Chlorinated insecticides (toxaphene and endrin) affect oxytocin, testosterone, oestradiol and prostaglandin secretion from ovarian and uterine cells as well as myometrial contractions in cow in vitro

We examined the direct effects of toxaphene and endrin, chlorinated insecticides that are widespread in the environment, on myometrial contractions and on the secretion of hormones involved in regulating these contractions. Granulosa, luteal, endometrial and myometrial cells, and myometrial strips from non-pregnant cows were incubated with both insecticides at environmentally relevant doses. Toxaphene inhibited and endrin stimulated the secretion of testosterone and oestradiol from granulosa cells. Toxaphene also inhibited and endrin stimulated the expression of the mRNA encoding the precursor of oxytocin (OT), as well OT secretion in luteal cell cultures. Moreover, endrin increased OT secretion from granulosa cells. Neither insecticide exerted an effect on progesterone secretion from luteal cells. Only toxaphene decreased the secretion of prostaglandins (PGF2 and PGE2) from endometrial cells. Meanwhile, only endrin decreased basal myometrial contractions, which was accompanied by inhibition of PGF2 secretion from the myometrium. Both endrin and toxaphene also decreased the force of the OT-stimulated myometrial contractions, whereas only toxaphene inhibited the stimulatory effect of OT on the force of myometrial contractions. In contrast to endrin, toxaphene decreased synthesis and secretion of one of the primary stimulators of myometrial contractions (OT) and indirectly inhibited OT signal reception in the myometrium by reducing E2 secretion. Both insecticides decreased OT-stimulated myometrial contractions; therefore, they may inhibit further transmission of the OT signal. Moreover, endrin inhibited basal myometrial contractions, potentially resulting from reduced PGF2 secretion from the myometrium. Our data indicate the potential of these insecticides to disturb the course of the oestrous cycle or fertilisation.

Comparative effects of TCDD, endrin, naphthalene and chromium (VI) on oxidative stress and tissue damage in the liver and brain tissues of mice

The mechanism of toxicity of structurally diverse environmental toxicants including heavy metals and polyhalogenated and polycyclic hydrocarbons may involve a common cascade of events which entails an oxidative stress and production of reactive oxygen species. We have determined the comparative effects of single 0.01, 0.10 and 0.50 LD(50) doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), endrin, naphthalene and sodium dichromate (chromium VI) on lipid peroxidation, DNA fragmentation and enhanced production of superoxide anion (cytochrome c reduction) in liver and brain tissues of C57BL/6NTac mice. The effects of a single acute oral 0.50 LD(50) dose of these xenobiotics on hepatic and brain lipid peroxidation were investigated at 0, 12, 24, 48, and 96 h after treatment, while the effects of 0.10 LD(50) and 0.01 LD(50) doses of these xenobiotics were at 0, 24, 48, 72, and 96 h after treatment. Dose- and time-dependent effects were observed with all four xenobiotics. At a 0.50 LD(50) dose of TCDD, endrin, naphthalene and chromium VI, maximum increases in cytochrome c reduction (superoxide anion production) of approximately 5.7-, 5.4-, 5.3- and 4.1-fold, respectively, were observed in hepatic tissues. TCDD showed an increasing effect through 96 h. Endrin and naphthalene demonstrated a maximum effect at 12-24 h, while chromium VI exhibited a maximum effect at 48 h. With respect to lipid peroxidation, at a 0.50 LD(50) dose both endrin and chromium VI induced the maximum effect at 48 h of treatment, while naphthalene demonstrated the maximum effect after 24 h of treatment. TCDD demonstrated a continued effect through 96 h of treatment. At a 0.50 LD(50) dose TCDD, endrin, naphthalene and chromium VI produced maximum increases in hepatic lipid peroxidation of approximately 3.5-, 3.1-, 3.7- and 3.3-fold in hepatic tissues, respectively. Similar results were obtained in hepatic and brain DNA fragmentation at 0.50 LD(50) doses. Lesser effects were observed with 0.10 and 0.01 LD(50) doses of these xenobiotics as compared to the 0.50 LD(50) dose. The results clearly demonstrate that these diverse xenobiotics induce dose- and time-dependent oxidative stress and tissue damage in the liver and brain tissues of mice.

Role of p53 tumor suppressor gene in the toxicity of TCDD, endrin, naphthalene, and chromium (VI) in liver and brain tissues of mice

It has been postulated that tumor suppressor genes are involved in the cascade of events leading to the toxicity of diverse xenobiotics. Therefore, we have assessed the comparative effects of 0.01, 0.10, and 0.50 median lethal doses (LD(50)) of 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD), endrin, naphthalene, and sodium dichromate (VI) [Cr(VI)] on lipid peroxidation, DNA fragmentation, and enhanced production of superoxide anion (cytochrome c reduction) in liver and brain tissues of p53-deficient and standard C57BL/6NTac mice to determine the role of p53 gene in the toxic manifestations produced by these diverse xenobiotics. In general, p53-deficient mice are more susceptible to all four xenobiotics than C57BL/6NTac mice, with dose-dependent effects being observed. Specifically, at a 0.50 LD(50) dose, naphthalene and Cr(VI) induced the greatest toxicity in the liver tissue of mice, and naphthalene and endrin exhibited the greatest effect in the brain tissue. At this dose, TCDD, endrin, naphthalene, and Cr(VI) induced 2.3- to 3.7-fold higher increases in hepatic lipid peroxidation and 1.8- to 3.0-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. At a 0. 10 LD(50) dose, TCDD, endrin, naphthalene, and Cr(VI) induced 1.3- to 1.8-fold higher increases in hepatic lipid peroxidation and 1.4- to 1.9-fold higher increases in brain lipid peroxidation in p53-deficient mice than in C57BL/6NTac mice. Similar results were observed with respect to DNA fragmentation and cytochrome c reduction (superoxide anion production). For example, at the 0.10 LD(50) dose, the four xenobiotics induced increases of 1.6- to 3. 0-fold and 1.5- to 2.1-fold in brain and liver DNA fragmentation, respectively, and increases of 1.5- to 2.3-fold and 1.4- to 2.5-fold in brain and liver cytochrome c reduction (superoxide anion production), respectively, in p53-deficient mice compared with control C57BL/6NTac mice. These results suggest that the p53 tumor suppressor gene may play a role in the toxicity of structurally diverse xenobiotics.

