Nicotinic infertility: assessing DNA and plasma membrane integrity of human spermatozoa

Resveratrol reverses male reproductive damage in rats exposed to nicotine during the intrauterine phase and breastfeeding

BACKGROUND

Nicotine leads to reproductive changes culminating in male infertility and subfertility. Resveratrol, a polyphenol, is a biological modulator. Sirtuin 1 (SIRT1) protein can positively act on male reproduction, and its expression can be affected by nicotine and modulated by resveratrol.

OBJECTIVES

The capability of resveratrol to reverse the reproductive damage in adult male offspring, which was nicotine-exposed during the intrauterine phase and breastfeeding, was investigated.

MATERIALS AND METHODS

Four groups were established with male offspring born from nicotine-exposed and non-exposed rat dams during pregnancy and lactation. Forty-eight male Wistar rats were distributed into four groups: sham control (SC), resveratrol (R), nicotine (N), and nicotine + resveratrol (NR). Rat dams of the N and NR offspring were exposed to nicotine (2 mg/kg/day) during pregnancy and lactation using a subcutaneously implanted minipump. The offspring of the R and NR groups received resveratrol (300 mg/kg of body weight, gavage) for 63 days from puberty. At 114 days of age, the male rats were euthanized.

RESULTS

Nicotine did not alter the body weight, biometry of reproductive organs, or quantitative sperm parameters of adult offspring but caused an evident worsening of all sperm qualitative parameters studied. Daily treatment with resveratrol from puberty up to adulthood improved all qualitative sperm parameters significantly, leading some of them close to the control values. Resveratrol also improved the morphological integrity and expression of SIRT1 in the seminiferous epithelium of nicotine-exposed offspring.

CONCLUSION AND DISCUSSION

Resveratrol reversed the male reproductive damage caused by nicotine. Nicotine crosses the blood-placental membrane and is present in the breast milk of mothers who smoke. Resveratrol restored the altered reproductive parameters in the male adult offspring that were nicotine-exposed during intrauterine life and breastfeeding. The epigenetic modulating action of resveratrol can be involved in this nicotine damage reversion. Resveratrol may be a promising candidate to be investigated regarding the adjuvant strategies in the treatment of male infertility.

A systems omics-based approach to decode substance use disorders and neuroadaptations

Substance use disorders (SUDs) are a group of neuropsychiatric conditions manifesting due to excessive dependence on potential drugs of abuse such as psychostimulants, opioids including prescription opioids, alcohol, inhalants, etc. Experimental studies have generated enormous data in the area of SUDs, but outcomes from such data have remained largely fragmented. In this review, we attempt to coalesce these data points providing an important first step towards our understanding of the etiology of SUDs. We propose and describe a 'core addictome' pathway that behaves central to all SUDs. Besides, we also have made some notable observations paving way for several hypotheses; MECP2 behaves as a master switch during substance use; five distinct gene clusters were identified based on respective substance addiction; a central cluster of genes serves as a hub of the addiction pathway connecting all other substance addiction clusters. In addition to describing these findings, we have emphasized the importance of some candidate genes that are of substantial interest for further investigation and serve as high-value targets for translational efforts.

Genotoxic effect induced by dried nicotiana tabacum leaves from tobacco barns (kiln-houses) in chinese hamster lung fibroblast cells (V79)

Nicotiana tabacum is the most cultivated tobacco species in the state of Rio Grande do Sul, Brazil. Workers who handle the plant are exposed to the leaf components during the harvesting process and when separating and classifying the dried leaves. In addition to nicotine, after the drying process, other components may be found including tobacco-specific nitrosamines, polycyclic aromatic hydrocarbons, as well as pesticides residues. The objective of this study was to examine the genotoxicity attributed to the aqueous extract of dried tobacco leaves obtained from tobacco barns using Chinese hamster lung fibroblast cells (V79) as a model system by employing alkaline comet assay, micronucleus (MN) and Ames test. MTT assay was used to assess cytotoxicity and establish concentrations for this study. Data demonstrated cell viability > 85% for concentrations of 0.625-5 mg/ml while the comet assay indicated a significant increase in DNA damage at all concentrations tested. A significant elevation of MN and nuclear buds (NBUD) was found for 5 mg/ml compared to control and other dry tobacco leaves concentrations (0.625-2.5 mg/ml). Mutagenicity was not found using the Salmonella/Microsome test (TA98, TA100, and TA102 strains) with and without metabolic activation. The concentration of inorganic elements was determined employing the PIXE technique, and 13 inorganic elements were detected. Using CG/MS nicotine amounts present were 1.56 mg/g dry tobacco leaf powder. Due to the observed genotoxicity in V79 cells, more investigations are needed to protect the health of tobacco workers exposed daily to this complex mixture of toxic substances present in dry tobacco leaves.

Application of the comet assay for the evaluation of DNA damage in mature sperm

DNA integrity is considered an important parameter of semen quality and is of significant value as a predictor of male fertility. Currently, there are several methods that can assess sperm DNA integrity. One such assay is the comet assay, or single-cell gel electrophoresis, which is a simple, sensitive, reliable, quick and low-cost technique that is used for measuring DNA strand breaks and repair at the level of individual cells. Although the comet assay is usually performed with somatic cells from different organs, the assay has the ability to detect genotoxicity in germ cells at different stages of spermatogenesis. Since the ability of sperm to remove DNA damage differs between the stages, interpretation of the results is dependent on the cells used. In this paper we give an overview on the use and applications of the comet assay on mature sperm and its ability to detect sperm DNA damage in both animals and humans. Overall, it can be concluded that the presence in sperm of significantly damaged DNA, assessed by the comet assay, is related to male infertility and seems to reduce live births. Although there is some evidence that sperm DNA damage also has a long-term impact on offspring's health, this aspect of DNA damage in sperm is understudied and deserves further attention. In summary, the comet assay can be applied as a useful tool to study effects of genotoxic exposures on sperm DNA integrity in animals and humans.

Oxidative stress and male infertility

BACKGROUND

Between 30% and 80% of patients with male infertility produce excessive reactive oxygen species (ROS) in their ejaculate even though the cause of male infertility is unexplained in approximately half of cases. The strong connection between oxidative stress (OS) and male infertility has led recent investigators to propose the term "Male Oxidative Stress Infertility (MOSI)" to describe OS-associated male infertility.

METHODS

We searched the PubMed database for original and review articles to survey the effects of OS on male infertility, and then verified the effects and treatments.

