Vanadate, an inhibitor of tyrosine phosphatases, induced premature anaphase in oocytes and aneuploidy and polyploidy in mouse bone marrow cells

Alzheimer-like cell death after vanadium pentoxide inhalation

Vanadium (V) toxicity depends on its oxidation state; it seems that vanadium pentoxide (V₂O₅) is the most toxic to the living cells. It has been reported that oral administration induces changes in motor activity and learning; in rats, I.P. administration increases lipid peroxidation levels in the cerebellum and the concentration of free radicals in the hippocampus and cerebellum. Mice that inhaled V₂O₅ presented a reduced number of tubulin+ in Leydig and Sertoli cells; it has also been reported that inhaled V₂O₅ induces loss of dendritic spines, necrosis, and hippocampus neuropil alterations; considering the direct consequence of the interaction of V with cytoskeletal components, makes us believe that V₂O₅ exposure could cause neuronal death in the hippocampus similar to that seen in Alzheimer disease. This work aimed to determine pyramidal hippocampal CA1 cytoskeletal alterations with Bielschowsky stain in rats exposed to V2O5. Male Wistar rats inhaled 0.02 M of V2O5 one h two times a week for two and six months. We found that rats, which inhaled V2O5 reached 56,57% of dead neurons after six months of inhalation; we recognize strong argyrophilic and collapsed somas and typical flame-shaped in all V-exposed rats hippocampus CA1 compared to controls. We also observe somatodendritic distortions. Axons and dendrites displayed thick dark bands replaced by noticeable thickening and nodosities and the cytoskeleton fibrillary proteins' linear traces. Our findings suggest that V2O5 inhalation induces Alzheimer-like cell death with evident cytoskeletal alterations.

Vanadium(IV)-diamine complex with hypoglycemic activity and a reduction in testicular atrophy

The insulin enhancing activity, histological analysis and, testicular degeneration by a V^IVO-complex containing the 2,2'-(ethane-1,2-diylbis(azanediyl))diethanolate ligand, VO^IV(C₆H₁₄N₂O₂-κ²N,κ²O), abbreviated V^IVO(BHED), were investigated in diabetic male Wistar rats. The complex was administered by oral gavage of freshly prepared solutions of vanadium complex. Biological studies demonstrated that the vanadium complex normalized the elevated glucose levels in male Wistar rats with streptozotocin-induced diabetes and these compounds also avoided common responses in diabetic animals such as weight loss and reduction in the size of the epididymis, prostate, testis and seminal gland. The ⁵¹V NMR and EPR studies showed the formation of V^IVO(BHED) and the oxidation product [V^VO₂BHED]^- with two possible decomposition pathways. In summary, these studies demonstrate that the V^IVO(BHED) complex or its decomposition products show similar effects as insulin in decreasing elevated blood glucose levels.

Vanadium in Biological Action: Chemical, Pharmacological Aspects, and Metabolic Implications in Diabetes Mellitus

Vanadium compounds have been primarily investigated as potential therapeutic agents for the treatment of various major health issues, including cancer, atherosclerosis, and diabetes. The translation of vanadium-based compounds into clinical trials and ultimately into disease treatments remains hampered by the absence of a basic pharmacological and metabolic comprehension of such compounds. In this review, we examine the development of vanadium-containing compounds in biological systems regarding the role of the physiological environment, dosage, intracellular interactions, metabolic transformations, modulation of signaling pathways, toxicology, and transport and tissue distribution as well as therapeutic implications. From our point of view, the toxicological and pharmacological aspects in animal models and humans are not understood completely, and thus, we introduced them in a physiological environment and dosage context. Different transport proteins in blood plasma and mechanistic transport determinants are discussed. Furthermore, an overview of different vanadium species and the role of physiological factors (i.e., pH, redox conditions, concentration, and so on) are considered. Mechanistic specifications about different signaling pathways are discussed, particularly the phosphatases and kinases that are modulated dynamically by vanadium compounds because until now, the focus only has been on protein tyrosine phosphatase 1B as a vanadium target. Particular emphasis is laid on the therapeutic ability of vanadium-based compounds and their role for the treatment of diabetes mellitus, specifically on that of vanadate- and polioxovanadate-containing compounds. We aim at shedding light on the prevailing gaps between primary scientific data and information from animal models and human studies.

