Characterization of serotonin following exposure to antibiotics in white-tailed deer.

Developing baseline concentrations of serotonin in healthy white-tailed deer will allow for the development of a biomarker using non-invasive sample tissues in sick animals, for example, non-clinical cases of chronic wasting disease. It will also allow some further insight into whether the use of antibiotics as growth promoters (AGP), such as chlortetracycline, is affecting serotonin concentrations in white-tailed deer. Florfenicol and tulathromycin impacts on serotonin concentration changes were also investigated. An analytical method for the detection and confirmation of serotonin, 5-hydroxytryptamine (5-HT), in white-tailed deer tissues was developed and validated. Serum and urine samples were extracted with acetonitrile. Liquid chromatography separation was attained on a Phenomenex C18 column with a Security Guard ULTRA guard column with gradient elution using a mobile phase of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. This methodology was applied to baseline (control), chlortetracycline (CTC) treated, florfenicol treated and tulathromycin treated white-tailed deer serum and urine samples.

Assessment of gonadal and thyroid histology in Gulf killifish (Fundulus grandis) from Barataria Bay Louisiana one year after the Deepwater Horizon oil spill.

We examined gonads and thyroid glands of Gulf killifish (Fundulus grandis) 1yr after the Deepwater Horizon oil spill. F. grandis were trapped from two impacted sites in Barataria Bay (Bayou St. Denis, Bay Jimmy) and an un-impacted site in East Texas (Sabine Pass). The greatest number of F. grandis were collected at Sabine Pass. F. grandis collected at Bayou St. Denis were smaller and had smaller Fulton condition factor scores than fish collected at Sabine Pass. Sex ratios were biased roughly 2:1 in favor of females at Sabine Pass and Bayou St. Denis. Gonad-somatic index (GSI) in males from Sabine Pass was double that of fish from Bay Jimmy while germinal epithelium thickness of the testes was 2.7 fold smaller in males from the impacted site. GSI and oocyte diameters in females from Bayou St. Denis were significantly smaller than females from Bay Jimmy or the reference site. There were no differences in thyroid follicle cell height. While total polyaromatic hydrocarbons at the impacted sites were no different from the reference site, the impacted sites did have greater concentrations of benzo[a]pyrene in sediment pore water. The finding of smaller GSI and testicular germinal epithelium in males from an impacted site suggest that exposure to a combination of oil and dispersants may adversely impact testicular function.

Changes in gastric sodium-iodide symporter (NIS) activity are associated with differences in thyroid gland sensitivity to perchlorate during metamorphosis.

We investigated stage-dependent changes in sensitivity of the thyroid gland to perchlorate during development of African clawed frog tadpoles (Xenopus laevis) in relation to non-thyroidal iodide transporting tissues. Perchlorate-induced increases in thyroid follicle cell size and colloid depletion were blunted when exposures began at Nieuwkoop-Faber (NF) stage 55 compared to when exposures began at NF stages 49 or 1-10. To determine if the development of other iodide transporting tissues may contribute to this difference we first examined which tissues expressed transcripts for the sodium dependent iodide symporter (NIS). RT-PCR analysis revealed that NIS was expressed in stomach and small intestine in addition to the thyroid gland of X. laevis tadpoles. NIS mRNA was not detected in lung, kidney, skin, gill, muscle, heart or liver. Perchlorate sensitive (125)I uptake was found in stomach, lung, kidney, gill, and small intestine but not muscle, liver, or heart. Perchlorate-sensitive (125)I uptake by stomach was 6-10 times greater than in any other non-thyroidal tissue in tadpoles. While NF stage 49 tadpoles exhibited perchlorate-sensitive uptake in stomach it was roughly 4-fold less than that observed in NF stage 55 tadpoles. Although abundance of NIS gene transcripts was greater in stomachs from NF stage 55 compared to NF stage 49 tadpoles this difference was not statistically significant. We conclude that gastric iodide uptake increases between NF stages 49 and 55, possibly due to post-translational changes in NIS glycosylation or trafficking within gastric mucosal cells. These developmental changes in gastric NIS gene expression may affect iodide availability to the thyroid gland.

