Toxicity of a novel anti-tumor agent 20(S)-ginsenoside Rg3: A 26-week intramuscular repeated administration study in rats

The purpose of this study is to investigate the potential subchronic toxicity of 20(S)- Ginsenoside Rg3(Rg3), by a 26-week repeated intramuscular administration in rats. Rg3 was administrated to rats at dose levels of 0, 4.2, 10.0 or 20.0 mg/kg/day. There was no treatment-related mortality and, at the scheduled autopsy, dose-dependent increases in the absolute and relative spleen weights, of both the 10.0 mg/kg and 20.0 mg/kg dose groups were observed. Absolute and relative kidney weights were significantly elevated in the female 10.0 mg/kg dose group and in the male 20.0 mg/kg dose group. Hematological investigations revealed a dose-dependent increase in the total white blood cell (WBC) count and in the percentage of neutrophils, but a decrease in the percentage of lymphocytes, in rats treated with doses of 10.0/20.0 mg/kg. These effects were completely reversible during the recovery period, and no other adverse effects were observed. It was concluded that the 26-week repeated intramuscular dose of Rg3 caused increases in the spleen and kidney weights, WBC counts and in the percentage of neutrophils, but a decrease in the percentage of lymphocytes, with doses of 10.0 or 20.0 mg/kg/day. The no-observed-adverse-effect level for rats was considered to be 4.2 mg/kg/day.     

Acute and subchronic toxicity studies of pyrroloquinoline quinone (PQQ) disodium salt (BioPQQ™) in rats

The potential use of pyrroloquinoline quinone disodium salt (BioPQQ™), as a supplemental food ingredient, was evaluated in a range of oral toxicity studies in rats including an acute study, a 14-day preliminary and a 28-day repeated-dose study, and a 13-week subchronic study. The median lethal dose of BioPQQ™ was shown to be 1000–2000 mg/kg body weight (bw) in male and 500–1000 mg/kg bw in female rats. In the 14-day study, high doses of BioPQQ™ resulted in increases in relative kidney weights with associated histopathology in female rats only, while a follow-up 28-day study in female animals resulted in increases in urinary protein and crystals. These findings were reversible, and resolved during the recovery period. In the 13-week study, a number of clinical chemistry findings and histopathological changes were noted, which were deemed to be of no toxicological significance, as the levels were within the historical control range, were not dose-dependent, occurred at a similar frequency in control groups, or only occurred in the control group. Based on these findings, a no-observed-adverse-effect level of 100 mg/kg bw/day was determined for BioPQQ™ in rats, the highest dose tested in the 13-week study.     

Subchronic and chronic toxicity of ingested 1,3-dichloropropene in dogs

The potential toxicologic effects to dogs of 1,3-dichloropropene (1, 3-D), a soil fumigant used for the control of nematodes, were investigated. The 13-week subchronic toxicity study consisted of male and female beagle dogs (4/sex/dose group) given approximately 0, 5, 15, or 41 mg 1,3-D/kg body wt/day (approximately equivalent amounts of cis and trans isomers) via their diets. The 1-year chronic toxicity study consisted of male and female beagle dogs (4/sex/dose group) provided diets delivering approximately 0, 0.5, 2. 5, or 15 mg/kg body wt/day. The test material was stabilized in the feed by microencapsulation in a starch/sucrose matrix (80/20). In both the 13-week and the 1-year studies, the primary effect of 1,3-D in male and female dogs ingesting a dosage of >/=15 mg/kg/day was hypochromic, microcytic anemia. The anemia was regenerative, with increased erythropoietic activity characterized by polychromasia of erythrocytes and increased numbers of reticulocytes in peripheral blood. In the 13-week study, the anemia in dogs given 41 mg/kg/day progressively worsened over time, while the anemia in dogs given 15 mg/kg/day remained relatively constant between 42 and 90 days of dosing. Partial reversal of the anemia of high-dose animals occurred during a 5-week recovery period following the 13-week dosing regimen. In the 13-week study, terminal fasted body weights of males given 15 or 41 mg/kg/day were decreased 3 and 28%, respectively, and body weights of females given 5, 15, or 41 mg/kg/day were decreased 4.5, 12, and 24%, respectively, relative to controls. Males given 5 mg/kg/day for 13 weeks had no change in body weights relative to controls. In the 1-year study, the hypochromic microcytic anemia in dogs given 15 mg/kg/day remained relatively constant in severity between 3 and 12 months of treatment. Histopathologic alterations associated with anemia in the 1-year study consisted of increased hematopoiesis of the bone marrow and increased extramedullary hematopoiesis of the spleen. Body weights of males given 15 mg/kg/day were 5-12% lower than controls during the first 13 weeks of the study and 13-19% lower than controls during the remaining 9 months. Body weights of females given 15 mg/kg/day were 5-14% lower than controls over the majority of the dosing period. Males and females given 0.5 or 2.5 mg/kg/day for 1 year had no change in body weights relative to controls. A no-observed-effect level of 2.5 mg/kg/day was established for male and female dogs from the 1-year study.     