MAIN FINDINGS

Seminal plasma contains many antioxidants that protect sperm from ROS, because low amounts of ROS are required in the physiological fertilization process. The production of excessive ROS causes OS which can lower fertility through lipid peroxidation, sperm DNA damage, and apoptosis. Several assays are available for evaluating OS, including the MiOXSYS® analyzer to measure oxidation-reduction potential. Several measures should be considered for minimizing OS and improving clinical outcomes.

CONCLUSION

Accurately diagnosing patients with MOSI and identifying highly sensitive biomarkers through proteomics technology is vital for better clinical outcomes.

Impact of nicotine, alcohol, and cocaine exposure on germline integrity and epigenome

Converging evidence suggests that parental exposure to drugs of abuse can affect offspring phenotypes. The impacts of drug abuse on germ cell quality may mediate multigenerational and transgenerational inheritance, although biological pathways underlying this mode of inheritance are not yet characterized. Germline epigenetic marks are modified by drug exposure and have emerged as promising mechanistic candidates in recent work. Drug exposure also impacts overall germline integrity and reproductive functioning, although the role of these consequences in multi/transgenerational inheritance is unclear. This review synthesizes literature on effects of exposure to alcohol, cocaine, and nicotine on the germline with a focus on epigenetic modifications following drug exposure and broader impacts on germline integrity and reproductive functioning. We discuss potential interactions between reproductive functioning, germline integrity, and germline epigenome/transcriptome in pathways underlying multi/transgenerational inheritance. We find that existing data may support independent or interactive contributions of these germline impacts on offspring phenotypes in a manner that may mediate multi/transgenerational inheritance.

Assessment of the toxicity effects of nicotine on sperm and IVF and the potential protective role of silymarin—an experimental study in mice

Background

Male infertility is usually caused via the inability to produce adequate quantities of healthy and active sperms. Nicotine (NIC) is an alkaloid organic compound, predominantly found in the leaves of the tobacco plant. The major part of the nicotine is not ionized, so it can easily pass through cell membranes. Meanwhile, most of the disorders are caused by oxidative stress due to oxygen free radicals and other reactive species. Antioxidant supplements and antioxidant-rich foods can reduce induced oxidative stress without becoming destabilized themselves. This study aimed to examine spermato-protective potential of silymarin (SIL), on sperm and in vitro fertility (IVF) rate in nicotine-treated mice.

Results

Our results show a significant increase in the number of abnormal sperm morphology after nicotine exposure, when compared to control groups (p < 0.05). On the other hand, SIL had a significant effect on the sperm count at each of the treated doses. Further, in the mice that received nicotine plus silymarin, the viable sperm percentage and the progressive sperm motility were significant (p < 0.05). Also, a significant reduction in the number of two-cell embryos and blastocyst-derived embryo was seen with increment in the number of dead embryos in mice receiving nicotine alone (p < 0.05).

Conclusions

In conclusion, SIL could support prevention of the adverse reproductive effects of nicotine. Moreover, SIL200 mg/kg may be therefore considered as a spermato-protective agent in dietary and herbal supplements.

The protective effect of vitamin C on phenylhydrazine-induced hemolytic anemia on sperm quality and in-vitro embryo development in mice

Background

Phenylhydrazine (PHZ) induced anemia and was shown to have harmful effects on the male reproductive system.

Objective

To investigate the protective effect of vitamin C (Vit C) on sperm parameters quality, in vitro fertilization potential and embryonic development in a mouse model of hemolytic anemia induced by PHZ.

Materials and Methods

Thirty-two NMRI adult male mice (n = 8/each) were randomly classified into four groups. Group I (control) received normal saline, Group II (PHZ) received 8 mg/100 gr body weight PHZ as initial dose, continued by 6 mg/100 gr intraperitoneally every 48 hr, Group III (Vit C) received Vit C (10 mg/kg, daily, intraperitoneally), and group IV (PHZ + Vit C) received PHZ and Vit C. After 35 days, sperm quality parameters, the percentage of sperm with DNA damage and in vitro fertilization outcomes up to blastocyst stage were evaluated.

Results

A significant (p < 0.001) reduction in all of the sperm parameters (count, motility, viability and normal morphology) were observed in group II (PHZ) compared with group I (control). In group IV (PHZ ± Vit C), these parameters and sperm DNA damage (p < 0.001) improved significantly when compared with PHZ-treated mice. Furthermore, PHZ caused a significant (p < 0.001) decrease in the fertilization rate and the percentage of pre-implantation embryos' (two cell embryo and blastocyst) formation in comparison to group I (control), and Vit C supplementation in mice of group IV improved significantly the fertilization rate (p = 0.002), but it could not improve the percentage of two cell embryos and blastocyst production.

Conclusion

The data from this study indicated that Vit C decreased the adverse effects of PHZ on the quality of sperm parameters and in vitro fertilization rate, but it is insufficient to restore the in-vitro embryonic development and fertility potential.

Royal jelly protects male mice against nicotine-induced reproductive failure

This study evaluated the possible protective effect of royal jelly (RJ) on sperm parameters and sperm malondialdehyde (MDA) concentration and in vitro fertilizing potential in nicotine (NIC) exposed male mice. Thrtiy-six male BALB/c mice were randomly divided into six groups (n = 6). Group 1 received normal saline, group 2 received 100 mg kg-1 per day RJ, groups 3 and 4 received NIC at doses of 0.50 and 1.00 mg kg-1 per day, respectively and groups 5 and 6 received NIC at doses of 0.50 and 1.00 mg kg-1 per day, respectively plus RJ. Caudal epididymal sperm characteristics, lipid peroxidation and in vitro fertilizing capacity and embryo development were evaluated after 35 days. The NIC treatment caused a significant decrease in sperm motility and viability and fertilization rate along with poor blastocyst formation and increased sperm DNA damage and MDA levels. Moreover, the incidences of chromatin abnormality in spermatozoa were significantly higher in NIC-exposed mice than those of control. Nevertheless, RJ treatment improved sperm parameters and in vitro fertilization outcome as well as sperm lipid peroxidation level. Data from the current study suggest that RJ has a potential repro-protective action against NIC-induced sperm abnormalities and embryotoxicity in mice.