TCDD, endrin and lindane induced oxidative stress in fetal and placental tissues of C57BL/6J and DBA/2J mice

The abilities of TCDD, endrin and lindane to induce oxidative stress in fetal and placental tissues have been studied after the oral administration of these xenobiotics to pregnant C57BL/6J and DBA/2J mice. Production of superoxide anion, lipid peroxidation and DNA-single strand breaks (SSB) was determined in live fetal and placental tissues 48 hr after administration of single teratogenic doses of the compounds on day 12 of gestation. Oxidative stress and its biomarkers were also determined in livers of day 18 fetuses after administration on day 12 of gestation. TCDD given at doses of 30 and 60 micrograms/kg body weight to the C57BL/6J and DBA/2J mice, respectively, produced increases of 1.3-2.7-fold in superoxide anion production, 1.6-1.9-fold in lipid peroxidation and 2.1-4.4-fold in DNA-SSB. Endrin, given at a dose of 4.5 mg/kg body weight to C57BL/6J and DBA/2J mice, produced increases of 1.3-2.8-fold in superoxide production, 1.4-1.8-fold in lipid peroxidation and 1.4-4.7-fold in DNA-SSB. Lindane when given at a dose of 30 mg/kg body weight to C57BL/6J and DBA/2J mice produced increases of 1.6-3.0-fold in superoxide production, 1.3-2.1-fold in lipid peroxidation and 1.4-5.0-fold in DNA-SSB. The results suggest that superoxide production, lipid peroxidation and DNA-SSB in fetal and placental tissues may participate in the fetotoxic effects of TCDD and other polyhalogenated cyclic hydrocarbons, and that TCDD-induced oxidative damage in fetal and placental tissues is mediated at least in part by the Ah-receptor. The results also indicate that TCDD as an inducer of oxidative tissue damage in the embryos and placentas is approximately 150 and 1000 times more potent than endrin and lindane, respectively, in C57BL/6J mice, and 75 and 500 times more potent than endrin and lindane, respectively, in the DBA/2J mouse strain.

In vitro and in vivo induction of heat shock (stress) protein (Hsp) gene expression by selected pesticides

The chloroacetamide insecticide alachlor, polyhalogenated cyclic hydrocarbons endrin and chlordane and the organophosphate pesticides chlorpyrifos and fenthion induce oxidative tissue damaging effects including lipid peroxidation and nuclear DNA-single strand breaks. The mechanism involved in the induction of oxidative stress by these xenobiotics is unknown. No information is available regarding whether these pesticides can induce the expression of heat shock (stress) protein (Hsp) genes as a common protective mechanism against tissue damage. The pesticides were administered p.o. individually to female Sprague-Dawley rats in two 0.25 LD50 doses at 0 h and 21 h. The animals were killed at 24 h, and liver, brain, heart and lung tissues were removed to examine the induction of Hsps by Western and Northern blot analysis. In a separate series of experiments, cultured neuroactive PC-12 cells were treated 24 h with 50, 100 or 200 nM concentrations of these pesticides. Alachlor, endrin, chlorpyrifos and fenthion induced Hsp89 alpha and Hsp89 beta in hepatic and brain tissues, as well as in cultured PC-12 cells. Chlordane induced some expression of Hsp89 alpha but not Hsp89 beta in the hepatic and brain tissues of treated rats. Some expression of Hsp89 beta was observed in lung tissues of endrin and alachlor treated animals. These findings were substantiated by Western blot analysis using Hsp90 antibody. Except chlordane all these pesticides induced enhanced synthesis of Hsp90 in cultured PC-12 cells. The results indicate striking tissue differences in the patterns of the Hsps induced by the pesticides which were used, and demonstrate that these pesticides can induce the expression of Hsp89 alpha and Hsp89 beta genes in various target organs of rats. The results support the hypothesis that these genes may be mechanistically involved in protecting tissues against oxidative stress induced by structurally diverse pesticides.

Comparative teratological studies on TCDD, endrin and lindane in C57BL/6J and DBA/2J mice

The teratogenic effects of endrin and lindane have been determined and compared to those induced by TCDD in the fetuses of C57BL/6J and DBA/2J mice after the administration of single oral doses to pregnant mice on day 12 of gestation. TCDD produced dose-dependent decreases in fetal weight, fetal thymic weight and placental weight, and dose-dependent increases in fetolethality, cleft palate formation and hydronephrosis at doses of 10-30 and 30-60 micrograms/kg body weight in C57BL/6J and DBA/2J mice, respectively. No maternal death was observed at the given doses in both strains of mice. Endrin (4.5 and 6 mg/kg body weight) and lindane (30 and 45 mg/kg body weight) produced significant decreases in fetal weight and placental weight in C57BL/6J and DBA/2J mice, and dose-dependent decreases in fetal thymic weight in C57BL/6J mice but not DBA/2J mice. Endrin and lindane caused 0-25 and 14-25% maternal deaths, respectively, at the above mentioned doses. Neither cleft plate nor hydronephrosis were induced by endrin or lindane in the two strains of mice. The results support the hypothesis that TCDD-induced cleft plate and hydronephrosis involve mechanisms that are Ah (aryl hydrocarbon) receptor mediated. However, other fetotoxic effects induced by TCDD, and the fetotoxic effects induced by endrin and lindane may involve additional unknown mechanisms that are not related to the Ah-receptor.