Scientific evaluation of the chronic toxicity of the herbal medicine CGX in beagle dogs

CGX is a potential hepatoprotective herbal medicine used to treat various chronic liver disorders. The purpose of the study was to evaluate the pharmaceutical safety of CGX via a systemic 13-week repeated dose toxicity test in beagle dogs. Male and female beagle dogs were divided into four groups and two animals each from the control and high-dose group (400 mg/kg) were allocated into recovery groups. The dogs were administered with CGX (0, 100, 200, 400 mg/kg) for 13 weeks. During the experimental period, the dogs were observed for signs of gross toxicity and for behavioral changes; body weight and food consumption were measured. An ophthalmologic examination and urinalysis were performed at 0 and 13th week and blood biochemistry and hematological parameters analyses were performed at 0, 6th, and 13th week. A histopathological examination was also performed at the end of the experiment. There were no CGX-induced abnormalities in clinical signs, organ weights, food consumption, hematological, urine, and blood biochemical parameters, or histopathological findings in any of the groups during or after the 13 weeks. We demonstrated the safety of CGX for 13-week repeated dose and considered that it is safe for chronic clinical use.     

Subchronic and chronic safety studies with genistein in dogs.

Genistein is a phytoestrogen that occurs naturally in the diet, especially in soy-based foods. There is widespread interest in phytoestrogens as chemopreventive agents for a variety of diseases and cancers based on epidemiologic evidence. Although soy and its constituents, such as genistein, have been consumed at high levels in several Asian populations without apparent adverse effects, concern has been raised about potential adverse effects due to estrogenic and other activities. The subchronic and chronic safety of genistein were evaluated in the beagle dog including a 4-week study and a 52-week safety study with a 13 week interim sacrifice and a 4 week recovery period. In both studies at doses of 50, 150 and 500 mg/kg/day, genistein was well tolerated. In the 4 week study, except for an increase in uterine weights in female dogs at 500 mg/kg/day, there were no other treatment related findings. In the 52-week study, the primary effects of genistein were observed on the reproductive tract, which included for male dogs: reduced size and/or weight of the testes, epididymus and prostate of 2/2 dogs after 13 weeks of treatment and in 1/4 dogs after 52 weeks of treatment at 500 mg/kg/day. The histological changes observed in the affected dogs at 500 mg/kg/day indicated atrophy of the testes and prostate gland and absent spermatozoa in the epididymus. At the mid-dose of 150 mg/kg/day, although there was a reduction to a lesser extent in testes weight after 13, but not 52 weeks, there were no histopathological changes. In female dogs, the reproductive tract effects included increased uterine weight at 500 mg/kg/day after 13 weeks of treatment, but not after 52 weeks of treatment. There was also a small decrease in ovarian weights at 150 and 500 mg/kg/day after 13 weeks and at 500 mg/kg/day after 52 weeks of treatment. There were no histopathological correlates to the changes in organ weights in female dogs. In the 4-week recovery group dogs, no changes were observed in dogs previously treated for 52 weeks with 500 mg/kg/day of genistein. It is concluded that the administration of genistein to dogs for a period of 4-52 weeks was well tolerated and did not result in systemic toxicity. Effects of genistein on the reproductive tract at very high doses were functional in nature and are of a type that would be expected in view of the relatively weak estrogenic activity of genistein and were considered not adverse effects. In the 4-week study, the no observed adverse effect level (NOAEL) for genistein was considered to be >500 mg/kg/day and the no observed effect level (NOEL) was considered to be 150 mg/kg/day. For the 52-week study, the NOAEL is considered to be >500 mg/kg/day and the NOEL is considered to be 50 mg/kg/day.     

