Evidence of oxidative damage and reproductive dysfunction accompanying 4-vinylcyclohexene diepoxide exposure in female Wistar rats

Maternal exposure to 4-vinylcyclohexene diepoxide during pregnancy leads to disorder of gut microbiota and bile acid metabolism in offspring

Our previous study reveals that maternal exposure to 4-vinylcyclohexene diepoxide (VCD) during pregnancy causes insufficient ovarian follicle reserve and decreased fertility in offspring. The present study aims to further explore the reasons for the significant decline of fecundity in mice caused by VCD, and to clarify the changes of gut microbiota and microbial metabolites in F1 mice. The ovarian metabolomics, gut microbiota and microbial metabolites were analyzed. The results of ovarian metabolomics analysis showed that maternal VCD exposure during pregnancy significantly reduced the concentration of carnitine in the ovaries of F1 mice, while supplementation with carnitine (isovalerylcarnitine and valerylcarnitine) significantly increased the number of ovulation. The results of 16 S rDNA-seq and microbial metabolites analysis showed that maternal VCD exposure during pregnancy caused disordered gut microbiota, increased abundance of Parabacteroides and Flexispira bacteria that are involved in secondary bile acid synthesis. The concentrations of NorDCA, LCA-3S, DCA and other secondary bile acids increased significantly. Our results indicate that maternal exposure to VCD during pregnancy leads to disorder in gut microbiota and bile acid metabolism in F1 mice, accompanying with decreased ovarian function, providing further evidence that maternal exposure to VCD during pregnancy has intergenerational deleterious effects on offspring.

Maternal exposure to 4-vinylcyclohexene diepoxide during pregnancy induces subfertility and birth defects of offspring in mice

4-vinylcyclohexene diepoxide (VCD), widely used in industry, is a hazardous compound that can cause premature ovarian failure, but whether maternal VCD exposure affects the health and reproduction of offspring is unknown. Here we focused on the effects of VCD on fertility and physical health of F1 and F2 offspring in mice. The pregnant mice were injected intraperitoneally with different dosages of VCD once every day from 6.5 to 18.5 days post-coitus (dpc). We showed that maternal exposure to VCD during pregnancy significantly reduced the litter size and ovarian reserve, while increasing microtia occurrences of F1 mice. The cytospread staining showed a significant inhibition of meiotic prophase I progression from the zygotene stage to the pachytene stage. Mechanistically, the expression level of DNA damage marker (γ-H2AX) and BAX/BCL2 ratios were significantly increased, and RAD51 and DMC1 were extensively recruited to DNA double strand breaks sites in the oocytes of offspring from VCD-exposed mothers. Overall, our results provide solid evidence showing that maternal exposure to VCD during pregnancy has intergenerational deleterious effects on the offspring.

Low-Intensity Pulsed Ultrasound Promotes Repair of 4-Vinylcyclohexene Diepoxide-Induced Premature Ovarian Insufficiency in SD Rats

Women with premature ovarian insufficiency (POI) may be more vulnerable to a variety of health risks. To seek a new method to treat the disease, the effects of low-intensity pulsed ultrasound (LIPUS) on promoting repair of ovarian injury in female SD rats induced by 4-vinylcyclohexene diepoxide (VCD) were explored in this research. A total of 24 female SD rats were subjected to intraperitoneal injection of VCD to induce POI. Successful modeling was achieved in 22 rats, which were then randomized into VCD + LIPUS group (n = 13) and VCD group (n = 9). The control group (n = 5) was injected with equal normal saline. Hematoxylin and eosin staining, enzyme-linked immunosorbent assay, Western blot analysis, scanning electron microscope, immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated nick end labeling assay were applied to detect the results. The results indicated that rats in the VCD group showed disorder in the estrous cycle, the number of atresia follicles and apoptosis granulosa cells increased (p < .05). After the LIPUS treatment, the estrous cycle recovered, the number of follicles increased (p < .05), the level of E2 and anti-Müllerian hormone enhanced (p < .05), and the follicle-stimulating hormone decreased (p < .05). The expression of NF-κB p65, TNFα, Bax, ATF4, and caspase-3 in ovarian tissue was significantly decreased (p < .05). These findings showed that LIPUS could promote the repair of the VCD-induced ovarian damage in SD rats, which has the potential to be further applied in the clinic.

