Developmental toxicity of the dopamine agonist pergolide mesylate in CD-1 mice. I: Gestational exposure

Pergolide was given by oral gavage to mated CD-1 female mice at doses of 0, 1, 20, or 60 mg/kg/day on gestation days (GD) 6-15. Animals assigned to the teratology segment were killed on GD 18 for evaluation of maternal organ weights, and fetal viability, weights and morphology. Animals assigned to the postnatal segment were allowed to deliver and physical development and behavioral performance of the progeny were monitored until weaning. Maternal organ weights were collected at termination after weaning. One F1 offspring per sex per litter was maintained for postweaning physical, behavioral and reproductive assessments and for terminal examinations and organ weight evaluations. No adverse effects of pergolide treatment were found in the 1 mg/kg/day group. Dose-related hyperactivity, chewing and squinting that were consistent with dopaminergic stimulation occurred following dosing in the 20 and 60 mg/kg/day groups; F0 body weights and food consumption were reduced during the initial phase of treatment in the 60 mg/kg/day group. Gravid uterine weights and fetal weights were decreased in the 60 mg/kg/day group of the teratology segment, but there was no indication of teratogenicity in any group. Mammary inflammation, attributed to increased progeny suckling, occurred during the second week postpartum in a few postnatal segment females of the 20 and 60 mg/kg/day groups. Mean negative geotaxis performance was delayed slightly, but mean progeny survival and body weights were not affected. Although after weaning the F1 offspring from the treatment-derived groups tended to weigh more than controls and to perform more effectively in the active avoidance task, these findings were attributed to unusually low values obtained in the control group. Startle amplitudes were increased significantly in the males from the 60 mg/kg/day treatment-derived group. These dose-related maternal and developmental findings were all consistent with the mixed D1/D2 agonist properties of pergolide mesylate, and suggest that only very high doses may result in persistent effects on the developing central dopaminergic systems.     

Bromodeoxyuridine leaves evidence of prenatal exposure in the postnatal skeleton in CD-1 mice.

Mice from two series of experiments (S1, S2) involving intraperitoneal (ip) injection of dams with 300 (High or H), 60 (Low or L), or 0 (VEH) mg 5'-bromodeoxyuridine (BUDR) per kilogram body weight (mg/kg) in water (15 mL/kg) on day seven (D7), day eight (D8), or in S2 only, day nine (D9) of gestation (9DPC), and untreated (UNTD) controls, were examined between 60 and 65 days postnatal (DPN) for 88 variations of the skeleton. In S1, 65 variants occurred, and in S2 there were 58 variants that occurred. Substantial numbers of significant differences (P less than 0.01) in frequency of occurrence (%) were seen in High dose only. The number of variants that differed from UNTD were 13, 13, 12, 15, and 11 in S1-D7H, S2-D7H, S1-D8H, S2-D8H, and S2-D9H, respectively; the average absolute difference in frequency among significantly affected variants was 16% to 20%. In the same order as above, 13, 12, 8, 10, and 9 variants differed significantly from VEH, and 9, 8, 7, 8, and 8 variants differed significantly from both UNTD and VEH. In contrast, 0, 0, 1, 1, and 0 variants differed from both UNTD and VEH in S1-D7L, S2-D7L, S1-D8L, S2-D8L, and S2-D9L, respectively. Agreement between the two series was good; 11 traits were affected in High dose litters in both series in at least 3 or 4 comparisons (compared with UNTD, VEH, in S1, S2).(ABSTRACT TRUNCATED AT 250 WORDS)     

Perinatal exposure to the xenoestrogen bisphenol-A induces mammary intraductal hyperplasias in adult CD-1 mice

Humans are routinely exposed to bisphenol-A (BPA), an estrogenic compound that leaches from consumer products. Given the sensitivity of the developing organism to hormones, exposure of fetuses and infants is a concern. Here, CD-1 mice were exposed to environmentally relevant doses of BPA during gestation and the lactational period (gestational day 8 through postnatal day 16). At 3, 9 and 12–15 months of age, mammary glands from exposed offspring were examined for structural changes. BPA-exposed females demonstrated altered mammary phenotypes including the appearance of alveolar buds. Additionally, intraductal hyperplasias were observed exclusively in BPA-exposed females. These lesions had the appearance of “beaded” ducts, with epithelial cells present inside the ductal lumen and increased proliferation indexes compared to normal ducts. Similar structures have also been observed following exposure to other estrogens. These results are further evidence that perinatal BPA exposure can alter the morphology of the rodent mammary gland in adulthood.     