Concentrations of vanadium in urine and seminal plasma in relation to semen quality parameters, spermatozoa DNA damage and serum hormone levels

Widespread human exposure to vanadium has been well documented. Vanadium exposure was reported to induce male reproductive toxicity in toxicological studies, yet human epidemiologic studies are lacking. Here we determined the associations between environmental exposure to vanadium and semen quality, spermatozoa DNA damage and serum reproductive hormones. Concentrations of vanadium in seminal plasma and repeated urine samples were determined among 764 men recruited from a reproductive medicine centre. Associations of vanadium concentrations with semen quality parameters (n = 764), DNA integrity measures (n = 404) and serum reproductive hormones (n = 381) were assessed by logistic or linear regression models with adjustment for potential confounders. Significant positive dose-response relationships were observed between vanadium concentrations in seminal plasma and tail length and serum estradiol, as well as odds ratios for a below-reference-value sperm concentration; whereas inverse relationships between seminal plasma vanadium with total testosterone (T) and free T (all p values for trends <0.05) were observed. These relationships were maintained after adjusting for seminal plasma concentrations of other elements (i.e., arsenic, cadmium, copper, selenium, or tin). No significant associations was revealed between urinary vanadium concentrations and semen quality, spermatozoa DNA integrity and reproductive hormones. Our findings suggested that elevated vanadium exposure may be adversely associated with male reproductive health, and that seminal plasma vanadium may be a more direct exposure biomarker for the male reproductive system than urinary vanadium.

Intraperitoneal sodium metavanadate exposure induced severe clinicopathological alterations, hepato-renal toxicity and cytogenotoxicity in African giant rats (Cricetomys gambianus, Waterhouse, 1840)

Pollution of environment due to increased exploitation of minerals has been on the rise, and vanadium, a metal in the first transition series essential for mammalian existence, is a major component of air pollution. This study investigated the clinico-pathological, hepato-renal toxicity, and cytogenotoxicity of intraperitoneal exposure of African giant rats (AGRs), a proposed model for ecotoxicological research to sodium metavanadate. A total of 27 adult male African giant rats weighing 975 ± 54.10 g were distributed into two major groups: sodium metavanadate (SMV) treated and control. They were observed daily for clinical signs of toxicity. Four rats from each group were randomly collected and sacrificed after 3, 7, and 14 days of SMV treatment. Liver, kidney, and bone marrow were analyzed for histopathology and micronucleated normochromated and polychromated erythrocytes (MNNCE and MNPCE), respectively. Clinical signs in treated AGR include sluggish and weak movements, un-groomed fur, and labored breathing. Histology of the kidney revealed severe glomerular atrophy, tubular ectasia, and vacuolar degeneration of tubular epithelium, while liver histology showed sinusoidal congestion and severe hepatocellular necrosis after 14 days SMV exposure. Also, MNNCE and MNPCE significantly increased with a decrease in PCE/NCE ratio in SMV-treated AGR, suggestive of alternations in bone marrow cell proliferation. Hence, SMV treatment to AGR resulted to severe clinicopathologic alterations, kidney, and liver dysfunction and cytogenotoxicity evident by somatic mutation induction which could be severe with prolonged exposure. This suggests African giant rat as an ecotoxicological model to measure major health risks to animals and human populations in highly polluted environment.