An intrinsic CRF signaling system within the optic tectum.

Previous work indicates that CRF administration inhibits visually guided feeding in amphibians. We used the African clawed frog Xenopus laevis to examine the hypothesis that CRF acts as a neurotransmitter in the optic tectum, the major brain area integrating the visual and premotor pathways regulating visually guided feeding in anurans. Reverse transcriptase PCR revealed that cells in the optic tectum express mRNA for CRF and the CRF R1 receptor but not the CRF R2 receptor. Radioligand binding studies indicated that specific binding of [(125)I]-Tyr-oCRF to tectal cell membranes can be displaced by the CRF R1 antagonists antalarmin or NBI-27914. CRF increased the expression of mRNA encoding regulator of G-protein signaling 2 (rgs2) in tectal explants and this effect was blocked by antalarmin. CRF had no effect on basal glutamate or gamma-aminobutyric acid (GABA) secretion but inhibited secretion of norepinephrine from tectal explants, an effect that completely blocked by antalarmin. Using a homologous radioimmunoassay we determined that CRF release from tectal explants in vitro was potassium- and calcium-dependent. Basal and depolarization-induced CRF secretion was greater from optic tectum than hypothalamus/thalamus, telencephalon, or brainstem. We concluded that the optic tectum possesses a CRF signaling system that may be involved in modulating communication between sensory and motor pathways involved in food intake.

Routine delivery of artemisinin-based combination treatment at fixed health facilities reduces malaria prevalence in Tanzania: an observational study.

BACKGROUND: Artemisinin-based combination therapy (ACT) has been promoted as a means to reduce malaria transmission due to their ability to kill both asexual blood stages of malaria parasites, which sustain infections over long periods and the immature derived sexual stages responsible for infecting mosquitoes and onward transmission. Early studies reported a temporal association between ACT introduction and reduced malaria transmission in a number of ecological settings. However, these reports have come from areas with low to moderate malaria transmission, been confounded by the presence of other interventions or environmental changes that may have reduced malaria transmission, and have not included a comparison group without ACT. This report presents results from the first large-scale observational study to assess the impact of case management with ACT on population-level measures of malaria endemicity in an area with intense transmission where the benefits of effective infection clearance might be compromised by frequent and repeated re-infection. METHODS: A pre-post observational study with a non-randomized comparison group was conducted at two sites in Tanzania. Both sites used sulphadoxine-pyrimethamine (SP) monotherapy as a first-line anti-malarial from mid-2001 through 2002. In 2003, the ACT, artesunate (AS) co-administered with SP (AS + SP), was introduced in all fixed health facilities in the intervention site, including both public and registered non-governmental facilities. Population-level prevalence of Plasmodium falciparum asexual parasitaemia and gametocytaemia were assessed using light microscopy from samples collected during representative household surveys in 2001, 2002, 2004, 2005 and 2006. FINDINGS: Among 37,309 observations included in the analysis, annual asexual parasitaemia prevalence in persons of all ages ranged from 11% to 28% and gametocytaemia prevalence ranged from <1% to 2% between the two sites and across the five survey years. A multivariable logistic regression model was fitted to adjust for age, socioeconomic status, bed net use and rainfall. In the presence of consistently high coverage and efficacy of SP monotherapy and AS + SP in the comparison and intervention areas, the introduction of ACT in the intervention site was associated with a modest reduction in the adjusted asexual parasitaemia prevalence of 5 percentage-points or 23% (p < 0.0001) relative to the comparison site. Gametocytaemia prevalence did not differ significantly (p = 0.30). INTERPRETATION: The introduction of ACT at fixed health facilities only modestly reduced asexual parasitaemia prevalence. ACT is effective for treatment of uncomplicated malaria and should have substantial public health impact on morbidity and mortality, but is unlikely to reduce malaria transmission substantially in much of sub-Saharan Africa where individuals are rapidly re-infected.

Effects of chronic 2,4,6,-trinitrotoluene, 2,4-dinitrotoluene, and 2,6-dinitrotoluene exposure on developing bullfrog (Rana catesbeiana) tadpoles.