Subacute toxicity and recovery tests of mequitazine in beagle dogs (author's transl)

Subacute toxicity and recovery tests of Mequitazine, a new phenothiazine ;type anti-histamine agent, were carried out using each 20 male and female dogs. The drugs was administered orally in doses of 0, 1, 5 and 25 mg/kg day for 14 weeks. Recovery test was carried out for following 4 weeks. As a result, transient decrease of the body weights and somnolences were observed in both male and female dogs given 25 mg/kg. In a female dog given 25 mg/kg, extrapyramidal reaction accompanied with tremors and muscle stiffenings was observed. But no dead animals were observed throughout experimental period. Vomitings, mydriasis and loss of appetite were observed with the dose-responsiveness, but these symptoms were reduced after 1-2 weeks administration. No abnormal changes were observed in hematological, serum biochemical, and other examinations. In histopathological examinations, slights changes were observed in liver, kidneys, mesenteric lymph nodes, palpebra and conjunctival membrane. But these changes were reversible in recovery period. From these results, it was suggested that the maximum non-effective and maximum safety doses were 1 mg/kg/day and 5 mg/kg/day, respectively.     

Subchronic toxicity studies with ginsenoside compound K delivered to dogs via intravenous administration

Compound K, i.e., 20-O-β-d-glucopyranosyl-20(S)-protopanaxadiol, is the main metabolite of the protopanaxadiol type of ginseng saponin produced by intestinal bacteria after oral administration of ginseng extract. In the present study, the toxicity of compound K was evaluated in male and female dogs after 90 days continuous intravenous infusion. Beagle dogs were treated with compound K at doses of 6.7, 20 and 60 mg/kg/day, and observed for 90 days followed by recovery periods. Measurements included clinical observations, body weight, food consumption, temperature, electrocardiogram (ECG), hematology, blood chemistry, urinalysis, gross necropsy, organ weight and histopathology. Under the conditions, the clinical condition of the animals, body weights, body weight gains and food consumption were unaffected by compound K administration relative to the control group. Hematology, ECG data and urinalysis parameters were also unaffected. However, the hepatotoxicity was evident from the observation of multiple parameters, including histopathological evaluation of liver tissue upon necropsy as well as large increases in plasma levels of liver enzymes (alanine aminotransferase, ALT, Gamma-glutamyltranspeptidase, γ-GT, alkaline phosphatase,ALP) in groups receiving compound K (20 or 60 mg/kg/day), and this hepatoxicity might be reversible. In addition, the NOAEL of compound K is 6.7 mg/kg/day in this 90 days toxicity study.     

Acute and subchronic toxicological evaluation of the semipurified extract of seeds of guaraná (Paullinia cupana) in rodents

We evaluated the toxicity of a semipurified extract (EPA fraction, containing caffeine and several flavan-3-ols and proanthocyanidins) of seeds of the native Amazon plant Paullinia cupana (guaraná) in rodents. Acute toxicity was tested in male Swiss mice, which received different doses orally (OR) and intraperitoneally (ip); control groups received water. These tests produced acute mortality, with LD₅₀ of 1.825 g/kg (OR) and 0.827 g/kg (ip), and a significant weight decrease in lungs of mice receiving a dose of 0.1 g/kg. In the repeated-dose toxicity test, the EPA was administered OR daily to male and female Wistar rats at doses of 30, 150, and 300 mg/kg/day/90 days. Their behavior, mortality, weight changes, laboratory tests, and the weights and histopathology of organs were evaluated. No rats died during the tests. Males dosed at 150 or 300 mg/kg gained weight more slowly and lost kidney weight (absolute and relative weights, compared to the control group). Hematological and biochemical tests showed few changes, differing somewhat between males and females; the histopathological evaluation indicated no significant changes. These results indicate that the EPA fraction of guaraná caused no toxicity in rats at the smallest dose evaluated (30 mg/kg). No other species was evaluated.     

