Altered ovarian progesterone secretion induced by cadmium fails to interfere with embryo transport in the oviduct of the rat

Effects of Cadmium, Lead, and Mercury on the Structure and Function of Reproductive Organs

Reproductive organs are essential not only for the life of an individual but also for the survival and development of the species. The response of reproductive organs to toxic substances differs from that of other target organs, and they may serve as an ideal “barometer” for the deleterious effects of environmental pollution on animal and human health. The incidence of infertility, cancers, and associated maladies has increased in the last fifty years or more, while various anthropogenic activities have released into the environment numerous toxic substances, including cadmium, lead, and mercury. Data from epidemiological studies suggested that environmental exposure to cadmium, lead, and mercury may have produced reproductive and developmental toxicity. The present review focused on experimental studies using rats, mice, avian, and rabbits to demonstrate unambiguously effects of cadmium, lead, or mercury on the structure and function of reproductive organs. In addition, relevant human studies are discussed. The experimental studies reviewed have indicated that the testis and ovary are particularly sensitive to cadmium, lead, and mercury because these organs are distinguished by an intense cellular activity, where vital processes of spermatogenesis, oogenesis, and folliculogenesis occur. In ovaries, manifestation of toxicity induced by cadmium, lead, or mercury included decreased follicular growth, occurrence of follicular atresia, degeneration of the corpus luteum, and alterations in cycle. In testes, toxic effects following exposure to cadmium, lead, or mercury included alterations of seminiferous tubules, testicular stroma, and decrease of spermatozoa count, motility and viability, and aberrant spermatozoa morphology.

Blood Cadmium Concentrations in Women with Ectopic Pregnancy

The purpose of this study is to investigate the relationship between the blood level of cadmium and the occurrence of ectopic pregnancy. Forty-one (41) case patients with ectopic pregnancy and 41 uncomplicated intrauterine pregnant patients as controls were recruited. The concentrations of cadmium (Cd) were measured from blood samples using atomic absorption spectrometry. The cases and controls were similar in age, body mass index, and smoking habits. The median blood level of Cd was 0.32 μg/l (interquartile range [IQR] 0.00-0.71) in the women with ectopic pregnancies and 0.34 μg/l (IQR 0.09-0.59) in the controls. There was no significant association between blood cadmium levels and ectopic pregnancy.

Effect of cigarette smoking on human oviductal ciliation and ciliogenesis

OBJECTIVE

To investigate the effect of cigarette smoke exposure on ciliation and ciliogenesis in human oviductal epithelium.

DESIGN

Molecular analysis using human tubal segments.

SETTING

Academic medical center.

PATIENT(S)

Twenty women undergoing elective tubal sterilization procedure.

INTERVENTION(S)

Expression of ciliated cell-specific markers was compared in tubal segments from smokers and nonsmokers using quantitative immunohistochemistry and Western blot analysis. The expression of transcription factors in the motile ciliogenesis program was compared using quantitative polymerase chain reaction and quantitative immunohistochemistry.

MAIN OUTCOME MEASURE(S)

Oviductal ciliation and expression of transcription factors involved in ciliogenesis.

RESULT(S)

No significant differences were detected in density of ciliation between groups. Neither number of years of smoking nor pack-year history correlated with density of ciliation. Expression of ciliogenic transcription factors FOXJ1, RFX2, and RFX3 was consistent between groups.

CONCLUSION(S)

Few studies have evaluated the relationship between smoking and ciliated epithelium in human oviducts. Cigarette smoking does not seem to result in quantitative differences in the density of ciliation nor expression of ciliogenesis factors. Our findings suggest that pathophysiologic mechanisms other than ciliation account for the increased risk of ectopic pregnancy in women who smoke.