Chronic aqueous exposures were conducted using bullfrog (Rana catesbeiana) tadpoles (8 d old) exposed to TNT (0-4 mg/L), 2,4-DNT (0-4 mg/L), and 2,6-DNT (0-8 mg/L) for 90 d. Survival of tadpoles examined using Cox proportional hazard models was reduced at all concentrations tested. Percent of abnormal swimming and other morphological abnormalities after sublethal exposure to TNT, 2,4-DNT, and 2,6-DNT at 2 mg/L were also evaluated. The effects of TNT, 2,4-DNT, and 2,6-DNT on wet body mass, snout vent length (SVL), and developmental stage of surviving tadpoles were examined. Only 2,4-DNT did not have a significant effect on body mass or SVL, but all three compounds tested had significant effects on survival. Long-term continuous exposure to these compounds at concentrations of 0.25 mg/L could lead to significant changes in growth and survival of larval amphibians.

Neurodegenerative Implications of Neuronal Cytoplasmic Protein Dysfunction in Response to Environmental Contaminants.

Neurodegenerative diseases account for a significant portion of public health concerns particularly in the aging population. The dysfunction of interfilament proteins has been identified as a key event in the initiation of neurodegeneration and subsequent progression to neurodegenerative diseases. In addition, several studies have found associations between the dysfunction of interfilament proteins and exposure to environmental contaminants. Therefore, in this review, the role of interfilament proteins in neuronal cells, their connection to neurotoxicity from environmental contaminants, and finally the resulting neurodegeneration are discussed.

Effects of atrazine on fish, amphibians, and aquatic reptiles: a critical review.

The herbicide atrazine is widely used in agriculture for the production of corn and other crops. Because of its physical and chemical properties, atrazine is found in small concentrations in surface waters--habitats for some species. A number of reports on the effects of atrazine on aquatic vertebrates, mostly amphibians, have been published, yet there is inconsistency in the effects reported, and inconsistency between studies in different laboratories. We have brought the results and conclusions of all of the relevant laboratory and field studies together in this critical review and assessed causality using procedures for the identification of causative agents of disease and ecoepidemiology derived from Koch's postulates and the Bradford-Hill guidelines. Based on a weight of evidence analysis of all of the data, the central theory that environmentally relevant concentrations of atrazine affect reproduction and/or reproductive development in fish, amphibians, and reptiles is not supported by the vast majority of observations. The same conclusions also hold for the supporting theories such as induction of aromatase, the enzyme that converts testosterone to estradiol. For other responses, such as immune function, stress endocrinology, parasitism, or population-level effects, there are no indications of effects or there is such a paucity of good data that definitive conclusions cannot be made.

Reproduction, larval growth, and reproductive development in African clawed frogs (Xenopus laevis) exposed to atrazine.

Reproductive success and development of F2 offspring from F1 adult African clawed frogs (Xenopus laevis) exposed to atrazine throughout larval development and as sexually mature adults was examined. Larval X. laevis were exposed to one of four nominal concentrations of atrazine (0, 1, 10, 25 microg atrazine/l) beginning 96 hr after fertilization and continuing through two years post-metamorphosis. Clutch size and survival of offspring were used as measurement endpoints to gauge reproductive success of the F1 frogs. Larval survivorship and time to metamorphosis were used to gauge developmental success of the F2 offspring from atrazine-exposed frogs. Testes in F1 and F2 frogs were examined for incidence of anomalies, such as testicular ovarian follicles, and sex ratios in F2 offspring were investigated to determine if exposure to atrazine caused trans-generational effects (effects on F2 individuals due to exposure of F1 individuals). There were no effects of any of the studied concentrations of atrazine on clutch size of F1 frogs. There were also no effects on hatching success or time to metamorphosis. Sex ratios did not differ between F2 offspring among treatments. There was no evidence to suggest a transgenerational effect of atrazine on spawning success or reproductive development of X. laevis. This is consistent with the presence of robust populations of X. laevis in areas where they are exposed to atrazine that has been used for several decades for weed control in production of corn. Our observations also are consistent with the results of most other studies of frogs where no effects were found to be associated with exposure to atrazine. Our data do not support the hypothesis that atrazine significantly affects reproductive fitness and development of frogs.