Paternal lifestyle factors in relation to semen quality and in vitro reproductive outcomes

This prospective-cohort study aimed at investigating the influence of paternal lifestyle factors on semen parameters and intracytoplasmic sperm injection (ICSI) outcomes. The influence of paternal lifestyle factors on seminal quality and ICSI outcomes was investigated in male patients undergoing conventional semen analysis. Cigarette smoking negatively influenced semen volume (B: -0.417, slope: 1.570, p = 0.047), sperm count/ml (B: -7.363, slope: 52.298, p = 0.014), total sperm count (B: -4.43, slope: 178.165, p = 0.023), total motile sperm count (B: -1.38, slope: 100.276, p = 0.045) and SDF (B: 0.014, slope: 9.767, p = 0.033). Alcohol consumption negatively influenced sperm count/ml (B: -12.527, slope: 42.255, p = 0.040) and sperm DNA fragmentation (B: 5.833, slope: 9.680, p = 0.002). There were no significant influences of other paternal lifestyle factors. Cigarette smoking negatively influenced the fertilisation rate (B: -1.349, slope: 21.950, p = 0.039) and the blastocyst formation rate (B: -14.244, slope: 28.851, p = 0.025). Alcohol consumption negatively influenced fertilisation rate (B: -3.617, slope: 20.138, p = 0.041) and blastocyst formation rate (B: -34.801, slope: 30.044, p = 0.042). Cigarette smoking and alcohol consumption appear to reduce semen quality, fertilisation and blastocyst formation rates; thus, it would be wise to recommend that male partners reconsider their lifestyle during in vitro reproduction treatment.

Fatherhood and Sperm DNA Damage in Testicular Cancer Patients

Testicular cancer (TC) is one of the most treatable of all malignancies and the management of the quality of life of these patients is increasingly important, especially with regard to their sexuality and fertility. Survivors must overcome anxiety and fears about reduced fertility and possible pregnancy-related risks as well as health effects in offspring. There is thus a growing awareness of the need for reproductive counseling of cancer survivors. Studies found a high level of sperm DNA damage in TC patients in comparison with healthy, fertile controls, but no significant difference between these patients and infertile patients. Sperm DNA alterations due to cancer treatment persist from 2 to 5 years after the end of the treatment and may be influenced by both the type of therapy and the stage of the disease. Population studies reported a slightly reduced overall fertility of TC survivors and a more frequent use of ART than the general population, with a success rate of around 50%. Paternity after a diagnosis of cancer is an important issue and reproductive potential is becoming a major quality of life factor. Sperm chromatin instability associated with genome instability is the most important reproductive side effect related to the malignancy or its treatment. Studies investigating the magnitude of this damage could have a considerable translational importance in the management of cancer patients, as they could identify the time needed for the germ cell line to repair nuclear damage and thus produce gametes with a reduced risk for the offspring.

Relationship of DNA integrity to HRG C633T SNP and ART outcome in infertile couples

The status of sperm DNA fragmentation, protamine deficiency, free thiols and disulphide bonds in colloid-selected samples and its relationship to ART outcome or HRG C633T SNP is not known. The objective of this study was to determine these relationships in spermatozoa from men with male factor or unknown factor infertility (n = 118) undergoing in vitro fertilisation (IVF) or intracytoplasmic sperm injection (ICSI). Sperm DNA integrity was analysed by flow cytometry using three fluorescent probes (acridine orange, monobromobimane and chromomycin A3). Principal component analysis (PCA) was used to identify the parameters that most influenced fertility. The relationships of sperm DNA integrity with seminal parameters, HRG C633T SNP and ART outcome were established using ANOVA and t-test. Sperm concentration and yield after preparation accounted for 27% of the total variance; sperm DNA integrity (%DFI and disulphide bonds) accounted for 16% of the variance in men from infertile couples. Sperm %DFI was significantly higher (P < 0.05) in older men than in younger men. A significant difference (P < 0.01) was observed in %DFI between smokers and non-smokers. Sperm %DFI was significantly higher (P < 0.01) in male factor infertility compared to either female factor or unknown factor infertility while free thiols were significantly higher (P < 0.01) in unknown infertility factor. No significant difference was observed between IVF success/failure in any of the seminal parameters studied. There was a tendency for protamine deficiency to be higher and disulphide concentration to be lower in men with HRG 633T. Such assessments may provide additional useful information about the prognosis for ART outcome, although more research is needed before clinical guidelines can be provided.

Simultaneous determination of nicotine, cotinine, and nicotine N-oxide in human plasma, semen, and sperm by LC-Orbitrap MS

Nicotine (Nic) distribution in human fluids and tissues has a deleterious effect on human health. In addition to its poisoning profile, Nic may contribute to the particular impact of smoking on human reproduction. Although present in seminal fluid, still nobody knows whether nicotine is available in sperm or not. Herein, we developed and validated a new bioanalytical method, for simultaneous determination of Nic, cotinine (Cot), and nicotine N'-oxide (Nox) in human plasma, semen, and sperm by LC-ESI-orbitrap-MS. Blood and semen samples were collected from 12 healthy smoking volunteers in this study. Sperm bodies were then separated quantitatively from 1 mL of semen samples by centrifugation. The developed method was fully validated for plasma following European and American guidelines for bioanalytical method validation, and partial validation was applied to semen analysis. Plasma, semen, and sperm samples were treated by trichloroacetic acid solution for protein direct precipitation in single extraction step. The established calibration range for Nic and Nox in plasma and semen was linear between 5 and 250 ng/mL, and for Cot between 10 and 500 ng/mL. Nic and Cot were detected in human sperm at concentrations as high as in plasma. In addition, Nox was present in semen and sperm but not in plasma. Graphical abstract Nicotine correlation between plasma and semen a; Nicotine correlation between semen and sperm c; Cotinine correlation between plasma and semen b; Cotinine correlation between semen and sperm d.

Sperm DNA damage-the effect of stress and everyday life factors

The clinical significance of sperm DNA damage lies in its association with natural conception rates and also might have a serious consequence on developmental outcome of the newborn. The aim of the present study is to determine whether stress and everyday life factors are associated with sperm DNA damage in adult men. The study population consisted of 286 men who attended the infertility clinic for diagnostic purposes and who had normal semen concentration of 20-300 m ml(-1) or with slight oligozoospermia (semen concentration of 15-20 m ml(-1)) (WHO, 1999). Participants were interviewed and provided a semen sample. The sperm chromatin structure assay was assessed using flow cytometry. In the present study, we found evidence for a relationship between sperm DNA damage parameters and everyday life factors. High and medium level of occupational stress and age increase DNA fragmentation index (P=0.03, P=0.004 and P=0.03, respectively). Other lifestyle factors that were positively associated with percentage of immature sperms (high DNA stainability index) included: obesity and cell phone use for more than 10 years (P=0.02 and P=0.04, respectively). Our findings indicate that stress and lifestyle factor may affect sperm DNA damage. Data from the present study showed a significant effect of age, obesity, mobile phone radiation and occupational stress on sperm DNA damage. As DNA fragmentation represents an extremely important parameter indicative of infertility and potential outcome of assisted reproduction treatment, and most of the lifestyle factors are easily modifiable, the information about factors that may affect DNA damage are important.

