Effects of 1,1-dichloro-2,2-bis[p-chlorophenyl]ethylene (DDE) on lactation in rats

An inverse correlation between the concentration of DDE in human breast milk samples and the duration of breast feeding prompted the present study of the effects of DDE administration on the lactational performance of primiparous rats. Daily doses of 10 mg p,p'-DDE/kg body weight were given to virgin female Sprague-Dawley rats 5 d/wk for 5 wk prior to mating and continued throughout the gestation and lactation periods. Lactation capacity was determined by monitoring neonatal growth and by measuring milk production, milk composition (total protein, total lipid, and lactose), and mammary-gland weight and nucleic acid content on d 9 and 20 postpartum. Gross toxicity was assessed by monitoring clinical signs and body weight of the dams, and by measuring organ weights of the dams on lactation d 9 and 20. Histopathological evaluation of the mammary glands and selected organs in the dams and pups was also performed. The dose level of DDE employed was apparently not toxic to the dams and did not have a pronounced effect on neonatal mortality. No significant differences between DDE-treated and control groups were observed for any of the lactation parameters, even though the concentration of DDE in the milk of treated rats was approximately two orders of magnitude greater than the upper range of the DDE levels measured in human milk samples. These findings indicate that DDE does not adversely affect lactation or neonatal growth in Sprague-Dawley rats at the dose level used in this study.     

Thiol stimulation of the cytochrome p-450-dependent reduction of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) to 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD)

The enzymatic reduction of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) to 1,1 dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) was studied with rat hepatic microsomal fractions. The reaction required NADPH and was inhibited by dioxygen and carbon monoxide, which shows that the reaction is catalyzed by cytochromes P-450. Moreover, when the reaction was studied in the presence of deuterium oxide, no deuterium was incorporated into the DDD, which suggests that a one-electron reduction of DDT to the 1,1-dichloro-2,2-bis(p-chlorophenyl)ethyl radical followed by hydrogen atom abstraction accounts for the formation of DDD. The microsomal reduction of DDT to DDD was stimulated markedly by several thiols, including glutathione. The stimulatory effect of thiols was concentration dependent and was not due to conservation of cytochrome P-450, because nonthiol antioxidants failed to stimulate the reaction. The mechanism of the stimulation is not understood, but thiols do not promote the formation of DDD by preventing the alkylation of microsomal lipids and, thereby, stimulating the formation of a reduced alkane. Finally, these results show that soluble, lowmolecular weight compounds may enhance the activity of membrane-bound enzymes.     

Effects of perinatal, combined exposure to 1,4-dichlorobenzene and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene on rat female reproductive system

Prenatal or early postnatal exposure to some synthetic chemicals may affect the later reproductive system of the offspring. 1,4-Dichlorobenzene (DCB) is used as an air freshener and a moth repellent and 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p'-DDE) is a persistent metabolite of 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane that was used as a pesticide before. DCB concentrations of residential air and oral p,p'-DDE intake through marine products are demonstrated to be rather high in Japan. Such situations lead to high body burden of these pollutants in pregnant women. Consequently, foetuses and neonates will be exposed much more to DCB and p,p'-DDE via the mother. Therefore, the effects of the perinatal, combined exposure to DCB and p,p'-DDE on the female reproductive system have been investigated in mature rat female offspring of dams ingesting 25 p.p.m. DCB (approximately 2 mg/kg) and 125 p.p.m. p,p'-DDE (approximately 10 mg/kg) during the gestational and lactational period. Sexual maturation was fully developed in the rat female offspring perinatally exposed to DCB and/or p,p'-DDE through maternal exposure. The combined effect of DCB and p,p'-DDE was observed, and the ovarian weight was seen to decrease to approximately 80% of the control rat in matured female offspring following perinatal exposure to DCB and p,p'-DDE. This alteration might lead to reproductive dysfunction in matured female offspring. However, biological relevance of the alteration in the ovary remained uncertain in the present study. Further investigations concerning the reproductive function and mechanistic implication are required for elucidating the combined effects of perinatal exposure to DCB and p,p'-DDE on the later female reproductive system entirely.     