In Vivo Effects of Vanadium Pentoxide and Antioxidants (Ascorbic Acid and Alpha-Tocopherol) on Apoptotic, Cytotoxic, and Genotoxic Damage in Peripheral Blood of Mice

This study was conducted to investigate the effects of vanadium pentoxide (V2O5), ascorbic acid (AA), and alpha-tocopherol (α-TOH) on apoptotic, cytotoxic, and genotoxic activity. Groups of five Hsd:ICR mice were treated with the following: (a) vehicle, distilled water; (b) vehicle, corn oil; (c) AA, 100 mg/kg intraperitoneally (ip); (d) α-TOH, 20 mg/kg by gavage; (e) V2O5, 40 mg/kg by ip injection; (f) AA + V2O5; and (g) α-TOH + V2O5. Genotoxic damage was evaluated by examining micronucleated polychromatic erythrocytes (MN-PCE) obtained from the caudal vein at 0, 24, 48, and 72 h after treatments. Induction of apoptosis and cell viability were assessed at 48 h after treatment in nucleated cells of peripheral blood. Treatment with AA alone reduced basal MN-PCE, while V2O5 treatment marginally increased MN-PCE at all times after injection. Antioxidants treatments prior to V2O5 administration decreased MN-PCE compared to the V2O5 group, with the most significant effect in the AA + V2O5 group. The apoptotic cells increased with all treatments, suggesting that this process may contribute to the elimination of the cells with V2O5-induced DNA damage (MN-PCE). The necrotic cells only increased in the V2O5 group. Therefore, antioxidants such as AA and α-TOH can be used effectively to protect or reduce the genotoxic effects induced by vanadium compounds like V2O5.

Activation of Janus kinase/signal transducers and activators of transcription pathway involved in megakaryocyte proliferation induced by vanadium resembles some aspects of essential thrombocythemia

Vanadium (V) is an air pollutant released into the atmosphere by burning fossil fuels. Also, it has been recently evaluated for their carcinogenic potential to establish permissible limits of exposure at workplaces. We previously reported an increase in the number and size of platelets and their precursor cells and megakaryocytes in bone marrow and spleen. The aim of this study was to identify the involvement of Janus kinase/signal transducers and activators of transcription (JAK/STAT) pathway and thrombopoietin (TPO) receptor, and myeloproliferative leukemia virus oncogene (Mpl), in megakaryocyte proliferation induced by this compound. Mice were exposed twice a week to vanadium pentoxide inhalation (0.02 M) and were killed at 4th, 6th, and 8th week of exposure. Phosphorylated JAK2 (JAK2 ph), STAT3 (STAT3 ph), STAT5, and Mpl were identified in mice spleen megakaryocytes by cytofluorometry and immunohistochemistry. An increase in JAK2 ph and STAT3 ph, but a decrease in Mpl at 8-week exposure was identified in our findings. Taking together, we propose that the morphological findings, JAK/STAT activation, and decreased Mpl receptor induced by V leads to a condition comparable to essential thrombocythemia, so the effect on megakaryocytes caused by different mechanisms is similar. We also suggest that the decrease in Mpl is a negative feedback mechanism after the JAK/STAT activation. Since megakaryocytes are platelet precursors, their alteration affects platelet morphology and function, which might have implications in hemostasis as demonstrated previously, so it is important to continue evaluating the effects of toxics and pollutants on megakaryocytes and platelets.

A review of current toxicological concerns on vanadium pentoxide and other vanadium compounds: gaps in knowledge and directions for future research