Risk factors for erectile dysfunction in patients with cardiovascular disease

Objective

To examine the relationship between risk factors for cardiac disease and erectile dysfunction (ED) in men from Xi’an, China.

Methods

Participants were patients with cardiovascular disease who visited the Cardiovascular Medicine Department of Xi’an Jiaotong University First Affiliated Hospital between September 2011 and March 2012. Two hundred and fifty patients were issued with questionnaires and underwent a physical examination and blood test.Risk factors for ED were identified using univariate and multivariate analyses.

Results

In total, 222 participants returned valid questionnaires (89% response rate), underwent a physical examination and blood test, and were included in the study. The most common cardiovascular diseases were hypertension (n = 142; 64%), coronary heart disease (n = 90; 41%) and angina pectoris (n = 78; 35%). Most patients (n = 144; 65%) had two or more cardiovascular diseases. Age, smoking, body mass index, total cholesterol level, hypertension and the ratio of total cholesterol to high-density lipoprotein cholesterol were significantly associated with ED. Domestic location, level of education, participation in physical activity, diabetes and drinking alcohol were not associated with ED.

Conclusions

Common risk factors for cardiovascular disease are associated with ED in patients with cardiovascular disease. This study furthers understanding of the risk factors for ED in Chinese patients with cardiovascular disease and paves the way for further research into the prevention of ED.

Nicotine: Carcinogenicity and Effects on Response to Cancer Treatment - A Review

Tobacco use is considered the single most important man-made cause of cancer that can be avoided. The evidence that nicotine is involved in cancer development is reviewed and discussed in this paper. Both tobacco smoke and tobacco products for oral use contain a number of carcinogenic substances, such as polycyclic hydrocarbons and tobacco-specific N-nitrosamines (TSNA), which undoubtedly contribute to tobacco related cancer. Recent studies have shown that nicotine can affect several important steps in the development of cancer, and suggest that it may cause aggravation and recurrence of the disease. TSNA may be formed from nicotine in the body. The role of nicotine as the major addictive component of tobacco products may have distracted our attention from toxicological effects on cell growth, angiogenesis, and tumor malignancy. Effects on cancer disease are important aspects in the evaluation of possible long-term effects from sources of nicotine, such as e-cigarettes and products for nicotine replacement therapy, which both have a potential for life-long use.

Evaluation of Effect of Cigarette Smoking on Vital Seminal Parameters which Influence Fertility

INTRODUCTION

Cigarette smoke contains many compounds which are proven carcinogens having detrimental effect on various organs. The free radicals and other carcinogens have a harmful effect on testicular function which may affect male fertility directly.

AIM

Although many studies have been conducted to establish the relationship between cigarette smoking and male infertility, their conclusions have been highly controversial. This evoked our interest to investigate this intriguing research question.

MATERIALS AND METHODS

One hundred and twenty three subjects were included in the present study amongst which 20 were non smokers, 42 with smoking history of less than 5 years and 61 with more than 5 years.

RESULTS

Cigarette smoking was found to have a detrimental effect on both the sperm motility and the sperm count, but the effect on sperm motility was greater than that of sperm count.

CONCLUSION

This study throws light on the detrimental effect of cigarette smoking on male fertility as reflected by decreased vital parameters of semen like sperm motility and sperm count.

Nicotine causes genotoxic damage but is not metabolized during long-term exposure of human nasal miniorgan cultures

Human nasal miniorgan cultures (MOC) are a useful tool in ecogenotoxicology. Repetitive exposure to nicotine showed reversible DNA damage, and stable CYP2A6 expression was demonstrated in nasal MOC in previous investigations. The aim of the present study was to evaluate the genotoxic effect of nicotine in nasal MOC after chronic nicotine exposure, and to monitor possible metabolism capacities. MOC were dissected from human nasal mucosa and cultured under standard cell culture conditions. MOC were exposed to nicotine for 3 weeks at concentrations of 1 μM and 1 mM. The concentrations were chosen based on nicotine plasma levels in heavy smokers, and possible concentrations used in topical application of nicotine nasal spray. DNA damage was assessed by the comet assay at days 7, 14 and 21. Concentrations of nicotine and cotinine were analyzed in cell culture medium by gas chromatography/mass spectrometry to determine a possible metabolism of nicotine by MOC. Distinct DNA damage in MOC could be demonstrated after 1 week of exposure to 1 μM and 1 mM nicotine. This effect decreased after 2 and 3 weeks with no statistically relevant DNA migration. No nicotine metabolism could be detected by changes in nicotine and cotinine concentrations in the supernatants. This is the first time genotoxic effects have been evaluated in nasal MOC after chronic nicotine exposure for up to 3 weeks. Genotoxic effects were present after 1 week of culture with a decrease over time. Down-regulation of nicotinic acetylcholine receptors, which are expressed in nasal mucosa, may be a possible explanation. The lack of nicotine metabolism in this model could be explained by the functional loss of CYP2A6 during chronic nicotine exposure. Further investigations are necessary to provide a more detailed description of the underlying mechanisms involved in DNA damage by nicotine.

Effects of nicotine on the testicular toxicity of streptozotocin-induced diabetic rat

The aim of the present study is to investigate whether nicotine augmented the testicular toxicity and angiotensin converting enzyme inhibitor, enalapril, can ameliorate the effects in diabetic rat. Male Sprague Dawley rats were randomized into five groups: control, nicotine, diabetic, Diab + Nico, and Diab + Nico + Enal. Animals were made diabetic by single injection of streptozotocin (55 mg/kg/intraperitoneally). Nicotine dissolved in drinking water at a concentration of 100 µg/ml was given ad libitum and enalapril was given orally at a dose of 10 mg/kg/day for four consecutive weeks. After 4 weeks of treatment, animals were killed and biochemical parameters glucose, glycosylated hemoglobin, cotinine, and the testosterone levels were measured. Testicular toxicity was evaluated using sperm count, sperm comet assay, histology, and immunohistochemical staining of 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxo-dG) and the proinflammatory markers (nuclear factor kappa B (NF-κB), cyclooxygenase (COX-2), and tissue necrotic factor alpha (TNF-α)) evaluated by western blotting. Results showed that nicotine did not alter the blood glucose and glycosylated hemoglobin level, significantly decreased the sperm count and increased the sperm DNA damage. These changes were accompanied by significant increases in the 8-oxo-dG, NF-κB, COX-2, and TNF-α expression. Furthermore, the intervention of enalapril in nicotine-treated diabetic rat attenuated the testicular damage and restored sperm count, sperm DNA damage, as well as reduced the expression of NF-κB, COX-2, and TNF-α. These findings clearly suggest that nicotine not only augmented the testicular toxicity in the diabetic rat but also increases the risk of germ cell toxicity effects that were attenuated by enalapril treatment.

