Victor P. Eroschenko

Neonatal exposures to technical methoxychlor alters ovaries in adult mice.

Technical grade methoxychlor (MXC) is an estrogenic pesticide currently used for pest control in the US. To determine the long-term effects of technical MXC on ovaries and estrous cycles, neonatal mice received 14 daily intraperitoneal injections of sesame oil only, 10.0 micrograms estradiol-17 beta, or 0.05 mg, 0.1 mg, 0.5 mg, or 1.0 mg of technical MXC. At 3, 6, and 12 months, vaginal smears were examined for 12 d and ovaries collected. All technical MXC doses and estradiol increased the duration of vaginal cornification but only estradiol, 0.5, or 1.0 mg technical MXC induced ovarian atrophy, relative ovarian weight loss, and depletion of corpora lutea. Technical MXC doses of 0.05 or 0.1 mg produced the opposite effects; the ovaries remained heavy, large, and filled with corpora lutea. On the other hand, follicular cysts were recorded in all groups, except the 1.0 mg MXC group. These augmentary and inhibitory effects of MXC at low and high doses mimic the estrogen effects at low and high doses, and were probably due to the altered hypothalamic-hypophyseal function.

Effects of progesterone and estrogen on the histology of the oviduct of the garter snake, Thamnophis elegans

Abstract Silastic capsules packed with estradiol and/or progesterone were implanted in ovariectomized viviparous garter snakes ( Thamnophis elegans ) in order to define the role of these steroids in inducing histological recrudescence in the uterine segment of the oviduct. During the preovulatory period, the uterine tubuloalveolar glands and tall columnar, luminal epithelium of intact snakes were exceedingly well-developed and possessed numerous PAS-positive granules. Plasma estrogen concentrations were quite high (1833 ± 167 pg/ml) at this time and progesterone levels were variable (3.3 ± 2.3 ng/ml). Ovariectomy significantly reduced plasma levels of estrogen (79 ± 48 pg) and progesterone (1.1 ± 0.3 ng/ml) as well as the height and secretory condition of the luminal and glandular epithelium of the uterus. Administration of estradiol to ovariectomized garter snakes for 10 days elevated plasma estrogen levels to 758 ± 351 pg/ml and partially restored epithelial cell height and glandular activity. Administration of progesterone elevated plasma levels to physiological concentrations (4.3 ± 2.6 ng/ml) but had little or no stimulatory effect on uterine histology. Simultaneous administration of estradiol and progesterone for 10 days failed to induce additional stimulatory effects on uterine histology over and above those produced by estradiol alone. Results of this study indicate that estradiol is the most important ovarian hormone in regulating development of the uterus. However, additional hormones, other than progesterone, may possibly be required for full restoration of the garter snake uterus to the preovulatory condition.

Estrogenic activity of the insecticide chlordecone in the reproductive tract of birds and mammals.

Effects of the insecticide chlordecone (Kepone) on female reproduction in birds and mammals were reviewed. In different avian species, chlordecone inhibited or reduced reproduction and decreased egg hatchability and survival of the newborn. In Japanese quail, chronic chlordecone ingestion decreased total egg production and clutch size and increased egg breakage. Eggs produced by treated quail were significantly weaker and thinner. Chlordecone also decreased follicular development, induced ovarian regression, and inhibited ovulation and egg laying. Histological studies showed that when chlordecone was fed to sexually immature quail, the oviducts exhibited accelerated growth, cytodifferentiation, cellular hypertrophy, secretory activity, and maturation. Ultrastructure of the oviduct surface showed increased growth of microvilli and profuse ciliation. Chlordecone also stimulated granular endoplasmic reticulum and Golgi development and induced full secretory activity in the cytoplasm of estrogen‐sensitive qua...

Altered behaviors in male mice, male quail, and salamander larvae following early exposures to the estrogenic pesticide methoxychlor.