Cadmium associated with inhaled cadmium oxide nanoparticles impacts fetal and neonatal development and growth

One industrially important metal oxide nanoparticle (NP) is cadmium oxide (CdO). A study was performed using timed-pregnant CD-1 mice to determine if Cd associated with inhaled CdO NP could reach the placenta and adversely affect the developing fetus and/or neonate. Pregnant mice were exposed by inhalation either every other day to 100 μg of freshly generated CdO/m(3) (exposure 1) or daily to 230 μg CdO/m(3) (exposure 2). In each exposure, mice were exposed to CdO NP or carrier gas (control) for 2.5 h from 4.5 days post coitus (dpc) through 16.5 dpc. At 17.5 dpc, fetuses and placentas from both exposures 1 and 2 were collected, measured, and weighed. A subgroup from the second exposure was allowed to give birth, and neonates were weighed daily until weaning. Cadmium in the uterus and placenta, as well as in other maternal organs, was elevated in NP-treated mice, but was undetectable in fetuses at 17.5 dpc. Daily inhalation of 230 μg CdO NP/m(3) decreased the incidence of pregnancy (i.e., no evidence of implantation) by 23%, delayed maternal weight gain, altered placental weight, and decreased fetal length, as well as delayed neonatal growth. This study demonstrates that inhalation of CdO NP during pregnancy adversely affects reproductive fecundity and alters fetal and postnatal growth of the developing offspring.

Effect and mechanism of cadmium on the progesterone synthesis of ovaries

The paper presents results of the effect of cadmium on the progesterone synthesis of ovaries. In the current study, we investigated whether Cd also disrupts progesterone synthesis via steroidogenic acute regulatory protein (StAR) and P450 cholesterol side-chain cleavage (P450scc), which play important roles in progesterone synthesis. The Wistar rats were exposed to cadmium in vivo (at 2.5, 5, 7.5mg/kg, as a single s.c. dose). We showed that the serum P(4) and granule cells P(4) of rats were significantly lower than control group. Ovaries granule cells were incubated in Dulbecco-modified Eagle medium +15% fetal bovine serum with 0, 10, 20, or 40 microM CdCl(2) in vitro, progesterone levels were declined in a dose-dependent manner. Our data showed that the expression of StAR and P450scc in vivo or in vitro were inhibited when treated with CdCl(2) (p<0.05). Coculture with 8-bromo-cAMP enhanced progesterone secretion in untreated cultures and reversed the decline in progesterone secretion induced by CdCl(2) treatment; the expression of StAR mRNA and P450scc mRNA in 8-Br-cAMP+40 microM CdCl(2) were significantly higher than 40 microM CdCl(2), and were lower than control group. We concluded that StAR, which delivers cholesterol to the inner mitochondrial membrane, is one site at which Cd interferes with progesterone production in cultured rats ovarian granule cells; P450scc, which conveys cholesterol to pregnenolone, is anther site. The mechanisms were mainly controlled by the cAMP-dependent pathway.

Smoking and reproduction: the oviduct as a target of cigarette smoke

The oviduct is an exquisitely designed organ that functions in picking-up ovulated oocytes, transporting gametes in opposite directions to the site of fertilization, providing a suitable environment for fertilization and early development, and transporting preimplantation embryos to the uterus. A variety of biological processes can be studied in oviducts making them an excellent model for toxicological studies. This review considers the role of the oviduct in oocyte pick-up and embryo transport and the evidence that chemicals in both mainstream and sidestream cigarette smoke impair these oviductal functions. Epidemiological data have repeatedly shown that women who smoke are at increased risk for a variety of reproductive problems, including ectopic pregnancy, delay to conception, and infertility. In vivo and in vitro studies indicate the oviduct is targeted by smoke components in a manner that could explain some of the epidemiological data. Comparisons between the toxicity of smoke from different types of cigarettes, including harm reduction cigarettes, are discussed, and the chemicals in smoke that impair oviductal functioning are reviewed.

Effects of in vitro cadmium exposure on ovarian steroidogenesis in rats

The purpose of this study was to evaluate the direct effect(s) of in vitro cadmium (Cd) exposure on steroidogenesis in rat ovaries during different reproductive states. Sprague-Dawley rats were killed on the day of proestrus, or on gestation day 6 or 16. Ovaries were removed, placed in medium and minced. Culture from each ovary was incubated with Cd2+ ions in concentrations of 0, 100, 500, 1000, 1500, or 2000 microM. One-hour whole-ovary production of progesterone (P4), testosterone and estradiol (E2) in culture medium was evaluated in the absence and presence of human chorionic gonadotropin (hCG) or hCG plus pregnenolone by specific radioimmunoassay. Under in vitro Cd exposure the most affected were productions of P4 and testosterone in proestrus rats and less in pregnant dams, whereas E2 was not affected at all. Cadmium appears to interfere with the ovarian steroidogenic pathway in rats at more than one site.

