the testes obviously increased after Zn-deficient mice were stimulated with CCl₄, whereas reduced glutathione (GSH) and glutathione peroxidase (GSH-Px) showed reduced activities. In addition, proteins associated with the apoptosis signaling pathway were detected with ELISA kits. P-p53, cleaved caspase-3, cleaved PRAP, p-Bad, p-JNK, p-ERK, and p-NF-κB p65 increased by varying degrees under zinc deficiency or CCl₄ stimulation. All the data indicated that Zn deficiency significantly enhanced the harm to the testis induced by oxidative stress and damage, while CCl₄ stimulation exacerbated the oxidative damage in testicular cells, leading to apoptosis through the activation of p53, MAPK, and NF-κB.

A pilot study on the effect of early provision of dietary docosahexaenoic acid on testis development, functions, and sperm quality in rats exposed to prenatal ethanol

BACKGROUND

Prenatal ethanol (EtOH) exposure is associated with adverse effect on the male reproductive function. Dietary docosahexaenoic acid (DHA) is known to improve testis function and sperm parameters, thereby male fertility. This study piloted whether dietary DHA influences testis development and function in rats exposed to prenatal EtOH.

METHODS

Pregnant female Sprague-Dawley rats (n = 30) received either EtOH (3 g/kg, twice a day, n = 14) or dextrose (n = 16) throughout pregnancy. Moreover, they were fed either diet supplemented with (Cont + DHA, n = 8, EtOH + DHA, n = 6) or without DHA (1.4% w/w of total fatty acids) (Cont, EtOH, n = 8 each), with pups being continued on their mothers' diet after weaning. Tissues were collected at gestational day (GD) 20, postnatal day (PD) 4, 21, 49 and 90 for analyzing testicular developmental markers and sperm parameters, and plasma for testosterone.

RESULTS

Dietary DHA increased serum testosterone at GD20 (p < .05) and sperm normal morphology at PD90 (p < .0001) compared to the group without DHA supplementation. Dietary DHA also increased the height of germinal epithelium at peripuberty, PD49 (p < .03). The EtOH exposure induced a marked decline in the testicular gene expression of StAR at PD49 (p < .02) than those of non-EtOH treated group.

CONCLUSIONS

These findings indicate that dietary DHA may positively contribute to male fertility by impacting sperm normal morphology likely by increasing fetal testosterone level. Prenatal EtOH exposure did not adversely affect the overall testis developmental markers during development and sperm parameters in adulthood.

Zinc: A Necessary Ion for Mammalian Sperm Fertilization Competency

The importance of zinc for male fertility only emerged recently, being propelled in part by consumer interest in nutritional supplements containing ionic trace minerals. Here, we review the properties, biological roles and cellular mechanisms that are relevant to zinc function in the male reproductive system, survey available peer-reviewed data on nutritional zinc supplementation for fertility improvement in livestock animals and infertility therapy in men, and discuss the recently discovered signaling pathways involving zinc in sperm maturation and fertilization. Emphasis is on the zinc-interacting sperm proteome and its involvement in the regulation of sperm structure and function, from spermatogenesis and epididymal sperm maturation to sperm interactions with the female reproductive tract, capacitation, fertilization, and embryo development. Merits of dietary zinc supplementation and zinc inclusion into semen processing media are considered with livestock artificial insemination (AI) and human assisted reproductive therapy (ART) in mind. Collectively, the currently available data underline the importance of zinc ions for male fertility, which could be harnessed to improve human reproductive health and reproductive efficiency in agriculturally important livestock species. Further research will advance the field of sperm and fertilization biology, provide new research tools, and ultimately optimize semen processing procedures for human infertility therapy and livestock AI.

Effects of zinc deficiency on impaired spermatogenesis and male infertility: the role of oxidative stress, inflammation and apoptosis

Zinc (Zn) is necessary for the normal function of the male reproductive system and spermatozoa. Although influences of zinc deficiency on impaired spermatogenesis and male infertility have been widely considered, the molecular and cellular mechanisms of these abnormalities are not well understood. General abnormalities, including hypogonadism, Leydig cells damage, deficiency of sex hormone production and impaired spermatogenesis, as well as inflammation, antioxidant depletion, sperm death and male infertility can be observed during zinc deficiency. However, it is not obvious which pathways are relevant to the pathogenesis of zinc deficiency. Oxidative stress (OS) induced by reactive oxygen species is likely as the main mechanism of zinc deficiency which is associated with sperm DNA fragmentation, decrease in sperm membrane integrity, apoptosis, depletion of antioxidants, and consequently poor sperm quality and male infertility. Therefore, identification of these pathways will give valuable information regarding the mechanisms of zinc deficiency on the male reproductive system and the potential way for developing a better clinical approach. In this review, we aim to discuss the proposed cellular and molecular mechanisms of zinc deficiency on the male reproductive system, the importance of OS and mechanisms by which zinc deficiency induces OS and depletion of other antioxidants.