Effects of perinatal simultaneous exposure to tributyltin (TBT) and p,p'-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene) on male offspring of Wistar rats

p,p'-DDE [1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene; DDE] and tributyltin (TBT) are ubiquitous in the environment and in Japan were shown to bioaccumulate in marine products. Thus these chemicals serve as a source of contaminant in the mammalian food chain. Fetuses and neonates through maternal ingestion may be exposed to DDE and TBT. Therefore, the effects of concurrent exposure to DDE and TBT were investigated in male Wistar rat offspring of dams ingesting these two contaminants. In this study, TBT suppressed the growth and delayed eye opening. However, both growth retardation and delayed eye opening produced by TBT failed to occur in the presence of DDE. Unexpectedly, the prostate weight of male rat offspring was significantly reduced with the administration of TBT but restored in the presence of DDE. These results indicate that TBT and DDE affected the development of male rat offspring following maternal exposure, and simultaneous administration of DDE prevented some of the observed effects of TBT, especially of an antagonistic nature, through a mechanism, still to be determined.     

Effects of perinatal combined exposure to 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) and tributyltin (TBT) on rat female reproductive system

1,1-Dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p′-DDE) is the most prevalent metabolite of DDT used as a pesticide before and tributyltin (TBT) compounds are used primarily as antifouling agents on vessels, ships, and aqua culture facilities, as they exert biocidal actions. Currently, p,p′-DDE and TBT are ubiquitously distributed in the environment and bio-accumulated in marine products, especially fish or shellfish. Thus, oral p,p′-DDE and TBT intake through marine products is demonstrated to be rather high in Japan. Consequently, the fetus and neonate will be exposed to p,p′-DDE and TBT via mother. Therefore, effects of perinatal combined exposure to p,p′-DDE and TBT on the female reproductive system after maturation have been investigated in rat female offspring of dams ingesting 125 ppm p,p′-DDE (approximately 10 mg/kg) and 25 ppm TBT (approximately 2 mg/kg) during the perinatal period from gestation to lactation. In the present study, no deleterious reproductive outcomes were recognized in p,p′-DDE and/or TBT-treated dams. In contrast, growth retardation had developed in rat female offspring following perinatal exposure to TBT and sustained even after cessation of exposures. Further, reduced ovarian weights with elevated serum follicle-stimulating hormone (FSH) concentrations were observed in the reproductive system of matured female offspring following perinatal exposure to TBT. At present, biological relevance of these alterations remains unknown, but there is a possibility that these alterations lead to reproductive malfunctions in matured female offspring.     

Effects of concurrent exposure to tributyltin and 1,1-dichloro-2,2 bis (p-chlorophenyl) ethylene (p,p'-DDE) on immature male Wistar rats

Tributyltin and 1, 1-dichloro-2, 2 bis (p-chlorophenyl) ethylene (p,p'-DDE) have been ubiquitously distributed over the world. In Japan, p,p'-DDE and tributyltin are ingested through marine products, in which these substances are accumulated through bio-concentration and the food chain. However, the consequence of potential combined hazards of these substances remains unknown. Therefore, the effects of concurrent exposure to 125 ppm p,p'-DDE and 25 ppm tributyltin were investigated in immature male Wistar rats by oral administration during puberty. In this study, tributyltin promoted the growth of pubertal male rats, while p,p'-DDE itself did not affect the growth but inhibited the growth enhancement by tributyltin. Furthermore, tributyltin reduced thymus weight but p,p'-DDE also prevented this weight reduction. Neither development of male sexual accessory organs nor sexual maturation was affected even by concurrent exposure to p,p'-DDE and tributyltin. No significant changes of serum testosterone, luteinizing hormone, follicle-stimulating hormone concentrations, and epididymal sperm numbers were observed with the administration of p,p'-DDE and/or tributyltin. These results indicate that sexual maturation, male reproductive organ development and sperm production is scarcely affected in immature male Wistar rats even by concurrent exposure to p,p'-DDE and tributyltin at a daily dose of ca. 2 mg/kg tributyltin and 10 mg/kg p,p'-DDE. Moreover, the simultaneous administration of p,p'-DDE with tributyltin counterbalanced the effects that were attributed to tributyltin alone.     