Subchronic Toxicity of Ingested 1,3-Dichloropropene in Rats and Mice

Male and female Fischer 344 rats and B6C3F1 mice (10/sex/dosegroup) were given 0, 5, 15, 50, or 100 mg/kg/day (rats) or 0,15, 50, 100, or 175 (mice) mg/kg/day racemic 1,3-dichloropropene(1,3-D), respectively, via their diets for 13 weeks. Satellitegroups of rats (recovery = 10 rats/sex/group) ingesting 0 or100 mg/kg/day 1,3-D were provided control feed for an additional4 weeks to examine recovery. The test material was stabilizedin the feed by microencapsulation in a starch/sucrose matrix(80/20). The body weights of male and female rats Ingesting>5 and >15 mg/kg/day, respectively, and of all treatmentgroups of mice were decreased relative to controls. The terminalbody weights of high dose group rats and mice were decreasedapproximately 13–16%. A number of changes in serum biochemicalparameters and decreases in organ weights accompanied the depressedbody weights of these animals. Histologically, the only treatment-relatedchange observed was a slight degree of basal cell hyperplasiaand hyperkeratosis in the nonglandular portion of the stomachsof a majority of male and female rats ingesting >15 mg/kg/day.After the 4-week recovery period, most treatment-related changeswere noted to be reversible in nature. No treatment-relatedhistopathological changes were observed in the tissues of treatedmice. Based upon relatively slight depressions in body weightsat the lowest dosages tested, the no-observed-adverse-effectlevels for male rats and both sexes of mice were determinedto be 5 mg/kg/day and 15 mg/kg/day, respectively. A no-observed-effectlevel of 5 mg/kg/day was established for female rats.     

Subacute toxicity and toxicokinetics of CJ-10882, a type IV phosphodiesterase inhibitor, after 4-week repeated oral administration in dogs.

The subacute toxicity and toxicokinetics of a type IV phosphodiesterase inhibitor, CJ-10882, were evaluated after single (on the 1st day) and 4-week (on the 27th day) oral administration of the drug, in doses of 0 (to serve as a control), 2, 10 and 50 mg/kg/day, to male and female dogs (n=3 for male and female dogs for each dose). During the test period, clinical signs, mortality, body weight, food consumption, ophthalmoscopy, urinalysis, hematology, serum biochemistry, gross findings, organ weight and histopathology were examined. The 4-week repeated oral doses of CJ-10882 resulted in salivation, vomiting, and atrophy of the thymus. The absolute toxic dose was 50 mg/kg/day and the level at which no adverse effects were observed was 2 mg/kg/day for male and female dogs. There were no significant gender differences in the pharmacokinetic parameters of CJ-10882 for each dose after both single and 4-week oral administration. The pharmacokinetic parameters of CJ-10882 were dose independent after a single oral administration; the time to reach a peak plasma concentration (T(max)) and the dose-normalized area under the plasma concentration-time curve from time zero to 8 h in plasma (AUC(0-8 h)) were not significantly different among three doses. The accumulation of CJ-10882 after 4-week oral administration was not notable at the toxic dose of 50 mg/kg/day. For example, after 4-week administration, the dose-normalized AUC(0-8 h) value at 50 mg/kg/day (0.132 microg h/ml) was not significantly greater than that at 10 mg/kg/day (0.131 microg h/ml). After 4-week oral administration, the dose-normalized C(max) and AUC(0-8 h) at 50 mg/kg/day were not significantly higher and greater, respectively, than those after the single oral administration.     

Safety studies conducted on a proprietary high-purity aloe vera inner leaf fillet preparation,Qmatrix®

The aloe vera plant has a long history of safe use for oral and topical applications. This publication describes safety studies conducted on a proprietary high-purity aloe vera inner leaf fillet preparation, Qmatrix®. In a 13-week study in rats, Qmatrix® was administered via gavage at 0, 500, 1000 and 2000 mg/kg body weight (bw)/day. There were no significant changes in food or water consumption, body weight, serum biochemistry or hematology at any of the doses tested. Sporadic, significant increases were observed in some of the measured urinalysis parameters; however, these variations were not treatment-related, as most were observed only in one sex, not dose-dependent and within historical control values. Organ weights were unaffected, except for a statistically significant, though not dose-dependent, increase in absolute and relative weights of the right kidney in males at 500 and 2000 mg/kg bw/day, respectively. Histopathological analysis revealed no abnormal signs. Qmatrix® was non-mutagenic in an Ames test and a chromosomal aberration test at concentrations up to 10,000 μg/plate, and in an in vivo bone marrow micronucleus test at doses up to 5000 mg/kg bw/day. Based on these results, Qmatrix® is not genotoxic in vitro or in vivo and; has an oral NOAEL greater than 2000 mg/kg bw/day following 90 days of oral exposure.     

