DISTRIBUTION OF C14-DDT AND C14-DIELDRIN IN PREGNANT MICE DETERMINED BY WHOLE-BODY AUTORADIOGRAPHY

Effect of DDT or Parathion on Audiogenic Seizures of Offspring from Ddt- or Parathion-Treated Mothers

DDT, Parathion, or corn oil (control) was administered to gravid mice during the first, second, and third trimesters of pregnancy. Incidence of audiogenic seizure was used to study the effect of the insecticides in the offspring. These compounds affected the maturation of the nervous system regardless of the stage of pregnancy during which they were administered. The high incidence of seizures in all of the groups of offspring had passed by 28 days of age. The insecticides did not influence the percentage of incidence after 20 days of age.

Assessment of DDT relative bioavailability and bioaccessibility in historically contaminated soils using an in vivo mouse model and fed and unfed batch in vitro assays

In this study, DDTr (DDTr = DDT + DDD + DDE) relative bioavailability in historically contaminated soils (n = 7) was assessed using an in vivo mouse model. Soils or reference materials were administered to mice daily over a 7 day exposure period with bioavailability determined using DDTr accumulation in adipose, kidney, or liver tissues. Depending on the target tissue used for its calculation, some variability in DDTr relative bioavailability was observed; however, it did not exceed 25% (range 2-25%). When DDTr bioaccessibility was determined using organic physiologically based extraction test (Org-PBET), unified BARGE method (UBM), and fed organic estimation human simulation test (FOREhST) in vitro assays, bioaccessibility was less than 4% irrespective of the assay utilized and the concentration of DDTr in the contaminated soil. Pearson correlations demonstrate a poor relationship between DDTr relative bioavailability and DDTr bioaccessibility (0.47, 0.38, and 0.28, respectively), illustrating the limitations of the static in vitro methods for predicting the dynamic processes of the mammalian digestive system for this hydrophobic organic contaminant.

Effects of lipophilic complex formation on the disposition of nickel in experimental animals

Dithiocarbamates, thiuram sulphides, xanthates, pyridinethiones and halogenated 8-hydroxyquinolines are groups of compounds which can form lipophilic complexes with Ni2+. These compounds are widely used as drugs and pesticides, and in industry. We have exposed rodents (mice, rats) and fish (brown trout) to substances belonging to these groups of compounds together with 63Ni2+ (as 63NiCl2) and then examined the uptake of the 63Ni2+ in the tissues of the animals. One dithiocarbamate--sodium diethyldithiocarbamate, which is used clinically in nickel carbonyl intoxications--was also examined with regard to effects on the tissue disposition of the metal in mice exposed to 63Ni(CO)4. The studies with 63Ni2+ showed that some of the complexing substances examined caused highly increased tissue levels of the metal in the animals. However, the enhancing effect varied with different complexing compounds. A facilitated penetration of the lipophilic 63Ni2+ complexes across the cellular membranes may underlie the increments in the tissue levels of the metal, but the effects on the disposition of the 63Ni2+ may vary depending on the lipophilicity and the stability of the complexes. In mice exposed to 63Ni(CO)4 by inhalation, sodium diethyldithiocarbamate decreased the levels of the metal in tissues such as the lung, brain and heart. These tissues are targets in nickel carbonyl intoxications and will attain high levels of the metal following inhalation of the compound. The nickel is present in nickel carbonyl as Ni0, but will be oxidized to Ni2+ in the tissues. The experiments presented here indicate that the diethyldithiocarbamate is able to reach and bind the intracellular Ni2+ in the critical target tissues and this property may underlie the ability of the compound to act as an antidote in nickel carbonyl intoxications. However, the ability of diethyldithiocarbamate to act as a nickel antidote may be limited to nickel carbonyl. Generally, the increased uptake of nickel induced by the compounds forming lipophilic complexes with the metal may imply risks of noxious combination effects.

Tissue accumulation of lipoprotein associated toxaphene in normo- and hypolipidemic mice

Normo- and hypolipidemic mice were given a single i.v. injection of 14C-toxaphene associated with low density lipoprotein (LDL), high density lipoprotein (HDL) or dimethyl sulfoxide (DMSO). The tissue distribution of radioactivity was studied 20 min and 4 h after the application. In the normolipidemic mice at 20 min postinjection there was high uptake of the 14C-toxaphene preparations in the liver and adrenals followed after 4 h by a redistribution to the adipose tissues. In the hypolipidemic mice, proportionally less label accumulated initially in the liver and adrenals while more radioactivity was seen in the kidneys and heart. The radioactivity then redistributed to the liver with a very small uptake in the adipose tissue compared to the normolipidemic mice after 4 h. The results indicate that changes in the lipid pattern, e.g. hypolipidemic conditions, may influence the tissue distribution of lipophilic xenobiotics.