Qualitative and quantitative drug residue analyses: Chlortetracycline in white-tailed deer (Odocoileus virginianus) and supermarket meat by liquid chromatography tandem-mass spectrometry.

Chlortetracycline is (CTC) is a tetracycline antibiotic which is being in the white-tailed deer industry to improve production and animal health. In this paper, we present a method for determining chlortetracycline residues in edible white-tailed deer tissues, using liquid chromatography with heated electrospray ionization and mass spectrometry detection. The procedure involved extraction with EDTA-McIlvaine buffer at pH 4.0, followed by solid-phase extraction cleanup using a hydrophilic-lipophilic balance (HLB) cartridge. The liquid chromatography analysis was performed with heated electrospray ionization and mass spectrometry detection. The limit of quantification for the method was 2.7 ng/g and limit of detection was 0.8 ng/g. The recovery values were >78.5% for muscle, 65.1% for kidney, 63.1% for liver. Mean tissue residue concentration of chlortetracycline and it's epimer, 4-epi chlortetracycline (4-epi-CTC) at 10-day withdrawal period for kidney, liver, muscle was 122.8, 44.7 and 26.7 ng/g, respectively. Chlortetracycline tissue residue concentration at 45-day withdrawal period for kidney, liver, muscle was 19.2, 28.9 and 10.7 ng/g, respectively. Mean tissue concentration of CTC was less than the established maximum residual limit (MRL) values for bovine tissues. We have validated and successfully applied this method in the qualitative and quantification of chlortetracycline in white-tailed deer tissue samples.

Terminology of gonadal anomalies in fish and amphibians resulting from chemical exposures.

Given the recent increase in the number of studies describing the ability of chemicals to exert endocrine-disrupting effects, not only in fish but in a variety of other oviparous groups such as amphibians and reptiles, there is an urgent need to harmonize the terminology currently used in describing pathological changes of the gonads. In addition to difficulties in comparing results from different studies, there is also the risk of miscommunication by using terms that imply a certain clinical relevance which may not be true for the species examined. Especially in the case of the recent and controversial issue about potential effects of the triazine herbicide atrazine on amphibians, clinical terminology has been utilized beyond its true meaning by using terms such as "chemical castration" to describe occurrence of TOs or ovarian tissue in the testis of male frogs exposed to environmental chemicals (Hayes 2004). In clinical terminology, castration is defined as the removal of the gonads or their destruction by an external influence, resulting in a nonfertile organism. However, Hayes (2004) did not investigate any possible effects on the fertility of the test animals and thus did not know if these animals were truly castrated. Similarly, terms such as intersex, hermaphrodite, and sex reversal have been used in ways that appear inappropriate with regard to their clinical meaning in a series of different studies with fish or frogs (see previous sections for a detailed discussion). To ensure the appropriate use of certain terminology in a field as controversial and complex as the study of endocrine disruption, we have attempted, in this chapter, to harmonize the terminology used to describe changes in gonadal development of vertebrates such as fish and amphibians, especially frogs (see Table 3). Where appropriate, the terminology suggested was adopted directly from the clinical terminology. However, as outlined here there are substantial differences between the developmental biology of oviparous vertebrates and mammals, and especially humans, that necessitate modification of the definitions of some of the clinical terms. Where appropriate, therefore, the terminology proposed in this manuscript was redefined based on the biological meanings of the terms used in clinical diagnosis. Considering the large increase in research in the area of reproductive endocrine disruption over the past decades, the authors see an increasing need for a harmonization of terms to be used to describe effects observed in the investigated species. Agreement on a common terminology will allow scientists to better communicate and compare their work, and will enable risk assessors to conduct large-scale evaluations of environmental endocrine disruption by fitting the information from individual studies into a synthesis of normal and abnormal conditions of gonadal tissues.