Subacute toxicities and toxicokinetics of a new erectogenic, DA-8159, after single and 4-week repeated oral administration in dogs.

The subacute toxicities and toxicokinetics of a new erectogenic, DA-8159, were evaluated after single (at the 1st day) and 4-week (at the 28th day) oral administration of the drug, in doses of 0 (to serve as a control), 12.5, 50 and 200 mg/kg/day, to male and female dogs (n=3 for male and female dogs for each dose). DA-8159 had an effect on the immune-related organs (or tissues), circulatory systems, liver, adrenal glands, ovaries and pancreas. The toxic dose was 200 mg/kg and no observed adverse effect level was less than 50 mg/kg for male and female dogs. There were no significant gender differences in the pharmacokinetic parameters of DA-8159 for each dose after both single and 4-week oral administration. The pharmacokinetic parameters of DA-8159 were dose-independent after single oral administration; the time to reach a peak plasma concentration (T(max)) and the dose-normalized area under the plasma concentration-time curve from time zero to 24 h in plasma (AUC(0-24 h)) were not significantly different among three doses. However, accumulation of DA-8159 after 4-week oral administration was considerable at toxic dose, 200 mg/kg/day. For example, after 4-week administration, the dose-normalized AUC(0-24 h) value at 200 mg/kg/day (4.71 and 15.3 microg h/ml) was significantly greater than that at 12.5 mg/kg/day. After 4-week oral administration, the dose-normalized C(max) and AUC(0-24 h) at 200 mg/kg/day were significantly higher and greater, respectively, than those after a single oral administration.     

N-acetyl-glutamic acid: Evaluation of acute and 28-day repeated dose oral toxicity and genotoxicity

N-acetyl-glutamic acid (NAG) is an endogenously produced mammalian substance and minor constituent of commonly consumed foods. This paper reports the outcome of genotoxicity and acute and repeated dose (28-day) oral toxicology studies conducted with NAG. No evidence of genotoxicity was observed with NAG in in vitro or in vivo studies. No mortalities or evidence of adverse effects was observed in Sprague–Dawley rats following acute oral gavage with NAG at a dose of 2000 mg/kg of body weight. No adverse effects were observed in rats following repeated dose dietary exposure to NAG at target concentrations corresponding to doses of 100, 500, or 1000 mg/kg of body weight/day for 28 days. All rats survived until scheduled sacrifice and no biologically significant or test substance related differences were observed in body weights, feed consumption, clinical signs, functional observational battery (FOB), ophthalmology, hematology, coagulation, clinical chemistry, organ weights or histopathology of any of the treatment groups. Based on the observed results it is concluded that NAG is not genotoxic or acutely toxic. The no-observed-adverse-effect-level (NOAEL) for systemic toxicity from repeated dose (28-day) dietary exposure to NAG was 914 mg/kg of body weight/day for male rats and 1007 mg/kg of body weight/day for female rats.     

Acute oral safety study of dairy fat rich in trans-10 C18:1 versus vaccenic plus conjugated linoleic acid in rats

The acute oral toxicity of a trans-10 C18:1-rich milk fat (T10, 20% of total FA), and a trans-11 C18:1 + cis-9 trans-11 C18:2-rich milk fat (T11-CLA, 14% and 4.8% of total FA, respectively) was studied in rats receiving a single oral dose of 2000 mg/kg body weight (BW). T10 and T11-CLA milk fats were well tolerated; no adverse effects or mortality were observed during the 2-week observation period. Two weeks following a single oral dose of 2000 mg/kg BW of T10 and T11-CLA milk fats there were no changes in haematological and serum chemistry parameters (excepting plasma lipid) organ weights, gross pathology or histopathology. In rats treated with T10 milk fat a significant increase of triglycerides was observed. In contrast, in rats treated with T11-CLA milk fat significantly decreased triglycerides were detected. It was concluded that dairy fats rich in T10 and T11-CLA have a low order of acute toxicity, the oral lethal dose (DL₅₀) for male and female rats are in excess of 2000 mg/kg BW. Our results suggest that the T10 milk fat treatment tended to increase triglycerides concentrations, whereas the T11-CLA milk fat treatment tended to reduce it.     