Perinatal exposure to the xenoestrogen bisphenol-A induces mammary intraductal hyperplasias in adult CD-1 mice

Humans are routinely exposed to bisphenol-A (BPA), an estrogenic compound that leaches from consumer products. Given the sensitivity of the developing organism to hormones, exposure of fetuses and infants is a concern. Here, CD-1 mice were exposed to environmentally relevant doses of BPA during gestation and the lactational period (gestational day 8 through postnatal day 16). At 3, 9 and 12–15 months of age, mammary glands from exposed offspring were examined for structural changes. BPA-exposed females demonstrated altered mammary phenotypes including the appearance of alveolar buds. Additionally, intraductal hyperplasias were observed exclusively in BPA-exposed females. These lesions had the appearance of “beaded” ducts, with epithelial cells present inside the ductal lumen and increased proliferation indexes compared to normal ducts. Similar structures have also been observed following exposure to other estrogens. These results are further evidence that perinatal BPA exposure can alter the morphology of the rodent mammary gland in adulthood.     

Neurobehavioral development of CD-1 mice after combined gestational and postnatal exposure to ozone

 Outbred CD-1 mice were exposed continuously to ozone (O₃, 0.6 ppm) from 6 days prior to the formation of breeding pairs to the time of weaning of the offspring on postnatal day 22 (PND 22) or to PND 26. One half of the mice in each of eight O₃ and eight control litters were subjected on PND 24 to a 20-min open-field test after IP treatment by either saline or scopolamine (2 mg/kg). The remaining mice (those exposed until PND 26) were subjected on PNDs 28–31 to a conditioned place preference (CPP) test, using a short schedule with a single IP injection on PND 29 of either d-amphetamine (3.3 mg/kg) or saline. Subsequently, the saline mice of the open-field experiment were used on PND 59 for an activity test in one of the CPP apparatus compartments after IP treatment by either d-amphetamine (same dose) or saline. In addition, the saline mice of the CPP experiment underwent a multi-trial, step-through passive avoidance (PA) acquisition test on PND 59 or 60, followed 24 h later by a single-trial retention test. In the absence of effects on reproductive performance (proportion of successful pregnancies, litter size, offspring viability, and sex ratio), O₃ offspring showed a long-lasting reduction in body weight without modification of sex differences. Ozone effects on neurobehavioral development were not large and quite selective, including: attenuation of the sex differences in several responses (rearing and sniffing in the open-field, activity in the final CPP test session); a change in response choices in the final CPP test, in the absence of a main effect on conditioning; a reduction of grooming in the activity test on PND 29; and impairment of PA acquisition limited to the initial period of training. Received: 3 November 1994/Accepted: 30 January 1995     

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 pregmant animals by gastric intubation at multiple dose levels throughout the period of organogenesis. The dams were sacrified 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.     

Behavioral characterization of the new potent nonselective dopamine agonist pergolide.

Pergolide (LY127809, CAS 66104-23-2), a non-selective dopamine agonist, was evaluated for broad behavioral properties in a wide range of pharmacological tests. The selective dopamine2(D2) agonist, bromocriptine, served as a reference standard for those tests where behavioral activity was noted with pergolide. Pergolide and bromocriptine were administered orally to mice at doses of 0.3-30 and 3-300 mg/kg, respectively. Both compounds produced biphasic effects on spontaneous activity, increased hexobarbital-induced sleep time, and lowered mouse body temperature. Qualitative changes with pergolide were observed with some mice showing hyporeactiveness, ptosis, slowed respiration and placing loss. Reserpine-induced hypothermia was reversed by pergolide with significant increases in the body temperature of reserpine-treated mice. However, a further reduction in the body temperature of reserpinized hypothermic mice was seen following bromocriptine administration. Acetic acid-induced writhing and performance on the rotarod were both impaired by higher doses of pergolide. Bromocriptine administration also reduced writhing at higher doses but did not alter performance on the rotarod. Pergolide had no effect on seizure activity as evaluated by electroshock, pentylenetetrazol (pentetrazol) or strychnine. Oxotremorine-induced tremors and salivation, grip strength, and tail-flick were not affected by pergolide. Neither pergolide nor bromocriptine altered established shuttle-avoidance behavior in rats at oral doses of 0.1 to 30 mg/kg. Behavioral assessment of pergolide in dogs was complicated by severe emetic responses at clinically relevant doses greater than 0.003 mg/kg. In summary, these data suggest that pergolide produces a behavioral profile which is characteristic of dopaminergics.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prenatal and postnatal assessment of Maneb-exposed CD-1 mice