o,p'-DDD in the mouse lung: selective uptake, covalent binding and effect on drug metabolism

By means of autoradiography a high and selective accumulation was observed in the lung alveolar region of C57Bl mice injected with o,p'-[14C]DDD. Exhaustive extraction of lung tissue showed that a large fraction of the radioactivity was covalently bound to protein. Covalent binding in liver was 20-30 times lower and represented a smaller fraction of the total radioactivity present in this tissue. Formation of a cytochrome P-450 catalysed reactive metabolite in lung and liver was indicated by a decreased covalent binding in these tissues in mice pretreated with metyrapone. Both beta-naphthoflavone (beta NF) and phenobarbital (PB) pretreatment decreased binding of o,p'-DDD in lung tissue, while binding in the liver was induced by PB but remained unaffected by beta NF. Pretreatment with high doses of o,p'-DDD and p,p'-DDT gave a significantly decreased binding of o,p'-[14C]DDD in lung, whereas binding in liver remained unchanged. Conjugation with glutathione does not appear to be a major inactivation pathway for the reactive lung metabolite, since a high dose of o,p'-DDD did not deplete non-protein thiols (NPSH) in lung tissue. Pretreatment with o,p'-DDD decreased the N-demethylation of [dimethyl-14C]aminopyrine in both lung and liver in a dose-dependent manner, suggesting that the drug-metabolizing enzyme system may be a target for o,p'-DDD in vivo.

Distribution and retention of some chlorinated hydrocarbons and a phthalate in the mouse brain during the pre-weaning period

In a quantitative retaining study and a whole-body autoradiographic study 5 14C-labelled compounds, bis-(4-chlorophenyl)trichloroethane (DDT), 2,2',4,4',5,5'-hexachlorobiphenyl (6-CB), hexachlorophene (HCP), polychlorohexadecane (PCHD) and diethylhexylphthalate (DEHP) were each administered to mice at the age of 3, 10 and 20 days. The mice were killed 24 h or 7 days after treatment and the amount of radioactivity in the whole brain was measured and its distribution studied. The retention of radioactivity was most pronounced in mice receiving DDT, PCHD, and 6-CB during the tenth day of life. Here the level of radioactivity 7 days after treatment was nearly as high as that observed after 24 h (ratio between 0.86 and 0.74). In contrast, HCP showed a rapid elimination from the brain and was hardly retained at all in the 20-day-old mouse brain. The retention of DEHP in the brain was minimal. Some of the autoradiographic sections were also subjected to myelin staining. Large amounts of radioactivity were found in the myelinated areas of the brain after HCP and PCHD administration. DDT and 6-CB showed a more even distribution within the brain and were not particularly concentrated in the myelin. There was no obvious relationship between the lipophilicity of the parent compounds and their retention in the brain.

Effect of thiuram sulphides on the uptake and distribution of nickel in pregnant and non-pregnant mice

Oral administration of 63Ni2+ together with thiuram sulphides (tetramethylthiuram disulphide, tetraethylthiuram disulphide, tetrabutylthiuram disulphide, dipentamethylenethiuram monosulphide or dipentamethylenethiuram tetrasulphide) or sodium diethyldithiocarbamate resulted in highly increased levels of 63Ni2+ in several tissues of mice in comparison with animals given 63Ni2+ alone. Administration of these substances to pregnant animals induced increased levels of 63Ni2+ in the fetuses. The uptake of 63Ni2+ in the brains of both adults and fetuses was usually very markedly enhanced by these compounds--dipentamethylenethiuram monosulphide and tetraethylthiuram disulphide being the most efficient compounds in this respect. Determination of the chloroform/water partition coefficients for nickel in the presence of thiuram sulphides or sodium diethyldithiocarbamate showed that these compounds are able to form lipophilic complexes with the metal. A facilitated penetration through the cellular membranes of the lipophilic complexes between nickel and these substances can explain the effects on the fate of the nickel. However, the partition coefficient for nickel in presence of sodium diethyldithiocarbamate was much higher than for the thiuram sulphides, but in spite of that, the effect of sodium diethyldithiocarbamate on the disposition of 63Ni2+ in the mice was not more marked than for most of the thiuram sulphides. It has been shown that tetraethylthiuram disulphide undergoes a reductive fission in the gut to diethyldithiocarbamate, which is considered to be the active form of tetraethylthiuram disulphide. The marked effects on the disposition of the 63Ni2+ induced by the other thiuram sulphides examined in the present study suggest that a similar fission to chelating thiocarbamates will take place. However, the formation of lipophilic complexes with the original thiuram sulphides may contribute to the effects on the disposition of the 63Ni2+.