In vitro and in vivo generation of reactive oxygen species, DNA damage and lactate dehydrogenase leakage by selected pesticides

Reactive oxygen species may be involved in the toxicity of various pesticides and we have, therefore, examined the in vivo effects of structurally dissimilar polyhalogenated cyclic hydrocarbons (PCH), such as endrin and chlordane, chlorinated acetamide herbicides (CAH), such as alachlor, and organophosphate pesticides (OPS), such as chlorpyrifos and fenthion, on the production of hepatic and brain lipid peroxidation and DNA-single strand breaks (SSB), two indices of oxidative stress and oxidative tissue damage. The selected pesticides were administered p.o. to female Sprague-Dawley rats in two 0.25 LD50 doses at 0 h and 21 h and killed at 24 h. In a parallel set of experiments, we have determined the in vitro effects of these pesticides on the DNA-SSB and enhanced lactate dehydrogenase leakage (LDH) from neuroactive PC-12 cells in culture. In vitro production of reactive oxygen species by these pesticides was also assessed by determining the enhanced chemiluminescence responses of hepatic and brain homogenates. Following treatment of rats with endrin, chlordane, alachlor, chlorpyrifos and fenthion, increases of 2.8-, 3.0-, 4.2-, 4.3- and 4.8-fold were observed in hepatic lipid peroxidation, respectively, while at these same doses, increases in lipid peroxidation of 2.4-, 2.1-, 3.6-, 4.6- and 5.3-fold, respectively, were observed in brain homogenates. Increases of 4.4-, 3.9-, 1.6-, 3.0- and 3.5-fold were observed in hepatic DNA-SSB following treatment of the rats with endrin, chlordane, alachlor, chlorpyrifos and fenthion, respectively, while at these same doses, increases of 1.9-, 1.7-, 2.2-, 1.4-, 1.4-fold, respectively, were observed in brain nuclear DNA-SSB. Following in vitro incubation of hepatic and brain tissues with 1 nmol/ml of each of the five pesticides, maximum increases in chemiluminescence occurred within 4-7 min of incubation and persisted for over 10 min. Increases of 3.0-, 2.7-, 3.6-, 4.9- and 4.4-fold were observed in chemiluminescence following in vitro incubation of the liver homogenates with endrin, chlordane, alachlor, chlorpyrifos and fenthion, respectively, while increases of 1.7-, 1.8-, 2.0-, 3.4- and 3.7-fold, respectively, were observed in the brain homogenates. Increases of 2.2-, 2.3-, 2.9-, 2.9- and 3.4-fold were observed in the chemiluminescence responses in the liver homogenates of the animals treated with endrin, chlordane, alachlor, chlorpyrifos and fenthion, respectively, while increases of 1.8-, 2.0-, 3.2-, 2.9- and 2.4-fold, respectively, were observed in the brain homogenates. Cultured neuroactive PC-12 cells were incubated with the pesticides and the release of the enzyme lactate dehydrogenase (LDH) into the media as an indicator of cellular damage and cytotoxicity was examined. Maximal release of LDH from cultured PC-12 cells was observed at 100 nM concentrations of the pesticides. Increases of 2.3-, 2.5-, 2.8-, 3.1 and 3.4-fold were observed in LDH leakage following incubation of the PC-12 cells with endrin, chlordane, alachlor, chlorpyrifos and fenthion, respectively. Following incubation of the cultured PC-12 cells with 100 nM concentrations of these same pesticides, increases in DNA-SSB of 2.5-, 2.2-, 2.1-, 2.4- and 2.5-fold, respectively, were observed. The results clearly demonstrate that these different classes of pesticides induce production of reactive oxygen species and oxidative tissue damage which may contribute to the toxic manifestations of these xenobiotics. Reactive oxygen species may serve as common mediators of programmed cell death (apoptosis) in response to many toxicants and pathological conditions.

Predicting ecotoxicological impacts of environmental contaminants on terrestrial small mammals

This review examines whether the effects of environmental contaminants on wild small mammals can be predicted from the results of single-species, laboratory toxicity studies. Heavy metals, organochlorines, chlorinated aromatic hydrocarbons, and OP/carbamate pesticides were identified as the groups of xenobiotics for which there are toxicity data for terrestrial small mammals and that, on the basis of persistence, acute toxicity, and bio-accumulation potential, present the greatest hazard to wild mammals. Laboratory-generated toxicity data, which used lethality and reproduction as measurable endpoints, were reviewed and intake and residue LOAELs estimated for representative chemicals (lead, endrin, PCBs) from the heavy metal, organochlorine, and chlorinated aromatic hydrocarbon substance groups; the OPs and carbamates were reviewed as a whole. Intakes and residues of these compounds in wild small mammals were compared with laboratory-defined LOAELs and the likelihood of effects predicted. The accuracy of these predictions was examined and the efficacy of extrapolating toxicity data from laboratory to wild species assessed. Qualitative extrapolation from laboratory to wild species was good for all the chemicals considered, laboratory tests correctly identifying the types of effects chemicals had on a wide range of wild mammals. In contrast, the quantitative extrapolation of dose-response data was either poor or largely unvalidated. This is because interspecies variation in sensitivity to xenobiotics and the effects on toxicity of differences in exposure pattern between laboratory and wild species are largely unquantified. Based upon the limited evidence available, errors in the direct extrapolation of dose-response data from laboratory to field may be as large as three orders of magnitude. Direct extrapolation of residue-response data from laboratory to wild mammals is good both for the effects of heavy metals on specific organs and for residues and acetylcholinesterase inhibition associated with pesticide-induced mortality. The use of organ residues or biomarkers to predict the severity of sublethal effects on reproductive output may be possible, although large residues or biomarker responses are not necessarily indicative of the severity of wider physiological effect. Appropriate residues/biomarkers may differ for various xenobiotics and even between species for the same xenobiotic. Further research is required to identify suitable markers that can be correlated with the occurrence and magnitude of ecologically important effects. Xenobiotics likely to have a direct effect on population dynamics are those that are persistent and adversely affect survival and reproduction. At present, this weak correlation is the only one that can be made between single-species laboratory tests and population effects.(ABSTRACT TRUNCATED AT 400 WORDS)

