Exposure to environmentally relevant concentrations of ambient fine particulate matter (PM2.5) depletes the ovarian follicle reserve and causes sex-dependent cardiovascular changes in apolipoprotein E null mice.

BACKGROUND: Fine particulate matter (PM2.5) exposure accelerates atherosclerosis and contains known ovotoxic chemicals. However, effects of exposure to PM2.5 on the finite ovarian follicle pool have hardly been investigated, nor have interactions between ovarian and cardiovascular effects. We hypothesized that subchronic inhalation exposure to human-relevant concentrations of PM2.5 results in destruction of ovarian follicles via apoptosis induction, as well as accelerated recruitment of primordial follicles into the growing pool. Further, we hypothesized that destruction of ovarian follicles enhances the adverse cardiovascular effects of PM2.5 in females. RESULTS: Hyperlipidemic apolipoprotein E (Apoe) null ovary-intact or ovariectomized female mice and testis-intact male mice were exposed to concentrated ambient PM2.5 or filtered air for 12 weeks, 5 days/week for 4 h/day using a versatile aerosol concentration enrichment system. Primordial, primary, and secondary ovarian follicle numbers were decreased by 45%, 40%, and 17%, respectively, in PM2.5-exposed ovary-intact mice compared to controls (P < 0.05). The percentage of primary follicles with granulosa cells positive for the mitosis marker Ki67 was increased in the ovaries from PM2.5-exposed females versus controls (P < 0.05), consistent with increased recruitment of primordial follicles into the growing pool. Exposure to PM2.5 increased the percentages of primary and secondary follicles with DNA damage, assessed by γH2AX immunostaining (P < 0.05). Exposure to PM2.5 increased the percentages of apoptotic antral follicles, determined by TUNEL and activated caspase 3 immunostaining (P < 0.05). Removal of the ovaries and PM2.5-exposure exacerbated the atherosclerotic effects of hyperlipidemia in females (P < 0.05). While there were statistically significant changes in blood pressure and heart rate variability in PM2.5-compared to Air-exposed gonad-intact males and females and ovariectomized females, the changes were not consistent between exposure years and assessment methods. CONCLUSIONS: These results demonstrate that subchronic PM2.5 exposure depletes the ovarian reserve by increasing recruitment of primordial follicles into the growing pool and increasing apoptosis of growing follicles. Further, PM2.5 exposure and removal of the ovaries each increase atherosclerosis progression in Apoe-/- females. Premature loss of ovarian function is associated with increased risk of osteoporosis, cardiovascular disease and Alzheimer's disease in women. Our results thus support possible links between PM2.5 exposure and other adverse health outcomes in women.

NRF2/ARE pathway negatively regulates BACE1 expression and ameliorates cognitive deficits in mouse Alzheimer's models.

BACE1 is the rate-limiting enzyme for amyloid-ß peptides (Aß) generation, a key event in the pathogenesis of Alzheimer's disease (AD). By an unknown mechanism, levels of BACE1 and a BACE1 mRNA-stabilizing antisense RNA (BACE1-AS) are elevated in the brains of AD patients, implicating that dysregulation of BACE1 expression plays an important role in AD pathogenesis. We found that nuclear factor erythroid-derived 2-related factor 2 (NRF2/NFE2L2) represses the expression of BACE1 and BACE1-AS through binding to antioxidant response elements (AREs) in their promoters of mouse and human. NRF2-mediated inhibition of BACE1 and BACE1-AS expression is independent of redox regulation. NRF2 activation decreases production of BACE1 and BACE1-AS transcripts and Aß production and ameliorates cognitive deficits in animal models of AD. Depletion of NRF2 increases BACE1 and BACE1-AS expression and Aß production and worsens cognitive deficits. Our findings suggest that activation of NRF2 can prevent a key early pathogenic process in AD.

Antioxidant supplementation partially rescues accelerated ovarian follicle loss, but not oocyte quality, of glutathione-deficient mice†.