Four-week repeated dose oral toxicity study of BMY-28100 in juvenile beagle dogs

Three groups, each consisting of 3 male and 3 female juvenile beagle dogs, were orally given BMY-28100 for 4 weeks at dose levels of 50, 160 and 500 mg/kg/day, respectively. Additionally, one male and one female dogs were added to each of the control and high dose groups in order to examine the recovery, and observed for 4 weeks after withdrawal of BMY-28100. The results obtained are summarized as follows: 1. BMY-28100 provoked an increased incidence of emesis in the 500 mg/kg group during the treatment period. 2. BMY-28100 sporadically brought distention of the cecum containing considerable amounts of contents in dogs sacrificed after the 4-week administration period. However, no macroscopic or microscopic changes were observed in the cecum itself after removal of the contents. In the 500 mg/kg group, hypocellularity in the sternum bone marrow was observed in a male and a female, and thymic atrophy in a male. 3. No changes ascribed to BMY-28100 treatment were detected after the 4-week recovery period. Based upon these results, the no-effect dose level of BMY-28100 was estimated to be 160 mg/kg/day, except for effects on the cecum.     

Toxicology studies with N-acetylglycine

N-acetylglycine (NAGly) has been identified as a minor constituent of numerous foods. The current paper reports the outcome of in vitro and in vivo genotoxicity, acute oral and repeated dose dietary toxicology studies conducted with NAGly. No evidence of genotoxicity was observed with NAGly in vitro bacterial tester strains or in vivo bone marrow micronucleus studies conducted in mice. No mortalities or evidence of adverse effects were observed in Sprague–Dawley rats following acute oral gavage with NAGly at a dose of 2000 mg/kg of body weight or following repeated dose dietary exposure to NAGly at targeted doses of 100, 500, or 1000 mg/kg of body weight/day for 28 days. No biologically significant or test substance related differences were observed in body weights, feed consumption, or clinical pathology response variables in any of the treatment groups. Based on these results it was concluded that NAGly is not genotoxic or acutely toxic. Further, the no-observed adverse-effect-level (NOAEL) for systemic toxicity from repeated dose dietary exposure to NAGly was 898.9 mg/kg of body weight/day for male rats and 989.9 mg/kg of body weight/day for female rats.     

Repeated sub-chronic oral toxicity study of xylooligosaccharides (XOS) in dogs

In this study, Beagle dogs were administered xylooligosaccharide (XOS, CAS # 87099-0) at doses of 0, 1250, 2500, and 5000 mg/kg/day by oral gavage for 26 weeks. A 4-week recovery period was added to observe delayed or reversible toxicity. Measurements included body weight, food consumption, clinical observations, temperature, electrocardiogram (ECG), urinalysis, blood chemistry, hematology, organ weight, gross necropsy, and histopathological examination. Except for transient diarrhea or vomiting, no treatment-related adverse effects were noted. In the mid-dose groups, transitional diarrhea was observed in the initial 1–2 weeks. In the high-dose groups, diarrhea and/or vomiting were observed episodically over the duration of treatment. However, they disappeared after XOS was withdrawn in the recovery period. Although there was a tendency toward less weight gain in the high-dose group animal group, this is typical in animals and humans fed non-digestible carbohydrates. This chronic toxicity study demonstrated that the no observed adverse effect level (NOAEL) of XOS is 2500 mg/kg body weight (BW)/day. Based on body surface area (conversion factor of 0.54 for dogs to human), this corresponds to daily doses of 1350 mg/kg BW or 81–108 g XOS in human adults weighing 60–80 kg.     

