Effect of Aflatoxin B1 on Some Liver Microsomal Enzymes in Mice Fed Cyanide Supplemented Diets

ABSTRACT

Aniline hydroxylase, glucose-6-phosphatase, NADPH-and NADH-cytochrome C reductase activities were measured in liver microsomes prepared from four groups of female mice. Mice were fed either control diets alone or KCN (0.357, ug/kg body wt/day) supplemented diets or control diets plus AFB₁ (0.35ug/kg body wt/day) administration (ip) on the 8, 9 and 10th day or the KCN supplemented diet plus AFB, administration (ip) on the 8.9 and 10th day. KCN and AFB₁ consistently elevated the activities of the enzymes. Simultaneous administration of both toxins potentiated their effects on the enzymes with the exception of glucose-6-phosphatase. Increases in microsomal protein/liver wt ratios, liver wt/body wt ratios and these enzyme activities were probably indicative of microsomal enzyme induction.     

Effect of aflatoxin B1 on some liver microsomal enzymes in mice fed cyanide supplemented diets

Aniline hydroxylase, glucose-6-phosphatase, NADPH- and NADH-cytochrome C reductase activities were measured in liver microsomes prepared from four groups of female mice. Mice were fed either control diets alone or KCN (0.357, microgram/kg body wt/day) supplemented diets or control diets plus AFB1 (0.35 microgram/kg body wt/day) administration (ip) on the 8, 9 and 10th day or the KCN supplemented diet plus AFB, administration (ip) on the 8, 9 and 10th day. KCN and AFB1 consistently elevated the activities of the enzymes. Simultaneous administration of both toxins potentiated their effects on the enzymes with the exception of glucose-6-phosphatase. Increases in microsomal protein/liver wt ratios, liver wt/body wt ratios and these enzyme activities were probably indicative of microsomal enzyme induction.     

Studies on the toxicity of hexachlorophene in the rat

Acute and subacute toxic effects of hexachlorophene (HCP) were studied in Wistar rats. The ip LD50 of HCP ranged between 21.8 mg/kg in mature rats and 40.0 mg/kg in weanlings. The oral LD50 varied similarly with age from 57.6 to 87.0 mg/kg, respectively. HCP was slightly less toxic to male rats than to females. Signs of intoxication were general lethargy, posterior paralysis, increased respiration rate, hyperthermia and diarrhea. Maximum body temperatures were attained approximately 1.5 hr after ip injection.In subacute studies, HCP was fed to weanling rats at dietary concentrations from 12.5 to 400 ppm HCP for a 16-week period. Animals on the 400 ppm diet, ingesting an average of 28.9 mg HCP/kg/day, developed severe posterior paralysis during the first few days of the study, and died within 10 days. No drug related mortality was observed in the other groups. Paralysis was also observed initially in rats fed the 200 ppm HCP diet (average intake 23.6 mg/kg/day) but by the second week, these animals had apparently recovered. Rats fed diets containing 100 and 200 ppm HCP (average intake 7.73 and 14.9 mg/kg/day) developed significant histopathologic changes in the brain, characterized by extensive vacuolization and edema of the myelinated areas. Significant growth depression and reduced plasma alkaline phosphatase activities were also found at 8 and 16 weeks in rats receiving the 200 ppm diet. The minimum “no effect” intake of HCP under the conditions of this study was between 3.7 mg/kg/day and something less than 7.7 mg/kg/day.     

Subchronic Toxicity of Benzyl Selenocyanate and 1,4-Phenylenebis(methylene)selenocyanate in F344 Rats