The tripeptide thiol antioxidant glutathione (GSH) has multiple physiological functions. Female mice lacking the modifier subunit of glutamate cysteine ligase (GCLM), the rate-limiting enzyme in GSH synthesis, have decreased GSH concentrations, ovarian oxidative stress, preimplantation embryonic mortality, and accelerated age-related decline in ovarian follicles. We hypothesized that supplementation with thiol antioxidants, N-acetyl cysteine (NAC), or α-lipoic acid (ALA) will rescue this phenotype. Gclm-/- and Gclm+/+ females received 0 or 80 mM NAC in drinking water from postnatal day (PND) 21-30; follicle growth was induced with equine chorionic gonadotropin (eCG) on PND 27, followed by an ovulatory dose of human CG and mating with a wild type male on PND 29 and zygote harvest 20 h after hCG. N-acetyl cysteine supplementation failed to rescue the low rate of second pronucleus formation in zygotes from Gclm-/- versus Gclm+/+ females. In the second study, Gclm-/- and Gclm+/+ females received diet containing 0, 150, or 600 mg/kg ALA beginning at weaning and were mated with wild type males from 8 to 20 weeks of age. α-Lipoic acid failed to rescue the decreased offspring production of Gclm-/- females. However, 150 mg/kg diet ALA partially rescued the accelerated decline in primordial follicles, as well as the increased recruitment of follicles into the growing pool and the increased percentages of follicles with γH2AX positive oocytes or granulosa cells of Gclm-/- females. We conclude that ovarian oxidative stress is the cause of accelerated primordial follicle decline, while GSH deficiency per se may be responsible for preimplantation embryonic mortality in Gclm-/- females.

Glutathione deficiency sensitizes cultured embryonic mouse ovaries to benzo[a]pyrene-induced germ cell apoptosis.

Mice lacking the modifier subunit of glutamate cysteine ligase (Gclm), the rate-limiting enzyme in glutathione (GSH) synthesis, have decreased tissue GSH. We previously showed that Gclm-/- embryos have increased sensitivity to the prenatal in vivo ovarian toxicity of the polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP) compared with Gclm+/+ littermates. We also showed that BaP-induced germ cell death in cultured wild type embryonic ovaries is caspase-dependent. Here, we hypothesized that GSH deficiency increases sensitivity of cultured embryonic ovaries to BaP-induced germ cell death. 13.5 days post coitum (dpc) embryonic ovaries of all Gclm genotypes were fixed immediately or cultured for 24 h in media supplemented with DMSO vehicle or 500 ng/ml BaP. The percentage of activated caspase-3 positive germ cells varied significantly among groups. Within each genotype, DMSO and BaP-treated groups had increased germ cell caspase-3 activation compared to uncultured. Gclm+/- ovaries had significantly increased caspase-3 activation with BaP treatment compared to DMSO, and caspase-3 activation increased non-significantly in Gclm-/- ovaries treated with BaP compared to DMSO. There was no statistically significant effect of BaP treatment on germ cell numbers at 24 h, consistent with our prior observations in wild type ovaries, but Gclm-/- ovaries in both cultured groups had lower germ cell numbers than Gclm+/+ ovaries. There were no statistically significant BaP-treatment or genotype-related differences among groups in lipid peroxidation and germ cell proliferation. These data indicate that Gclm heterozygous or homozygous deletion sensitizes embryonic ovaries to BaP- and tissue culture-induced germ cell apoptosis.

Phytocannabinoids, the Endocannabinoid System and Male Reproduction.