Nicotine derived genotoxic effects in human primary parotid gland cells as assessed in vitro by comet assay, cytokinesis-block micronucleus test and chromosome aberrations test

Genotoxic effects of nicotine were described in different human cells including salivary gland cells. Based on the high nicotine concentration in saliva of smokers or patients using therapeutic nicotine patches, the current study was performed to evaluate the genotoxic potential of nicotine in human salivary gland cells. Therefore, primary salivary gland cells from 10 patients undergoing parotid gland surgery were exposed to nicotine concentrations between 1 μM and 1000 μM for 1 h in the absence of exogenous metabolic activation. The acinar phenotype was proven by immunofluorescent staining of alpha-amylase. Genotoxic effects were evaluated using the Comet assay, the micronucleus test and the chromosome aberration test. Cytotoxicity and apoptosis were determined by trypan blue exclusion test and Caspase-3 assay. Nicotine was able to induce genotoxic effects in all three assays. The chromosome aberration test was the most sensitive and increases in numerical and structural (chromatid-type and chromosome-type) aberrations were seen at ≥1 μM, whereas increases in micronuclei frequency were detected at 10 μM and DNA damage as measured in the Comet assay was noted at >100 μM. No cytotoxic damage or influence of apoptosis could be demonstrated. Nicotine as a possible risk factor for tumor initiation in salivary glands is still discussed controversially. Our results demonstrated the potential of nicotine to induce genotoxic effects in salivary gland cells. These results were observed at saliva nicotine levels similar to those found after oral or transdermal exposure to nicotine and suggest the necessity of careful monitoring of the use of nicotine in humans.

Karyotype rearrangements and telomere analysis in Myzuspersicae (Hemiptera, Aphididae) strains collected on Lavandula sp. plants

Karyotype analysis of nine strains of the peach-potato aphid Myzuspersicae (Sulzer, 1776), collected on Lavandula sp. plants, evidenced showed that five of them had a standard 2n = 12 karyotype, one possessed a fragmentation of the X chromosome occurring at the telomere opposite to the NOR-bearing one and three strains had a chromosome number 2n = 11 due to a non-reciprocal translocation of an autosome A3 onto an A1 chromosome. Interestingly, the terminal portion of the autosome A1 involved in the translocation was the same in all the three strains, as evidenced by FISH with the histone cluster as a probe. The study of telomeres in the Myzuspersicae strain with the X fission evidenced that telomerase synthesised de novo telomeres at the breakpoints resulting in the stabilization of the chromosomal fragments. Lastly, despite the presence of a conserved telomerase, aphid genome is devoid of genes coding for shelterin, a complex of proteins involved in telomere functioning frequently reported as conserved in eukaryotes. The absence of this complex, also confirmed in the genome of other arthropods, suggests that the shift in the sequence of the telomeric repeats has been accompanied by other changes in the telomere components in arthropods in respect to other metazoans.

Reproductive effects of two neonicotinoid insecticides on mouse sperm function and early embryonic development in vitro

Acetamiprid (ACE) and imidacloprid (IMI) are two major members in the family of neonicotinoid pesticides, which are synthesized with a higher selectivity to insects. The present study determined and compared in vitro effects of ACE, IMI and nicotine on mammalian reproduction by using an integrated testing strategy for reproductive toxicology, which covered sperm quality, sperm penetration into oocytes and preimplantation embryonic development. Direct chemical exposure (500 µM or 5 mM) on spermatozoa during capacitation was performed, and in vitro fertilization (IVF) process, zygotes and 2-cell embryos were respectively incubated with chemical-supplemented medium until blastocyst formation to evaluate the reproductive toxicity of these chemicals and monitor the stages mainly affected. Generally, treatment of 500 µM or 5 mM chemicals for 30 min did not change sperm motility and DNA integrity significantly but the fertilization ability in in vitro fertilization (IVF) process, indicating that IVF process could detect and distinguish subtle effect of spermatozoa exposed to different chemicals. Culture experiment in the presence of chemicals in medium showed that fertilization process and zygotes are adversely affected by direct exposure of chemicals (P<0.05), in an order of nicotine>IMI>ACE, whereas developmental progression of 2-cell stage embryos was similar to controls (P>0.05). These findings unveiled the hazardous effects of neonicotinoid pesticides exposure on mammalian sperm fertilization ability as well as embryonic development, raising the concerns that neonicotinoid pesticides may pose reproductive risks on human reproductive health, especially in professional populations.

OGG1 Ser326Cys polymorphism interacts with cigarette smoking to increase oxidative DNA damage in human sperm and the risk of male infertility

8-Oxoguanine DNA glycosylase 1 (OGG1) plays an important role in repairing oxidative DNA damage induced by chemical agents, such as tobacco. This study examined the effects of OGG1 Ser326Cys polymorphism and cigarette smoking, alone or combined, on sperm oxidative DNA damage and the risk of male infertility. A total of 620 idiopathic infertile subjects and 480 fertile controls were recruited in this study. Sperm 8-hydroxydeoxyguanine (8-OHdG) was measured by immunofluorescent assay using flow cytometry and genotypes were determined by OpenArray platform with a chip-based Taq-Man genotyping technology. Our results demonstrated that both cigarette smoking and OGG1 polymorphism can affect the sperm 8-OHdG levels. Individuals with variant Cys/Cys homozygote showed higher levels of sperm 8-OHdG than wide-type homozygote carriers (Ser/Ser). Stratified analysis found that the association between OGG1 polymorphism and sperm 8-OHdG levels was only observed among smokers with pack-years ≥5 but not among those subjects with pack-years<5 (pack-years=packs smoked per day×years as a smoker). Further analysis based on the case-control study revealed that variant allele (Cys) of OGG1 was significantly associated with male infertility risk in a dominant model (OR=1.35, 95% CI: 1.01-1.82; trend P<0.001). Furthermore, we found a significant gene-environment interaction between OGG1 Ser326Cys polymorphism and cigarette smoking in relation to male infertility risk (Pinteration=0.0003). These findings provided the first evidence about potential interactive effects of OGG1 polymorphism and cigarette smoking on male infertility risk.