Chemopreventive agents benzyl selenocyanate (BSC) and 1,4-phenylenebis(methylene)selenocyanate(p-XSC) were fed in NIH-07 diet to male and female F344 rats(4, 2, and 0.5 mg/kg/day for BSC and 20, 10, and 5 mg/kg/dayfor p-XSC) for 13 weeks. Weight gains were depressed for maleand female rats fed 4 and 2 mg/kg/day BSC, females fed 0.5 mg/kg/dayBSC, and male rats fed 20 and 10 mg/kg/day p-XSC. At necropsy,no clear treatment-related lesions were noted, but dose-dependenthepatomegaly was observed in both sexes of BSC and p-XSC groups.Plasma transaminases AST and ALT were elevated in the higherdose groups, while hemoglobin, HCT, and RBC were reduced inmost BSC and some p-XSC treatment groups. Plasma glucose wasreduced in BSC-treated males. Significant histologic findingsincluded moderate to severe hepatic centrilobular hypertrophywith fatty change in all males and females in the 4 mg/kg/dayBSC groups and in 9/15 males and 3/15 females in the 2 mg/kg/dayBSC groups. Dose-dependent, mild centrilob ular hypertrophywith minimal fatty change was observed in the mid-and low-doseBSC groups and in all p-XSC groups. Mild to moderate renal tubularand interstitial nephritis occurred in the 4 mg/kg/day maleBSC group. Dietary maximum tolerated dose levels for chemopreventionstudies are 0.5 mg/kg/day (3.0 ppm Se) for BSC and 5 mg/kg/day(32.5 ppm Se) for p-XSC, compared to literature values of 2–3ppm Se for Na₂SeO₃.     

Acute Inhalation Toxicity of T-2 Mycotoxin in the Rat and Guinea Pig

Acute Inhalation Toxicity of T-2 Mycotoxin in the Rat and GuineaPig. CREASIA, D. A., THURMAN, J. D., WANNEMACHER, R. W., JR.,AND BUNNER, D. L. (1990). Fundam. Appl. Toxicol 14, 54–59.In this study, concentration-response parameters were determinedfor rats and guinea pigs systematically exposed to an aerosolof T-2 toxin. The LC50 for a 10-min exposure to T-2 toxin aerosolwas 0.02 mg T-2/liter air for rats and 0.21 mg T-2/liter airfor guinea pigs. Data from total T-2 deposition in rats andguinea pigs exposed to their respective LC50 aerosol concentrationgave an LD50 of 0.05 mg T-2/kg body weight for the rat and 0.4mg T-2/kg body weight for the guinea pig. These data show thatinhaled T-2 toxin is approximately 20 times more toxic to therat (0.05 mg T-2/kg body wt inhaled vs 1.0 mg T-2/kg body wtip) and at least twice as toxic to the guinea pig (0.4 mg T-2/kgbody wt inhaled vs 1-2 mg T-2/kg body wt ip) than ip administeredT-2 toxin. Histopathologic examination of major organs in boththe rat and guinea pig after respiratory exposure to T-2 toxinindicated that lesions were similar to those described aftersystemic administration of the toxin. Gross and microscopicalterations of respiratory tract tissue after T-2 aerosol exposurewere minimal and could not account for the increase in toxicity.     

Cisplatin-induced loss of kidney copper and nephrotoxicity is ameliorated by single dose diethyldithiocarbamate, but not mesna.

Platinum, copper, and zinc concentrations in kidney and liver were monitored following administration of cis-diamminedichloroplatinum (Cisplatin, CDDP) alone or in combination with diethyldithiocarbamate (DDC) or mercaptoethanesulfonate (mesna). Compounds were administered in saline to F344 female rats as single bolus ip doses: 7.5 mg CDDP/kg body wt; 500 mg DDC/kg body wt 1 hr after CDDP; and 100 mg mesna/kg body wt 1 hr before CDDP, at the same time as CDDP, or 1 hr after CDDP. Tissues were collected at 4 hr, 1 day, 4 days, and 7 days post-CDDP dosing. CDDP alone produced significant increases in blood urea nitrogen (fourfold) and plasma creatinine (threefold) concentrations by Day 4. Concurrent with the toxicity, CDDP lowered kidney copper (-71%) by Day 4, but had little effect on liver copper except in copper-pretreated rats. Copper-pretreated rats initially had a twofold higher kidney copper concentration and a fourfold higher liver copper concentration, but by Day 4, CDDP lowered copper concentrations in both organs to near the noncopper-treated levels. Platinum in kidney and liver rose 72-100% of peak levels within 4 hr post-CDDP and was relatively stable throughout the 7-day test period. Kidney zinc rose significantly by day 4 only in CDDP-treated rats. DDC protected against the kidney toxicity of CDDP and markedly changed kidney copper loss. Within 4 hr, DDC reduced kidney copper 60% while increasing kidney platinum to the highest concentration of any of the treatments. By Day 4, DDC-treated rats had approximately 50% lower kidney platinum while copper returned toward control levels. A single dose of mesna did not significantly protect against CDDP nephrotoxicity and had little effect on kidney platinum, copper, or zinc. The patterns of copper loss and toxicity from CDDP alone or with DDC suggest that copper be further evaluated for its role in the mechanism of CDDP cytotoxicity.     