The sperm factor: paternal impact beyond genes

The fact that sperm carry more than the paternal DNA has only been discovered just over a decade ago. With this discovery, the idea that the paternal condition may have direct implications for the fitness of the offspring had to be revisited. While this idea is still highly debated, empirical evidence for paternal effects is accumulating. Male condition not only affects male fertility but also offspring early development and performance later in life. Several factors have been identified as possible carriers of non-genetic information, but we still know little about their origin and function and even less about their causation. I consider four possible non-mutually exclusive adaptive and non-adaptive explanations for the existence of paternal effects in an evolutionary context. In addition, I provide a brief overview of the main non-genetic components found in sperm including DNA methylation, chromatin modifications, RNAs and proteins. I discuss their putative functions and present currently available examples for their role in transferring non-genetic information from the father to the offspring. Finally, I identify some of the most important open questions and present possible future research avenues.

Importance of zinc for the human body in the aspect of zinc supplementation

Cynk jest jednym z głównych pierwiastków śladowych organizmu, spełniającym rolę katalityczną, strukturalną i regulacyjną. Jest niezbędny do podziałów komórkowych i różnicowania powstających komórek, uczestniczy w homeostazie, reakcjach odpornościowych, w apoptozie i starzeniu się organizmu. Cynk jest również składnikiem wielu enzymów i białek oraz odgrywa ważną rolę w spermatogenezie i syntezie hormonów steroidowych. Niedostateczna podaż cynku dotyczy ok. 30% ludności świata. Oprócz niedostatecznej podaży z pokarmem, przyczyną niedoboru cynku mogą być niektóre schorzenia oraz nieprawidłowe wchłanianie tego pierwiastka. Schorzenia, wynikające z niedoboru tego pierwiastka, mogą występować zarówno u dzieci, jak i dorosłych. Suplementacja diety preparatami cynku w wielu przypadkach jest niezbędna, jednak samodzielne jego stosowanie, bez stwierdzonego niedoboru i bez konsultacji z lekarzem, może doprowadzić do występowania działań niepożądanych w wyniku jego nadużywania, w tym także niebezpiecznych interakcji z innymi stosowanymi preparatami i żywnością.

Impact of maternal and postnatal zinc dietary status on the prostate of pubescent and adult rats

Zinc is important for cell physiology and alteration of its levels during development can modulate a series of biological events. The aim of this study was to investigate whether dietary zinc deficiency or supplementation during morphogenesis and early postnatal development could interfere in prostate maturation. Pregnant rats were exposed to a standard diet (NZ:35 mg Zn/kg chow), low-zinc diet (LZ:3 mg of Zn/kg chow) and zinc-supplemented diet (HZ:180 mg/Kg chow) from gestational day 10 (GD10) through postnatal day 21 (PND21). After weaning, male offspring were divided into three groups that were submitted to the same food conditions as their mothers until PND53. The animals were euthanized at PND53 and PND115. The ventral prostate was removed, weighed and its fragments were subjected to histological, western blot and zymography analysis. PND53: body and prostate weight were lower in LZ compared to NZ; the epithelial compartment was reduced while the stromal compartment was increased in LZ compared to NZ; there was an increase in the amount of collagen and reduction in AR and SIRT1 expression in LZ compared to NZ. PND115: body weight was lower in LZ compared to NZ and prostate weight was similar among the groups; peripheral physiological hyperplasia was observed, as well as an increased epithelial proliferation index and reduced PAR4 expression in LZ and HZ compared to NZ. Zinc deficiency during prostate morphogenesis and differentiation is potentially harmful to its morphology, however, by restoring the standard dietary environment, the gland responds to the new microenvironment independent of the previous dietary condition.

Molecular basis for the effects of zinc deficiency on spermatogenesis: An experimental study in the Sprague-dawley rat model

Introduction:

The objective of this study is to investigate the molecular mechanisms underlying the effects of zinc deficiency on spermatogenesis in the Sprague-Dawley (SD) rat.