The impact of lead and cadmium on selected motility, prooxidant and antioxidant parameters of bovine seminal plasma and spermatozoa

The aim of this study was to investigate the effects of lead (Pb) and cadmium (Cd) content on basic motility characteristics (motility-MOT, progressive motility-PROG) as well as selected markers of the prooxidant-antioxidant balance (catalase-CAT, glutathione-GSH, malondialdehyde-MDA) in bovine seminal plasma and spermatozoa. Twenty five semen samples were collected from breeding bulls and used in the study. Motility analysis was carried out using the Computer Assisted Sperm Analysis (CASA) system. The samples were centrifuged, fractions of seminal plasma and spermatozoa were separated, lysates were prepared from the sperm cell fractions. Pb and Cd concentrations were determined by the voltametric method (ASV), antioxidants and MDA were analyzed by UV/Vis spectrophotometry. The analysis showed that the average concentration of Pb in the seminal plasma was 0.23 ± 0.02 μg/mL, while its amount in the sperm cells was significantly higher (0.41 ± 0.07 μg/mL; P < 0.05). The average Cd content in bovine seminal fractions was similar and non-significant: 0.09 ± 0.01 μg/mL in the seminal plasma and 0.11 ± 0.01 μg/mL in spermatozoa (P > 0.05). The correlation analysis revealed that both heavy metals were significantly negatively correlated with MOT and PROG (P < 0.05; P < 0.01; P < 0.001), CAT (P < 0.05; P < 0.01) as well as GSH (P < 0.05; P < 0.01) but significantly positively associated with MDA as the marker of lipid peroxidation (P < 0.05; P < 0.01). Moreover the samples were categorized in three quality groups (Excellent, Good, Moderate) according to their motility values. The lowest Pb, Cd and MDA concentrations but the best antioxidant characteristics were found in samples of the best quality, moderate quality samples exhibited the highest Pb, Cd and MDA content together with the worst antioxidant capacity. This study demonstrates that Pb and Cd are serious toxic elements, which are able to increase the risk of seminal oxidative stress development and a subsequent decrease of male fertility.

Karyotype variations in Italian populations of the peach-potato aphid Myzus persicae (Hemiptera: Aphididae)

In this study, we present cytogenetic data regarding 66 Myzus persicae strains collected in different regions of Italy. Together with the most common 2n = 12 karyotype, the results showed different chromosomal rearrangements: 2n = 12 with A1-3 reciprocal translocation, 2n = 13 with A1-3 reciprocal translocation and A3 fission, 2n = 13 with A3 fission, 2n = 13 with A4 fission, 2n = 14 with X and A3 fissions. A 2n = 12-13 chromosomal mosaicism has also been observed. Chromosomal aberrations (and in particular all strains showing A1-3 reciprocal translocation) are especially frequent in strains collected on tobacco plants, and we suggest that a clastogenic effect of nicotine, further benefited by the holocentric nature of aphid chromosomes, could be at the basis of the observed phenomenon.

Assessment of nicotine-induced DNA damage in a genotoxicological test battery

The role of the tobacco-alkaloid nicotine in tumour biology is widely discussed in the literature. Due to a strong capacity to induce angiogenesis, a pro-mutagenic potential in non-tumour and cancer cells, and a pro- and anti-apoptotic influence, nicotine seems to promote the growth of established tumours. However, results indicating DNA damage and genetic instability associated with nicotine have been contradictory thus far. A variety of markers and endpoints of genotoxicity are required to characterize the genotoxic potential of nicotine. Induction of DNA single- and double-strand breaks, the formation of micronuclei, and the induction of sister chromatid exchange and chromosome aberrations represent possible genotoxicological endpoints at different cellular levels. Human lymphocytes were exposed to nicotine concentrations between 1μM and 1mM for 24h in vitro. The comet assay, the cytokinesis-block micronucleus test, the chromosome aberration (CA) test, and the sister chromatid exchange (SCE) test were then applied. Viability and apoptosis were measured by flow cytometry in combination with the annexin V-propidium iodide staining test. In this test setting, no enhanced DNA migration was measured by the comet assay. An increase in the micronucleus frequency was detected at a concentration of 100μM nicotine without affecting the frequency of apoptotic cells. A distinct genotoxic effect was determined by the CA test and the SCE test, with a significant increase in CA and SCE at a concentration of 1μM. In the annexin V test, nicotine did not influence the proportion of apoptotic or necrotic cells. The current data indicating the induction of CA by nicotine underscore the necessity of ongoing investigations on the potential of nicotine to initiate mutagenesis and tumour promotion. Taking into account the physiological nicotine plasma levels in smokers or in nicotine-replacement therapy, particularly the long-term use of nicotine should be critically discussed.

The genotoxic effect of nicotine on chromosomes of human fetal cells: the first report described as an important study

CONTEXT

Recent studies have suggested a direct contribution of nicotine--the addictive component of tobacco and tobacco smoke--to human carcinogenesis, and it remains the most common harmful substance to which pregnant women are exposed. Also, it has deleterious effects on the fetus. The sperm of smoking fathers and newborns of smoking mothers have elevated frequencies of chromosome translocations and DNA strand breaks.

OBJECTIVE

We tried to understand the genotoxic effect of nicotine in pregnancies of active or passive smoking mothers. For this reason, we provide the evidence that nicotine exposure in vitro has detrimental effects on fetal cells.

MATERIALS AND METHODS

We examined the effect of nicotine sulphate on amniotic cells by designing an experimental setting consisting fetal cells grown in nicotine containing medium (25 ng/mL) in study group and fetal cells grown in control medium, which did not contain nicotine.

RESULTS

According to our findings, there is a significant difference of chromosomal aberrations (CAs) between nicotine containing medium grown cells and control medium grown cells, determined by the χ² test (P <0.001). We found CAs in 21.5% of cells analyzed. The 19.4% of the all cells had numerical aberrations. Chromosomes 21, 22, 8, 15 and 20 related numerical abnormalities were found to be the most frequent numerical abnormalities.

CONCLUSION

Results of this study confirm that the nicotine leads to significant direct genotoxic effects in human fetal cells in vitro. We speculate that there is an association between prenatal exposure to cigarette smoke and in utero aneuploidies.