Numerous publications show that methoxychlor (MXC), in use today as a DDT substitute, is a reproductive toxicant; it produces deleterious effects on the structure and function of the reproductive organs in exposed species. Exposure of mice (33 mg/kg body weight) to purified (95%) MXC at the time of implantation, or injection, of 5 mg MXC into freshly laid quail eggs prior to artificial incubation, altered sexual arousal and sexual behavior in adult males of both species. When placed near a plastic partition with an estrus female behind it, the MXC-exposed male mice showed no sexual arousal, spent less time near the partition, and exhibited lower testosterone levels. Similarly, adult quail males that were exposed to MXC during incubation showed a lack of sexual interest and copulatory behavior when presented with a receptive female. Some males showed a longer latency period before mounting the female, while others did not show any sexual interest at all. Exposure of salamander embryos to purified MXC at or above 0.3 microM (0.1 mg/l) induced precocial hatching of embryos and reduced the startle response and the distance traveled in response to startle. Exposing hatched larvae to MXC for 3 days also resulted in a blunted startle response. Due to the blunted startle response and decreased avoidance travel, the exposed salamander larvae appear more susceptible to predation and these effects may contribute to amphibian population declines. The results of these studies indicate that developmental exposures to environmental chemicals with hormonal activities produce undesirable behaviors that may affect population dynamics and survivability of exposed species.

Purified methoxychlor stimulates the reproductive tract in immature female mice

Methoxychlor is an estrogenic pesticide currently used as a substitute for DDT. The estrogenic effects of 98% pure methoxychlor or base-washed pure methoxychlor were examined on reproductive organs of immature mice and compared to control and estradiol-treated mice. Within 24 hours of birth, neonatal mice received 14 daily intraperitoneal injections of one of the following chemicals: sesame oil only, 10.0 micrograms of 17-beta estradiol, or 0.05 mg, 0.5 mg, or 1.0 mg of 98% pure methoxychlor, or 1.0 mg base-washed 98% pure methoxychlor. Equal doses (1.0 mg) of 98% pure or base-washed methoxychlor stimulated the reproductive organs of immature females such that the effects closely resembled those seen after estradiol treatments. In comparison to control mice, these pesticide treatments also induced precocious vaginal opening, persistent vaginal cornification, increased reproductive tract weights, and epithelial hypertrophy in both the vagina and uterus. However, only estradiol treatments significantly elevated albumin levels in the uterine fluid of the immature mice while the highest methoxychlor doses significantly increased the uterine cell heights when compared to all other groups.

Estradiol or methoxychlor stimulates estrogen receptor (ER) expression in uteri.

The estrogenic pesticide methoxychlor (MXC) abnormally alters reproduction in rodents. The influence of MXC on expression of the estrogen receptor (ER) gene was investigated in the uterus of BALB/c mice and compared to the effect of estradiol. Uterine epithelium in control mice is devoid of ER until 5 d of life. Sesame oil, 10.0 micrograms estradiol 17 beta or 1.0 mg of base-washed 95% MXC were injected into neonates (days 1 to 4) and immature mice (days 10 to 14), after which they were sacrificed. By day 5, E or MXC induced production of nuclear ER mRNA and its translation in uterine epithelium. The mRNA was detected by in situ hybridization and ER protein by immunocytolocalization. In controls, ER was present only in stroma and myometrium. By day 15, the nuclei of uterine epithelium, stroma, and myometrium expressed the ER gene, with no apparent influence of E or MXC. Both E and MXC induce premature nuclear expression of the ER gene in neonatal uterine epithelium, without apparent change in ER gene expression between days 10 and 14 of life.

Neonatal exposure to technical methoxychlor alters pregnancy outcome in female mice.