Age-dependent characterization of pendrin gene expression in various tissues of deer mice.

Pendrin is a membrane transport protein which functions as the transporter of chloride, bicarbonate, formate, and iodide. In this study, we characterized pendrin gene expression in various tissues of deer mice (Peromyscus maniculatus), a sentinel wildlife species. Deer mice were euthanized at post-natal day (PND) 21 (day of weaning) and PND 45 (24 days post-weaning) for tissue collection. A deer mouse-specific partial pendrin cDNA sequence was generated, from which Taqman-specific probe and primers were designed for quantification of mRNA equivalents of pendrin gene expression using real-time polymerase chain reaction (PCR). The expression profile was standardized to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Results indicate that the pendrin gene was expressed at different levels in the different tissues of developing deer mice relative to GAPDH expression. Expression in the tissues was determined to be age-dependent. Pendrin gene was highly expressed in the kidney, lungs and reproductive tissues. PND 21 expression in the kidney and testes was significantly lower than PND 45. This study represents the first identification of differential expression of pendrin gene in various deer mouse tissues.

Development and optimization of a Q-RT PCR method to quantify CYP19 mRNA expression in testis of male adult Xenopus laevis: comparisons with aromatase enzyme activity.

Due to limitations of the currently used enzymatic assays, it is difficult to determine aromatase activity in testicular tissue of amphibians. Quantitative reverse transcription polymerase chain reaction (Q-RT PCR) is a sensitive and reliable technique to detect low amounts of mRNA for specific genes. This study was designed to develop and optimize a SYBR Green I-based Q-RT PCR method to quantify CYP19 mRNA in testicular tissue from male Xenopus laevis. Four quantification methods for measuring CYP19 mRNA expression were compared. The established test system proved to be highly sensitive (detectable mRNA copies < 10), reproducible (interassay CV < 5.4%, intraassay CV < 0.9%), precise and specific for the CYP19 gene. To confirm the validity of the applied test system, an ex vivo testicular and ovarian explant study with a known inducer of aromatase, forskolin, was conducted. Forskolin induced CYP19 gene expression in both ovarian (3.7-fold) and testicular (2.6-fold) explants. Of the four quantification methods, the absolute standard curve and the comparative CT method appear to be optimal as indicated by their highly significant correlation (r2 = 0.998, p < 0.001). In conclusion, we recommend the comparative CT method over the standard curve method because it is more economical in terms of both cost and labor. Although both aromatase activity and CYP19 mRNA were clearly detectable in testes of X. laevis, both aromatase enzyme activity and CYP19 gene expression were very low. Also, no significant relationships were found between aromatase enzyme activity and gene expression. This is likely due the fact that the aromatase enzyme may have been dormant at the developmental stage the frogs were in during the experiment.

Reproductive effects of hexahydro-1,3,5-trinitroso-1,3,5-triazine in deer mice (Peromyscus maniculatus) during a controlled exposure study.

Contamination with hexahydro-1,3,5-trinitro-1,3,5-triazine (Royal Demolition Explosive [RDX]) has been identified at areas of explosive manufacturing, processing, storage, and usage. Thus, the potential exists for exposure to N-nitroso compounds, hexahydro-1-nitroso-3,5-dinitro-1,3,5-triazine, hexahydro-1,3-dinitroso-5-nitro-1,3,5-triazine, and hexahydro-1,3,5-trinitroso-1,3,5-triazine (TNX), formed via anaerobic transformation of RDX. Following exposure, reproductive toxicity of TNX was evaluated in three consecutive litters of deer mice (Peromyscus maniculatus). Hexahydro-1,3,5-trinitroso-1,3,5-triazine was administered ad libitum via drinking water at four doses: 0 (control), 1, 10, and 100 microg/L. Endpoints investigated included reproductive success, offspring survival, offspring weight gain, offspring organ weights, and liver TNX residues. Data from the present study indicate that TNX bioaccumulates in the liver and is associated with postpartum mortality, dose-dependent decrease in body weight from birth to weaning, and decrease in kidney weight of deer mice offspring.