Analysis of nicotine-induced DNA damage in cells of the human respiratory tract

Epithelium of the upper and lower airways is a common origin of tobacco-related cancer. The main tobacco alkaloid nicotine may be associated with tumor progression. The potential of nicotine in inducing DNA mutations as a step towards cancer initiation is still controversially discussed. Different subtypes of nicotinic acetylcholine receptors (nAChR) are expressed in human nasal mucosa and a human bronchial cell line representing respiratory mucosa as a possible target for receptor-mediated pathways. In the present study, both cell systems were investigated with respect to DNA damage induced by nicotine and its mechanisms. Specimens of human nasal mucosa were harvested during surgery of the nasal air passage. After enzymatic digestion over night, single cells were exposed to an increasing nicotine concentration between 0.001 mM and 4.0mM. In a second step co-incubation was performed using the antioxidant N-acetylcysteine (NAC) and the nAChR antagonist mecamylamine. DNA damage was assessed using the alkali version of the comet assay. Dose finding experiments for mecamylamine to evaluate the maximal inhibitory effect were performed in the human bronchial cell line BEAS-2B with an increasing mecamylamine concentration and a constant nicotine concentration. The influence of nicotine in the apoptotic pathway was evaluated in BEAS-2B cells with the TUNEL assay combined with flow cytometry. After 1h of nicotine exposure with 0.001, 0.01, 0.1, 1.0 and 4.0mM, significant DNA damage was determined at 1.0mM. Further co-incubation experiments with mecamylamine and NAC were performed using 1.0mM of nicotine. The strongest inhibitory effect was measured at 1.0mM mecamylamine and this concentration was used for co-incubation. Both, the antioxidant NAC at a concentration of 1.0mM, based on the literature, as well as the receptor antagonist were capable of complete inhibition of the nicotine-induced DNA migration in the comet assay. A nicotine-induced increase or decrease in apoptosis as assessed by the TUNEL assay in BEAS-2B could not be detected. These results support the hypothesis that oxidative stress is responsible for nicotine-induced DNA damage. Similar results exist for other antioxidants in different cell systems. The decrease in DNA damage after co-incubation with a nAChR antagonist indicates a receptor-dependent pathway of induction for oxidative stress. Further investigations concerning pathways of receptor-mediated DNA damage via nAChR, the role of reactive oxygen species and apoptosis in this cell system will elucidate underlying mechanisms.

Effects of dermal exposure to Nicotiana tabacum (Jean Nicot, 1560) leaves in mouse evaluated by multiple methods and tissues

Tobacco farmers are routinely exposed to complex mixtures of the compounds present in tobacco leaves, including organic and inorganic pesticides. Penetration through skin is the most significant route of uptake in occupational exposure to chemicals, including dust and liquids containing toxic and carcinogenic substances. This study evaluates the genotoxic effect of tobacco leaves with and without dermal exposure to flumetralin in Mus musculus, determining cell damage by the micronucleus test and the Comet assay as well as antioxidant enzyme activities and hematologic parameters. Nicotine was used as positive control. Blood samples were collected for 0, 3, 24 and 48 h exposure periods, and DNA damage by Comet assay and micronucleus test was evaluated for all these periods. Bone marrow and liver cells were also evaluated for the 48 h exposure period. Significant differences between Comet assay results in blood cells from animals exposed to tobacco leaves with and without pesticide were found in 24 and 48 h exposure periods in relation to negative control. Bone marrow cells from the group exposed to leaves with pesticide (48 h) also demonstrated significant increase in DNA damage. Concerning the micronucleus test, only animals exposed to tobacco leaves without pesticide (24 h) showed increase in frequency of micronuclei when compared to the negative control. Oxidative stress activities also were demonstrated for different groups. The results demonstrate the injury effect caused by tobacco leaves in different Mus musculus tissues, suggesting that the effects of dermal exposure to tobacco leaves are caused by complex mixtures present in the plant, but mainly by nicotine.

Phagocytosis of dying cells: influence of smoking and static magnetic fields

It is becoming evident that failure in the removal of dying cells causes and/or promotes the onset of chronic diseases. Impairment of phagocytosis of apoptotic cells can be due not only to genetic or molecular malfunctioning but also to external/environmental factors. Two of these environmental factors have been recently reported to down regulate the clearance of apoptotic cells: cigarette smoke and static magnetic fields. Cigarette smoke contains highly reactive carbonyls that modify proteins which directly/indirectly affects cellular function. Human macrophages interacting with carbonyl or cigarette smoke modified extracellular matrix (ECM) proteins dramatically down regulated their ability to phagocytose apoptotic neutrophils. It was postulated that changes in the ECM environment as a result of cigarette smoke affect the ability of macrophages to remove apoptotic cells. This decreased phagocytic activity was as a result of sequestration of receptors involved in the uptake of apoptotic cells towards that of recognition of carbonyl adducts on the modified ECM proteins leading to increased macrophage adhesion. Downregulation of the phagocytosis of apoptotic cells was also described when performed in presence of static magnetic fields (SMFs) of moderate intensity. SMFs have been reported to perturb distribution of membrane proteins and glycoproteins, receptors, cytoskeleton and trans-membrane fluxes of different ions, especially calcium [Ca(2+)]i, that in turn, interfere with many different physiological activities, including phagocytosis. The effects of cigarette smoke and SMF on the phagocytosis of dying cells will be here discussed.

Genotoxicity of nicotine in cell culture of Caenorhabditis elegans evaluated by the comet assay

To assess the genotoxicity of nicotine, its DNA-damaging effect on Caenorhabditis elegans cells was tested with the alkaline single-cell microgel electrophoresis (comet) assay. The degree of DNA migration (a measure of possible DNA single-strand breaks, alkali-labile sites, and incomplete excision repair sites) was expressed as the head DNA%, tail length, and Olive tail moment. Large differences were found between experimental variants: 0, 1, 10, and 100 microM (-)-nicotine. At concentrations of 1 and 10 microM, no damages were detected by the comet assay, and the Olive tail moment and tail length were significantly lower than in the control (P < 0.001). The highest head DNA% and the lowest tail length and Olive tail moment were observed in the presence of 1 microM of nicotine. At 100 microM of nicotine, a significant increase (P < 0.001) was observed in Olive tail moment and tail length (up to 2.7- and 3-fold, respectively, compared to the control). The results are consistent with the lowest head DNA% among the three tested variants. This study demonstrated that nicotine treatment had dose-dependent effects on the level of DNA damage. Generally, a high dose of nicotine (100 microM) is genotoxic, while a reasonably low concentration has a protective effect. The possible participation of reactive oxygen species in the DNA-damaging potential of nicotine in C. elegans is discussed.

