Gamma-radiation-induced follicular degeneration in the prepubertal mouse ovary

Effect of radiation on serum anti-Müllerian hormone during hysterosalpingography in female infertility

RESEARCH QUESTION

Does radiation exposure during hysterosalpingography (HSG) negatively affect serum anti-Müllerian hormone (AMH) levels in infertile women?

DESIGN

Prospective cohort study conducted at Songklanagarind Hospital, Thailand, between April 2021 and May 2023. Thirty-two infertile women and 34 control participants were enrolled. Serum AMH levels were assessed in the infertile group at baseline before the HSG procedure and at 1 and 3 months after the procedure. Control participants, who self-reported no medical conditions, underwent the same AMH level assessments. Changes in serum AMH levels were compared.

RESULTS

Infertile women had a mean age of 32.4 ± 3.8 years, body mass index of 21.2 ± 2.0 kg/m2 and baseline mean AMH level of 3.66 ng/ml (95% CI 3.00 to 4.32), which did not significantly differ from the control group. One month after HSG, mean AMH level significantly declined (0.33 ng/ml, 95% CI -0.65 to -0.01; P = 0.045) in the infertile group. The change in serum AMH levels between baseline and 1 month was significantly different in the HSG group compared with controls (-0.33 ng/ml, 95% CI -0.65 to -0.01 versus 0.36 ng/ml, 95% CI 0.06 to 0.67; P = 0.002). Changes in serum AMH levels from baseline to 3 months did not differ between the two groups.

CONCLUSIONS

One month after the HSG, infertile women experienced a significant decrease in serum AMH levels compared with controls. The change in serum AMH levels between baseline and 3 months after HSG did not significantly differ from that of the control group.

Honokiol alleviates radiation-induced premature ovarian failure via enhancing Nrf2

BACKGROUND

The ovary is highly sensitive to radiation, and patients receiving radiotherapy are at significant risk of premature ovarian failure (POF). This study aimed to explore the radioprotective effect of honokiol (HKL) on ionizing radiation (IR)-induced POF.

METHODS

Female C57BL/6 mice were administered intraperitoneally with vehicle or HKL once daily for 7 days. On day 7, the mice in the IR and HKL+IR groups were exposed to 3.2 Gy whole-body radiation for one hour after the intraperitoneal injection and sacrificed 12 or 72 h after radiation exposure. The gonadosomatic index (GSI) was calculated. Blood samples were collected for enzyme-linked immunosorbent assay (ELISA). Ovaries were harvested for histological examination, immunohistochemistry, immunofluorescence, TUNEL, western blot, and qPCR. The fertility assessment was evaluated by calculating live offspring number.

RESULTS

The optimum dose of HKL against radiation was 10 mg/kg via intraperitoneal injection. POF was induced 72 h after irradiation with significantly downregulated proliferating cell nuclear antigen (PCNA). The numbers of primordial and preantral follicles decreased significantly after irradiation (p < .001), whereas the number of atretic follicles increased (p < .001). The serum levels of estradiol (E2 ) and anti-Müllerian hormone (AMH) decreased to 50% of the control group after irradiation (p < .05). Moreover, the GSI after irradiation was 27% lower than in the control group (p < .05). The number of offspring in the IR group dropped by 50% compared with the control group (p < .05). HKL pretreatment protected the animals' fertility, GSI, PCNA, serum levels of E2 and AMH, and the number of primordial and preantral follicles. Significant upregulation of apoptosis-related proteins such as Pho-P53, Bax, Cyto C, C-caspase-3, C-PARP, and pyroptosis-related proteins such as Pho-NF-κB p65, NLRP3, caspase-1, IL-1β, and IL-18 was observed after irradiation, while the expression of Bcl-2 decreased. HKL pretreatment prevented these changes. After irradiation, malondialdehyde (MDA), Nrf2, and HO-1 were upregulated. HKL treatment activated the expression of Nrf2 and HO-1 and promoted the nucleus translocation of Nrf2. Furthermore, HKL did not affect ovarian reserves under physiological conditions.

CONCLUSIONS

HKL ameliorated IR-induced POF by inhibiting apoptosis and pyroptosis by enhancing Nrf2 expression and translocation.