The endocannabinoid system (ECS) is comprised of a set of lipid-derived messengers (the endocannabinoids, ECBs), proteins that control their production and degradation, and cell-surface cannabinoid (CB) receptors that transduce their actions. ECB molecules such as 2-arachidonoyl-sn-glycerol (2-AG) and anandamide (arachidonoyl ethanolamide) are produced on demand and deactivated through enzymatic actions tightly regulated both temporally and spatially, serving homeostatic roles in order to respond to various challenges to the body. Key components of the ECS are present in the hypothalamus-pituitary-gonadal (HPG) axis, which plays critical roles in the development and regulation of the reproductive system in both males and females. ECB signaling controls the action at each stage of the HPG axis through CB receptors expressed in the hypothalamus, pituitary, and reproductive organs such as the testis and ovary. It regulates the secretion of hypothalamic gonadotropin-releasing hormone (GnRH), pituitary follicle-stimulating hormone (FSH) and luteinizing hormone (LH), estrogen, testosterone, and affects spermatogenesis in males. Δ9-tetrahydrocannabinol (THC) and other phytocannabinoids from Cannabis sativa affect a variety of physiological processes by altering, or under certain conditions hijacking, the ECB system. Therefore, phytocannabinoids, in particular THC, may modify the homeostasis of the HPG axis by altering CB receptor signaling and cause deficits in reproductive function. While the ability of phytocannabinoids, THC and/or cannabidiol (CBD), to reduce pain and inflammation provides promising opportunities for therapeutic intervention for genitourinary and degenerative disorders, important questions remain regarding their unwanted long-term effects. It is nevertheless clear that the therapeutic potential of modulating the ECS calls for further scientific and clinical investigation.

Adolescent exposure to low-dose Δ9-tetrahydrocannabinol depletes the ovarian reserve in female mice.

Cannabis use by adolescents is widespread, but its effects on the ovaries remain largely unknown. Δ9-tetrahydrocannabinol (THC) exerts its pharmacological effects by activating, and in some conditions hijacking, cannabinoid receptors (CBRs). We hypothesized that adolescent exposure to THC affects ovarian function in adulthood. Peripubertal female C57BL/6N mice were given THC (5 mg/kg) or its vehicle, once daily by intraperitoneal injection. Some mice received THC from postnatal day (PND) 30-33 and their ovaries were harvested PND34; other mice received THC from PND30-43, and their ovaries were harvested PND70. Adolescent treatment with THC depleted ovarian primordial follicle numbers by 50% at PND70, 4 weeks after the last dose. The treatment produced primordial follicle activation, which persisted until PND70. THC administration also caused DNA damage in primary follicles and increased PUMA protein expression in oocytes of primordial and primary follicles. Both CB1R and CB2R were expressed in oocytes and theca cells of ovarian follicles. Enzymes involved in the formation (N-acylphosphatidylethanolamine phospholipase D) or deactivation (fatty acid amide hydrolase) of the endocannabinoid anandamide were expressed in granulosa cells of ovarian follicles and interstitial cells. Levels of mRNA for CBR1 were significantly increased in ovaries after adolescent THC exposure, and upregulation persisted for at least 4 weeks. Our results support that adolescent exposure to THC may cause aberrant activation of the ovarian endocannabinoid system in female mice, resulting in substantial loss of ovarian reserve in adulthood. Relevance of these findings to women who frequently used cannabis during adolescence warrants investigation.

Prenatal exposure to benzo[a]pyrene depletes ovarian reserve and masculinizes embryonic ovarian germ cell transcriptome transgenerationally.

People are widely exposed to polycyclic aromatic hydrocarbons, like benzo[a]pyrene (BaP). Prior studies showed that prenatal exposure to BaP depletes germ cells in ovaries, causing earlier onset of ovarian senescence post-natally; developing testes were affected at higher doses than ovaries. Our primary objective was to determine if prenatal BaP exposure results in transgenerational effects on ovaries and testes. We orally dosed pregnant germ cell-specific EGFP-expressing mice (F0) with 0.033, 0.2, or 2 mg/kg-day BaP or vehicle from embryonic day (E) 6.5-11.5 (F1 offspring) or E6.5-15.5 (F2 and F3). Ovarian germ cells at E13.5 and follicle numbers at postnatal day 21 were significantly decreased in F3 females at all doses of BaP; testicular germ cell numbers were not affected. E13.5 germ cell RNA-sequencing revealed significantly increased expression of male-specific genes in female germ cells across generations and BaP doses. Next, we compared the ovarian effects of 2 mg/kg-day BaP dosing to wild type C57BL/6J F0 dams from E6.5-11.5 or E12.5-17.5. We observed no effects on F3 ovarian follicle numbers with either of the shorter dosing windows. Our results demonstrate that F0 BaP exposure from E6.5-15.5 decreased the number of and partially disrupted transcriptomic sexual identity of female germ cells transgenerationally.