Circulating naphthionic acid in nonpregnant and pregnant rats after feeding amaranth

Naphthionic acid (NA) [1-naphthylamine-4-sulfonic acid], is one of the azoreduction products absorbed from the rat's gut after oral ingestion of amaranth [FD&C Red No. 2, C.I. 16185; CAS [915-67-3]]. This report describes the blood levels of NA in male and nonpregnant female rats as well as the level of NA in fetal blood, amniotic fluid, and maternal blood of rats fed various doses of amaranth. Three groups of five male and eight female rats were fed diets for 9 days to provide estimated daily doses of 20, 200, and 2000 mg amaranth/kg body wt. Five male and six female rats were fed a control diet. Blood samples were collected twice daily after 1, 2, 3, 4, 5, and 8 days of feeding and analyzed for NA. After the ninth day, the male rats were fasted and blood was collected at specific intervals over the next 96 hr. The female rats were mated with untreated males and received the same dosages of amaranth throughout mating and gestation. The amniotic fluids and blood from each fetus as well as the maternal blood were collected between the 19th and 21st day of gestation for the NA determination. A significant elevation in plasma NA concentrations occurred in male and female rats receiving estimated doses of 200 or 2000 mg amaranth/kg body wt. Plasma NA concentrations were slightly but not significantly increased at 20 mg amaranth/kg body wt. The NA concentrations in fetal plasma and amniotic fluid from the 2000 mg amaranth/kg body wt dose group were significantly less than (p < 0.05) 10-fold higher than those from the 200 mg amaranth/kg body wt dose group. The NA concentrations in maternal blood from the 2000 mg amaranth/kg body wt dose group were less than (although not significant statistically) 10-fold higher than from the 200 mg amaranth/kg body wt dose group. The NA concentrations in maternal plasma were about five times higher than in plasma of their fetuses. There was a significant increase in the NA concentrations in amniotic fluid between the 20th and 21st day of gestation.     

Teratogenic potential of carbaryl given to rabbits and mice by gavage or by dietary inclusion.

The teratogenic potential of the insecticide carbaryl (1-naphthyl methylcarbamate) was evaluated in New Zealand rabbits and CF-1 mice. Rabbits were given 150 or 200 mg carbaryl/kg/day by gavage from Days 6 through 18 of gestation. Mice were given 100 or 150 mg carbaryl/kg/day by gavage or were given a diet containing 5660 ppm of carbaryl (1166 mg carbaryl/kg body wt/day) from Days 6 through 15 of gestation. An increased incidence of omphalocele was observed among the offspring of rabbits given 200 mg carbaryl/kg/day, which was a maternally toxic dose, and another case was observed among the offspring of rabbits given 150 mg/kg/day, a dosage which produced mild maternal toxicity. In comparison, carbaryl was not teratogenic in mice given maternally toxic doses of the compound either by gavage or by dietary inclusion.     