The different doses of radiation therapy-induced damage to the ovarian environment in rats

PURPOSE

The sequelae of premature loss of ovarian function can undoubtedly have undesirable effects for a woman although radiotherapy is one of the most relevant treatment modalities for various types of malignancies. The aim of this study was to determine the effect of different doses of radiation on ovarian folliculogenesis, inflammation, and apoptotic markers.

MATERIALS AND METHODS

For this purpose, 40 healthy Wistar albino female rats divided into four groups: 1) Control group; 2) those that were exposed to total body 1 Gy of gamma rays; 3) those that were exposed to the total body 5 Gy of gamma rays, and 4) those that were exposed to total body 10 Gy of gamma rays. External irradiation to the total body was given with gamma irradiation delivered by the Co60 teletherapy machine. The day after radiation application the rats were sacrificed and the ovaries were removed in all groups. Histopathologic examination, follicle counting, and classification were performed in the ovarian tissues. The expression of AMH, TNF-α, IL1-β, Bax, and Bcl-2 was detected. The stained sections were examined for caspase 3 positive apoptotic cell numbers.

RESULTS

The recorded results revealed that increased radiation dose induced obvious ovarian injuries that were indicated by histopathological, and immunohistochemical alterations, including elevation of ovarian injury markers. A significantly lower number of total and primordial follicles was detected with increasing radiation dose compared with the control group. According to our immunohistochemical results, 10 Gy of gamma rays group had the lowest AMH expression levels, while had the highest TNF-α, IL1-β expression level compared to the control group. When the groups were evaluated in terms of apoptosis, it was seen that the number of caspase 3 positive cells and Bax immunoreactivity intensity increased with radiation dose. In contrast, Bcl-2 immunoreactivity intensity decreased with increasing radiation dose compared with the control group.

CONCLUSIONS

We demonstrate here that dose rate plays an important role when estimating the relation between exposure to an increased dose of ionizing radiation and the risk of ovarian disease. According to these results, certain factors have to be optimized before introducing them into clinics.

Protective effect of edaravone against radiation-induced ovarian injury: a histopathological and immunohistochemical evaluation in an experimental rat model

PURPOSE

We aimed to evaluate the protective effect of edaravone on radiation-induced ovarian damage in an experimental rat model.

METHODS

Thirty-two Wistar albino female rats were randomly divided into four groups. Group 1: control, no treatment, and radiation was applied throughout the study; Group 2: sham, only radiation was applied; Group 3: 45 mg/kg edaravone and radiation were applied; Group 4: 450 mg/kg edaravone and radiation were applied. Edaravone was administered intraperitoneally 30 min before radiotherapy (5 Gy). Two days after radiation exposure, the rats were sacrificed and the ovaries were removed. Histologic changes under light microscopy and immunoreactivity for anti-caspase-3 were noted and compared between the four groups.

RESULTS

There was a statistically significant difference in follicle counts, vascular congestion, edema, cytoplasmic vacuolization, hemorrhage, and interstitial cell degeneration between the groups. Radiation causes deterioration in most histopathological parameters. Administration of edaravone at different doses seems to reverse these alterations and alleviate the injury. Antioxidant defense mechanisms appear to be enhanced by edaravone as shown by histopathologically and decreased apoptosis by reducing the expression of anti-caspase-3 activity as demonstrated immunohistochemically.

CONCLUSION

This is the first study evaluating the protective effects of edaravone on radiation-induced ovarian damage. Edaravone decreased the follicular apoptosis and attenuates the radiation-induced ovarian damage in rats.

Evaluation of induced biological effects in rats by continuous and natural gamma radiation using a physical simulator

PURPOSE

The effects of radioactivity on human health have been debated for many years but there are still important gaps that need to be addressed especially related to the effects of high natural background radiation on the local population. The beach of Meaípe, in the city of Guarapari (Brazil), emits natural gamma radiation due to the presence of monazite sands. We aimed to investigate the effects of gamma radiation doses on the biological system of wistar rats using a physical simulator of gamma radiation designed using Meaípe monazite sands.

METHODS

Female Wistar rats were divided into three groups, submitted to no radiation (control group) and to continuous radiation levels, one of very high level (20 μSv h^-1) and another of high level (3.6 μSv h^-1). The three group of animals were monitored weekly for 3 months and at the end of the study the animals were sacrificed, and the organs were extracted and weighed for anthropometric, oxidative stress and histological evaluations.