Comparative effects of endrin on hepatic lipid peroxidation and DNA damage, and nitric oxide production by peritoneal macrophages from C57BL/6J and DBA/2 mice

1. Endrin is a polyhalogenated cyclic hydrocarbon which produces hepatic and neurologic toxicity. In order to further assess the mechanism of toxicity of endrin, the dose-dependent effects of endrin on hepatic lipid peroxidation and DNA damage, and nitric oxide (NO) production by peritoneal exudate cells (primarily macrophages) were investigated in C57BL/6J and DBA/2 mice which vary at the Ah receptor genetic locus. C57BL/6J mice are dioxin-responsive, while DBA/2 mice are dioxin-insensitive. 2. Mice of both strains were treated with 0, 1, 2 or 4 mg endrin kg-1 as a single oral dose in corn oil, and the animals were killed 24 hr post-treatment. At doses of 1, 2 and 4 mg endrin kg-1 in C57BL/6J mice, hepatic mitochondrial lipid peroxidation increased 1.2-, 2.2- and 3.2-fold, respectively, and 1.8-, 2.3- and 3.5-fold with microsomes, respectively. At these same doses in DBA/2 mice, hepatic mitochondrial lipid peroxidation increased 1.3-, 2.0- and 2.6-fold, respectively, and 1.5-, 1.9- and 2.5-fold with microsomes, respectively. 3. Increases of 2.3-, 2.4- and 4.9-fold were observed in hepatic DNA damage (elution constants) in C57BL/6J mice at doses of 1, 2 and 4 mg endrin kg-1, respectively, while at these same three doses, increases of 1.9-, 2.1- and 2.3-fold were observed for DBA/2 mice, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative studies on lipid peroxidation and DNA-single strand breaks induced by lindane, DDT, chlordane and endrin in rats

1. A variety of structurally dissimilar polyhalogenated cyclic hydrocarbons produce similar toxic effects. The molecular mechanisms involved in the production of these toxic manifestations is not known. 2. We have proposed that reactive oxygen species may be involved, and have therefore examined the time-dependent effects of lindane (30 mg/kg), DDT (40 mg/kg), chlordane (120 mg/kg), and endrin (4.5 mg/kg) on the production of hepatic mitochondrial and microsomal lipid peroxidation and DNA single strand breaks, two indices of oxidative stress. 3. All four xenobiotics resulted in significant increases in hepatic lipid peroxidation and DNA damage. Earliest (6 hr) increases in both lipid peroxidation and DNA damage were observed following lindane administration. Time-dependent increases in both parameters were observed following endrin administration. 4. Maximum increases in DNA single strand breaks of 2.8- and 2.5-fold were observed 12 hr after DDT and chlordane administration, respectively, while a 4.4-fold increase was observed 24 hr after endrin administration. 5. The results demonstrate that the four structurally dissimilar polyhalogenated hydrocarbons produce oxidative tissue damage which may contribute to the toxic manifestations of these xenobiotics, and exhibit different toxicokinetic properties.

In vitro induction of reactive oxygen species by 2,3,7,8-tetrachlorodibenzo-p-dioxin, endrin, and lindane in rat peritoneal macrophages, and hepatic mitochondria and microsomes

Hepatic mitochondria and microsomes as well as peritoneal macrophages from female Sprague-Dawley rats were incubated for up to 30 min at 37 degrees C in the presence of 0-200 ng/ml 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), endrin (1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4 alpha,5,6,7,8,8 alpha-octahydroendo, endo-1,4:5,8-dimethanonaphthalene), and lindane (hexachlorocyclohexane). Production of reactive oxygen species was determined by chemiluminescence and cytochrome c reduction, while potential tissue damage was assessed by alterations in membrane fluidity. Chemiluminescence, a sensitive but nonspecific measure of free radical generation, increased 40-70% when macrophages (3 x 10(6) cells/ml), mitochondria and microsomes (1 mg/ml) were incubated with the three polyhalogenated cyclic hydrocarbons (PCH). Maximum increases in chemiluminescence occurred within 5-10 min of incubation and persisted for over 30 min. The cytochrome c reduction assay is most specific for superoxide anion production. When hepatic mitochondria were incubated with endrin and lindane for 15 min at 100 ng/ml, increases in cytochrome c reduction of 6.5- and 7.5-fold occurred, respectively, while when microsomes were incubated with these same two PCH, increases in cytochrome c reduction of 8.6- and 11.6-fold occurred, respectively. When mitochondria, microsomes, and macrophages were incubated with TCDD under identical conditions, small increases in superoxide anion production were detected. Changes in microsomal membrane fluidity were determined spectrofluorometrically following incubation with the three PCH using diphenyl-1,3,5-hexatriene as the fluorescent probe. TCDD, endrin, and lindane enhanced microsomal membrane apparent microviscosity by 2.3-, 2.1-, and 2.5-fold, respectively, indicating a significant decrease in membrane fluidity.(ABSTRACT TRUNCATED AT 250 WORDS)