Effects of nonylphenol, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), and pentachlorophenol on the adult female guinea pig reproductive tract

The guinea pig exhibits cyclic and luteal similarities to the human, a feature not present in other small experimental animals such as rats, mice, or rabbits. Studies were undertaken to investigate the in vivo effects of three persistent environmental xenobiotics (nonylphenol, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene [p,p'-DDE], and pentachlorophenol) on the microanatomy of the adult female guinea pig reproductive system. The effects brought about by these compounds (40 mg/kg/day) were compared to those caused by the synthetic estrogen diethylstilbestrol (DES; 50 microg/kg/day). Adult female guinea pigs, intact and castrated, were treated with 14 daily subcutaneous (s.c.) doses of one of these agents. The 50% decline in the weight of the tract that occurred following castration, was prevented by administration of nonylphenol, p,p'-DDE, and DES, but not of pentachlorophenol. Nonylphenol produced weak estrogenic stimulation of the tract of intact animals and maintained a relatively normal histologic appearance in castrated animals. Focal mucinous metaplasia of the endometrium, however, was observed in both groups. Treatment of intact and castrated animals with p,p'-DDE resulted in cystic hyperplasia and mucinous metaplasia of the endometrium, hyperplasia of the cervical epithelium, estrogenic stimulation of the vagina, and dilation of the rete ovarii. Treatment of intact or castrated animals with DES resulted in effects that were qualitatively similar to those caused by p,p'-DDE. The appearance of the vaginal epithelium, however, was abnormal and the rete ovarii were less dilated. Pentachlorophenol had minimal effect on the histology of the tract of castrated or intact animals. These data support our hypothesis that some environmental toxicants can substitute for estradiol in regulating the microanatomy of the female reproductive tract. They indicate the potential of these compounds to act as endocrine disrupting agents.     

Effects of perinatal combined exposure to 1,1-dichloro-2,2 bis (p-chlorophenyl) ethylene and tributyltin on male reproductive system

Prenatal or early postnatal exposure to some synthetic chemicals may affect the later reproductive system of the offspring. There may also be unique responses observed due to exposure to combinations of chemicals that are not observed when the chemicals are present individually. 1,1-Dichloro-2,2 bis (p-chlorophenyl) ethylene (p,p'-DDE) is a persistent metabolite of DDT and tributyltin (TBT) compounds are used primarily as antifouling agents, as they exert biocidal actions. p,p'-DDE and TBT are ubiquitously distributed in the environment. Oral p,p'-DDE and TBT intake through marine products is demonstrated to be high in Japan. Consequently, the foetus and neonate are supposed to be exposed much more to p,p'-DDE and TBT via the maternal body. Therefore, effects of perinatal exposure to p,p'-DDE and/or TBT on the reproductive system after maturation have been investigated in rat male offspring of dams orally administered 125 ppm p,p'-DDE (approximately 10 mg/kg) and 25 ppm TBT (approximately 2 mg/kg) during the gestational and lactational period. In this study, growth retardation attributed to TBT has sustained in rat male offspring after perinatal exposure. However, perinatal exposure to p,p'-DDE and TBT failed to affect the male reproductive organs and sperm parameters in matured male offspring.     

A mechanistic study of the metabolism of 1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD) to 2,2-bis(p-chlorophenyl)acetic acid (DDA)

The metabolism of [1-²H]-1,1-dichloro-2,2-bis(p-chlorophenyl)ethane (DDD-d) and [1-²H]-1-chloro-2,2-bis(p-chlorophenyl)ethene (DDMU-d) and their corresponding non-deuterated isomers DDD and DDMU was studied in female Swiss mice over a 96-hr period. The only detected urinary metabolite of DDD-d and DDD was 2,2-bis(p-chlorophenyl)acetic acid (DDA). Animals administered DDD excreted ～2.4-fold more DDA than those treated with DDD-d over the total collection period. The initial (0–36 hr) linear excretion rates of DDA for DDD and DDD-d were 17.1 and 5.5 μg/hr respectively. DDMU- and DDMU-d-treated mice excreted significant quantities of DDA, 2,2-bis(p-chlorophenyl)ethanol (DDOH) and 2,2-bis(p-chlorophenyl)ethanal (DDCHO). The only quantitative difference between DDMU and DDMU-d was that the non-deuterated isomer afforded ～1.8 times more DDA over the 96-hr collection. The initial (0–36 hr) linear excretion rates of DDMU and DDMU-d were 10.7 and 6.2 μg/hr respectively. The qualitative and quantitative results are consistent with DDD being metabolized to DDA via enzyme-mediated hydroxylation on the C-1 side chain carbon.     