RESULTS

Exposure to radiation released by the monazite sands did not cause anthropometric alterations or blood pressure change in the animals. Similarly, there was no change in the quantification of ovarian follicles between the radiation groups and the control group. There was no difference in the oxidative stress quantification by the thiobarbituric acid reactive substance and advanced oxidation protein product methods in the ovaries. There were no evidenced damages in the structure of the renal tissue. It was observed the presence of granulomas in the hepatic tissue and alterations in the nuclei of the hepatocytes.

CONCLUSIONS

Our results suggest that the continuous exposure of females rats to 3.6 and 20 μSv h^-1 doses of gamma radiation slightly affected the hepatic tissue, but did not alter the histological parameters in the kidneys and ovaries and oxidative stress.

Phytoestrogen genistein hinders ovarian oxidative damage and apoptotic cell death-induced by ionizing radiation: co-operative role of ER-β, TGF-β, and FOXL-2

Radiotherapy is a well-known cause of premature ovarian failure (POF). Therefore, we investigated the molecular influence of genistein (GEN) on the ovarian reserve of rats exposed to ϒ-radiation. Female Sprague Dawley rats were exposed to a 3.2 Gy γ-radiation to induce POF and/or treated with either GEN (5 mg/kg, i.p.) or Ethinyl estradiol (E2; 0.1 mg/kg, s.c.), once daily for 10 days. GEN was able to conserve primordial follicles stock and population of growing follicles accompanied with reduction in atretic follicles. GEN restored the circulating estradiol and anti-Müllerian hormone levels which were diminished after irradiation. GEN has potent antioxidant activity against radiation-mediated oxidative stress through upregulating endogenous glutathione levels and glutathione peroxidase activity. Mechanistically, GEN inhibited the intrinsic pathway of apoptosis by repressing Bax expression and augmenting Bcl-2 expression resulted in reduced Bax/Bcl-2 ratio with subsequent reduction in cytochrome c and caspase 3 expression. These promising effects of GEN are associated with improving granulosa cells proliferation. On the molecular basis, GEN reversed ovarian apoptosis through up-regulation of ER-β and FOXL-2 with downregulation of TGF-β expression, therefore inhibiting transition of primordial follicles to more growing follicles. GEN may constitute a novel therapeutic modality for safeguarding ovarian function of females' cancer survivors.

Use of a Small Animal Radiation Research Platform (SARRP) facilitates analysis of systemic versus targeted radiation effects in the mouse ovary

BACKGROUND

Radiation exposure is known to cause accelerated aging and damage to the ovary, but the contribution of indirect versus direct effects is not well understood. We used the Small Animal Radiation Research Platform (SARRP) (Xstrahl) to deliver radiation to precise fields equivalent to clinical practice, allowing us to investigate systemic versus targeted damage in a structure as small as the mouse ovary. The X-ray dose was kept constant at 1 Gy, but the field varied. Mice either received total body irradiation (TBI), radiation targeted to both ovaries (T2), or radiation targeted to one ovary (left) while the contralateral ovary (right) was spared (T1). Sham mice, handled similarly to the other cohorts but not exposed to radiation, served as controls. Two weeks post-exposure, ovaries were harvested and analyzed histologically to identify and count follicles within each ovary.

RESULTS

Radiation significantly reduced primordial follicles in the TBI and T2 cohorts compared to the Sham cohort. There were no significant differences between these two irradiated groups. These findings suggest that at 1 Gy, the extent of damage to the ovary caused by radiation is similar despite the different delivery methods. When investigating the T1 cohort, targeted ovaries showed a significant decrease in primordial and growing follicles compared to non-targeted contralateral ovaries.

CONCLUSIONS

These findings demonstrate that the SARRP is an effective strategy for delivering precise ionizing radiation to small organs such as mouse ovaries. Such tools will facilitate identifying the relative risks to ovarian function associated with different radiation fields as well as screening the efficacy of emerging fertoprotective agents.

Examination of the effect of ovarian radiation injury induced by hysterosalpingography on ovarian proliferating cell nuclear antigen and the radioprotective effect of amifostine: an experimental study

Aim

The aim of this study was to examine the effect of amifostine on cellular injury in the ovarian tissue induced by hysterosalpingography (HSG).