The relationship of 4-vinylcyclohexene diepoxide toxicity with cell death, oxidative stress, and gap junctions in female rat ovaries

PURPOSE

It was aimed to investigate the damage caused by VCD toxicity in the ovary, which women working in the industrial field are frequently exposed to, and to show the relationship between gap junction protein, oxidative stress, and apoptosis, which is thought to be effective in the emergence of this damage.

METHODS

Rats were divided into three groups as control, sham, and VCD. Histological stainings were performed for histopathological evaluations in ovary. Serum AMH level was measured with the ELISA. Then, iNOS, caspase 3, connexin 43 protein, and mRNA expression levels were analyzed by immunohistochemistry and RT-qPCR methods.

RESULTS

As a result of the analyses, different amounts of degenerations such as hemorrhage, vacuolization, and fibrosis were observed in the ovary. VCD group AMH level decreased compared to control. In VCD group, iNOS and caspase 3 expressions increased, while connexin 43 expression decreased.

CONCLUSIONS

It was shown that VCD caused damage to all ovarian tissue. Also, it was revealed for the first time that VCD triggered apoptosis by increasing oxidative stress in the ovary and suppressed connexin 43 which was also effective in the survival of granulosa cells. The devastating effect of exposure to occupational chemicals such as VCD on fertility was demonstrated in this study.

Adipose-Derived Mesenchymal Stem Cell Transplantation in Chemotherapy-Induced Premature Ovarian Insufficiency: the Role of Connexin and Pannexin

In women undergoing chemotherapy, it is inevitable that infertility risk will increase because of impaired reproductive functions. Premature ovarian insufficiency (POI), which occurs as a devastating result of chemotherapy, is the complete depletion or dysfunction of ovarian follicles. Adipose-derived mesenchymal stem cells (ADMSCs) transplantation is among the alternative treatment methods for POI, which currently do not have an effective treatment method. Apoptosis of granulosa cells in POI is seen as the main mechanism of the disease. It is also reported that in addition to molecules directly associated with apoptosis, connexins, and pannexins are also potential effector molecules in apoptosis. The roles of these molecules in POI, which are known to play a role in many important mechanisms in the ovary, are unknown. In this study, it was aimed to analyze the expressions of Connexin43 and Pannexin1, which are thought to be effective in the formation of POI, and to show the relationship between the antiapoptotic effects of ADMSCs transplantation and these molecules in POI. For this purpose, Caspase3, Connexin43, Pannexin1 proteins, and mRNA expressions were analyzed by immunohistochemistry and RT-qPCR, and AMH levels were measured by ELISA. It was determined that Pannexin1, Caspase3 proteins, and mRNA levels increased in the POI, while Pannexin1 and Caspase3 expressions decreased in the ADMSCs treated group. While Connexin43 level decreased in POI, Connexin43 protein and mRNA levels increased in ADMSCs group. Consequently, this study demonstrated for the first time that Connexin43 and Pannexin1 were associated with apoptosis in POI. In addition, it was revealed that ADMSCs transplantation could produce antiapoptotic effects by modulating these molecules.

Effect of Jiajian Guishen Formula on the senescence-associated heterochromatic foci in mouse ovaria after induction of premature ovarian aging by the endocrine-disrupting agent 4-vinylcyclohexene diepoxide

ETHNOPHARMACOLOGICAL RELEVANCE

Jiajian Guishen Formula (JJGSF), which is a prescription of Traditional Chinese Medicine (TCM), has been reported to be useful in the treatment of premature ovarian insufficiency (POI).