Skeletons of CD-1 mice exposed in utero during days 6 to 15 of gestation by gavage of their dams with 1200 mg/kg/day of Maneb in 1.0% carboxymethylcellulose (CMC), were examined between 60 and 65 days postnatal (DPN) for the 88 variants of the skeletal variant assay system (SVAS). Of the 58 variants that appeared, 13 differed (P < 0.01) from untreated (UNTD), and 15 from vehicle-treated (VEH), despite absence of malformations at birth, weaning, or time of sacrifice. Major changes in frequencies of Parted Frontals, Abnormal Metoptic Roots, Reduced Articular Processes of the Thoracic (Th) Vertebrae, and Carpal Fusions occurred. Several variants affecting the Spinous Process of Th2 occurred in significant proportions as an unusual effect of this compound. In a series of 20 Maneb-treated litters dissected at 18 days post coitus (DPC), of 168 live fetuses, 9 had minor abnormalities, one was exencephalic, and 14 showed growth retardation. Prenatal mortality (20%) was higher than in UNTD (7.5%); litter size and litter weight were not significantly reduced. Ossification of cervical vertebral centra, and caudal vertebrae were significantly reduced, sternebra and limb ossification were not. Occurrence of 14-Ribs was increased. Although maternal mortality complicates interpretation, both traditional prenatal and postnatal examination focusing primarily on the skeleton revealed effects of exposure in the absence of frank malformations.     

Developmental toxicity study with diethylene glycol dosed by gavage to CD rats and CD-1 mice.

Diethylene glycol (DEG; CAS Number 111-46-6) is a widely used industrial liquid chemical with a potential for human exposure. In view of the established teratogenic effects caused by ethylene glycol in laboratory animals, the developmental toxicity of DEG was investigated in mice and rats, species known to be sensitive to the developmental toxicity of ethylene glycol. Timed-pregnant CD-1 mice and CD rats were dosed daily by gavage with undiluted DEG over gestational days (gd) 6-15. Based on probe studies, mouse dosages were 0 (distilled water), 559, 2795 and 11,180 mg/kg/day, and those for rats 0, 1118, 4472 and 8944 mg/kg/day. They were examined daily for clinical signs of toxicity, and body weights, food consumption and water consumption measured periodically throughout gestation. At necropsy, on gd 18 (mice) or gd 21 (rats), dams were examined for gross pathology and body, gravid uterus, liver and kidney weights were measured. Maternal rat kidneys were examined histologically. Fetuses were weighed, sex determined, and examined for external, visceral and skeletal variations and malformations. With mice there was maternal toxicity at 11,180 mg/kg/day (mortality, signs, increased water consumption) and at 2795 mg/kg/day (increased water consumption). Implantations were comparable across all groups. Fetal body weights were significantly reduced at 11,180 mg/kg/day. There were no increases in variations or malformations, either total, by category, or individually. With rats, maternal toxicity was present at 8944 mg/kg/day (mortality, signs, reduced body weight gain, reduced food consumption, increased water consumption, increased liver weight, increased kidney weight, and renal histopathology), and 4472 mg/kg/day (increased water consumption). There were no treatment-related effects on corpora lutea or implantations. Fetal body weights were reduced at 8944 mg/kg/day. There were no significant effects with respect to total or individual external or visceral variations. Individual skeletal variations were significantly increased at 8944 mg/kg/day (poorly ossified interparietal, poorly ossified thoracic centra number 10 and number 13, and bilobed thoracic centrum number 10) and 4472 mg/kg/day (split anterior arch of atlas and bilobed thoracic centrum number 10). This pattern of delayed ossification is consistent with reduced fetal body weight. Malformations, total, by category, or individually, were similar between the control and DEG groups. Thus, under the conditions of these studies, the no-observed-effect-level (NOEL) for DEG given by gavage over gd 6-15 was 559 mg/kg/day with the mouse and 1118 mg/kg/day with the rat for maternal toxicity, and 2795 mg/kg/day with mice and 1118 mg/kg/day with rats for developmental toxicity (fetotoxicity). There were no indications of embryotoxicity or teratogenic effects at any dosage in either species.     