Effects of perinatal combined exposure to 1,4-dichlorobenzene and 1,1-dichloro-2, 2-bis (p-chlorophenyl) ethylene on rat male offspring

1,4-Dichlorobenzene (DCB) is used as an air deodorant or a moth repellent and 1, 1-dichloro-2, 2-bis (p-chlorophenyl) ethylene (p,p'-DDE) is a persistent metabolite of 1, 1, 1-trichloro-2, 2-bis (p-chlorophenyl) ethane (DDT) which was used as a pesticide before. DCB concentrations of residential air and oral p,p'-DDE intake through marine products are demonstrated to be very high in Japan and consequently, foetuses and neonates may be exposed much more to DCB and/or p,p'-DDE via the maternal body. It has recently been reported that DCB is oestrogenic and that p,p'-DDE is antiandrogenic. Therefore, the combined effects of perinatal exposure to DCB and p,p'-DDE have been investigated in rat male offspring of dams ingesting these contaminants during the perinatal period from gestational day 1 to postpartum day 21 for 42 days. In this study, no obvious developmental effects on male offspring have been recognized until 6 weeks of age, following oral administration of 25 ppm DCB (approximately 2 mg/kg) and/or 125 ppm p,p'-DDE (approximately 10 mg/kg) to dams. In contrast to female offspring, the thymus weight in male offspring was not affected by DCB at 6 weeks of age, but there might be sexual differences concerning the effects of DCB on the thymus.     

The insecticide 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (DDT) alters the membrane raft location of the TSH receptor stably expressed in Chinese hamster ovary cells

DDT is a highly lipophilic molecule known to deplete membrane rafts of their phosphoglycolipid and cholesterol contents. However, we have recently shown that DDT can also alter the thyroid homeostasis by inhibiting TSH receptor (TSHr) internalization. The present study was undertaken to verify whether DDT goitrogenic effects are due to the insecticide acting directly on TSHr or via alteration of the membrane rafts hosting the receptor itself. Our results demonstrate that, in CHO-TSHr transfected cells, TSHr is activated in the presence of TSH, while it is inhibited following DDT exposure. DDT can also reduce the endocytic vesicular traffic, alter the extension of multi-branched microvilli along their plasma membranes and induce TSHr shedding in vesicular forms. To verify whether TSHr displacement might depend on DDT altering the raft constitution of CHO-TSHr cell membranes the extent of TSHr and lipid raft co-localization was examined by confocal microscopy. Evidence shows that receptor/raft co-localization increased significantly upon exposure to TSH, while receptors and lipid rafts become dislodged on opposite cell poles in DDT-exposed CHO-TSHr cells. As a control, under similar culturing conditions, diphenylethylene, which is known to be a lipophilic substance that is structurally related to DDT, did not affect the extent of TSHr and lipid raft co-localization in CHO-TSHr cells treated with TSH. These findings corroborate and extend our view that, in CHO cells, the DDT disrupting action on TSHr is primarily due to the insecticide acting on membranes to deplete their raft cholesterol content, and that the resulting inhibition on TSHr internalization is due to receptor dislodgement from altered raft microdomains of the plasma membrane.     

The diverse mechanism of action of dichlorodiphenyldichloroethylene (DDE) and methoxychlor in ovarian cells in vitro