Nicotine induces DNA damage in human salivary glands

The tobacco alkaloid nicotine is responsible for addiction to tobacco and supposed to contribute to tobacco carcinogensis, too. Recently, genotoxic effects of nicotine have been reported in human cells from blood and upper aerodigestive tract. Because of nicotine accumulation in saliva, the study of possible in vitro genotoxic effects of nicotine have been extended to human salivary gland cells. Specimens of parotid glands of 10 tumor patients were obtained from tumor-free tissue. Single cells were prepared by enzymatic digestion immediately after surgery and exposed for 1h to 0.125-4.0mM of nicotine. Possible genotoxic effects were determined by the Comet assay using the % DNA in tail (DT) as a reliable indicator of DNA damage. Nicotine induced a significant dose-dependent increase of DNA migration in parotid gland single-cells. The mean DT was 1.12-fold (0.125mM) to 2.24-fold (4.0mM) higher compared to control. The lowest concentration eliciting significant DNA damage within 1h, 0.25mM nicotine, is only 10-fold higher than maximal concentrations of nicotine reported in saliva after unrestricted smoking. Although conclusive evidence for a carcinogenic potential of nicotine is still lacking, the safety of long-term nicotine replacement therapy should be carefully monitored.

The comet assay in male reproductive toxicology

Due to our lifestyle and the environment we live in, we are constantly confronted with genotoxic or potentially genotoxic compounds. These toxins can cause DNA damage to our cells, leading to an increase in mutations. Sometimes such mutations could give rise to cancer in somatic cells. However, when germ cells are affected, then the damage could also have an effect on the next and successive generations. A rapid, sensitive and reliable method to detect DNA damage and assess the integrity of the genome within single cells is that of the comet or single-cell gel electrophoresis assay. The present communication gives an overview of the use of the comet assay utilising sperm or testicular cells in reproductive toxicology. This includes consideration of damage assessed by protocol modification, cryopreservation vs the use of fresh sperm, viability and statistics. It further focuses on in vivo and in vitro comet assay studies with sperm and a comparison of this assay with other assays measuring germ cell genotoxicity. As most of the de novo structural aberrations occur in sperm and spermatogenesis is functional from puberty to old age, whereas female germ cells are more complicated to obtain, the examination of male germ cells seems to be an easier and logical choice for research and testing in reproductive toxicology. In addition, the importance of such an assay for the paternal impact of genetic damage in offspring is undisputed. As there is a growing interest in the evaluation of genotoxins in male germ cells, the comet assay allows in vitro and in vivo assessments of various environmental and lifestyle genotoxins to be reliably determined.

Adverse effects of cadmium on bull spermatozoa

Cadmium (Cd) is a widespread environmental pollutant. Because of its long biological half-life (10-30 years in humans), Cd accumulates in the biological systems such as gonads. The present study was designed to evaluate the effect of Cd in the concentration range 50-750 micromol/L, in vitro, on the membrane integrity, motility and acrosomal status of bull spermatozoa. The samples were processed for sperm analyses using semen-diluting fluid (phosphate-buffered saline, pH 7.2). A significant elevation in the malondialdehyde level/lipid peroxidation (LPO) rate and a decrease in the spermatocrit values, particularly at a concentration of 750 micromol/L Cd, indicated the deleterious effect of Cd on sperm membrane integrity. There was also a negative correlation between LPO rate and percentage of motile spermatozoa (r = 0.992). The gelatin test indicates that Cd may alter the integrity of acrosomal membranes and shows an abnormal acrosome reaction. In this regard, a strong negative correlation was found between LPO rate and % halos (bright clear zone around sperm heads after gelatin digestion) (r = 0.990). Taking the results together, Cd proved to be a potential toxicant in the category of environmental factors that induce membrane impairment, lower motility, and decrease the rate of acrosome reactions, leading to male infertility. Apparently, the presence of Cd in the environment and seminal plasma exerts a toxic effect on sperm cells.

In vitro mercury exposure on spermatozoa from normospermic individuals

Epidemiological evidence suggests that exposure to industrial metal aerosols is detrimental to the male reproductive system. Oxidative stress has been identified as a crucial factor leading to male factor infertility largely due to peroxidative damage to the sperm cell membrane. The objectives of the present study were to test the effect of mercury in the concentration range from 50 to 800 micromol(-1), in vitro, on the sperm membrane and DNA integrity, motility and acrosomal status of human spermatozoa. We found a significant increase in the Lipo Per Oxidation (LPO) indicating the deleterious effect of mercury on the sperm membrane integrity. This effect was prominent at the concentration of 800 microM mercury. There was also a strong negative correlation between LPO rate and percentage of viable spermatozoa (r = -0.941, p<0.001). Data obtained from SCGE assay technique revealed that mercury is capable of inducing DNA breaks in the sperm nuclei. Almost, 88% of DNA breaks were of double-stranded. The correlation between LPO rate and percentage of DNA breaks was found to be 0.918 (p<0.001). Performing the gelatin digestion test indicates that mercury was able to alter the integrity of acrosomal membranes showing an abnormal acrosome reaction. In this regard, a strong correlation was found between LPO rate and percentage of halos (r = -0.893, p<0.001). Taken together, mercury induced membrane impairments, lowered sperm viability, DNA breaks and a decreased rate in the acrosome reaction of human spermatozoa leading to sperm dysfunction. Entering mercury in the male gonads and seminal plasma may exert deleterious effects on the human spermatozoa. Hence, considering the wide spread use of mercury and its compounds, these metals should regarded with more concern.

The genotoxic and cytotoxic effects of nicotine in the mouse bone marrow

The objective of the present study was to investigate the potential of nicotine to induce micronucleated polychromatic erythrocytes (MNPCE) in bone marrow of male and female mice. Cyclophosphamide at 40mg/kg was used as positive control clastogen. Single doses of 4, 8 or 16mg/kg nicotine were given via oral intubation and bone marrow was sampled at 18, 24, 30, 36 and 48h after treatment. Cyclophosphamide yielded the expected positive results. Despite the evident signs of acute toxicity shown by the animals, mainly at the 8 and 16mg/kg doses of nicotine, and the reduction in the % PCE, the results show that the MNPCE frequency in male and female mice was not affected by treatment with any of the selected doses of nicotine, in either of the sampling times 18 or 24h. However, at 30 and 36h after treatment, the MNPCE showed significant increases in both genders after doses of 8 and 16mg/kg. A sex-dependent response was recorded, with males having more MNPCE than females after treatment with 8 or 16mg/kg nicotine and sampling at 30h. However, at 36h more MNPCE were induced in females than in males, suggesting different degrees of dose interaction in the sexes under the conditions of the assay. The response was directly correlated with bone-marrow toxicity, as greater bone-marrow suppression was noted in females than in males when 36h samples were examined. By 48h recovery was observed even though the cytotoxicity was high. These findings suggest that nicotine at high doses and after prolonged time intervals is genotoxic and cytotoxic for mouse bone marrow.