Sodium and GABA-activated channels as the targets of pyrethroids and cyclodienes

The symptoms of poisoning by the pyrethroid and cyclodiene insecticides are characterized by hyperexcitation and convulsions followed by paralysis. The main target site of the pyrethroids has been identified to be the sodium channels which are kept open for unusually long periods of time, causing a prolonged sodium current to flow which, in turn, leads to hyperexcitation of the nervous system. We have now found large differential sensitivity to the pyrethroids in two types of sodium channels. The dorsal root ganglion neurons of the rat were endowed with two types of sodium channels, one sensitive to the blocking action of tetrodotoxin (TTX) and the other insensitive to TTX. The type I pyrethroid allethrin and the type II pyrethroid deltamethrin were both effective in prolonging the sodium current in the TXX-resistant sodium channel but had only a small effect on the TTX-sensitive sodium channel. These two types of sodium channels also exhibited marked differences in their physiological properties, including the time course of current, the activation voltage, and the steady-state inactivation. In contrast to the pyrethroids, lindane and the cyclodienes endrin, isobenzan, dieldrin and heptachlor-epoxide suppressed the GABA-induced chloride current. The initial transient component of the chloride current was blocked more than the late sustained component. The suppression of the GABA-mediated synaptic inhibition would cause hyperexcitation of the nervous system. The results are compatible with the convulsant action of these insecticides.

Endrin-induced urinary excretion of formaldehyde, acetaldehyde, malondialdehyde and acetone in rats

Previous studies have shown that endrin induces an oxidative stress in rats as demonstrated by an increase in hepatic lipid peroxidation, a decrease in glutathione content and a decrease in the activity in selenium-dependent glutathione peroxidase. We have therefore examined the effects of orally administering 1.5, 3.0, 4.5 and 6.0 mg endrin/kg on the urinary excretion of the lipid metabolites formaldehyde, malondialdehyde, acetaldehyde and acetone. The simultaneous determination of these four lipid metabolites may be a useful biomarker for assessing exposure to xenobiotics which induce an oxidative stress and enhanced lipid peroxidation. Urine samples were collected up to 72 h post-treatment. The identities of the lipid metabolites were confirmed by gas chromatography-mass spectroscopy, while the 2,4-dinitrophenylhydrazine derivatives of these metabolic products were quantitated by high pressure liquid chromatography. Maximum increases in the excretion of the four lipid metabolites occurred at approx. 24 h post-treatment at all doses with no significant increases in excretion occurring thereafter. The maximum increases in excretion of malondialdehyde, formaldehyde, acetaldehyde and acetone were approx. 160%, 93%, 121% and 162%, respectively, relative to control values. Seventy-two hours after endrin administration, the liver weight/body weight and spleen weight/body weight ratios significantly increased while the thymus weight/body weight ratio markedly decreased. The results demonstrate that endrin induces dose- and time-dependent alterations in lipid metabolism with the enhanced excretion of specific metabolic products in the urine.

Excretion of formaldehyde, malondialdehyde, acetaldehyde and acetone in the urine of rats in response to 2,3,7,8-tetrachlorodibenzo-p-dioxin, paraquat, endrin and carbon tetrachloride

Formaldehyde (FA), acetaldehyde (ACT), malondialdehyde (MDA) and acetone (ACON) were simultaneously identified in urine, and their excretion quantitated in response to chemically induced oxidative stress. Urine samples of female Sprague-Dawley rats were collected over dry ice and derivatized with 2,4-dinitrophenylhydrazine. The hydrazones of the four lipid metabolic products were quantitated by high-performance liquid chromatography on a Waters 10-microns mu-Bondapak C18 column. The identities of FA, ACT, MDA and ACON in urine were confirmed by gas chromatography-mass spectrometry. An oxidative stress was induced by orally administering 100 micrograms/kg 2,3,7,8-tetrachlorodibenzo-p-dioxin, 75 mg/kg paraquat, 6 mg/kg endrin or 2.5 ml/kg carbon tetrachloride to rats. Urinary excretion of FA, ACT, MDA and ACON increased relative to control animals 24 h after treatment with all xenobiotics. The system has wide-spread applicability to the investigation of altered lipid metabolism in disease states and exposure to environmental pollutants.

Intrinsic lethality of chloride-channel-directed insecticides and convulsants in mammals

The intrinsic lethality of a series of chloride-channel-directed convulsants and insecticides was determined by intracerebral injection into mice. The toxicities of the cyclodiene insecticides and picrotoxinin were potentiated by intracerebral injection, when compared to their reported intraperitoneal LD50s. In contrast, the toxicities of lindane, abamectin, and the bicyclic convulsants TBPS and a TBOB analog were approximately the same by either route of administration. These results suggest that the brain is the primary target site for the cyclodienes and picrotoxinin, while the peripheral nervous system may be relatively more important in the toxic action of lindane, abamectin, and bicyclic convulsants such as TBPS. With the exception of picrotoxinin these compounds showed, overall, a good correlation between acute intracerebral toxicity and potency for inhibiting GABA-dependent chloride uptake. The evidence that multiple chloride-channel subtypes serve as targets for these compounds and the potential impact this had on the results of these studies are discussed.