Dichlorodiphenyldichloroethylene (DDE), the most stable metabolite of the organochlorine insecticide dichlorodiphenyltrichloroethane (DDT), and the DDT analog methoxychlor can have adverse effects on reproduction. These chemicals have been identified as having estrogenic activity. The aim of the current study was to examine the effects of dichlorodiphenyldichloroethylene (DDE), methoxychlor, and estradiol-17β on steroidogenesis and FSH responsiveness in ovarian cells in vitro. Experiments were performed on a primary culture of porcine granulosa cells and a culture of Chinese hamster ovary (CHO) cells, the latter stably transfected with the FSH receptor (CHO-FSH-R). DDE (10 μM) and estradiol-17β (0.1 μM) but not methoxychlor (10 μM), increased proliferation of the granulosa cells. DDE (100 and 10 μM, respectively) decreased FSH-stimulated cAMP synthesis in the granulosa and CHO-FSH-R cells. DDE also decreased progesterone synthesis in the granulosa cells. Methoxychlor (10 μM) inhibited progesterone synthesis in the granulosa cells, but it did not affect the generation of cAMP in either type of cells studied. However, methoxychlor inhibited estradiol-17β-stimulated progesterone synthesis in the granulosa cells. We conclude that DDE primarily inhibited the generation of cAMP, while methoxychlor supressed progesterone synthesis through a mechanism distal to cAMP generation. The present results indicate that DDE and methoxychlor are not limited to a mimicking of the endocrine effects of estradiol-17β in cultured ovarian cells. Therefore, a non-estrogenic component of the endocrine disrupting activities of DDE and methoxychlor must be considered in evaluating their reproductive toxicity.     

Association of serum levels of p,p’- Dichlorodiphenyldichloroethylene (DDE) with type 2 diabetes in African American and Caucasian adult men from agricultural (Delta) and non-agricultural (non-Delta) regions of Mississippi

Epidemiological associations were reported in several studies between persistent organochlorine organic pollutants and type 2 diabetes mellitus (T2D). Mississippi is a highly agricultural state in the USA, particularly the Delta region, with previous high usage of organochlorine (OC) insecticides such as p,p’- dichlorodiphenyltrichloroethane (DDT). In addition, there is a high proportion of African Americans who display elevated prevalence of T2D. Therefore, this State provides an important dataset for further investigating any relationship between OC compounds and metabolic diseases. The aim of this study was to assess whether soil and serum levels of OC compounds, such as p,p’- dichlorodiphenyldichloroethylene (DDE), arising from the heavy historical use of legacy OC insecticides, might serve as an environmental public health indicator for T2D occurrence. Soil samples from 60 Delta and 60 non-Delta sites randomly selected were analyzed for the presence of OC compounds. A retrospective cohort study of adult men (150 from each region) was recruited to provide a blood sample for OC compound quantitation and select demographic and clinical information including T2D. Using multivariable logistic regression, an association was found between increasing serum DDE levels and T2D occurrence in non-Delta participants (those subjects with lower serum DDE levels), as opposed to Delta participants (individuals with higher serum DDE levels). Thus, while there was a relationship between serum DDE levels and T2D in those with lower burdens of DDE, the lack of association in those with higher levels of DDE indicates a complex non-monotonic correlation between serum DDE levels and T2D occurrence complicating the goal of finding a public health marker for T2D.

Abbreviations: BMI, body mass index; CVD, cardiovascular disease; CDC, Center for Disease Control, United States of America; DDE, p,p’- dichlorodiphenyldichloroethylene; DDT, p,p’- dichlorodiphenyltrichloroethane; GC/MS, gas chromatography/mass spectrometry; GIS, geographic information system; GPS, global positioning system; HDL, high-density lipoprotein; HTN, hypertension; IDW, inverse distance weighting; IRB, Institutional Review Board; LDL, low-density lipoprotein; LOQ, limit of quantitation; NHANES, National Health and Nutrition Examination Surveys; POPs, persistent organic pollutants; OC, organochlorine; PCB, polychlorinated biphenyl; SIM, single-ion monitoring; T2D, type 2 diabetes mellitus; USA, United States of America.     

Quantitative measurement of microsomal subfractions isolated from livers of rats fed with 1,1,1-trichloro-2,2-bis (p-chlorophenyl ethane (DDT)

Fractions enriched in smooth and rough endoplasmic reticulum were prepared from rat liver microsomal membranes by centrifugation and were characterized by analysis of their protein, RNA and phospholipid contents and by electron microscopy. Upon inclusion of 1, 1, 1-trichloro-2, 2-bis (p-chlorophenyl) ethane (DDT) in the diet, the amount of liver smooth endoplasmic reticulum increased rapidly and transitorily in both weanling and adult rats to approximately twice that of control animals. The increase was more pronounced in males than in females irrespective of age, but the rate of increase (although not the maximum extent of proliferation) in male animals became significantly less as they matured.