Materials and Methods:

Three groups of eight adult male SD rats were maintained for 4 weeks on a normal diet as control, zinc deficient diet and zinc deficient diet with zinc supplementation of 28 mg zinc/kg body weight respectively. Using standard techniques, the following parameters were compared between the three groups of experimental animals at the end of 4 weeks: (a) Serum zinc, magnesium (Mg), copper (Cu), selenium (Se) and cadmium (Cd), (b) serum sex hormones, malondialdehyde (MDA), superoxide dismutase (SOD) and glutathione peroxidase (GPX), (c) interleukin-4 (IL-4), tumor necrosis factor-alpha (TNF-α), Bcl-2, Bax and caspase-3 expression in the testes, (d) assessment of apoptosis of testicular cells using electron microscopy and (e) testicular volume and histology using the orchidometer and Johnsen score, respectively.

Results:

The zinc deficient group showed a reduction of testicular volume, serum concentrations of Zn, Cu, Se, Mg, SOD, GPX, IL-4, Bcl-2 and testosterone (P < 0.05), as well as increased levels of serum Cd, MDA and tissue TNF-α, Bax, caspase-3 and apoptosis of the germ cells (P < 0.05) compared with control and zinc supplementation groups.

Conclusion:

Zinc deficiency is associated with impaired spermatogenesis because of reduced testosterone production, increased oxidative stress and apoptosis. These findings suggest that zinc has a role in male reproduction.

Condition-dependent expression of pre- and postcopulatory sexual traits in guppies

Female choice can impose persistent directional selection on male sexually selected traits, yet such traits often exhibit high levels of phenotypic variation. One explanation for this paradox is that if sexually selected traits are costly, only the fittest males are able to acquire and allocate the resources required for their expression. Furthermore, because male condition is dependent on resource allocation, condition dependence in sexual traits is expected to underlie trade-offs between reproduction and other life-history functions. In this study we test these ideas by experimentally manipulating diet quality (carotenoid levels) and quantity in the guppy (Poecilia reticulata), a livebearing freshwater fish that is an important model for understanding relationships between pre- and post-copulatory sexually selected traits. Specifically, we test for condition dependence in the expression of pre- and postcopulatory sexual traits (behavior, ornamentation, sperm traits) and determine whether diet manipulation mediates relationships among these traits. Consistent with prior work we found a significant effect of diet quantity on the expression of both pre- and postcopulatory male traits; diet-restricted males performed fewer sexual behaviors and exhibited significant reductions in color ornamentation, sperm quality, sperm number, and sperm length than those fed ad libitum. However, contrary to our expectations, we found no significant effect of carotenoid manipulation on the expression of any of these traits, and no evidence for a trade-off in resource allocation between pre- and postcopulatory episodes of sexual selection. Our results further underscore the sensitivity of behavioral, ornamental, and ejaculate traits to dietary stress, and highlight the important role of condition dependence in maintaining the high variability in male sexual traits.

Nutritional deficiencies and phospholipid metabolism

Phospholipids are important components of the cell membranes of all living species. They contribute to the physicochemical properties of the membrane and thus influence the conformation and function of membrane-bound proteins, such as receptors, ion channels, and transporters and also influence cell function by serving as precursors for prostaglandins and other signaling molecules and modulating gene expression through the transcription activation. The components of the diet are determinant for cell functionality. In this review, the effects of macro and micronutrients deficiency on the quality, quantity and metabolism of different phospholipids and their distribution in cells of different organs is presented. Alterations in the amount of both saturated and polyunsaturated fatty acids, vitamins A, E and folate, and other micronutrients, such as zinc and magnesium, are discussed. In all cases we observe alterations in the pattern of phospholipids, the more affected ones being phosphatidylcholine, phosphatidylethanolamine and sphingomyelin. The deficiency of certain nutrients, such as essential fatty acids, fat-soluble vitamins and some metals may contribute to a variety of diseases that can be irreversible even after replacement with normal amount of the nutrients. Usually, the sequelae are more important when the deficiency is present at an early age.