Study of alterations produced by cadmium and cadmium/lead administration during gestational and early lactation periods in the reproductive organs of the rat

Administration of cadmium (10 mg/liter) and cadmium+lead (300 mg/liter) via drinking water to Wistar rats during gestation and early lactation until delivery and (5 days after parturition) damaged pup reproductive systems. The effects are additive in the decreased gonad weight and additive or even synergistic in the reduced DNA gonadal content. The effects on protein reduction are similar for both cations. In the testes, the effects of cadmium are more important in the reduction of seminiferous tubule diameter, whereas the effects of lead are more overt in the reduction of the number of prospermatogonia.

Influence of organochlorine pesticides on development of mouse embryos in vitro

The effect of DDT, methoxychlor (MXC), and gamma-hexachlorocyclohexane (gamma HCH) on preimplantation mouse embryos in culture was evaluated by the proportion of eight-cell stage embryos developing to expanded and hatched blastocysts. A concentration of 29 micrograms/mL DDT or gamma HCH led to a complete degeneration of exposed embryos. The addition of 29 micrograms/mL MXC showed blastocyst formation (72.3%), but fewer than half of the blastocysts were intact and only 4.3% hatched from the zona pellucida. A concentration of 14.5 micrograms/mL DDT led to 57.5% blastocyst formation and to 6.8% hatched blastocysts; the same concentration of gamma HCH and MXC showed 66.7 and 95.9% blastocyst formation and 22.9 and 49% hatched blastocysts, respectively. The addition of 7.25 micrograms/mL led to 85.9% (DDT), 77.6% (gamma HCH), and 81% (MXC) blastocysts in total, and to 28.2, 35.5, and 49.4% hatched blastocysts, respectively. Compared with untreated controls, only the 3.625 micrograms/mL concentration for all pesticides showed no significant differences in blastocyst formation and hatching. These results show different toxicity of these three pesticides for the preimplantation mouse embryo in the order MXC < gamma HCH < or = DDT).

Acute cadmium exposure and ovarian steroidogenesis in cycling and pregnant rats

The purpose of this study was to evaluate the effect(s) of acute in vivo cadmium (Cd) exposure on steroidogenesis in rat ovaries during different reproductive states. Sprague-Dawley rats were injected subcutaneously on the day of diestrus, or on day 7 or 16 of gestation with a single dose of 0, 3, or 5 mg Cd/kg bw, and evaluated 24 h later. Serum progesterone and estradiol concentrations were determined. Whole-ovary culture was used to evaluate Cd effects on the production of progesterone, testosterone, and estradiol. Liver, kidney, spleen, ovary, placenta, and blood were analyzed for Cd and iron (Fe) concentrations. No general toxic effects, no disruption of estrous cyclicity, and no change in fetal viability were seen. Histologic evaluation revealed moderate Cd-related thecal congestion in ovaries of pregnant rats. The highest Cd concentrations, except for liver, were found in the fetal portion of the placenta. Interestingly, Cd-related decreases in Fe concentration were found in several tissues from rats in proestrus and on gestation day 8, and in fetal placenta from rats on gestation day 17. Cadmium appears to interfere with normal steroidogenesis at a number of sites in the biosynthetic pathway with serum estradiol concentration and ovarian estradiol production the most affected. Acute Cd effects on steroidogenesis are most severe in rats evaluated in proestrus or in early pregnancy, while in late pregnancy steroidogenesis is relatively unaffected.

Age dependent accumulation of cadmium in the human ovary

Cadmium (Cd) was determined by atomic absorption spectrophotometry in small pieces (< 1 g) of healthy human ovaries excised for histologic examination. Cd levels in the ovary increased linearly between 30 and 65 years of age. Below 30 years, there was no age dependent increase and over 65 a tendency was observed for ovarian Cd levels to decrease. There was no difference in the Cd content of fresh luteal and nonluteal tissue taken from regularly cycling ovaries. In smokers, the amount of Cd in the ovaries was elevated compared to nonsmokers. In multiparous women (more than 3 children) a tendency of decreased Cd ovarian levels was observed. There was no difference between ovarian Cd content of physical and mental workers. It can be proposed that Cd may be a risk factor for conception and pregnancy in women in their forties.