Qualitative and Quantitative Drug residue analyses: Florfenicol in white-tailed deer (Odocoileus virginianus) and supermarket meat by liquid chromatography tandem-mass spectrometry.

A method for confirmation and detection of Florfenicol amine residues in white-tailed deer tissues was developed and validated in our laboratory. Tissue samples were extracted with ethyl acetate and cleaned up on sorbent (Chem-elut) cartridges. Liguid chromatography (LC) separation was achieved on a Zorbax Eclipse plus C18 column with gradient elution using a mobile phase composed of ammonium acetate in water and methanol at a flow rate of 300µL/min. Qualitative and quantitative analyses were carried out using liquid chromatography - heated electrospray ionization(HESI) and atmospheric pressure chemical ionization (APCI)-tandem mass spectrometry in the multiple reaction monitoring (MRM) interface. The limits of detection (LODs) for HESI and APCI probe were 1.8ng/g and 1.4ng/g respectively. Limits of quantitation (LOQs) for HESI and APCI probe were 5.8ng/g and 3.4ng/g respectively. Mean recovery values ranged from 79% to 111% for APCI and 30% to 60% for HESI. The validated method was used to determine white-tailed deer florfenicol tissue residue concentration 10-days after exposure. Florfenicol tissue residues concentration ranged from 0.4 to 0.6µg/g for liver and 0.02-0.05µg/g for muscle and a trace in blood samples. The concentration found in the tested edible tissues were lower than the maximum residual limit (MRL) values established by the federal drug administration (FDA) for bovine tissues. In summary, the resulting optimization procedures using the sensitivity of HESI and APCI probes in the determination of florfenicol in white-tailed deer tissue are the most compelling conclusions in this study, to the extent that we have applied this method in the evaluation of supermarket samples drug residue levels as a proof of principle.

Effects of atrazine on CYP19 gene expression and aromatase activity in testes and on plasma sex steroid concentrations of male African clawed frogs (Xenopus laevis).

Some investigators have suggested that the triazine herbicide atrazine can cause demasculinization of male amphibians via upregulation of the enzyme aromatase. Male adult African clawed frogs (Xenopus laevis) were exposed to three nominal concentrations of atrazine (1, 25, or 250 microg atrazine/l) for 36 days, and testicular aromatase activity and CYP19 gene expression, as well as concentrations of the plasma sex steroids testosterone (T) and 17beta-estradiol (E2), and gonad size (GSI) were measured. There were no effects on any of the parameters measured, with the exception of plasma T concentrations. Plasma T concentrations in X. laevis exposed to the greatest concentration of atrazine were significantly less (p = 0.034) than those in untreated frogs. Both CYP19 gene expression and aromatase activities were low regardless of treatment, and neither parameter correlated with the other. We conclude that aromatase enzyme activity and gene expression were at basal levels in X. laevis from all treatments, and that the tested concentrations of atrazine did not interfere with steroidogenesis through an aromatase-mediated mechanism of action.

Plasma concentrations of estradiol and testosterone, gonadal aromatase activity and ultrastructure of the testis in Xenopus laevis exposed to estradiol or atrazine.

The ultrastructure of testicular cells of adult male African clawed frogs (Xenopus laevis) exposed to either estradiol (0.1 microg/L) or 2-chloro-4-ethylamino-6-isopropyl-amino-s-triazine (atrazine; 10 or 100 microg/L) was examined by electron microscopy and compared to plasma concentrations of the steroid hormones, testosterone (T) and estradiol (E2), testicular aromatase activity and gonad growth expressed as the gonado-somatic index (GSI). Exposure to E2 caused significant changes both at the sub-cellular and biochemical levels. Exposure to E2 resulted in significantly fewer sperm cells, inhibition of meiotic division of germ cells, more lipid droplets that are storage compartments for the sex steroid hormone precursor cholesterol, and lesser plasma T concentrations. Although not statistically significant, frogs exposed to E2 had slightly smaller GSI values. These results may be indicative of an inhibition of gonad growth and disrupted germ cell development by E2. Concentrations of E2 in plasma were greater in frogs exposed to E2 in water. Exposure to neither concentration of atrazine caused effects on germ cell development, testicular aromatase activity or plasma hormone concentrations. These results suggest that atrazine does not affect testicular function. In contrast, exposure of male X. laevis to E2 led to sub-cellular events that are indicative of disruption of testicular development, and demasculinization processes (decrease of androgen hormone titers). These results indicate that atrazine does not cause responses that are similar to those caused by exposure to E2.