AIM OF THE STUDY

To investigate the therapeutic effects of JJGSF on the treatment of POI induced by 4-vinylcyclohexene diep-oxide (VCD), an endocrine-disrupting chemical (EDC), and to elucidate the potential mechanism.

MATERIALS AND METHODS

Female 8-week-old ICR mice (N = 72) were randomized into six groups, containing the Model group, Control group, three JJGSF groups, and Progynova group which was served as a positive control. After model establishment by VCD, the Progynova group were given a daily intragastric administration of Progynova, and the three JJGSF groups (high dose group, medium dose group and low dose group) received a daily intragastric administration of JJGSF at doses of 9, 4.5 and 2.25 g/kg for four weeks. The general growth of the mice was observed and the estrous cycles were examined. The serum hormone concentrations were measured by enzyme-linked immunosorbent assay (ELISA). To explore the potential mechanism of effect, the protein expressions of H3K9me3, HP1, and HMGA1/HMGA2 related to senescence-associated heterochromatic foci (SAHF), were determined by Immunofluorescence and Western blot analysis, respectively.

RESULTS

After treating with JJGSF, the estrous cycles were improved significantly. The level of estrogen (E2) and anti-müllerian hormone (AMH) was increased and the ratio of follicle-stimulating hormone (FSH) to luteinizing hormone (LH) in serum was decreased significantly. Furthermore, a significant down-regulation of HMGA1/HMGA2 on protein level, a reduction distribution of HP1 and H3K9me3 in ovarian, and a lower fraction of SAHF-positive cells were observed after the administration with JJGSF, additionally effects showed a positive correlation with dosages.

CONCLUSIONS

JJGSF could treat POI by the mechanism of inhibiting SAHF.

The effects of prenatal and postnatal exposure to electromagnetic field on rat ovarian tissue

Exposure to an electromagnetic field (EMF) can have adverse effects on many organs and tissues, including the reproductive system. This study aimed to investigate the effects of EMF exposure during prenatal and postnatal periods on ovarian development in rat offspring. In this study, rat pups born from eight pregnant rats were used. EMF exposure was initiated on the first day of pregnancy and continued until the 42nd postnatal day. The blood and ovarian tissue samples of female offspring in sham and EMF groups were collected when they reached the age of 42 days. Follicle-stimulating hormone levels were significantly higher in the EMF group than in the sham group. Estradiol levels were significantly lower in the EMF group than in the sham group. Tissue-inducible nitric oxide synthase (iNOS) levels and expression were significantly greater in the EMF group than in the sham group. In the EMF group, congestion, bleeding areas, and degeneration of follicle structures were observed in ovarian tissue. The findings suggest that exposure to 50-Hz, 3-mT EMF used in this study during prenatal and postnatal periods may lead to impaired ovarian structure and function in female offspring. EMF may affect ovarian physiology by increasing iNOS levels and may lead to fertility disorders.

Rescue role of hesperidin in 4-vinylcyclohexene diepoxide-induced toxicity in the brain, ovary and uterus of wistar rats

Background The ovotoxicity of 4-vinylcyclohexene diepoxide (VCD) has been established in several experimental models. Hesperidin (HSD) is a bi-flavonoid found in citrus fruits and has been reported to be a potent antioxidant and anti-inflammatory agent. Here, we have evaluated the rescue role of hesperidin on VCD-induced toxicity in the brain, ovary, and uterus of rats. Methods Six groups of rats containing ten rats in each group were orally given corn oil (control), hesperidin (100 mg/kg), hesperidin (200 mg/kg), VCD (250 mg/kg), VCD [(250 mg/kg)+hesperidin (100 mg/kg)] and VCD [(250 mg/kg)+hesperidin (200 mg/kg)] once a day for 30 days, respectively. Thereafter, we determined the selected biomarkers of oxidative damage, inflammation, endocrine balance, and histology of the reproductive organs. Results The data showed that hesperidin rescued VCD-induced increase in oxidative stress (hydrogen peroxide and malondialdehyde) and inflammatory (nitric oxide) biomarkers. In addition, hesperidin restored the reduction in antioxidant enzymes (catalase, glutathione S-transferase, glutathione peroxidase) activities and glutathione level in the brain, ovary, and uterus of rats (p<0.05). Lastly, hesperidin preserved the histological structure of the ovary and uterus of rats exposed to VCD. Conclusions Overall, the rescue role of hesperidin on VCD-induced toxicity in the brain and reproductive organs of female rats may be due to its antioxidative and anti-inflammatory properties.