妊娠中期可卡因对小鼠的发育毒性

目的:探讨可卡因对小鼠妊娠中期的发育毒性,尤其是对脑发育的影响.方法:建立妊娠中期给药的小鼠动物模型,体重相近的妊娠母鼠被分为三组:(1)可卡因注射自由饮食组(COC);(2)盐水注射伴有饮食对照组(SPF),饮食参考体重相近、妊娠时间相同的COC组母鼠;(3)盐水注射自由饮食组(SAL).从妊娠第8天(E8)至第12天(E12)给药,记录母鼠、胎鼠和仔鼠的各项生理指标,并用HPLC分析各组胎鼠纹状体中多巴胺、5-HT含量的变化.结果:尽管COC和 SPF组母鼠与 SAL组母鼠相比摄食量少,体重增加量少,但E17 天取材时,仅COC组胎鼠表现为脑和纹状体重量低;COC组仔鼠生后第 1天(P1)双顶径(BPD)也小于其它两组仔鼠.此外,COC组胎鼠表现出脑/体重比的降低,说明宫内暴露可卡因引起的胎鼠的发育迟缓是一个不平衡过程,脑组织的受累比其它组织严重.神经递质分析和组织学分析表明 COC组胎鼠脑内多巴胺和5-羟色胺的水平增高,肝脏呈现出形态学改变.结论:妊娠中期暴露可卡因可引起胎鼠宫内发育迟缓,尤其是脑发育迟缓.单纯母体营养不良在宫内暴露可卡因引起的后代发育迟缓过程中不能起决定性作用,而可能是药物直接作用的结果.     

Developmental toxicity study with triethylene glycol given by gavage to CD rats and CD-1 mice

Triethylene glycol (TEG) is a liquid industrial chemical with a potential for human exposure. The likelihood for developmental toxicity was investigated in two species. Timed-pregnant CD rats and CD-1 mice were dosed daily by gavage with undiluted TEG over gestational days (gd) 5-15 at 0.0 (water control), 1126, 5630 or 11,260 mg kg(-1) day(-1) with rats and 0.0, 563, 5630 or 11,260 mg kg(-1) day(-1) with mice. They were examined daily, and gestational body weights and food and water consumption measured throughout gestation. At necropsy on gd 21 (rats) or gd 18 (mice) dams were examined for body, gravid uterine, liver and kidney weights, and implantation sites. Maternal kidneys were examined histologically. Fetuses were weighed, sex determined, and examined for external, soft tissue and skeletal variations and malformations. Rat dams had reduced body weights, body weight gains, and food consumption, and increased water consumption and relative kidney weights at 11,260 mg kg(-1) day(-1). They also had reduced body weight and increased water consumption at 5630 mg kg(-1) day(-1). Mice had clinical signs and increased relative kidney weight at 11,260 mg kg(-1) day(-1). Renal histology was normal in both species. Neither species had treatment-related effects on corpora lutea or implantations. Fetal body weights were reduced at 11,260 mg kg(-1) day(-1) (both species) and 5630 mg kg(-1) day(-1) (mice). In rat fetuses there was a pattern of delayed ossification in the thoracic region at 11,260 mg kg(-1) day(-1). Mouse fetuses had delayed ossification in the frontal and supraoccipital bones, cervical region, hindlimb proximal phalanges and reduced caudal segments at 11,260 mg kg(-1) day(-1), and in the skull bones at 5630 mg kg(-1) day(-1). These patterns of delayed ossification are consistent with reduced fetal body weights. No biologically significant embryotoxicity or teratogenicity was observed at any dosage in either species. The NOEL for TEG given by gavage over the period of organogenesis was 1126 mg kg(-1) day(-1) in the rat and 5630 mg kg(-1) day(-1) in the mouse for maternal toxicity, and 5630 mg kg(-1) day(-1) (rat) and 563 mg kg(-1) day(-1) (mouse) for developmental toxicology.     

Chronic toxicity of thiabendazole (TBZ) in CD-1 mice.