Evaluation of adult quail and egg production following exposure to perchlorate-treated water.

Twenty-three adult female northern bobwhite (Colinus virginianus) quail were exposed to 0, 0.01, 0.1, and 1 mM ammonium perchlorate (AP) in drinking water for 30 d. Eggs laid in all treatment groups, including control, were collected, dated, given an identification number, and weighed. On day 30 of exposure, 10 birds were euthanized by carbon dioxide asphyxiation. Gross toxicological endpoints and thyroid histology were evaluated in 10 birds. Egg production and accumulation of perchlorate in the eggs (n = 10) and liver (n = 5) were determined. Perchlorate did not affect body or organ weights significantly; however, at 1 mM, AP caused alteration of thyroid gland morphology. Perchlorate did not affect egg production, but significant accumulation was observed in the eggs and livers of exposed birds.

In utero and lactational exposure to ammonium perchlorate in drinking water: effects on developing deer mice at postnatal day 21.

The effects of in utero and lactational exposure to ammonium perchlorate (AP), a component of rocket fuel and a thyroid toxicant, on developing deer mice (Peromyscus maniculatus) were evaluated. Breeding pairs were dosed continuously with 0, 1 nM, 1 micro M, or 1 mM AP in drinking water, from cohabitation until pups were euthanized at postnatal day (PND) 21. Pups from the second litter were used for evaluation in this study. No significant differences were observed in any analysis performed when litter means were used in statistical analysis. All reported significant differences occurred when statistical analysis was performed on individual pup data. Body weights were significantly different between treatments at PND 5 and PND 20, with the 1- micro M body weights being lower than that of controls. Body weight and liver weight in the 1-mM group were significantly higher than the 1- micro M weights at PND 21 when analyzed by analysis of variance (ANOVA). However, there were no significant differences in liver weights when analyzed with body weight as the covariate. Heart weights were significantly different between males and females. Male heart weights in the 1- microM and 1-mM groups were significantly lower than in controls when analyzed by analysis of covariance (ANCOVA) with body weight as the covariate. Litter size and survival percentage were not significantly different among treatments. Although significant differences were observed only when the individual pup was used as the experimental unit, these data suggest that AP exposure at different concentrations may variably alter body weight and male heart weight during mammalian development.

Effects of in utero and lactational ammonium perchlorate exposure on thyroid gland histology and thyroid and sex hormones in developing deer mice (peromyscus maniculatus) through postnatal day 21.

Thyroid gland hormone levels and histology and sex hormone levels in developing deer mice (Peromyscus maniculatus) were measured following in utero and lactational exposure to ammonium perchlorate (AP), a component of rocket fuel and a thyroid toxicant. Breeding pairs were dosed continuously with 0, 1 nM, 1 micro M, or 1 mM concentrations of AP in drinking water from the time of cohabitation until pups from the third litter were weaned. Pups from the second litter were used for evaluation in this study. The active (colloid-containing) thyroid follicle number per unit area was significantly different between treatment groups. The 1-nM and 1-mM treatment groups had significantly fewer active follicles per unit area than did controls. The 1-mM treatment group also had significantly fewer active follicles than the 1- micro M and the 1-nM treatment groups. Total T(4) concentrations were significantly increased in the 1-nM and 1- micro M groups compared to the controls. No significant difference was observed in total T(3) concentrations. None of the 1-mM plasma had concentrations of total testosterone above the detection limit, and only one of the 1- micro M samples was above the detection limit of the assay. All estradiol concentrations were below the detection limits of the assay. In contrast to the situation in adult rodents, it appears that AP increases thyroid hormone production in developing deer mice and produces variable effects with increasing concentrations.