Methods

In total, forty 4-month old female Wistar Albino rats were assigned into 8 groups. Each group contained 5 rats. Group 1 (G1): rats were decapitated without any procedure. Group 2 (G2): rats were decapitated after 3 hours of total body irradiation. Group 3 (G3): rats were decapitated 3 hours after HSG procedure. Group 4 (G4): rats were decapitated 3 hours after HSG procedure performed 30 min after receiving amifostine 200 mg/kg intraperitoneally. Group 5 (G5): rats were decapitated after 1 month without any procedure. Group 6 (G6): rats were decapitated after 1 month of total body irradiation. Group 7 (G7): rats were decapitated 1 month after HSG procedure. Group 8 (G8): rats were decapitated 1 month after HSG procedure performed 30 min after receiving amifostine 200 mg/kg intraperitoneally. After rats were decapitated under general anesthesia in all groups, blood samples were obtained and bilateral ovaries were removed. One of the ovaries was placed in 10% formaldehyde solution for histological germinal epithelial degeneration, apoptosis and proliferating cell nuclear antigen scoring. The other ovary and blood sera were stored at −80°C. TNF-α, total antioxidant status, total oxidant status, and malondialdehyde levels were studied in tissue samples and anti-mullerian hormone levels in blood samples.

Results

At the end of the first month, there was significant ovarian germinal epithelium degeneration. Proliferating cell nuclear antigen immunoreactivity was significantly reduced in all other groups when compared with G1 and G5.

Conclusion

In conclusion, amifostine could significantly reduce the ovarian cellular injury induced by HSG.

Very low doses of heavy oxygen ion radiation induce premature ovarian failure

Astronauts are exposed to charged particles during space travel, and charged particles are also used for cancer radiotherapy. Premature ovarian failure is a well-known side effect of conventional, low linear energy transfer (LET) cancer radiotherapy, but little is known about the effects of high LET charged particles on the ovary. We hypothesized that lower LET (16.5 keV/µm) oxygen particles would be less damaging to the ovary than we previously found for iron (LET = 179 keV/µm). Adult female mice were irradiated with 0, 5, 30 or 50 cGy oxygen ions or 50 cGy oxygen plus dietary supplementation with the antioxidant alpha lipoic acid (ALA). Six-hour after irradiation, percentages of ovarian follicles immunopositive for γH2AX, a marker of DNA double strand breaks, 4-HNE, a marker of oxidative lipid damage and BBC3 (PUMA), a proapoptotic BCL-2 family protein, were dose dependently increased in irradiated mice compared to controls. One week after irradiation, numbers of primordial, primary and secondary follicles per ovary were dose dependently decreased, with complete absence of follicles in the 50 cGy groups. The ED₅₀ for primordial follicle destruction was 4.6 cGy for oxygen compared to 27.5 cGy for iron in our previous study. Serum FSH and LH concentrations were significantly elevated in 50 cGy groups at 8 week. Supplementation with ALA mitigated the early effects, but not the ultimate depletion of ovarian follicles. In conclusion, oxygen charged particles are even more potent inducers of ovarian follicle depletion than charged iron particles, raising concern for premature ovarian failure in astronauts exposed to both particles during space travel.

Charged iron particles, components of space radiation, destroy ovarian follicles

STUDY QUESTION

Do charged iron particles, components of space radiation, cause premature ovarian failure?

SUMMARY ANSWER

Exposure to charged iron particles causes ovarian DNA damage, oxidative damage and apoptosis, resulting in premature ovarian failure.

WHAT IS KNOWN ALREADY

The ovary is very sensitive to follicle destruction by low linear energy transfer (LET) radiation, such as X-rays and γ-rays. However, it is completely unknown whether high-LET radiation, such as charged iron particles, also destroys ovarian follicles.

STUDY DESIGN, SIZE, DURATION

Twelve week old C57BL/6J female mice were exposed to single doses of 0, 5, 30 or 50 cGy (n = 8/group) charged iron particles (LET = 179 keV/µm) at energy of 600 MeV/u. Two groups were irradiated at the highest dose, one fed AIN-93M chow and the other fed AIN-93M chow supplemented with 150 mg/kg diet alpha lipoic acid (ALA).