Effect of endrin on the hepatic distribution of iron and calcium in female Sprague-Dawley rats

The distribution of iron and calcium in hepatic subcellular fractions of female rats treated with endrin (1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4 alpha,5,6,7,8,8 alpha- octahydroendo,endo-1,4:5,8-dimethanonaphthalene) was determined. Endrin in corn oil was administered orally to rats in single doses of 3, 4.5, or 6 mg/kg, and the animals were killed at 0, 12, 24, 48, or 72 hr post-treatment. Iron and calcium were determined by atomic absorption spectroscopy. The administration of endrin increased the iron content of mitochondria and decreased the iron content of microsomes and nuclei. Significant increases occurred in the calcium content of mitochondria, microsomes, and nuclei. Thus, the results indicate that with respect to the subcellular distribution of iron and calcium, endrin produces differential effects. Vitamin E succinate administration partially prevented the endrin-induced hepatic alterations in iron and calcium homeostasis. Endrin also produced dose- and time-dependent increases in the liver and spleen weight/body weight ratios, while decreasing the thymus weight/body weight ratios. The altered distribution of calcium and iron may contribute to the broad range of effects of endrin.

Endrin-induced histopathological changes and lipid peroxidation in livers and kidneys of rats, mice, guinea pigs and hamsters

Endrin toxicity may be due to an oxidative stress associated with increased lipid peroxidation, decreased glutathione content, and inhibition of glutathione peroxidase activity. Extensive interspecies variability exists in sensitivity towards endrin. Therefore, histopathological changes and lipid peroxidation in the livers and kidneys of rats, mice, hamsters, and guinea pigs were examined 24 hr after the administration of 4 mg endrin/kg body weight orally in corn oil. Degeneration and necrotic changes with inflammatory cell infiltration were observed in livers and kidneys, and interspecies variability occurred. Fatty changes in the form of hepatic foam cells with cytoplasmic vacuolation were present. Lipofuscin pigments, associated with lipid peroxidation, were observed in hepatocytes and Kupffer cells. These histopathological conditions were prevented in rats which had been pretreated with butylated hydroxyanisole, vitamins E and C, or cysteine, antioxidants and free radical scavengers which have previously been shown to inhibit lipid peroxidation. The extent of endrin-induced lipid peroxidation correlated well with the degree of histopathological changes. Thus, histological changes consistent with the induction of an oxidative stress were observed following the administration of endrin to various animal species.

Role of the brain t-butylbicyclophosphorothionate receptor in vertebrate resistance to endrin, 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane and cypermethrin

Certain populations of mosquitofish (Gambusia affinis) are highly resistant to endrin (42-fold), but are not cross-resistant to cypermethrin. These populations show relatively low levels of resistance (2-fold) to 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and t-butylbicyclophosphorothionate (TBPS). Studies comparing specific [35S]TBPS binding to brain membrane preparations from resistant and susceptible fish indicate a reduced binding capacity for TBPS in membranes from resistant fish. Endrin was about twice as potent in competitively inhibiting [35S] TBPS binding in vitro to membranes from susceptible fish as compared to membranes from resistant fish, suggesting that TBPS binding sites in resistant fish brain are less sensitive to endrin. Endrin was 37 times as potent in competitively inhibiting [35S]TBPS binding in vivo to membranes from susceptible fish compared to membranes from resistant fish, indicating that a contributory factor is involved in endrin resistance. Data for TBPS inhibition of [35S]TBPS binding revealed an approximate 2-fold difference between resistant and susceptible for both in vitro and in vivo IC50, indicating that an altered TBPS binding site is the only factor involved in TBPS resistance. DDT did not inhibit [35S] TBPS binding, suggesting that DDT resistance is not due to changes at the TBPS receptor. These data support the hypothesis that two factors operate in vertebrate resistance to endrin, whereas only one of these factors confers TBPS resistance. These resistance mechanisms are not functional against cypermethrin.

Effects of cyclodiene compounds on calcium pump activity in rat brain and heart

The in vitro and in vivo effects of aldrin, dieldrin, and endrin on calmodulin regulated Ca2+-pump activity in rat brain synaptosomes and heart sarcoplasmic reticulum were investigated. All the 3 cyclodiene compounds inhibited both brain synaptosomal and heart sarcoplasmic reticulum Ca2+-pump activity in vitro in a concentration dependent manner. Calmodulin depleted Ca2+-pump activity was insensitive to the action of toxic compounds. Oral administration of pesticides (0.5-10 mg/kg) to rats similarly decreased the Ca2+-pump activity, in addition to decreasing the levels of calmodulin of both brain and heart thus indicating disruption in membrane Ca2+ transport mechanisms. Exogenous addition of calmodulin (1-20 micrograms) could effectively reverse the pesticide induced inhibition. Ca2+-pump activity is more sensitive to the 3 cyclodiene compounds in brain than in heart. The results of the present study indicate that the cyclodiene compounds may produce neurotoxic effects by altering calmodulin regulated calcium dependent events in neurons.