Fate and specific tissue retention of toxaphene in mice

Series of female virgin and pregnant albino mice were i.v. injected with 14C-labelled- or unlabelled toxaphene (16 mg/kg b.w.). After survival times ranging from 1 min to 32 days the toxaphene distribution in the body was studied using whole-body autoradiography and capillary gas-chromatography. Autoradiographic studies have shown that after an initial accumulation in the liver, brown fat, lung, brain, kidney, and ovaria (corpora lutea) there was a gradual redistribution of radioactivity to the white fat within 4 h postinjection. The labelling was then decreasing rapidly and only negligible amounts of the radioactivity were present in the adipose tissue after 32 days. In the fetus only the liver and adrenals showed a distinct labelling. A specific and persistent accumulation of the label was detected in some zones of the adrenal cortex suggesting a possible direct interference of toxaphene with adrenal steroid hormone synthesis. The gas chromatographic pattern of toxaphene-derived residues in the tissue samples resembled that of the technical toxaphene, but was changing in different tissues with the time. The liver chromatograms indicated more extensive formation of metabolites.

Selective binding of aldrin and dieldrin in cartilage

Whole body autoradiography of 14C-aldrin and 14C-dieldrin in pregnant mice indicated a slow but persistent uptake of both substances in cartilage, e.g. in the vertebral and epiphyseal discs. Also in the fetal skeleton a marked accumulation was observed.

The distribution and metabolism of nickel carbonyl in mice

The distribution of 63Ni- and 14C-labelled nickel carbonyl was studied in mice by whole-body autoradiography and by liquid scintillation counting. Radioactivity from Ni(14CO)4 was found almost exclusively in the blood, probably because of the formation of 14CO-haemoglobin. After the administration of 63Ni(CO)4 the highest level of 63Ni was found in the lung. Other tissues accumulating a high amount of 63Ni were the brain and spinal cord, the heart muscle, the diaphragm, brown fat, the adrenal cortex and the corpora lutea of the ovaries. A high level of 63Ni was also present in the kidneys and the urinary bladder. Experiments designed to establish whether the nickel in the lung, the brain, the heart muscle and the blood was present in a non-ionised form, or as a cation, suggest that nickel is bound to these tissues in the cationic state (Ni++).

The effect of insecticides on Chinese hamster cell cultures

The effect of p,p'-isomers of DDT and its derivatives DDD, DDE and DDA on Chinese hamster cells in culture was studied. At different concentrations and various times of treatment the proliferation rate was inhibited most strongly by DDD and DDT, whereas DDE exhibited a markedly weaker influence. DDA was the least toxic compound of the four. The cytogenetic effects were also different. Again, DDA induced the least damage. Only enhanced gap rates but no chromosome breaks were observed. DDE was more active, and higher break rates occurred. DDD and DDT were by far the most damaging compounds, and they raised the gap and break rates markedly. However, no induction of configuration anomalies was found in any experiment. Chronic treatment of the cells for 3 months with DDT at 8 ppm did not alter the proliferation rate, the sensitivity to acute treatment with higher DDT concentrations or the chromosomal aberration rates. The results are discussed in relation to the relevance of differential pesticide effectivity in organs of higher animals and man.

Distribution of 14-C-PCB during fetal period. Whole-body autoradiography of pregnant mice

14-C-PCB containing 85% 2,2'-Dichlorobiphenyl was injected intramusculary in pregnant mice. The distribution of radioactivity was studied by using whole-body autoradiography technique. After its removal from the injection site, the major part of radioactivity was accumulated in maternal excretory organs: intestine, kidney, and urinary bladder. This indicated a rapid elimination of the 2,2'-Dichlorobiphenyl. High radioactivity could also be found in the gall bladder and a large amount in the liver. Comparatively less radioactive substance was present in the fat depots, skin, lung, and blood. At the beginning of the fetal period the uptake by fetuses was very low but about one day before the parturation moderate uptake occurred. At the end of gestation in fetuses, radioactivity was present predominately in the intestine and urinary bladder; it could also be detected in the liver and kidneys.

Effect of DDT or parathion on open-field behavior of offspring from DDT- or parathion-treated mothers

Mice offspring were prepared and raised from DDT-, Parathion-, or corn oil-treated mothers during the first, second, and third trimesters of pregnancy. All Ss were subjected to the open-field test when 60 to 66 days old. The offspring of DDT- and Parathion-treated mothers did not behave differently from the offspring of corn oil-treated mothers (control).