PARTICIPANTS/MATERIALS, SETTING, METHODS

We quantified the numbers of ovarian follicles, measured serum follicle stimulating hormone (FSH) and luteinizing hormone (LH) concentrations, and analyzed histone H2AX phosphorylation, oxidative damage and apoptosis markers in the ovarian follicles.

MAIN RESULTS AND THE ROLE OF CHANCE

H2AX phosphorylation, lipid peroxidation, protein nitration and apoptosis were highly induced in ovarian follicles at 6 h and remained increased 1 week after irradiation. As a result, numbers of healthy ovarian follicles were significantly and dose-dependently depleted at 1 and 8 weeks post-irradiation, with 57, 84 and 99% decreases in primordial follicles at 8 weeks at the 5, 30 and 50 cGy doses, respectively (P < 0.05 versus 0 cGy). Consistent with near-total depletion of ovarian follicles in the 50 cGy group, serum concentrations of FSH and LH were significantly elevated at 8 weeks. Dietary supplementation with ALA partially prevented the adverse ovarian effects of 50 cGy iron particles.

LIMITATIONS, REASONS FOR CAUTION

About 21% of the estimated radiation dose from exposure to galactic cosmic rays during a multi-year Mars mission will be due to high-LET particles, of which iron is only one. The effects of galactic cosmic rays, which contain a mixture of multiple charged particles, as well as protons, neutrons, and helium ions, may differ from the effects of iron alone.

WIDER IMPLICATIONS OF THE FINDINGS

We show for the first time that charged high-LET ions are highly damaging to the ovary even at low doses, causing premature ovarian failure. In addition to raising concerns for female astronauts, these findings raise concerns for ovarian damage due to clinical uses of high-LET particles for cancer treatment. In addition to causing infertility, premature ovarian failure has adverse implications for the functions of heart, brain, bone and muscle later in life.

STUDY FUNDING/COMPETING INTERESTS

This work was supported by a National Aeronautics and Space Administration grant NNX14AC50G to U.L. B.M. was partially supported by a National Space Biomedical Research Institute First Award, PF04302. Additional support was received from the University of California Irvine Center for Occupational and Environmental Health. The authors have no conflicts of interests.

Metabolic changes in serum steroids induced by total-body irradiation of female C57B/6 mice

The short- and long-term effects of a single exposure to gamma radiation on steroid metabolism were investigated in mice. Gas chromatography-mass spectrometry was used to generate quantitative profiles of serum steroid levels in mice that had undergone total-body irradiation (TBI) at doses of 0Gy, 1Gy, and 4Gy. Following TBI, serum samples were collected at the pre-dose time point and 1, 3, 6, and 9 months after TBI. Serum levels of progestins, progesterone, 5β-DHP, 5α-DHP, and 20α-DHP showed a significant down-regulation following short-term exposure to 4Gy, with the exception of 20α-DHP, which was significantly decreased at each of the time points measured. The corticosteroids 5α-THDOC and 5α-DHB were significantly elevated at each of the time points measured after exposure to either 1 or 4Gy. Among the sterols, 24S-OH-cholestoerol showed a dose-related elevation after irradiation that reached significance in the high dose group at the 6- and 9-month time points.

The role of ionizing radiaton on ovulation rate and oocyte morphology in mouse

We investigated the effects of ionizing radiation on maturation ability and radiosensitivity of oocytes enclosed in preantral and antral follicles. Balb/c female mice received total body single dose gamma radiation (7.2 Gy) at the diestrous to proestrous transition period. In the first experiment, spontaneously ovulated oocytes were collected from irradiated animals. In the second experiment, irradiated animals were allowed to superovulate to assess the ovarian function. The spontaneous ovulation rate of the follicles exposed at antral stage was significantly lower than the sham-irradiated mice (p < 0.01), and most of the oocytes were found at the metaphase I stage. Oocyte morphology and the ovulation rate of the follicles exposed at preantral stage were similar to the sham-irradiated group. Minimal morphological abnormalities were observed in the oocytes and the polar body as well. The superovulation response of all the irradiated animals was lower than the respective control animals. The superovulation rate was significantly lower in the first ovulation after irradiation (p < 0.01). In conclusion, our findings indicate that total body gamma irradiation, on a basis of estrous cycle stages, leads to ovulation failure in the antral stage while causes abnormal oocyte morphology in the preantral stage follicles in mice.