Sex Differences in Embryonic Gonad Transcriptomes and Benzo[a]pyrene Metabolite Levels After Transplacental Exposure.

Polycyclic aromatic hydrocarbons like benzo[a]pyrene (BaP) are generated during incomplete combustion of organic materials. Prior research has demonstrated that BaP is a prenatal ovarian toxicant and carcinogen. However, the metabolic pathways active in the embryo and its developing gonads and the mechanisms by which prenatal exposure to BaP predisposes to ovarian tumors later in life remain to be fully elucidated. To address these data gaps, we orally dosed pregnant female mice with BaP from embryonic day (E) 6.5 to E11.5 (0, 0.2, or 2 mg/kg/day) for metabolite measurement or E9.5 to E11.5 (0 or 3.33 mg/kg/day) for embryonic gonad RNA sequencing. Embryos were harvested at E13.5 for both experiments. The sum of BaP metabolite concentrations increased significantly with dose in the embryos and placentas, and concentrations were significantly higher in female than male embryos and in embryos than placentas. RNA sequencing revealed that enzymes involved in metabolic activation of BaP are expressed at moderate to high levels in embryonic gonads and that greater transcriptomic changes occurred in the ovaries in response to BaP than in the testes. We identified 490 differentially expressed genes (DEGs) with false discovery rate P-values < 0.05 when comparing BaP-exposed to control ovaries but no statistically significant DEGs between BaP-exposed and control testes. Genes related to monocyte/macrophage recruitment and activity, prolactin family genes, and several keratin genes were among the most upregulated genes in the BaP-exposed ovaries. Results show that developing ovaries are more sensitive than testes to prenatal BaP exposure, which may be related to higher concentrations of BaP metabolites in female embryos.

Oxidative damage increases and antioxidant gene expression decreases with aging in the mouse ovary.

Oxidative stress has been implicated in various aspects of aging, but the role of oxidative stress in ovarian aging remains unclear. Our previous studies have shown that the initiation of apoptotic cell death in ovarian follicles and granulosa cells by various stimuli is initiated by increased reactive oxygen species. Herein, we tested the hypothesis that ovarian antioxidant defenses decrease and oxidative damage increases with age in mice. Healthy, wild-type C57BL/6 female mice aged 2, 6, 9, or 12 mo from the National Institute on Aging Aged Rodent Colony were killed on the morning of metestrus. Quantitative real-time RT-PCR was used to measure ovarian mRNA levels of antioxidant genes. Immunostaining using antibodies directed against 4-hydroxynonenal (4-HNE), nitrotyrosine (NTY), and 8-hydroxy-2'-deoxyguanosine (8-OHdG) was used to localize oxidative lipid, protein, and DNA damage, respectively, within the ovaries. TUNEL was used to localize apoptosis. Ovarian expression of glutathione peroxidase 1 (Gpx1) increased and expression of glutaredoxin 1 (Glrx1), glutathione S-transferase mu 2 (Gstm2), peroxiredoxin 3 (Prdx3), and thioredoxin 2 (Txn2) decreased in a statistically significant manner with age. Statistically significant increases in 4-HNE, NTY, and 8-OHdG immunostaining in ovarian interstitial cells and follicles were observed with increasing age. Our data suggest that the decrease in mRNA expression of mitochondrial antioxidants Prdx3 and Txn2 as well as cytosolic antioxidants Glrx1 and Gstm2 may be involved in age-related ovarian oxidative damage to lipid, protein, DNA, and other cellular components vital for maintaining ovarian function and fertility.

Effect of Thermal Cycling on Transformation Behavior of Ti-24Nb-1Mo Alloy (at.%).