Moderate zinc deficiency reduces testicular Zip6 and Zip10 abundance and impairs spermatogenesis in mice

Male infertility accounts for ~40% of cases of failure to conceive. Testes have a strict zinc (Zn) requirement and severe Zn deficiency compromises spermatogenesis, sperm viability, and motility, compromising fertility in men. Despite the high prevalence of marginal Zn deficiency in humans, less emphasis has been placed on understanding the consequences on male reproduction. Swiss Webster mice were used to visualize Zip protein expression during spermatogenesis using immunohistochemistry. Data suggest Zip5 imports Zn into Sertoli cells and spermatocytes, augmented by Zip10 (primary spermatocytes) and Zip8 (secondary spermatocytes). Zip6, 8, and 10 expression was retained in round spermatids, although Zip8 and Zip10 expression disappears during spermatid maturation. Zip1 and Zip6 expression was detected in mature, elongated spermatids. Zip14 was detected in undifferentiated spermatogonia and Leydig cells. Mice fed diets (n = 10/group) reduced in Zn concentration [marginal-Zn diet (MZD), 10 mg Zn/kg; low-Zn diet (ZD), 7 mg Zn/kg] for 30 d had >35% lower liver Zn concentrations than mice fed the control diet (C; 30 mg Zn/kg) (P < 0.05). Plasma Zn and testosterone concentrations and the testes Zn concentration and weight were not significantly lower than in controls. Plasma Zn was greater in the ZD group than in the C and MZD groups. Mice fed ZD had a reduced number of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells (~50%; P < 0.05), compromised seminiferous tubule structure, and reduced Zip10 and Zip6 abundance (>50%; P < 0.5) compared with mice fed C. Our data provide compelling evidence that reduced Zn intake may be associated with infertility in men, perhaps independent of decreased levels of circulating Zn or testosterone, which warrants further investigation in human populations.

Effect of dietary zinc deficiency on testes of Wistar rats: Morphometric and cell quantification studies

The present study investigates the effect of dietary zinc deficiency on testes of Wistar rats. Pre-pubertal rats (40-50g) were divided into three groups of 10 each viz. zinc control (ZC) and pair fed (PF) [100ppm zinc diet] and zinc deficient (ZD) [1ppm zinc diet]. Experiments were set for 2- and 4-weeks. Pre-pubertal rats fed zinc deficient diet for 2- and 4-weeks exhibited significant (P<0.05) decrease in diet consumption when compared with their respective control groups. Parallel to the reduced diet consumption, a significant (P<0.05) decrease in body and testicular weight of ZD animals was also observed. These observations indicate that the zinc deficiency reduces diet consumption and growth of the animals. Histological studies revealed degeneration in testes of ZD rats as evident by decreased seminiferous tubular diameter and Leydig cell nuclear diameter. Decreased Leydig cell nuclear diameter is responsible for disruption of the biochemical function of Leydig cell. Testicular atrophy (viz. wavy tunica propria, karyolysis, pyknosis, karyorhexis, apoptotic bodies, multinucleated giant cells, few sperms in the lumen, atrophied Leydig cells and accumulation of oedematous fluid in the interstitium) accompanied by significant loss of germ/somatic cells (viz. Type A and Type B spermatogonia, leptotene, zygotene, pachytene spermatocytes, Golgi, cap and acrosome spermatids, Sertoli and Leydig cell) was evident in ZD groups. The degeneration was severe after 4-weeks of zinc deficiency. These observations provide evidence that the functional and morphological changes in testes are probably due to zinc deficiency. Further, the increased oedematous fluid in the interstitial region is due to the cellular death. Impairment of spermatogenesis can be attributed to the direct action of zinc on testes or indirectly from Leydig cell degeneration indicating that zinc is a critical component for maintenance of both mitotic and meiotic stages of spermatogenesis.

Seminal Plasma Zinc Level May be Associated with the Effect of Cigarette Smoking on Sperm Parameters

The aim of this study was to investigate the effect of cigarette smoking on seminal plasma zinc levels and sperm parameters, and to examine the role of seminal plasma zinc. Semen samples from 79 non-smokers and 68 smokers were obtained. There was a significant decrease in seminal plasma zinc in smokers and a clear correlation between seminal plasma zinc levels and the extent of smoking. Sperm parameters (concentration, motility and morphology) among smokers were significantly lower in comparison to non-smokers. These parameters were also significantly decreased among smokers with abnormal zinc levels, while there was no significant difference between non-smokers with normal zinc and non-smokers with abnormal zinc levels. As previous studies have shown that seminal plasma zinc is associated with a decrease of anti-oxidant defences, seminal plasma zinc could be a contributor to the effects of cigarette smoking on sperm parameters. In conclusion, cigarette smoking can affect sperm parameters and this study may help towards providing a mechanistic explanation.