Vanadium pentoxide (V(2)O(5)) and other inorganic vanadium compounds have recently been evaluated by several occupational exposure limit (OEL) setting (occupational exposure limit, OEL) committees and expert groups in response to the publication of several new studies, including the U.S. National Toxicology Program (NTP, 2002) carcinogenicity study of inhaled V(2)O(5) in rats and mice, which concluded that clear evidence of lung tumors was seen in mice of both genders and that there was some evidence of carcinogenicity in male rats. This study reviews the expert evaluations of several OEL committees and expert groups and attempts to understand the strengths and weaknesses in their scientific arguments. This study also evaluates some key studies relating to potential genotoxicity, carcinogenicity, and respiratory effects of vanadium compounds and discusses how they might elucidate the mechanism(s) by which V(2)O(5) induces lung cancer in mice. All expert groups appear to agree that the lung tumors induced in mice in the NTP (2002) study are a site-specific response and, in general, verify that existing in vitro and in vivo studies suggest that tumors were induced by a secondary mechanism (presumably non-genotoxic), which is supported, though not conclusively, by a mechanistic data set. As some vanadium compounds produce a range of DNA and chromosome damage, there is no consensus on which of these changes is critical for the carcinogenic process for V(2)O(5) or whether the findings for the lung tumors seen in mice exposed to V(2)O(5) can be extrapolated to other inorganic vanadium compounds. As such, the various expert committees used the evidence differently, some to read across, i.e., to predict an endpoint for a substance based on the endpoint information of another with similar characteristics (e.g., physicochemical properties [solubility, bioaccessibility, bioavailability], structure, fate [toxicokinetics], and toxicology) for carcinogenicity from V(2)O(5) to other inorganic vanadium compounds. It is noteworthy that the toxicity of metals does not necessarily relate to carcinogenicity in a direct manner; thus, no assumptions should be made a priori when trying to extrapolate from V(2)O(5) to other inorganic vanadium compounds. Recent studies evaluated in this review provided some further insights into possible mechanisms but do not cover all relevant endpoints, address only a limited number of vanadium compounds, and have not established no-effect thresholds for carcinogenicity or respiratory tract irritation. Thresholds need to be established in order for arguments to be made for setting a health-based OEL for non-genotoxic or secondary genotoxic carcinogens. In conclusion, important knowledge gaps preclude confident classification and risk assessment for all vanadium compounds. Evidence suggests that further research that may address some of these critical gaps is needed.

Bypass of hexavalent chromium-induced growth arrest by a protein tyrosine phosphatase inhibitor: enhanced survival and mutagenesis

Although the consequences of genotoxic injury include cell cycle arrest and apoptosis, cell survival responses after genotoxic injury can produce intrinsic death-resistance and contribute to the development of a transformed phenotype. Protein tyrosine phosphatases (PTPs) are integral components of key survival pathways, and are responsible for their inactivation, while PTP inhibition is often associated with enhanced cell proliferation. Our aim was to elucidate signaling events that modulate cell survival after genotoxin exposure. Diploid human lung fibroblasts (HLF) were treated with Cr(VI) (as Na(2)CrO(4)), the soluble oxyanionic dissolution product of certain particulate chromates, which are well-documented human respiratory carcinogens. In vitro soluble Cr(VI) induces a wide spectrum of DNA damage, in both the presence and absence of a broad-range PTP inhibitor, sodium orthovanadate (SOV). Notably, SOV abrogated Cr(VI)-induced clonogenic lethality. The enhanced survival of Cr(VI)-exposed cells after SOV treatment was predominantly due to a bypass of cell cycle arrest, as there was no effect of the PTP inhibitor on Cr-induced apoptosis. Moreover, the SOV effect was not due to decreased Cr uptake as evidenced by unchanged Cr-DNA adduct burden. Additionally, the bypass of Cr-induced growth arrest by SOV was accompanied by a decrease in Cr(VI)-induced expression of cell cycle inhibiting genes, and an increase in Cr(VI)-induced expression of cell cycle promoting genes. Importantly, SOV resulted in an increase in forward mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of certain types of DNA damage may lead to increased genomic instability, via bypass of cell cycle checkpoints.

Carcinogenic metal compounds: recent insight into molecular and cellular mechanisms

Mechanisms of carcinogenicity are discussed for metals and their compounds, classified as carcinogenic to humans or considered to be carcinogenic to humans: arsenic, antimony, beryllium, cadmium, chromium, cobalt, lead, nickel and vanadium. Physicochemical properties govern uptake, intracellular distribution and binding of metal compounds. Interactions with proteins (e.g., with zinc finger structures) appear to be more relevant for metal carcinogenicity than binding to DNA. In general, metal genotoxicity is caused by indirect mechanisms. In spite of diverse physicochemical properties of metal compounds, three predominant mechanisms emerge: (1) interference with cellular redox regulation and induction of oxidative stress, which may cause oxidative DNA damage or trigger signaling cascades leading to stimulation of cell growth; (2) inhibition of major DNA repair systems resulting in genomic instability and accumulation of critical mutations; (3) deregulation of cell proliferation by induction of signaling pathways or inactivation of growth controls such as tumor suppressor genes. In addition, specific metal compounds exhibit unique mechanisms such as interruption of cell-cell adhesion by cadmium, direct DNA binding of trivalent chromium, and interaction of vanadate with phosphate binding sites of protein phosphatases.