This study was designed to determine the ability of female mice who were exposed neonatally to the pesticide methoxychlor (MXC) to mate, ovulate, and become pregnant upon reaching sexual maturity. One-day-old female mice (5 to 8/group) were exposed daily by intraperitoneal (ip) injection for 14 d to either sesame oil or 10 microg estradiol-17beta or 0.1, 0.5 or 1.0 mg MXC suspended in sesame oil. The MXC exposures corresponded to 14 to 71, 68 to 357, or 135 to 714 mg/kg body weight, respectively. Three months later, female mice were placed with proven breeder males and checked daily for vaginal plugs. Mated female mice were sacrificed 18 d after the appearance of a vaginal plug to evaluate pregnancy. Uteri were examined for the presence of living fetuses and/or resorption sites. Ovaries were removed and prepared for histologic evaluation and tabulation of corpora lutea. All mice from all three MXC-treated groups did in fact mate, in comparison with only one of those exposed neonatally to estradiol. Increasing the dose of MXC produced a decreased number of pregnant animals at 18 d following mating. The mean number of live fetuses/litter was reduced in the 0.5 and 1.0 mg MXC-treated groups. Corpora lutea were significantly reduced in ovaries from only the 1.0 mg MXC group and the estradiol group. No effects of treatment were seen at 0.1 mg MXC. It is concluded that neonatal exposure to MXC does not interfere with mating. Instead, significant alterations are seen in initiating and/or maintaining pregnancy. The deleterious effects on pregnancy may be due to the influence of neonatal MXC treatments on the hypothalamic-pituitary-ovarian axis as well as on possible alteration of the uterine environment.

Decreased superovulation in adult mice following neonatal exposures to technical methoxychlor

To examine the effects of technical methoxychlor (MXC) on superovulation, neonatal mice received intraperitoneal (i.p.) injections of either sesame oil, 10 micrograms of estradiol 17 beta, or 0.1, 0.5, or 1 mg of technical MXC. At 2 and 4 months, half of the mice received a superovulatory regimen of 10 IU pregnant mares serum gonadotropin followed by 10 IU human chorionic gonadotropin. The mice were sacrificed 15 to 20 h later, the number of ovulated oocytes were counted, and the ovaries were removed for histology. In the lowest MXC dose, the ovaries appeared normal and at 2 months, ovulated the same number of oocytes as controls. Estradiol or the highest two MXC doses induced ovarian atrophy. Following gonadotropin injections, these ovaries also ovulated oocytes. However, the number of oocytes recovered from experimental mice exhibited a time- and dose-dependent decline, and by 4 months, their number was significantly reduced. Neonatal exposures to MXC reduces ovulatory rates and ovarian functions in adults.

Ultrastructure of vagina and uterus in young mice after methoxychlor exposure

Ultrastructural effects of 17 beta-estradiol were compared with technical pesticide methoxychlor in uterus and vagina of young mice. Neonates received 14 daily ip injections of either sesame oil, 10.0 micrograms 17 beta-estradiol, or 0.05, 0.1, 0.5, or 1.0 mg methoxychlor. Estradiol accelerated vaginal opening to 11 days, increased reproductive tract weight gain, and induced vaginal cornification, the cells of which exhibited complex surface microridge patterns. The hypertrophied uterine cells were covered with dense, enlarged microvilli with bulbous expansions or clumps. The highest three methoxychlor doses were stimulatory. Exposure to 0.5 or 1.0 mg methoxychlor increased reproductive tract weights threefold due to excessive fluid accumulation, and induced vaginal cornification and opening by 10 days. The cornified cells lacked complex surface microridges, while uterine cells exhibited dense microvilli growth, atypical morphology, and separation. Although 0.5 and 1.0 mg methoxychlor were highly stimulatory, the surface alterations in uterus and vagina appeared different from estradiol.

Neonatal administration of insecticide chlordecone and its effects on the development of the reproductive tract in the female mouse

Abstract One-day-old female mice received a total of 10 ip injections of sesame oil, estradiol 17β or the insecticide chlordecone (Kepone). The doses of estradiol 17β of 10 μg and chlordecone of 0.015, 0.03, 0.06 and 0.125 mg in 0.05 ml sesame oil were injected daily. The higher chlordecone doses of 0.18 and 0.25 mg were injected daily during the first 4 days and every 2 days for the remaining six injections. At least five neonates receiving estradiol and different chlordecone doses were terminated after every two injections, the last termination taking place after the 10th injection. The mice injected with sesame oil only were terminated at 12 days of age. All doses of chlordecone produced distinct morphological alterations in the epithelium lining both the vagina and uterus. The changes in the neonatal reproductive tract appeared dose related in that increased doses of administered chlordecone accelerated development of the vaginal epithelium leading to keratinization while cellular hypertrophy, hyperplasia, and glandular formation were observed in the uterus. These changes appeared identical to the developmental changes induced by the estradiol.