A Thirteen Week Repeated Inhalation Study of Ethylene Dibromide in Rats,,

A Thirteen Week Repeated Inhalation Study of Ethylene Dibromidein Rats. Nitschke, K.D., Kociba, R.J., Keyes, D.G. and McKenna,M.J. (1981). Fundam. Appl. Toxicol. 1:437–442. Male andfemale CDF (F 344) rats were exposed to 0, 3, 10 or 40 ppm ethylenedibromide (EDB), 6 hours/ day, 5 days/week for 13 weeks fora total of 67–68 exposures in 95–96 days. Scheduledsacrifices occurred after 1,6, and 13 weeks of exposure. Additionalrats were held for a recovery period of 88–89 days andsubsequently necropsied. Rats exposed to 3 ppm EDB showed noconsistent effect in any parameter measured. At 10 ppm, EDBcaused slight epithelial hyperplasia of the nasal turbinatesin animals necropsied after 1, 6 or 13 weeks of exposure; however,88 days after the last exposure to EDB, nasal turbinate changeswere not observed. Rats exposed to 40 ppm EDB exhibited a decreasein body weight gain throughout the 13-week exposure period,an increase in liver and kidney weights after 6 and 13 weeksof exposure, and hyperplasia and nonkeratinizing squamous metaplasiaof the respiratory epithelium of the nasal turbinates. Aftera recovery period of 88 days, there was a reversion to normalof the nasal turbinates in 19 of 20 rats and only an isolatedfocus of hyperplasia of the nasal epithelium in the one remainingrat. It is believed that this observation would have returnedto control limits if allowed a slightly longer recovery period.The most sensitive response associated with repeated subchronicexposure of rats to 10 or 40 ppm EDB involves pathologic changesin the respiratory epithelium of the nasal turbinates. Thesechanges regressed during a subsequent postexposure phase withno indication of a progression of the lesions. Since exposureof rats to 3 ppm EDB elicited no discernible response in anyof the tissues examined, 3 ppm was defined as the no-observable-effectlevel.     

4,4'-Methylenebis(2-chloroaniline) (MOCA): The Effect of Multiple Oral Administration, Route, and Phenobarbital Induction on Macromolecular Adduct Formation in the Rat

The effect of multiple oral administration of MOCA, a suspecthuman carcinogen, was studied in the adult male rat. As manyas 28 consecutive daily doses of [¹⁴C]MOCA at 28.1µmol/kgbody wt (5 µC1/day) were administered and rats were euthanizedat weekly intervals for 7 weeks. MOCA adduct formation for globinand serum albumin was evaluated by determination of [¹⁴C]MOCAcovalent binding. The covalent binding associated with globinshowed a linear increase over the 28-day exposure period with342 fmol/mg globin 24 hr after the final dose. More extensivecovalent binding was detected for albumin with 443 fmol/mg albuminafter the final dose, but increases were not linear. After cessationof dosing, the albumin adduct levels decreased rapidly (t _1/2=4.6 days) in relation to globin adduct levels (t _1/2 =16.1days). The MOCA-globin adduct t _1/2 is consistent with thatdetermined after a single 281 µmol/kg oral dose of MOCA.Significant differences related to route of administration weredetected for 24-hr globin covalent binding with ip > po >dermal. Distribution of undifferentiated [¹⁴C]MOCA was highestin the liver at 24 hr with tissue levels for liver > kidney> lung > spleen > testes > urinary bladder. Inductionof cytochrome P450 enzymes by administration of phenobarbital(100 mg/kg/day/3 days) resulted in a significant (p < 0.05)increase in MOCA-globin adduct formation detected with 33.5pmol/ mg globin for induced rats versus 13.6 pmol/mg globinfor control rats. Although MOCA-globin and albumin adducts showdiffering stability, quantification of such MOCA adducts maybe useful for long-term industrial biomonitoring of MOCA.     

Respiratory pathology in rats and mice after inhalation of 1,2-dibromo-3-chloropropane or 1,2 dibromoethane for 13 weeks

Seventy F344 rats and 144 B6C3F1 mice were subdivided into seven groups. Three groups were each exposed via inhalation to 1, 5, or 25 ppm of 1,2-dibromo-3-chloropropane (DBCP) for 6 h per day, 5 days per week for 13 weeks. Three additional groups were each similarly exposed to 3, 15, or 75 ppm of 1,2-Dibromoethane (EDB). The remaining group was exposed to room air under the same conditions. At 13 weeks, rats and mice showed severe necrosis and atrophy of the olfactory epithelium in the nasal cavity after inhalation of 5 or 25 ppm DBCP and 75 ppm EDB. Lower concentrations induced squamous cell metaplasia, hyperplasia and cytomegaly of the epithelium of the respiratory nasal turbinals. Squamous metaplasia, hyperplasia and cytomegaly of the epithelium was also seen in larynx, trachea, bronchi and bronchioles. Other compound related toxic lesions in rats were seen in the liver, kidney and testes.     