The effect of thermal cycling on the transformation behavior of a Ti-24Nb-1Mo alloy was investigated by means of electrical resistivity measurement, transmission electron microscopy (TEM), X-ray diffraction (XRD), tensile test and Vickers hardness tests. Electrical resistivity changes were not observed in all alloys. It indicates that thermally induced martensitic transformation does not take place in the alloys. After thermal cycling between 298 K and 77 K, clear X-ray diffraction peaks corresponding to ωath phase, which did not exist before thermal cycling, were observed. Volume fraction of ωath phase increased as increasing the number of thermal cycling. ωath phase formed during thermal cycling increased hardness of the alloy. Although thermally induced martensitic transformation did not occur in the alloys, superelastic deformation behavior was observed in the alloys. The superelastic recovery ratio decreased from 81% to 41% by increasing the number of thermal cycling, which came from the increase in the volume fraction of ωath phase.

Effects of low-level light therapy on hepatic antioxidant defense in acute and chronic diabetic rats.

Diabetes causes oxidative stress in the liver and other tissues prone to complications. Photobiomodulation by near infrared light (670 nm) has been shown to accelerate diabetic wound healing, improve recovery from oxidative injury in the kidney, and attenuate degeneration in retina and optic nerve. The present study tested the hypothesis that 670 nm photobiomodulation, a low-level light therapy, would attenuate oxidative stress and enhance the antioxidant protection system in the liver of a model of type I diabetes. Male Wistar rats were made diabetic with streptozotocin (50 mg/kg, ip) then exposed to 670 nm light (9 J/cm(2)) once per day for 18 days (acute) or 14 weeks (chronic). Livers were harvested, flash frozen, and then assayed for markers of oxidative stress. Light treatment was ineffective as an antioxidant therapy in chronic diabetes, but light treatment for 18 days in acutely diabetic rats resulted in the normalization of hepatic glutathione reductase and superoxide dismutase activities and a significant increase in glutathione peroxidase and glutathione-S transferase activities. The results of this study suggest that 670 nm photobiomodulation may reduce, at least in part, acute hepatic oxidative stress by enhancing the antioxidant defense system in the diabetic rat model.

Attenuation of TCDD-induced oxidative stress by 670 nm photobiomodulation in developmental chicken kidney.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a potent developmental teratogen inducing oxidative stress and sublethal changes in multiple organs, provokes developmental renal injuries. In this study, we investigated TCDD-induced biochemical changes and the therapeutic efficacy of photobiomodulation (670 nm; 4 J/cm(2)) on oxidative stress in chicken kidneys during development. Eggs were injected once prior to incubation with TCDD (2 pg/g or 200 pg/g) or sunflower oil vehicle control. Half of the eggs in each dose group were then treated with red light once per day through embryonic day 20 (E20). Upon hatching at E21, the kidneys were collected and assayed for glutathione peroxidase, glutathione reductase, catalase, superoxide dimutase, and glutathione-S-transferase activities, as well as reduced glutathione and ATP levels, and lipid peroxidation. TCDD exposure alone suppressed the activity of the antioxidant enzymes, increased lipid peroxidation, and depleted available ATP. The biochemical indicators of oxidative and energy stress in the kidney were reversed by daily phototherapy, restoring ATP and glutathione contents and increasing antioxidant enzyme activities to control levels. Photobiomodulation also normalized the level of lipid peroxidation increased by TCDD exposure. The results of this study suggest that 670 nm photobiomodulation may be useful as a noninvasive treatment for renal injury resulting from chemically induced cellular oxidative and energy stress.

Survivorship and mortality implications of developmental 670-nm phototherapy: dioxin co-exposure.