Male and female CD-1 mice (50 mice per group) were administered thiabendazole (TBZ) in diet at levels of 0 (control), 0.031, 0.125 and 0.5% for 78 weeks. A life time study was terminated after 78 weeks due to enhanced strain specific mortality. There were no significant differences in mortality between the control and treated groups. Mean body weights of high-dose groups showed significant decreases compared with the controls. The bladder weights of male and female mice of the 0.5% group were significantly higher than those of the control mice. Gross findings in treated mice included the renal atrophy, hydronephrosis, calculi in renal pelvis and/or bladder and ovarian atrophy. Microscopic findings in the kidneys of treated mice included the nephrosis, hydronephrosis or hyperplasia of transitional epithelium of renal pelvis or papilla. In the bladder of treated mice, hyperplasia or squamous metaplasia of transitional epithelium and one transitional cell papilloma were observed. Dose-dependent decreases in the incidence of spontaneous lesion in the male or female reproductive system were recognized. It is concluded that TBZ is not carcinogenic to CD-1 mice of both sexes. However, caution should be exercised in the long-term application of high TBZ doses.     

Spinosad insecticide: subchronic and chronic toxicity and lack of carcinogenicity in CD-1 mice.

The potential toxicologic and oncogenic effects of spinosad, a natural fermentation product with insecticidal properties, were investigated. The 13-week toxicity study consisted of groups of 10 CD-1 mice/sex provided diets containing 0, 0.005, 0.015, 0.045, or 0.12% spinosad (Study 1). The 0.12% group was terminated on Test Day 44 due to mortality and overt clinical signs of toxicity. An 18-month chronic oncogenicity study consisted of groups of 50 CD-1 mice/sex provided diets containing 0, 0.0025, 0.008, or 0.036% spinosad (Study 2). Two interim groups of 10 mice/sex/group were terminated after 3 and 12 months. Females given 0.036% were terminated on Day 455 due to markedly lower body weights and feed consumption, as well as excessive mortality. Because of the early termination of the female high-dose group, additional groups of 10 male and female mice (12-month interim necrospy) and 50 male and female mice (18-month necropsy) were provided diets containing 0, 0.0008, or 0.024% spinosad (Study 3) to fully assess potential chronic toxicity and oncogenicity. Standard toxicologic parameters were evaluated consistent with existing regulatory guidelines. The primary effect in the 13-week and 18-month studies was intracellular vacuolation of histiocytic and epithelial cells in numerous tissues and organs at doses of > or = 0.015%. The histological vacuolation corresponded to ultrastructural lysosomal lamellar inclusion bodies. This alteration was consistent with phospholipidosis, a condition that results from accumulation of polar lipids in lysosomes. Lesions with no apparent direct relation to vacuolation were hyperplasia of the glandular mucosa of the stomach, skeletal muscle myopathy, bone marrow necrosis, and anemia with associated splenic hematopoiesis. The incidence of tumors in mice given spinosad was not increased relative to controls at any dose level. The no observed effect level for the 13-week study was 0.005% (6 mg/kg/day) spinosad, and for the chronic toxicity/oncogenicity study was 0.008% (11 mg/kg/day) spinosad for male and female CD-1 mice.     

Developmental toxicity of perfluorooctanoic acid in the CD-1 mouse after cross-foster and restricted gestational exposures.

Perfluorooctanoic acid (PFOA) is a persistent pollutant and is detectable in human serum (5 ng/ml in the general population of the Unites States). PFOA is used in the production of fluoropolymers which have applications in the manufacture of a variety of industrial and commercial products (e.g., textiles, house wares, electronics). PFOA is developmentally toxic and in mice affects growth, development, and viability of offspring. This study segregates the contributions of gestational and lactational exposures and considers the impact of restricting exposure to specific gestational periods. Pregnant CD-1 mice were dosed on gestation days (GD) 1-17 with 0, 3, or 5 mg PFOA/kg body weight, and pups were fostered at birth to give seven treatment groups: unexposed controls, pups exposed in utero (3U and 5U), lactationally (3L and 5L), or in utero + lactationally (3U + L and 5U + L). In the restricted exposure (RE) study, pregnant mice received 5 mg PFOA/kg from GD7-17, 10-17, 13-17, or 15-17 or 20 mg on GD15-17. In all PFOA-treated groups, dam weight gain, number of implantations, and live litter size were not adversely affected and relative liver weight increased. Treatment with 5 mg/kg on GD1-17 increased the incidence of whole litter loss and pups in surviving litters had reduced birth weights, but effects on pup survival from birth to weaning were only affected in 5U + L litters. In utero exposure (5U), in the absence of lactational exposure, was sufficient to produce postnatal body weight deficits and developmental delay in the pups. In the RE study, birth weight and survival were reduced by 20 mg/kg on GD15-17. Birth weight was also reduced by 5 mg/kg on GD7-17 and 10-17. Although all PFOA-exposed pups had deficits in postnatal weight gain, only those exposed on GD7-17 and 10-17 also showed developmental delay in eye opening and hair growth. In conclusion, the postnatal developmental effects of PFOA are due to gestational exposure. Exposure earlier in gestation produced stronger responses, but further study is needed to determine if this is a function of higher total dose or if there is a developmentally sensitive period.     