Antiapoptotic and proliferative activity of curcumin on ovarian follicles in mice exposed to whole body ionizing radiation

The aim of this study was to evaluate the antiapoptotic and proliferative activity of curcumin (Cur) on the ovarian follicles in mice exposed to whole body ionizing radiation (Rd). The mice were exposed to 8.3 gray whole body Rd, and Cur groups were given as a daily dose of 100 mg/kg of Cur for 10 days (10 days before Rd). The ovaries were collected 3 and 12 h after irradiation. To date, no such studies have been performed on antiapoptotic and proliferative activity of Cur on the ovarian follicles in mice exposed to whole body Rd. Analysis of mice ovary after exposure to Rd by terminal-deoxynucleotidyl-transferase-mediated dUTP nick end labeling showed that there were apoptotic cells both in the follicular wall and the antrum, and that the number of follicles showing early atresic features was high 3 h after Rd. On the other hand, analysis of mice ovary 12 h after exposure to Rd showed that the number of follicles containing apoptotic cells with advanced atresic features was significantly higher when compared to the 3-h Rd exposure group. The proliferating cell nuclear antigen -positive granulosa cells were decreased in association with follicular atresia. The groups given treatment were observed to have some benefit from Cur against the damage caused by Rd. The results of this study demonstrate that Cur prevents follicular atresia in Rd-induced apoptosis in ovarian follicles.

Xenobiotic effects on ovarian preantral follicles

Women are born with a finite population of ovarian follicles, which are slowly depleted during their reproductive years until reproductive failure (menopause) occurs. The rate of loss of primordial follicles is determined by genetic and environmental influences, but certain toxic exposures can accelerate this process. Ionizing radiation reduces preantral follicle numbers in rodents and humans in a dose-dependent manner. Cigarette smoking is linked to menopause occurring 1-4 yr earlier than with nonsmokers, and components of smoke, polycyclic aromatic hydrocarbons, can cause follicle depletion in rodents or in ovaries in vitro. Chemotherapeutic agents, such as alkylating drugs and cisplatin, also cause loss of preantral ovarian follicles. Effects depend on dose, type, and reactivity of the drug, and the age of the individual. Evidence suggests DNA damage may underlie follicle loss induced by one common alkylating drug, cyclophosphamide. Occupational exposures have also been linked to ovarian damage. In an industrial setting, 2-bromopropane caused infertility in men and women, and it can induce ovarian follicle depletion in rats. Solvents, such as butadiene, 4-vinylcyclohexene, and their diepoxides, can also cause specific preantral follicle depletion. The mechanism(s) underlying effects of the latter compound may involve alterations in apoptosis, survival factors such as KIT/Kit Ligand, and/or the cellular signaling that maintains primordial follicle dormancy. Estrogenic endocrine disruptors may alter follicle formation/development and impair fertility or normal development of offspring. Thus, specific exposures are known or suspected of detrimentally impacting preantral ovarian follicles, leading to early ovarian failure.

Associations of ionizing radiation and breast cancer-related serum hormone and growth factor levels in cancer-free female A-bomb survivors

Levels of exposure to ionizing radiation are increasing for women worldwide due to the widespread use of CT and other radiologic diagnostic modalities. Exposure to ionizing radiation as well as increased levels of estradiol and other sex hormones are acknowledged breast cancer risk factors, but the effects of whole-body radiation on serum hormone levels in cancer-free women are unknown. This study examined whether ionizing radiation exposure is associated with levels of serum hormones and other markers that may mediate radiation-associated breast cancer risk. Serum samples were measured from cancer-free women who attended biennial health examinations with a wide range of past radiation exposure levels (N  =  412, ages 26-79). The women were selected as controls for separate case-control studies from a cohort of A-bomb survivors. Outcome measures included serum levels of total estradiol, bioavailable estradiol, testosterone, progesterone, prolactin, insulin-like growth factor-1 (IGF1), insulin-like growth factor-binding protein 3 (IGFBP-3), and ferritin. Relationships were assessed using repeated-measures regression models fitted with generalized estimating equations. Geometric mean serum levels of total estradiol and bioavailable estradiol increased with 1 Gy of radiation dose among samples collected from postmenopausal women (17%(1Gy), 95% CI: 1%-36% and 21%(1Gy), 95% CI: 4%-40%, respectively), while they decreased in samples collected from premenopausal women (-11%(1Gy), 95% CI: -20%-1% and -12%(1Gy), 95% CI: -20%- -2%, respectively). Interactions by menopausal status were significant (P  =  0.003 and P < 0.001, respectively). Testosterone levels increased with radiation dose in postmenopausal samples (30.0%(1Gy), 95% CI: 13%-49%) while they marginally decreased in premenopausal samples (-10%(1Gy), 95% CI: -19%-0%) and the interaction by menopausal status was significant (P < 0.001). Serum levels of IGF1 increased linearly with radiation dose (11%(1Gy), 95% CI: 2%-18%) and there was a significant interaction by menopausal status (P  =  0.014). Radiation-associated changes in serum levels of estradiol, bioavailable estradiol, testosterone and IGF1 were modified by menopausal status at the time of collection. No associations with radiation were observed in serum levels of progesterone, prolactin, IGFBP-3 or ferritin.