OBJECTIVE: We assessed the effect of 670-nm light therapy on dioxin-induced embryonic mortality in chickens (Gallus gallus). BACKGROUND DATA: Developmental photobiomodulation using 670-nm light-emitting diode (LED) arrays improves hatching success and increases body size in hatchling chickens. Photobiomodulation also stimulates signaling pathways resulting in improved energy metabolism, antioxidant production and cell survival. Dioxin causes embryonic mortality, including increases in the frequency of chicken embryos that pip but can't go to hatch. We hypothesized that 670-nm LED therapy would attenuate dioxin-induced embryo mortality. METHODS: Fertile chicken eggs were injected with control or 2, 20, or 200 ppt 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD; dioxin) prior to the start of incubation. Half of the eggs in each dose group were treated once per day from embryonic days 0-20 with 670-nm LED light at a fluence of 4 J/cm(2). In ovo survival and hatching success were compared between dose groups and LED treatment. RESULTS: LED therapy decreased the embryonic mortality rate by 41%, resulting in increased embryonic survival and improved hatching success in eggs exposed to 200 ppt dioxin. However, at sub-lethal dioxin concentrations and in oil-treated controls, LED therapy slightly increased mortality. CONCLUSION: Overall survivorship and hatching success of chicks developmentally exposed to dioxin concentrations above the lethality threshold (>100 ppt TCDD) is improved by 670-nm LED treatment administered throughout the gestation period, but the relationship may be complicated by an LED-oil interaction.

Brief report: embryonic growth and hatching implications of developmental 670-nm phototherapy and dioxin co-exposure.

OBJECTIVE: We assessed the effect of 670-nm light therapy on growth and hatching kinetics in chickens (Gallus gallus) exposed to dioxin. BACKGROUND DATA: Photobiomodulation has been shown to stimulate signaling pathways resulting in improved energy metabolism, antioxidant production, and cell survival. In ovo treatment with 670-nm light-emitting diode (LED) arrays improves hatching success and increases hatchling size in control chickens. Under conditions where developmental dioxin exposure is above the lethality threshold (100 ppt), phototherapy attenuates dioxin-induced early embryonic death. We hypothesized that 670-nm LED therapy would attenuate dioxin-induced developmental anomalies and increase hatching success. METHODS: Fertile chicken eggs were injected with control oil, 2, 20, or 200 ppt dioxin, or 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) prior to the start of incubation. Half of the eggs in each dose group were treated once per day from embryonic days 0-20 with 670-nm LED light at a fluence of 4 J/cm2. Hatchling size, organ weights, and energy parameters were compared between dose groups and LED treatment. RESULTS: LED therapy resulted in earlier pip times (small hole created 12-24 h prior to hatch), and increased hatchling size and weight in the 200 ppt dose groups. However, there appears to be an LED-oil interaction within the oil-treated controls that results in longer hatch times and decreased liver weight within the LED control dose groups in comparison to the non-LED control dose groups. CONCLUSION: Size and hatching times suggest that the hatching success and preparedness of chicks developmentally exposed to dioxin concentrations above the lethality threshold is improved by 670-nm LED treatment administered throughout the gestation period, but the relationship may be complicated by an LED-oil interaction.

Clinical and experimental applications of NIR-LED photobiomodulation.

This review presents current research on the use of far-red to near-infrared (NIR) light treatment in various in vitro and in vivo models. Low-intensity light therapy, commonly referred to as "photobiomodulation," uses light in the far-red to near-infrared region of the spectrum (630-1000 nm) and modulates numerous cellular functions. Positive effects of NIR-light-emitting diode (LED) light treatment include acceleration of wound healing, improved recovery from ischemic injury of the heart, and attenuated degeneration of injured optic nerves by improving mitochondrial energy metabolism and production. Various in vitro and in vivo models of mitochondrial dysfunction were treated with a variety of wavelengths of NIR-LED light. These studies were performed to determine the effect of NIR-LED light treatment on physiologic and pathologic processes. NIRLED light treatment stimulates the photoacceptor cytochrome c oxidase, resulting in increased energy metabolism and production. NIR-LED light treatment accelerates wound healing in ischemic rat and murine diabetic wound healing models, attenuates the retinotoxic effects of methanol-derived formic acid in rat models, and attenuates the developmental toxicity of dioxin in chicken embryos. Furthermore, NIR-LED light treatment prevents the development of oral mucositis in pediatric bone marrow transplant patients. The experimental results demonstrate that NIR-LED light treatment stimulates mitochondrial oxidative metabolism in vitro, and accelerates cell and tissue repair in vivo. NIR-LED light represents a novel, noninvasive, therapeutic intervention for the treatment of numerous diseases linked to mitochondrial dysfunction.