Short-term (6-week) oral toxicity study of selenium in Syrian hamsters

The subacute toxicity of selenium was tested by feeding sodium selenite to Syrian hamsters at dietary levels of 0.1, 1, 5, 10 and 20 ppm selenium for 42 days. General health, survival and organ weights were not adversely affected at any of the dose levels. Weight gain and food intake were relatively low in males fed the highest dose level. The differences from the control values were not statistically significant and there was no similar effect in females. Hamsters fed 10 or 20 ppm retained considerably higher levels of selenium in the liver than did the controls. Microscopic examination of the liver revealed degenerative changes in males and females in the 20-ppm group. The no-toxic-effect level of selenium fed in the diet for 42 days to Syrian hamsters was found to be 10 ppm, equivalent to an intake of about 0.7 mg selenium/kg body weight/day.     

Liver,kidney, and central nervous system toxicity of aluminum given intraperitoneally to rats: A multiple-dose subchronic study using aluminum nitrilotriacetate

In the first test, aluminum nitrolotriacetate (Al-NTA), aluminum chloride, aluminum potassium sulfate, or saline was infected ip, employing male Wistar rats. Each group consisted of ten rats. Al was given in a dose of 5 mg Al/kg body wt/day, for 14 days. Only those rats given Al-NTA showed morphological damage of the liver and kidney. Damages included diffuse midzonal coagulation necrosis of hepatocytes and acute proximal tubular necrosis of the kidney at Day 4. Seven of ten rats given Al-NTA died within 5 days. The second test was performed in metabolic cages. Al-NTA, in a dose of 1.5 to 2.0 mg Al/kg body wt/day, and NTA, of an equivalent dose, were injected ip for 54 days. Midzonal coagulation necrosis and some regenerative changes were observed in the hepatic parenchyma at Day 8. At the end of the study, complete regeneration occurred in the liver. Biochemical tests at Days 6, 13, and 28 showed high amounts of GOT, GPT, LDH, γ-GTP, and ALP. Necrosis of proximal tubular cells of the kidney and some regeneration was noted at Day 8. Metabolic acidosis was demonstrated at Days 6, 13, and 28. Moreover, from Day 38 on, atrophy of the nerve cells of the cerebrum and demyelination of the brain stem were observed. Control rats given NTA did not exhibit any organ damage. It is concluded that a relatively small dose of Al can produce toxicosis when give with certain metal chelators.     

Subchronic toxicity studies on perfluorooctanesulfonate potassium salt in cynomolgus monkeys.

This study was conducted to determine the earliest measurable response of primates to low-level perfluorooctanesulfonate (PFOS) exposure and to provide information to reduce uncertainty in human health risk assessment. Groups of male and female monkeys received 0, 0.03, 0.15, or 0.75 mg/kg/day potassium PFOS orally for 182 days. Recovery animals from each group, except the 0.03 mg/kg/day dose group, were monitored for one year after treatment. Significant adverse effects occurred only in the 0.75 mg/kg/day dose group and included compound-related mortality in 2 of 6 male monkeys, decreased body weights, increased liver weights, lowered serum total cholesterol, lowered triiodothyronine concentrations (without evidence of hypothyroidism), and lowered estradiol levels. Decreased serum total cholesterol occurred in the 0.75 mg/kg/day dose group at serum PFOS levels > 100 ppm. Hepatocellular hypertrophy and lipid vacuolation were present at term in the 0.75 mg/kg/day dose group. No peroxisomal (palmitoyl CoA oxidase) or cell proliferation (proliferating cell nuclear antigen immunohistochemistry) was detected. Complete reversal of clinical and hepatic effects and significant decreases in serum and liver PFOS occurred within 211 days posttreatment. Liver-to-serum PFOS ratios were comparable in all dose groups, with a range of 1:1 to 2:1. Serum concentrations associated with no adverse effects (0.15 mg/kg/day) were 82.6 +/- 25.2 ppm for males and 66.8 +/- 10.8 ppm for females. Comparison of serum PFOS concentrations associated with no adverse effect in this study to those reported in human blood samples (0.028 +/- 0.014 ppm) indicated an adequate margin of safety.     