Effect of endrin and endrin derivatives on hepatobiliary function and carbon tetrachloride-induced hepatotoxicity in male and female rats

The effects of the cyclodiene pesticide, endrin, and its aldehyde and ketone metabolites on hepatobiliary function and CCl4-induced hepatotoxicity were investigated in Sprague-Dawley rats. The rats were given control diet or diets containing 5 or 10 ppm endrin, 10 ppm endrin aldehyde or 5 ppm endrin ketone for 15 days. Three to six rats from each treatment group were given a single ip dose (100 microliter/kg body weight) of CCl4 in corn oil (1 ml/kg) on day 15. Levels of serum glutamic-oxalacetic transaminase (SGOT), glutamic-pyruvic transaminase (SGPT), isocitrate dehydrogenase and ornithine-carbamyl transferase, bile flow and biliary excretion of an anionic model compound, phenolphthalein glucuronide (PG), were measured on day 16. Dietary treatment with endrin at either dose level did not significantly elevate serum enzyme levels, while endrin aldehyde produced a slight increase in SGOT and SGPT and endrin ketone produced a small elevation in SGPT levels. Treatment with endrin aldehyde or endrin ketone did not result in significant alterations of bile flow or biliary PG excretion. Treatment with 5 ppm endrin produced a significant reduction in bile flow and a corresponding reduction in PG excretion by male rats, whereas treatment with 10 ppm endrin reduced only the PG excretion by male rats. Female rats treated with 5 or 10 ppm endrin showed a dose-dependent choleretic effect with a commensurate increase in PG excretion. With the exception of a further slight reduction in PG excretion by male rats, treatment with the endrin or endrin derivative did not potentiate CCl4-induced alterations in hepatobiliary functions. Although the levels of some serum enzymes of rats given endrin or endrin derivatives plus CCl4 were elevated over those of rats given CCl4 alone, the increases were not of the magnitude of those that have been reported previously for chlordecone. Generally, female rats challenged with CCl4 or endrin/CCl4 exhibited greater increases in serum enzyme levels than did male rats given corresponding treatments.

Potential consequences of a fire in an insecticide storage facility

Assumptions are identified and made in an attempt to model the acute human health risk associated with a hypothetical fire in an insecticide storage facility. The insecticides used in the model are endrin and dimethoate. The model indicates that persons residing a few hundred meters from the facility could suffer a variety of adverse effects, including possible death from contact with smoke from a prolonged, low-temperature fire. Knowledge of the special hazards of cool toxic smoke as well as current atmospheric conditions could be of use to fire fighters. That is, fire fighters might wisely choose to promote a fast, hot fire which would propel toxicants high into the atmosphere rather than risk local fumigation.

The science of teratology in a regulatory setting

The science of teratology is discussed from a regulatory point of view. A brief history of this branch of toxicology is presented with emphasis on specific instances of the inadvertent production of birth defects in humans as a result of exposure to exogenous agents. The basic principles of teratology are elucidated as a means of understanding current test protocols and their scientific rationale. A typical, general protocol is given and some of the major shortcomings of such a bioassay are presented. Among these shortcomings are the problems of significance of fetal toxicity and lack of a postnatal component to the teratology test system. The teratogenic and/or fetotoxic potential of selected pesticides are examined with special reference to the bioassay problems alluded to. Pesticides discussed include cacodylic acid, endrin, benomyl, ETU, nitrofen, and mirex. Finally, a brief discussion of a proposed teratology screen using pregnant laboratory animals is presented.

Physiological mechanism of toxic action of DDT and endrin in two euryhaline freshwater fishes, Anguilla vulgaris and Mugil cephalus

RBC counts, Ht value and Hb content in both species exposed to DDT and endrin concentrations were not significantly different from those of controls. WBC counts in both species exposed to the two pesticides for 96 hr decreased significantly at different concentrations. The variance ratios of cations and anions were consistently more concentrated in the serum of DDT- and endrin-exposed fishes. Serum cholesterol was sharply elevated in all the lots exposed to pesticides. Exposure to sublethal concentrations of DDT and endrin impaired liver function, as evidenced by the transfer of major cations from hepatic tissue to the serum and by elevated serum cholesterol.

Acute toxicities of toxaphene and endrin to larvae of seven species of amphibians

Seven species of amphibian larvae were exposed to toxaphene and endrin in a continuous-flow dosing system to determine differences in sensitivity to the two compounds, EC50 and LC50 estimates varied from those for Rana sphenocephala by no more than one order of magnitude when calculated on the basis of intended concentrations. Removal of pesticides from water by the test animals was significant and it makes interpretation of results difficult. Continuous-flow toxicity tests conflict with the adaptations of amphibian larvae for static water; use of such tests for amphibians requires further evaluation.

Perinatal toxicity of endrin in rodents. II. Fetotoxic effects of prenatal exposure in rats and mice

The fetotoxic potential of endrin in the CD rat and CD-1 mouse was investigated. Endrin was administered as a solution in corn oil to groups of pregnant animals by gastric intubation at multiple dose levels throughout the period of organogenesis. The dams were sacrificed prior to term and the fetuses were examined for skeletal and visceral anomalies. In addition, maternal livers and fetuses from rats in each dose level were analyzed for endrin content. In the mouse, endrin caused maternal liver enlargement at a dose of 0.5 mg/kg/day and reduced maternal weight gain at a dose of 1.0 mg/kg/day. Fetal weight and skeletal and visceral maturity were adversely affected at a dose of 1.0 mg/kg/day, but no teratogenic effect or embryo lethality was evident even at a dose level that produced maternal lethality (1.5 mg/kg/day). In the rat, endrin markedly reduced maternal weight at doses above 0.150 mg/kg/day but produced no apparent effects on the fetus. The data suggest that species differences in sensitivity to endrin may in part be due to differences in metabolism. Although endrin levels in rat fetuses at a maximally tolerated dosage level resembled those previously reported for the hamster, relatively less 12-ketoendrin was present, paralleling the change in fetal sensitivity.