Gender effects on the incidence of aneuploidy in mammalian germ cells

Aneuploidy occurs in 0.3% of newborns, 4% of stillbirths, and more than 35% of all human spontaneous abortions. Human gametogenesis is uniquely and gender-specific susceptible to errors in chromosome segregation. Overall, between 1% and 4% of sperm and as many as 20% of human oocytes have been estimated by molecular cytogenetic analysis to be aneuploid. Maternal age remains the paramount aetiological factor associated with human aneuploidy. The majority of extra chromosomes in trisomic offspring appears to be of maternal origin resulting from nondisjunction of homologous chromosomes during the first meiotic division. Differences in the recombination patterns between male and female meiosis may partly account for the striking gender- and chromosome-specific differences in the genesis of human aneuploidy, especially in aged oocytes. Nondisjunction of entire chromosomes during meiosis I as well as premature separation of sister chromatids or homologues prior to meiotic anaphase can contribute to aneuploidy. During meiosis, checkpoints at meiotic prophase and the spindle checkpoint at M-phase can induce meiotic arrest and/or cell death in case of disturbances in pairing/recombination or spindle attachment of chromosomes. It has been suggested that gender differences in aneuploidy may result from more permissive checkpoints in females than males. Furthermore, age-related loss of chromosome cohesion in oocytes as a cause of aneuploidy may be female-specific. Comparative data about the susceptibility of human male and female germ cells to aneuploidy-causing chemicals is lacking. Increases of aneuploidy frequency in sperm have been shown after exposure to therapeutic drugs, occupational agents and lifestyle factors. Conversely, data on oocyte aneuploidy caused by exogenous agents is limited because of the small numbers of oocytes available for analysis combined with potential maternal age effects. The vast majority of animal studies on aneuploidy induction in germ cells represent cause and effect data. Specific studies designed to evaluate possible gender differences in induction of germ cell aneuploidy have not been found. However, the comparison of rodent data available from different laboratories suggests that oocytes are more sensitive than male germ cells when exposed to chemicals that effect the meiotic spindle. Only recently, in vitro experiments, analyses of transgenic animals and knockdown of expression of meiotic genes have started to address the molecular mechanisms underlying chromosome missegregation in mammalian germ cells whereby striking differences between genders could be shown. Such information is needed to clarify the extent and the mechanisms of gender effects, including possible differential susceptibility to environmental agents.

Evaluation of genotoxicity of oral exposure to tetravalent vanadium in vivo

The trace element vanadium interacts with living cells, in which it exerts a variety of biological effects depending on its chemical form and oxidation state. Tetravalent vanadium was shown to affect several genotoxicity end-points in vitro, but its genotoxic potential in vivo is not elucidated. In this study, the genotoxic effects induced in vivo by subacute oral exposure to vanadyl sulphate (VOSO4), a tetravalent vanadium salt, were investigated. To this aim male CD1 mice were administered with VOSO4 in drinking water over the dose range 2-1000 mg/l for 5 weeks. The incidence of micronucleated blood reticulocytes was measured along treatment period. At the end of treatment, micronuclei in both blood reticulocytes and bone marrow polychromatic erythrocytes were determined; in addition, DNA lesions detectable by comet assay were assessed in marrow and testicular cells. Tissue distribution of vanadium at sacrifice was determined by atomic absorption spectrometry. Comet assays and the analysis of micronuclei in polychromatic erythrocytes did not reveal treatment related effects. A slight increase in micronucleated reticulocytes, with no relationship with the administered dose, was observed in some treated groups. The determination of vanadium content in kidney, liver, spleen, bone, stomach, small intestine and testis highlighted low internal exposure, especially in soft tissues. Overall, data indicate scarce bioavailability for orally administered tetravalent vanadium, and lack of significant genotoxic potential in vivo.