Use of dopamine agonist pergolide in outpatient treatment of cocaine dependence

The dopamine agonist pergolide was evaluated in the treatment of 42 men who manifested cocaine dependence in a single-blind, 4-week-long placebo-controlled study, during 1998-1999 in S?o Paulo, Brazil. The patients were randomly assigned to two groups: the first group received pergolide (0.05-0.2 mg per day) and the second group received placebo (one to four tablets per day). Urine toxicology screens were obtained. The groups were compared in terms of depressive symptoms, "craving," use of cocaine, side effects of medications, results of urine tests, and retention in treatment. At 3 months' follow-up, the participants were reassessed. No differences were found between the two groups.     

Effect of perinatal and postnatal bisphenol A exposure to the regulatory circuits at the hypothalamus-pituitary-gonadal axis of CD-1 mice

Bisphenol A (BPA) is used in the manufacture of many products and is ubiquitous in the environment. Adverse effects of BPA on animal reproductive health have been reported, however most of the studies relied on the approaches in the assessment of conventional histology and anatomical features. The mechanistic actions of BPA are not clear. In the present study, a murine model was used to study potential effects of BPA exposure during perinatal and postnatal periods on endocrine functions of hypothalamic-pituitary-gonadal (HPG)-axis. At the hypothalamic-pituitary level, BPA exposure resulted in the up-regulation of the expression levels of KiSS-1, GnRH and FSH mRNA in both male and female pups. At the gonadal levels, BPA caused inhibition in the expressions of testicular steroidogenic enzymes and the synthesis of testosterone in the male pups. Conversely exposure to BPA resulted in a greater aromatase expression level and the synthesis of estrogen in the female pups. BPA is a weak estrogen agonist and its effects reported on animal studies are difficult to reconcile with mechanistic action of estrogen. In this study we hypothesized that the effects of BPA on reproductive dysfunction may be due to its actions on gonadal steroidogenesis and so the anomalous releases of endogenous steroid hormones. This non-ER-mediated effect is more potent in affecting the feedback regulatory circuits in the HPG-axis.     

Pulmonary toxicity and metabolic activation of tetrandrine in CD-1 mice

Tetrandrine, a bisbenzylisoquinoline alkaloid, has demonstrated promising pharmacologic activities. The alkaloid has a great potential for clinical use, so a careful, thorough toxicity evaluation of the alkaloid is required. In the present study, 24 h acute toxicity of tetrandrine was evaluated in CD-1 mice. Single intraperitoneal doses of tetrandrine at 150 mg (0.24 mmol)/kg were found to cause alveolar hemorrhage and over 3-fold elevation of lactate dehydrogenase activity in bronchoalveolar lavage fluids. Ethidium-based staining showed loss of membrane integrity in significant numbers of cells in the lungs of the animals treated with the same doses of tetrandrine. As much as 60% reduction in cell viability was observed after 24 h of exposure to tetrandrine at 40 μM in human lung cell lines NL-20 and WI-38. Ketoconazole, an inhibitor of P450 3A, showed a protective effect on the pulmonary injury in mice given tetrandrine. A glutathione (GSH) conjugate derived from O-demethylated tetrandrine was detected in incubations of tetrandrine with NADPH- and GSH-supplemented human liver and mouse lung microsomes. The electrophilic metabolite trapped by GSH is considered to be a quinone methide derivative. The formation of the metabolite reactive to GSH was found to require the presence of NADPH. The coincubation of ketoconazole suppressed the generation of the GSH conjugate. Tetrandrine was incubated with a selection of recombinant human cytochrome P450 enzymes, and only P450s 3A4 and 3A5 were responsible for the production of the reactive metabolite. The results implicate a possible correlation between the formation of the quinone methide metabolite of tetrandrine and the pulmonary toxicity induced by tetrandrine.     