A 90 days oral toxicity of imidacloprid in female rats: Morphological,biochemical and histopathological evaluations

A 90 days oral toxicity study of imidacloprid was conducted in female rats with doses of 0, 5, 10, 20 mg/kg/day. Decrease in the body weight gain was observed at 20 mg/kg/day and at necropsy the relative body weights of liver, kidney and adrenal was also significantly increased at this dose level. No mortality occurred during treatment period while food intake was reduced at high dose level. In clinical chemistry parameters high dose of imidacloprid has caused significant elevation of serum GOT, GPT, glucose and BUN and decreased the activity of AChE in serum and brain. The spontaneous locomotor activity was also decreased at highest dose exposure where as there were no significant changes in hematological and urine parameters. The brain, liver and kidney of rats exposed with high dose of imidacloprid had showed mild pathological changes. Based on the morphological, biochemical, hematological and neuropathological studies it is evident that imidacloprid has not produced any significant effects at 5 and 10 mg/kg/day doses but induced toxicological effects at 20 mg/kg/day to female rats. Hence, 10 mg/kg/day dose may be considered as no observed effect level (NOEL) for female rats.     

Effects of in utero through lactational exposure to dicyclohexyl phthalate and p,p′-DDE in Sprague–Dawley rats

Anti-androgenic chemicals alter sexual differentiation by a variety of mechanisms, and the mechanisms between phthalate esters and p,p′-DDE are considered to be different. We performed an in utero through lactational exposure assay using dicyclohexyl phthalate and p,p′-DDE to investigate the sexual differentiation of these chemicals. Pregnant CD (SD) IGS rats were given dicyclohexyl phthalate or p,p′-DDE orally from gestational day (GD) 6 to postnatal day (PND) 20, and the endocrine-mediated effects in dams and their offspring were examined. The reproductive performance of offspring was also examined. The doses of dicyclohexyl phthalate were 0, 20, 100, and 500 mg/kg/day, and those of p,p′-DDE were 5, 15, and 50 mg/kg/day. Using the dicyclohexyl phthalate, a dam in the 500 mg/kg group showed dystocia and died. The viability index of offspring on PND 4 decreased in the 500 mg/kg group. Prolonged preputial separation, reduced ano-genital distance, increased areolas/nipple retention, hypospadia, decreased ventral prostate and levator ani/bulbocavernosus muscle weights and decreased testicular germ cells were observed in male offspring in the 500 mg/kg group. In the assay using p,p′-DDE, decreased viability index of offspring on PND 21, prolonged preputial separation in male offspring and early vaginal opening in female offspring were observed in the 50 mg/kg group. The copulation and fertility indices decreased in the reproductive performance of offspring in the 50 mg/kg group. The endocrine-mediated effects were detected in offspring of dams given 100 mg/kg dicyclohexyl phthalate, and in offspring of dams given 20 mg/kg p,p′-DDE. Our results suggest that the in utero through lactational exposure assay is a useful method to detect endocrine-mediated effects and that further comparative study between this assay and two-generation reproductive test are necessary when this assay becomes one of the definitive tests.     

Endocrine-mediated effects of two benzene related compounds, 1-chloro-4-(chloromethyl)benzene and 1,3-diethyl benzene,based on subacute oral toxicity studies using rats

The purpose of this study was to investigate the endocrine-mediated effects of the benzene-related compounds with reference to Organization for Economic Co-operation and Development (OECD) Test Guideline No. 407. Rats were orally gavaged with 0, 10, 50, and 250 mg/kg/day of 1-chloro-4-(chloromethyl)benzene, and 0, 25, 150, and 1000 mg/kg/day of 1,3-diethyl benzene for at least 28 days, beginning at 8 weeks of age. Thyroid dysfunction was observed in rats given the 1,3-diethyl benzene. Serum T4 values increased in all groups of male rats and in the 1000 mg/kg group of female rats, and TSH values also increased in the 1000 mg/kg groups of both sexes after 28 days’ administration. Decreased T3 values were observed in the 1000 mg/kg group of female rats after 28 days’ administration, and hormone values increased in the 1000 mg/kg groups of both sexes after the 14-day recovery period. In addition, thyroid weight increased in the 1000 mg/kg groups and thyroid follicular cell hyperplasia was detected in one male rat from the 1000 mg/kg group after 28 days’ administration. Endocrine-mediated effects, including thyroid dysfunction were not observed in any groups of rats treated with 1-chloro-4-(chloromethyl)benzene. Our results indicated that endocrine-mediated effects such as thyroid dysfunction were associated with some benzene-related compounds.