Protective effect of alpha lipoic acid on 4-vinylcyclohexene diepoxide induced primary ovarian failure in female rats

OBJECTIVE

The effects of alpha lipoic acid (ALA) and its possible mechanisms in treating Primary ovarian failure (POF) model was studied with 4 vinylcyclohexene diepoxide (VCD).

MATERIAL AND METHODS

Rats were divided into 4 groups (n = 7) as Control, VCD, VCD + ALA and ALA. POF model was induced by applying VCD intraperitoneally and ALA was administered by oral gavage as 100 mg/day to the VCD + ALA and ALA groups.

RESULTS

At the end of 42 days, ovarian and uterine tissues were received. The number of primordial and primary follicles were increased and corpus luteum and cystic follicles were decreased in ovarian tissues in VCD + ALA group compared to VCD group. Caspase-3 immunoreactivity in follicular cells was decreased in VCD + ALA group compared to VCD group. eNOS immunoreactivity and eNOS levels were decreased in VCD group and increased in VCD + ALA group while iNOS immunoreactivity and iNOS levels were increased in VCD group, decreased in VCD + ALA group in ovary and uterine tissue. Plasma FSH and LH hormone levels were increased in the VCD but decreased in VCD + ALA group. Estradiol level decreased in the VCD group compared to the other groups. The MDA values were significantly increased in the VCD + ALA group compared to VCD group. In addition, the levels of GSH values were decreased in VCD + ALA group compared to VCD group.

CONCLUSION

Alpha lipoic acid treatment of rats with VCD-induced POF had a beneficial effect on reducing ovarian damage by improving histological, immunohistochemical, hormone level and oxidative stress markers. Our results show that ALA is an effective treatment of VCD-induced POF rats.

Simultaneous exposure to vinylcyclohexene and methylmercury in Drosophila melanogaster: biochemical and molecular analyses

Background

Exposure to vinylcyclohexene (VCH) and methylmercury (MeHg⁺) can induce oxidative stress and gene modulation. Several studies have been evaluating the effects of VCH and MeHg⁺, but little is known about interactive effects between them. This work aimed to assess the exposure and co-exposure effects of MeHg⁺ and VCH on oxidative stress and gene modulation in Drosophila melanogaster.

Methods

Reactive species production, glutathione S-transferase (GST) and acetylcholinesterase (AChE) activities were evaluated after exposure and co-exposure to VCH (1 mM) and MeHg⁺ (0.2 mM) for one or three days in the head and body (thorax and abdomen) of flies. The expression of genes related to redox state and inflammatory response was evaluated after exposure and co-exposure to VCH and MeHg⁺ for three days.

Results

Survival decreased only in flies co-exposed to VCH and MeHg⁺ for three days. All treatments increased total reactive species production after one day of exposure. However, no significant changes were observed in the head after three days of exposure. One day of exposure to VCH caused an increase in the head GST activity, whereas MeHg⁺ induced an increase after three days of exposure. Regarding the body, all treatments increased GST activity after one day of exposure, but only the flies exposed to MeHg⁺ presented an increase in GST activity after three days of exposure. Treatments did not alter AChE activity in the head. As for gene expression, there was a significant increase in the Relish transcription factor gene in the flies’ body, but Nrf2, Keap1, Jafrac1, TrxR1, and NF-κβ were not altered.