Biochemical and behavioral evaluation of pergolide as a dopamine agonist in the rat brain

The ergot derivative pergolide was evaluated as a dopamine agonist using various behavioral and biochemical analyses. Spontaneous motor activity was decreased by small doses (O.1 mg/kg) of pergolide and increased with larger doses (above 0.5 mg/kg). Hypermotility after larger doses persisted for as long as 24 hr and was succeeded by a period of hypomotility. The doses of drug, sufficient to produce hypermotility, also produced stereotypy. With repeated daily injections (2 weeks), the period of hypermotility decreased and the ensuing period of hypomotility increased. Stereotyped behavior was similarly affected. Chronic administration of pergolide did not alter the magnitude of the behavioral responses.Levels of the dopamine (DA) metabolites, dihydroxyphenylacetate (DOPAC) and homovanillic acid (HVA), in the striatum and mesolimbic regions were decreased during the periods of hypermotility but returned to control levels during subsequent hypomotility.Activation of putative inhibitory presynaptic dopamine receptors by pergolide was studied by following accumulation of DOPA in rats treated with the dopamine neuron inhibiting agent, gamma-butyrolactone (GBL) and a DOPA-decarboxylase inhibitor. Pergolide significantly inhibited both striatal and mesolimbic accumulation of DOPA. In contrast, with changes in behavioral and metabolic indices, pergolideinduced inhibition of tyrosine hydroxylase was not affected by chronic treatment with pergolide.On the basis of both behavioral and biochemical data it is proposed that pergolide acts as a dopamine agonist with particularly long-lasting effects.     

Chronic toxicity/oncogenicity study of styrene in CD-1 mice by inhalation exposure for 104 weeks

Groups of 70 male and 70 female Charles River CD-1 mice were exposed whole body to styrene vapor at 0, 20, 40, 80 or 160 ppm 6 h per day 5 days per week for 98 weeks (females) or 104 weeks (males). The mice were observed daily; body weights, food and water consumption were measured periodically, a battery of hematological and clinical pathology examinations were conducted at weeks 13, 26, 52, 78 and 98 (females)/104 (males). Ten mice of each gender per group were pre-selected for necropsy after 52 and 78 weeks of exposure and the survivors of the remaining 50 of each gender per group were necropsied after 98 or 104 weeks. An extensive set of organs from the control and high-exposure mice were examined histopathologically, whereas target organs, gross lesions and all masses were examined in all other groups. Styrene had no effect on survival in males. Two high-dose females died (acute liver toxicity) during the first 2 weeks; the remaining exposed females had a slightly higher survival than control mice. Levels of styrene and styrene oxide (SO) in the blood at the end of a 6 h exposure during week 74 were proportional to exposure concentration, except that at 20 ppm the SO level was below the limit of detection. There were no changes of toxicological significance in hematology, clinical chemistry, urinalysis or organ weights. Mice exposed to 80 or 160 ppm gained slightly less weight than the controls. Styrene-related non-neoplastic histopathological changes were found only in the nasal passages and lungs. In the nasal passages of males and females at all exposure concentrations, the changes included respiratory metaplasia of the olfactory epithelium with changes in the underlying Bowman's gland; the severity increased with styrene concentration and duration of exposure. Loss of olfactory nerve fibers was seen in mice exposed to 40, 80 or 160 ppm. In the lungs, there was decreased eosinophilia of Clara cells in the terminal bronchioles and bronchiolar epithelial hyperplasia extending into alveolar ducts. Increased tumor incidence occurred only in the lung. The incidence of bronchioloalveolar adenomas was significantly increased in males exposed to 40, 80 or 160 ppm and in females exposed to 20, 40 and 160 ppm. The increase was seen only after 24 months. In females exposed to 160 ppm, the incidence of bronchiolo-alveolar carcinomas after 24 months was significantly greater than in the controls. No difference in lung tumors between control and styrene-exposed mice was seen in the intensity or degree of immunostaining, the location of tumors relative to bronchioles or histological type (papillary, solid or mixed). It appears that styrene induces an increase in the number of lung tumors seen spontaneously in CD-1 mice.