Prevention of Maternal and Developmental Toxicity in Rats via Dietary Inclusion of Common Aflatoxin Sorbents: Potential for Hidden Risks

In earlier work, we have reported that a phyllosilicate clay(HSCAS or NovaSil) can tightly and selectively bind the aflatoxinsin vitro and in vivo. Since then, a variety of untested clayand zeolitic minerals have been added to poultry and livestockfeeds as potential "aflatoxin binders." However, the efficacyand safety of these products have not been determined. A commonzeolite that has been frequently added to animal feed is clinoptilolite.Our objectives in this study were twofold: (1) to utilize thepregnant rat as an in vivo model to compare the potential ofHSCAS and clinoptilolite to prevent the developmental toxicityof aflatoxin B₁ (AfB₁), and (2) to determine the effect of thesetwo sorbents on the metabolism and bioavailability of AfB₁.Clay and zeolitic minerals (HSCAS or clinoptilolite) were addedto the diet at a level of 0.5% (w/w) and fed to pregnant Sprague-Dawleyrats throughout pregnancy (i.e., day 0 to 20). Treatment groups(HSCAS or clinoptilolite) alone and in combination with AfB₁were exposed to sorbents in the feed as well as by gavage. Untreatedand AfB₁ control animals were fed the basal diet without addedsorbent. Between gestation days 6 and 13, animals maintainedon diets containing sorbent were gavaged with corn oil in combinationwith an amount of the respective sorbent equivalent to 0.5%of the estimated maximum daily intake of feed. Animals receivingAfB₁ were dosed orally (between days 6 and 13) with AfB₁ (2mg/kg body wt) either alone or concomitantly with a similarquantity of the respective sorbent Evaluations of toxicity wereperformed on day 20. These included: maternal (mortality, bodyweights, feed intake, and litter weights), developmental (embryonicresorptions and fetal body weights), and histologjcal (maternallivers and kidneys). Sorbents alone were not toxic; AfB₁ aloneand with clinoptilolite resulted in significant maternal anddevelopmental toxicity. Animals treated with HSCAS (plus AfB₁)were comparable to controls. Importantly, clinoptilolite (plusAfB₁) resulted in severe maternal liver lesions (more severethan AfB₁ alone), suggesting that this zeolite may interactwith dietary components that modulate aflatoxicosis. In metabolismstudies, adult male Sprague-Dawley rats, maintained on dietscontaining 0.5% (w/w) HSCAS or clinoptilolite, were dosed orallywith 2.0 mg AfB₁/kg body wt. The concentration of the majorurinary metabolite (AfM₁) was considerably decreased in thepresence of HSCAS. These results suggest that the mechanismof protection of AfB₁-induced maternal and developmental toxicitiesin the rat may involve adsorption and reduction of AfB₁ bioavailabilityin vivo. Importantly, this study demonstrates the potentialfor significant hidden risks associated with the inclusion ofnonselective aflatoxin binders in feeds. Aflatoxin sorbentsshould be rigorously tested individually and thoroughly characterizedin vivo, paying particular attention to their effectivenessand safety in sensitive animal models and their potential fordeleterious interactions.     

Assessment in Rats of the Gonadotoxic and Hepatorenal Toxic Potential of Dibromochloropropane (DBCP) in Drinking Water