The Mouse Fetal Ovary Has Greater Sensitivity Than the Fetal Testis to Benzo[a]pyrene-Induced Germ Cell Death.

The polycyclic aromatic hydrocarbon pollutant benzo[a]pyrene (BaP) is a known developmental gonadotoxicant. However, the mechanism of BaP-induced germ cell death is unclear. We investigated whether exposure to BaP induces apoptotic germ cell death in the mouse fetal ovary or testis. Mouse fetal gonads were dissected at embryonic day 13.5 days postcoitum (dpc) and fixed immediately or cultured for 6, 24, 48, or 72 h with various concentrations of BaP (1-1000 ng/ml). Germ cells numbers, apoptosis, and proliferation were evaluated by immunostaining. Treatment of fetal ovaries with BaP for 72 h concentration-dependently depleted germ cells. Treatment with BaP elevated the expression of BAX protein at 6 h and activated downstream caspases-9 and -3 at 24 h in a concentration-dependent manner in germ cells of fetal ovaries. As a consequence, ovarian germ cell numbers were significantly and concentration-dependently decreased at 48 h. Pretreatment with z-VAD-fmk, a pan-caspase inhibitor, prior to exposure to 1000 ng/ml BaP prevented BaP-mediated ovarian germ cell death; there were no effects of BaP or z-VAD-fmk on germ cell proliferation. No significant effects of BaP exposure on caspase 3 activation or germ cell numbers were observed in fetal testes after 48 h of culture. Our findings show that BaP exposure increases caspase-dependent and BAX-associated germ cell apoptosis in the mouse fetal ovary, leading to germ cell depletion. In contrast, the cultured 13.5 dpc fetal testis is relatively resistant to BaP-induced germ cell death. This study provides a novel insight into molecular mechanisms by which BaP has direct gonadotoxicity in the mouse fetal ovary.

Effects of 670-nm phototherapy on development.

OBJECTIVE: The objective of the present study was to assess the survival and hatching success of chickens (Gallus gallus) exposed in ovo to far-red (670-nm) LED therapy. BACKGROUND DATA: Photobiomodulation by light in the red to near-infrared range (630-1000 nm) using low-energy lasers or light-emitting diode (LED) arrays has been shown to accelerate wound healing and improve recovery from ischemic injury. The mechanism of photobiomodulation at the cellular level has been ascribed to the activation of mitochondrial respiratory chain components resulting in initiation of a signaling cascade that promotes cellular proliferation and cytoprotecton. MATERIALS AND METHODS: Fertile chicken eggs were treated once per day from embryonic days 0-20 with 670-nm LED light at a fluence of 4 J/cm2. In ovo survival and death were monitored by daily candling (after Day 4). RESULTS: We observed a substantial decrease in overall and third-week mortality rates in the light-treated chickens. Overall, there was approximately a 41.5% decrease in mortality rate in the light-treated chickens (NL: 20%; L: 11.8%). During the third week of development, there was a 68.8% decrease in the mortality rate in light-treated chickens (NL: 20%; L: 6.25%). In addition, body weight, crown-rump length, and liver weight increased as a result of the 670-nm phototherapy. Light-treated chickens pipped (broke shell) earlier and had a shorter duration between pip and hatch. CONCLUSION: These results indicate that 670-nm phototherapy by itself does not adversely affect developing embryos and may improve the hatching survival rate.

Glutamate Cysteine Ligase Modifier Subunit (Gclm) Null Mice Have Increased Ovarian Oxidative Stress and Accelerated Age-Related Ovarian Failure.