Mechanisms and chemical induction of aneuploidy in rodent germ cells

The objective of this review is to suggest that the advances being made in our understanding of the molecular events surrounding chromosome segregation in non-mammalian and somatic cell models be considered when designing experiments for studying aneuploidy in mammalian germ cells. Accurate chromosome segregation requires the temporal control and unique interactions among a vast array of proteins and cellular organelles. Abnormal function and temporal disarray among these, and others to be identified, biochemical reactions and cellular organelles have the potential for predisposing cells to aneuploidy. Although numerous studies have demonstrated that certain chemicals (mainly those that alter microtubule function) can induce aneuploidy in mammalian germ cells, it seems relevant to point out that such data can be influenced by gender, meiotic stage, and time of cell-fixation post-treatment. Additionally, a consensus has not been reached regarding which of several germ cell aneuploidy assays most accurately reflects the human condition. More recent studies have shown that certain kinase, phosphatase, proteasome, and topoisomerase inhibitors can also induce aneuploidy in rodent germ cells. We suggest that molecular approaches be prudently incorporated into mammalian germ cell aneuploidy research in order to eventually understand the causes and mechanisms of human aneuploidy. Such an enormous undertaking would benefit from collaboration among scientists representing several disciplines.

Assessment of the in vivo genotoxicity of vanadate: Analysis of micronuclei and DNA damage induced in mice by oral exposure

Vanadium compounds are able to interact with living cells exerting a variety of biological effects. The pentavalent form is the most stable and toxic form of the element. In systems in vitro pentavalent vanadium is an effective genotoxic agent, inducing DNA damage and chromosome malsegregation at low doses. On the other hand, no adequate in vivo data are available for the characterization of the genotoxic hazard following oral intake, the most relevant route of human exposure. In this study, the genotoxic effects produced by the oral intake of sodium ortho-vanadate (Na(3)VO(4)) were investigated. Male CD-1 mice were treated for 5 weeks with a range of concentrations of Na(3)VO(4) in drinking water (0.75-1500 mg/l). Both micronuclei and primary DNA lesions as detected by comet assay were assessed in several tissues. Statistically significant increases of micronuclei in bone marrow were observed in mice receiving the two highest concentrations of Na(3)VO(4) (750 and 1500 mg/l). A significant increase of comet tail length was observed in splenocytes of mice receiving Na(3)VO(4) at 1500 mg/l, whereas no effect was observed in bone marrow and testis cells. No treatment-related effect on sperm chromatin structure or on testis cell population was observed. The determination of vanadium content in mouse tissues at the end of treatment highlighted a very low internal exposure, especially in soft tissues. Overall, the results obtained indicate that the genotoxic activity of pentavalent vanadium is expressed in vivo only following high dose exposure, possibly as a consequence of the poor bioavailability of the element.

Orthovanadate increased the frequency of aneuploid mouse sperm without micronucleus induction in mouse bone marrow erythrocytes at the same dose level

The objective of the current study was to investigate the ability of orthovanadate to induce aneuploidy in mouse sperm and micronuclei in mouse bone marrow cells at the same dose levels. The BrdU-incorporation assay was performed to test if the chemical treatment altered the duration of the meiotic divisions. It was found that orthovanadate (25mg/kg bw) treatment did not cause meiotic delay. To determine the frequencies of hyperhaploid and diploid sperm, male mice were treated by intraperitoneal (i.p.) injection with 5, 15 or 25mg/kg bw orthovanadate and sperm were sampled from the Caudae epididymes 22 days later. Fluorescence in situ hybridization (FISH) was performed with DNA-probes for chromosomes 8, X or Y. Significant increases in the frequencies of total hyperhaploid sperm (p<0.01) were found with 15 and 25mg/kg bw orthovanadate, indicating induced non-disjunction during male meiosis. The dose-response was described best by a linear equation. Orthovanadate did not significantly increase the frequencies of diploid sperm at any of the three doses tested, indicating that no complete meiotic arrest occurred. Orthovanadate was investigated also by the micronucleus test at i.p. doses of 1, 5, 15 or 25mg/kg bw, followed by bone marrow sampling 24h after treatment. None of the orthovanadate doses caused a significant increase in the rates of micronuclei (MN). Since the results show that orthovanadate induced non-disjunction during male meiosis without an accompanying induction of MN in bone marrow erythrocytes under the present experimental conditions and doses, it is concluded that male germ cells (meiosis) are more sensitive to the aneugenic effects of orthovanadate than somatic cells (mitosis). However, induction of micronuclei was reported in the literature with orthovanadate, vanadylsulfate and ammonium metavanadate, which contradicts the notion that vanadium compounds might be unique germ cell aneugens.