Overexpression of glutamate-cysteine ligase protects human COV434 granulosa tumour cells against oxidative and gamma-radiation-induced cell death

Ionizing radiation is toxic to ovarian follicles and can cause infertility. Generation of reactive oxygen species (ROS) has been implicated in the toxicity of ionizing radiation in several cell types. We have shown that depletion of the antioxidant glutathione (GSH) sensitizes follicles and granulosa cells to toxicant-induced apoptosis and that supplementation of GSH is protective. The rate-limiting reaction in GSH biosynthesis is catalysed by glutamate-cysteine ligase (GCL), which consists of a catalytic subunit (GCLC) and a regulatory subunit (GCLM). We hypothesized that overexpression of Gclc or Gclm to increase GSH synthesis would protect granulosa cells against oxidant- and radiation-induced cell death. The COV434 line of human granulosa tumour cells was stably transfected with vectors designed for the constitutive expression of Gclc, Gclm, both Gclc and Gclm or empty vector. GCL protein and enzymatic activity and total GSH levels were significantly increased in the GCL subunit-transfected cells. GCL-transfected cells were resistant to cell killing by treatment with hydrogen peroxide compared to control cells. Cell viability declined less in all the GCL subunit-transfected cell lines 1-8 h after 0.5 mM hydrogen peroxide treatment than in control cells. We next examined the effects of GCL overexpression on responses to ionizing radiation. ROS were measured using a redox-sensitive fluorogenic dye in cells irradiated with 0, 1 or 5 Gy of gamma-rays. There was a dose-dependent increase in ROS within 30 min in all cell lines, an effect that was significantly attenuated in Gcl-transfected cells. Apoptosis, assessed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling and activated caspase-3 immunoblotting, was significantly decreased in irradiated Gclc-transfected cells compared to irradiated control cells. Suppression of GSH synthesis in Gclc-transfected cells reversed resistance to radiation. These findings show that overexpression of GCL in granulosa cells can augment GSH synthesis and ameliorate various sequelae associated with exposure to oxidative stress and irradiation.

Ovarian expression of p53 and p21 apoptosis regulators in gamma-irradiated mice

Ovarian follicular degeneration is accelerated by gamma-radiation. To investigate the precise radiation-induced cellular and molecular biological changes in the ovary, prepubertal mice were whole-body irradiated with 6.94 Gy, which is the 30% of the lethal dose of gamma-radiation using a (60)Co source. At 0, 3, 6, 12, and 24 hr after irradiation, ovarian expression of p53 and p21 mRNA and protein were analyzed by reverse-transcription polymerase chain reaction and immunoblotting, respectively. Immunohistochemical localization of p53 and p21 antigens was also carried out. Immunoreactive p53 and p21 were expressed in the nuclei of granulosa cells, but were not detected on the theca. In control mouse ovaries, p21 was weakly expressed on granulosa but not on the theca cells. In gamma-irradiated mouse ovaries, however, immunoreactive p21 proteins were detected in the nuclei of follicular granulosa cells. After irradiation expression of p53 and p21 mRNA and protein was significantly increased compared to beta-actin. Taken together, these observations suggest that p53 and p21 are actively involved in gamma-radiation-induced follicular degeneration in the prepubertal mouse ovary.