This investigation was undertaken to assess the potential ofingested l,2-dibromo-3-chloropropane (DBCP) to cause tes-ticularand hepatorenal injury, in light of the paucity of data applicableto risk assessment of DBCP in drinking water. Adult male Sprague-Dawleyrats were supplied ad libitum with water containing 0, 5, 50,100, and 200 ppm DBCP for 64 days. A dose-related decrease inwater consumption occurred during the study. The 200-ppm animalsdrank less than half as much water as controls, consumed lessfood, and subsequently exhibited significantly lower body weightgain. DBCP ingestion thus was not directly proportional to thelevel of chemical in the water, although daily and cumulativeintake of DCP were concentration dependent. Average daily intakeof DBCP for the 64-day exposure period was as follows: 5 ppm= 0.4 mg/kg/day, 50 ppm = 3.3 mg/kg/day; 100 ppm = 5.4 mg/kg/day;200 ppm = 9.7 mg/kg/day. Blood samples were taken after 2,4,and 6 weeks of exposure and at the terminal sacrifice and assayedfor serum glutamic-oxaloacetic transaminase, glutamic-pyruvictransaminase, sorbitol dehydrogenase, and ornithine-carbamyltransferase activities and BUN levels. No evidence of liverdamage at any exposure level was indicated by either the clinicalchemistry indices or histopathology. His-tologic examinationrevealed an apparent increase in the number of nuclei per renalproximal tubule cross-section in the 200-ppm group, possiblyindicative of an increased turnover of proximal tubular cells.A slight, but statistically significant, decrease in absolutetesticular weight was manifest in the 200-ppm animals, althoughthe decrease was not significant when testicular weight wascalculated as g/100 g body wt. Epididymal sperm counts and serumluteinizing hormone, follicle stimulating hormone, and intratesticulartestosterone levels were not altered by any dose of DBCP. Aqualitative histopathological examination of the testicularseminiferous epithelium failed to reveal any abnormalities inthe spermatogenic process.     

The Effects of Ethylene Dibromide on Semen Quality and Fertility in the Rabbit: Evaluation of a Model for Human Seminal Characteristics

The Effects of Ethylene Dibromide on Semen Quality and Fertilityin the Rabbit: Evaluation of a Model for Human Seminal Characteristics.Williams, J., Gladen, B. C., Turner, T. W., Schrader, S. M.,and Chapin, R. E. (1991). Fundam. Appl. Toxicol. 16, 687–700.Mature (12 months old) male New Zealand White rabbits (8–10/group)were dosed subcutaneously with ethylene dibromide (EDB) in cornoil (untreated and vehicle controls, 15, 30, or 45 mg/kg bodywt/day for 5 days). Weekly semen samples (for 6 weeks preexposure,during treatment, and 12 weeks postdosing [pd]) were analyzedfor sperm concentration, number, morphology, viability, andmotion parameters (velocity, linearity, beat cross-frequency,amplitude of lateral head displacement (ALH), and circularity),and semen pH, osmolality, volume, fructose, citric acid, carnitine,protein, and acid phosphatase (AP). Male fertility was assessedpreexposure and at 4 and 12 weeks pd by artificial inseminationof three femaleS/male/time point with one million motile sperm.The percentage pregnant females, litter size, fetal body weights,and structural development were assessed. In the 45 mg/kg dosegroup of males there was 30% mortality and liver damage in 43%of the survivors as evidenced by increased levels of serum enzymes.Also in this group, EDB produced significant decreases in spermvelocity, percentage motility, and ALH (up to 25% at varioustimes pd). There were also dose-related decreases in semen pH(up to 2%) and total ejaculate volume (up to 23%, 15 and 30mg/kg dose groups only). AP activities were significantly elevated(up to 116%) 2 weeks pd in the 45 mg/kg dose group. All othersemen parameters evaluated were unaffected. Male fertility andfetal structural development were also unaffected. Of the sevensemen parameters perturbed by EDB in humans (Schrader et al.1988), four were also affected in the rabbit (sperm velocity,percentage motility, pH, and volume), whereas sperm number,viability, and morphology were not. Thus, some of the male reproductiveeffects of EDB in the human have been modelled in the rabbit,although the rabbit appears not to be as sensitive, since semenparameters were affected only at doses close to the LD50 (55mg/kg). The present study (together with other published data)suggests that the rabbit appears to be a potential model formale reproductive toxicity in humans, warranting further evaluation.     