Perinatal toxicity of endrin in rodents. III. Alterations of behavioral ontogeny

The behavioral development of rats and hamsters was observed following perinatal exposure to endrin, a central nervous system teratogen in the hamster but not the rat [1,2]. In the hamster, prenatal exposure to endrin at 1.5 mg/kg/day on days 5-14 of gestation produced a persistent elevation in the locomotor activity. Offspring of treated hamsters ambulated 75% more than controls in the open field at 15 days and 45% more at 20 days of age. Long term observations of locomotor activity in the figure-8 mazes indicated that a significant elevation of this behavior was still present at 125 days of age. Non-locomotor behaviors of the Offspring (including sexual, rearing and running wheel behaviors) were unaffected. The dams repeatedly exposed daily to endrin at 0.75 or 1.5 mg/kg/day were markedly hypoactive using the same testing conditions in which the pups were hyperactive. This dosing regime was toxic to the dams in the 1.5 mg/kg/day dose group, killing more than half of them. In the second experiment, rats exposed perinatally to endrin at 0.15 or 0.30 mg/kg/day were 30% more active than control prior to weaning, but not as adults. These doses did not kill dams or affect the pup survival or growth. The similarity of the behavioral changes noted in the young of both species is suggestive of similar alteration of central nervous system function even though endrin produces gross morphological defects only in the hamster.

Short-term effect of two pesticides on the survival, ovarian 32P uptake and gonadotrophic potency in a freshwater catfish, Heteropneustes fossilis (Blouch)

The effects of pesticides containing either an organophosphate malathion (Cythion) or an organochloride endrin (Hexadrin) on the survival, ovarian 32P uptake and the gonadotrophic potency of the pituitary gland and serum of Heteropneustes fossilis were studied for 96 h. Hexadrin was found to be more toxic than Cythion. Reduced ovarian 32P uptake and a significantly decreased level of total gonadotrophin in the pituitary gland and serum were seen when fish were placed either in a drug concentration that had been found to kill half the fish in 96 h or in a safe concentration of Hexadrin and cythion in aquarium water. Administration of LH or homologous pituitary extract during the exposure of the fish to the pesticides increased the ovarian 32P uptake. The data suggest that these pesticides retarded gonadotrophin secretion which in turn reduced ovarian 32P uptake. However, they did not interfere with the effects of exogenous LH or pituitary extract at the dose levels tested.

Perinatal toxicity of endrin in rodents. I. Fetotoxic effects of prenatal exposure in hamsters

The potential of the insecticide endrin to induce fetal toxicity was determined in hamsters exposed to the compound on either day 8 or days 5--14 of gestation. Endrin was administered by oral gavage as a solution in corn oil. Doses used included 0.5--10.0 mg/kg on day 8 and 0.75 to 3.5 mg/kg/day on days 5--14. Exposure to a single dose of endrin resulted in significant incidences of fused ribs and meningoencephaloceles at levels of 5 mg/kg or greater. No significant effects were noted in either maternal mortality and weight gain or in fetal mortality or weight gain. The administration of multiple doses of endrin resulted in few fetal defects, although a significant dose-related increase in fetal mortality and decrease in fetal weight was seen. Significant maternal lethality and weight reductions were noted at doses of 1.5 mg/kg/day or greater. At sacrifice, maternal liver and fetal tissues were collected and subsequently analyzed for endrin and a major metabolite, 12-ketoendrin. Endrin was found to cross the placenta and 20 ppb were found in fetuses from litters exposed to 2.5 mg/kg/day. Maternal livers from this dose group contained an average of 2500 pbb of endrin.

Endrin: effects on the entire life cycle of a saltwater fish, Cyprinodon variegatus

The sheepshead minnow (Cyprinodon variegatus) was continuously exposed for 23 wk to the organochlorine insecticide endrin, from the embryonic state through hatching until adulthood and spawing. The resultant progeny were monitored to determine the effects of the toxicant on their survival, growth, and reproduction. Average measured exposure concentrations were O (control), 0.027, 0.077, 0.12, 0.31, and 0.72 microgram/liter. Embryos exposed to 0.31 and 0.72 microgram/liter hatched early; all fry exposed to 0.72 microgram/liter died by day 9 of exposure. At 0.31 microgram/liter, fry were initially stunted and some died. Survivors seemed unaffected until maturity, when some females died during spawning; fewer eggs were fertile and survival of exposed progeny decreased. No significant effects were observed th roughout this fish's life cycle at an exposure concentration of 0.12 microgram/liter. Four-week-old juvenile fish accumulated 2,500 times the concentration of endrin in the exposure water; adults, 6,400 times; and their eggs, 5,700 times. The specific application factor (calculated by dividing the limits on the maximum acceptable toxicant concentration, greater than 0.12 and less than 0.31 microgram/liter, by the concentration lethal to 50% of the juvenile fish in 96 hr, 0.34 microgram/liter) ranged from 0.35 to 0.91. To our knowledge this is the first toxicity test carried out through the entire life cycle of an oviporous esturarine fish. Data from this experiment and from experiments with another estuarine fish and four freshwater fish all demonstrate that there is little difference between endrin concentrations that produce acute effects and concentrations that do not affect the fish in chronic exposures lasting four or more weeks.

Detoxication and bioactivation of endrin in the rat

1. Rats exhibit a sex difference in the rate of metabolism of endrin. 2. The major metabolite in both sexes is anti-12-hydroxyendrin which is excreted via the bile as the glucuronide. Male rats produce the metabolite at a higher rate than do females. 3. trans-4,5-Dihydroisodrin-4,5-diol is a minor metabolite. A mechanism for its formation is discussed. 4. There is a sex difference in the production and excretion of 12-ketoendrin which is observed as a urinary metabolite in male rat; the major urinary metabolite in female rats is anti-12-hydroxyendrin O-sulphate. 5. syn-12-Hydroxyendrin was not detected but may be an intermediate in the formation of 12-ketoendrin. 6. The formation of 12-ketoendrin is related to the acute toxicity of endrin.