Conclusion

The results suggest that exposure to VCH and MeHg⁺ induce oxidative stress and activation of an inflammatory response in fruit flies.

Assessing the toxicant effect of spontaneously volatilized 4-vinylcyclohexane exposure in nymphs of the lobster cockroach nauphoeta cinerea

Vinylcyclohexene (VCH) is an environmental contaminant well known for its ovotoxicant effects in several organisms. However, the mechanisms underlying the toxicity of VCH as well as its harmful effects toward other organs are until unclear. In this work, we assess some endpoint signals of toxicity induced by volatilized VCH exposure using nymphs of the lobster cockroach Nauphoeta cinerea. Nymphs were exposed to VCH via inhalation for 70 days. The levels of volatilized VCH were quantified by headspace gas chromatography and the concentration varied between 3.41 and 7.03 nmol/μl. VCH inhalation caused a reduction of 35% in the survival rate of the exposed animals. Nymphs exposed to volatilized VCH for 35 and 70 days had a reduction in the body weight gain of 1.8- and 2.6-fold, respectively with a reduction in dissected head, fat body, and maturing reproductive organs. The exposure did not change water consumption, excepting on the 20th day (with a 3-fold change) and decreased the food intake significantly. Regarding biochemical markers, we found that the activity of GST from the dissected organs was increased by volatilized VCH after both 35 and 70 days of exposure. The fat body presented the most prominent GST activity especially after 35 days of exposure with 1.6-fold higher than the control group. Exposure also caused an increase in RS levels in the fat body of 1.35-fold and 1.47-fold after 35 and 70 days, respectively and did not affect the activity of the AChE from the head. Our findings support the harmful impact of volatilized VCH inhalation, highlighting the cockroach N.cinerea as a valuable insect model to investigate environmental toxicants.

First-line antituberculosis drugs disrupt endocrine balance and induce ovarian and uterine oxidative stress in rats

BACKGROUND

The first-line antituberculosis (anti-TB) drugs, isoniazid (INH), rifampicin (RIF), ethambutol (EMB), and pyrazinamide (PZA), are effective in the treatment of pulmonary tuberculosis. However, the toxicity of these drugs in the clinical setting limits their use. Here, we evaluated the effects of anti-TB drugs on the reproductive system in female rats.

METHODS

Thirty-five female Wistar rats were assigned into five groups of seven animals each. The control group received normal saline, whereas others received INH (5 mg/kg), RIF (10 mg/kg), EMB (15 mg/kg), and PZA (15 mg/kg) through gavage thrice a week for 8 consecutive weeks.

RESULTS

Administration of anti-TB drugs significantly (p<0.05) reduced uterine and ovarian weight, as well as the relative weight of the uterus when compared with controls. In addition, anti-TB drugs increased the activities of alanine aminotransferase as well as the level of total bilirubin. Treatment with INH, RIF, and PZA significantly (p<0.05) reduced the levels of follicle-stimulating and luteinizing hormones, estrogen, and prolactin. The INH, RIF, EMB, and PZA caused significant (p<0.05) increases in uterine malondialdehyde (MDA) levels by 281%, 214%, 273% and 190%, respectively, whereas INH and EMB increased the ovarian malondialdehyde by 111% and 129%, respectively. These drugs significantly (p<0.05) decreased the activities of ovarian glutathione-S-transferase and uterine glutathione peroxidase, superoxide dismutase, and catalase. Histology revealed the erosion of uterine mucosa, debris in the lumen of the uterus, congestion, and underdeveloped follicles in ovaries.

CONCLUSIONS

The first-line anti-TB drugs elicited reproductive toxicity in the uterus and ovaries of rats through mechanisms that involved oxidative stress.