Hepatoprotective Effects of the Shark Bile Salt 5{beta}-Scymnol on Acetaminophen-Induced Liver Damage in Mice

The hepatoprotective effect of the shark bile salt 5ß-Scymnolhas been studied in the model of acute hepatotoxicity inducedby administration of acetaminophen (APAP, paracetamol). 5ß-Scymnolat doses of 20, 35, and 70 mg/kg intraperitoneally (ip) decreasedsignificantly the serum activity of alanine aminotransferase,sorbitol dehydrogenase, and lactate dehydrogenase (p < 0.05)caused by APAP treatment (350 mg/kg ip) alone. The highest doseof 5ß-Scymnol remained hepatoprotective when administered4 hr after the APAP overdose. N-Acetylcysteine (NAC) is protectiveagainst APAP-induced hepatotoxicity at 250 and 500 mg/kg (ip)when administered up to 3 hr after APAP overdose, as shown bya significant reduction in serum enzyme activity. Coadministrationof 5ß-Scymnol (70 mg/kg) and NAC (250 mg/kg) alsoreduced serum enzyme levels and histopathological effects; however,a similar level of hepatoprotection was conferred by 5ß-Scymnoltreatment alone. In addition, 5ß-scymnol has potenthydroxyl radical quenching activity as it markedly inhibiteddeoxyribose degradation in a ferrous/ascorbate Fenton reactionsystem. These results indicate a possible role for the use of5ß-scymnol, either alone or concomitant with NAC,in the prevention of hepatic necrosis following toxic dosesof APAP.     

Subchronic Oral Toxicity of Ethylene Glycol Monobutyl Ether in Male Rats

Subchronic Oral Toxicity of Ethylene Glycol Monobutyl Etherin Male Rats. KRASAVAGE, W. J. (1986). Fundam Appl. Toxicol.6, 349–355. Adult male rats (Crl:COBS CD (SD)BR) weregiven undiluted ethylene glycol monobutyl ether (EGBE) by gavagein doses of 222, 443, or 885 mg/kg/day, 5 days/week over a 6-weekperiod. A dose-dependent decrease, which was statistically significantat the high dose, was seen in body weight gain. Feed consumptionwas also significantly reduced at the 885-mg/kg dose. The mostsignificant toxic effects produced by EGBE were on the red bloodcells including a significant dose-dependent decrease in hemoglobinconcentration. red blood cell counts, and mean corpuscular hemoglobinconcentration. Mean corpuscular hemoglobin and mean corpuscularvolume were increased at all dose levels. Effects secondaryto the red cell effects included increased spleen weights, spleniccongestion, and hemosiderin accumulation in the liver and kidneys.Relative liver weights and serum alkaline phosphatase (443-and 885-mg/kg doses) and serum alanine aminotransferase (885-mg/kgdose) levels were increased. Glucose was significantly reducedin the animals given 885 mg/kg/day. EGBE had no adverse effectson the testes, bone marrow, thymus, or white blood cells.     

Alkoxyresorufin Metabolism in White-Footed Mice at Relevant Environmental Concentrations of Aroclor 1254

Recent investigations have detected polychlorinated biphenyl(PCB) body burdens in wild white-footed mice (Peromyscus Ieucopus)captured at hazardous waste sites. Insufficient informationis currently available to interpret the toxicological significanceof these body burdens. In an effort to provide this information,we investigated hepatic changes and PCB body burdens in whitefootedmice following a 21-day dietary exposure to a PCB mixture, Aroclor1254. Dietary concentrations tested were 0, 2.5, 25, 50, and100 mg Aroclor 1254/kg diet (reported as ppm). Liver weightswere significantly increased at all concentrations except 2.5ppm. Ethoxyresorufin O-dealkylase (EROD) activity, an aryl hydrocarbonhydroxylase-type substrate, was significantly increased at allPCB concentrations, but the dose-response tended to plateauabove 25 ppm. Pentoxyresorufin O-dealkylase (PROD) activity,a putative phenobarbital-type substrate, was significantly increasedin a dose-dependent manner at 25 ppm PCB and above, with noplateau response. Pentobarbital sleep time was significantlydecreased at 25 ppm, but not at 2.5 ppm. Results indicate white-footedmice undergo a mixed-type in duction pattern following exposureto Aroclor 1254, with EROD the most sensitive indicator of PCBexposure. This investigation identified a no observed effectconcentration for liver weights and PROD activity at 2.5 ppmin the diet which is equivalent to a body burden of 2.0 mg Aroclor1254/kg wet wt of mice; the no observed effect concentrationfor EROD is below these levels. These results support the useof EROD, PROD, and liver weight as biomarkers of PCB exposurein field-captured rodents.