Follicle-Stimulating Hormone Affects Metaphase I Chromosome Alignment and Increases Aneuploidy in Mouse Oocytes Matured in Vitro1

Follicle-Stimulating Hormone (FSH) at a wide range of doses is routinely added to culture media during in vitro maturation (IVM) of oocytes, but the effects on oocyte health are unclear. The suggestion that superovulation may cause aneuploidy and fetal abnormalities prompted us to study the potential role of FSH in the genesis of chromosomal abnormalities during meiosis I. Mouse cumulus-oocyte complexes (COCs) isolated from the antral follicles of unprimed, sexually immature B6CBF1 mice were cultured in increasing concentrations of FSH. Following culture, matured oocytes were isolated, spread, stained with DAPI, and the numbers of chromosomes counted. Significantly increased aneuploidy, arising during the first meiotic division, was observed in metaphase II oocytes matured in higher concentrations of FSH (> or =20 ng/ml). The effect of FSH on spindle morphology and chromosome alignment during metaphase I was then explored using immunocytochemistry and three-dimensional reconstruction of confocal sections. High FSH had no effect on gross spindle morphology but did alter chromosome congression during prometaphase and metaphase, with the spread of chromosomes across the spindle at this time being significantly greater in oocytes cultured in 2000 ng/ml compared with 2 ng/ml FSH. Analysis of three-dimensional reconstructions of spindles in oocytes matured in 2000 ng/ml FSH shows that chromosomes are more scattered and farther apart than they are following maturation in 2 ng/ml FSH. These results demonstrate that exposure to high levels of FSH during IVM can accelerate nuclear maturation and induce chromosomal abnormalities and highlights the importance of the judicious use of FSH during IVM.

Genotoxicity potential of 8-Cl-cyclic adenosine monophosphate assessed with cytogenetic tests in vivo

BACKGROUND

Growth-modulating noncytotoxic activity of 8-chloro-adenosine 3',5'-cyclic monophosphate (8-Cl-cAMP) showed inhibitory effect on growth of a wide variety of cancer cell lines in vitro and in vivo. To assess possible genotoxic effects of 8-Cl-cAMP, we conducted a study in vivo using male BALB/c mice.

METHODS

Clastogenic effects were estimated by bone marrow micronucleus assay and cytogenetic test in adult mice BALB/c strain. 8-Cl-cAMP was administered intraperitoneally (i.p.) to three dose groups including 10 mg/kg body weight (b.w.), 90 mg/kg b.w., and 160 mg/kg b.w., with saline solution as negative control and cyclophosphamide, a known mutagen, and clastogen as positive control during a 7-day period in 24-h intervals.

RESULTS

Micronucleus test in vivo results showed consistently increasing dose-dependent pattern increase of dose regime (10 mg/kg body weight [b.w.], 90 mg/kg b.w., and 160 mg/kg b.w.), and increase in frequency of micronuclei in polychromatic erythrocytes (4.88 +/- 0.35, 8.32 +/- 0.57, and 11.74 +/- 0.37) compared to negative control (2.04 +/- 0.28). Quantitative effects are paralleled by structural changes in chromosome morphology. 8-Cl-cAMP induced structural (breaks, gaps, centric rings, acentrics, and Robertsonian translocations) and numerical-type chromosomal aberrations (aneuploidy and polyploidy).

CONCLUSIONS

Results of this study demonstrate that 8-Cl-cAMP has genotoxic potential in vivo.