Glutathione (GSH) is the one of the most abundant intracellular antioxidants. Mice lacking the modifier subunit of glutamate cysteine ligase (Gclm), the rate-limiting enzyme in GSH synthesis, have decreased GSH. Our prior work showed that GSH plays antiapoptotic roles in ovarian follicles. We hypothesized that Gclm(-/-) mice have accelerated ovarian aging due to ovarian oxidative stress. We found significantly decreased ovarian GSH concentrations and oxidized GSH/oxidized glutathione redox potential in Gclm(-/-) vs Gclm(+/+) ovaries. Prepubertal Gclm(-/-) and Gclm(+/+) mice had similar numbers of ovarian follicles, and as expected, the total number of ovarian follicles declined with age in both genotypes. However, the rate of decline in follicles was significantly more rapid in Gclm(-/-) mice, and this was driven by accelerated declines in primordial follicles, which constitute the ovarian reserve. We found significantly increased 4-hydroxynonenal immunostaining (oxidative lipid damage marker) and significantly increased nitrotyrosine immunostaining (oxidative protein damage marker) in prepubertal and adult Gclm(-/-) ovaries compared with controls. The percentage of small ovarian follicles with increased granulosa cell proliferation was significantly higher in prepubertal and 2-month-old Gclm(-/-) vs Gclm(+/+) ovaries, indicating accelerated recruitment of primordial follicles into the growing pool. The percentages of growing follicles with apoptotic granulosa cells were increased in young adult ovaries. Our results demonstrate increased ovarian oxidative stress and oxidative damage in young Gclm(-/-) mice, associated with an accelerated decline in ovarian follicles that appears to be mediated by increased recruitment of follicles into the growing pool, followed by apoptosis at later stages of follicular development.

Effects of deletion of the transcription factor Nrf2 and benzo [a]pyrene treatment on ovarian follicles and ovarian surface epithelial cells in mice.

Polycyclic aromatic hydrocarbons, like benzo[a]pyrene (BaP), are ubiquitous environmental pollutants and potent ovarian toxicants. The transcription factor NRF2 is an important regulator of the cellular response to electrophilic toxicants like BaP and to oxidative stress. NRF2 regulates transcription of genes involved in the detoxification of reactive metabolites of BaP and reactive oxygen species. We therefore hypothesized that Nrf2-/- mice have accelerated ovarian aging and increased sensitivity to the ovarian toxicity of BaP. A single injection of BaP dose-dependently depleted ovarian follicles in Nrf2+/+ and Nrf2-/- mice, but the effects of BaP were not enhanced in the absence of Nrf2. Similarly, Nrf2-/- mice did not have increased ovarian BaP DNA adduct formation compared to Nrf2+/+ mice. Ovarian follicle numbers did not differ between peripubertal Nrf2-/- and Nrf2+/+ mice, but by middle age, Nrf2-/- mice had significantly fewer primordial follicles than Nrf2+/+ mice, consistent with accelerated ovarian aging.

Compositionally graded Ti-Ni alloys prepared by diffusion bonding.

A Ti-Ni alloy compositionally graded along the thickness direction in order to obtain a shape change over a wide temperature range, which is beneficial to the actuator for precise position control, was prepared by spark plasma sintering (SPS) after stacking Ti-Ni alloy ribbons in the sequence of Ti-51Ni, Ti-50Ni, Ti-49Ni and Ti-48Ni (at%) followed by annealing. Then, the microstructure and martensitic transformation behavior were investigated by using FE-SEM, DSC and thermal cycling tests under a constant load. The inter-ribbon defects observed after SPS due to insufficient diffusional bonding between the ribbons were eliminated by post-SPS annealing at 1023 K for 36 ks. The compositionally graded sample showed compositional variation of 1.5 at% Ti along the thickness direction (- 120 µm) and a martensitic transformation temperature window as large as 91 K on cooling and 79 K on heating. A recoverable elongation of 0.9% was obtained under a stress of 80 MPa and the deformation rate, which is defined as the ratio of the recoverable elongation to the temperature range where the elongation occurred was 0.015%/K in the compositionally graded sample.