Effects of oral administration of nicotine on organ weight, serum testosterone level and testicular histology in adult male rats

This study investigated the effects of oral administration of nicotine on body and reproductive organ weight, serum testosterone level and testicular histology in adult male rats. Forty male rats divided into five groups and treated for a period of 30 days with 0.5mg/kg (low dose) and 1.0 mg/kg (high dose) body weight of nicotine while the control rats received 0.2 ml/kg normal saline. The fourth and fifth groups were gavaged with 0.5mg/kg and 1.0mg/kg body weight of nicotine but were left untreated for another 30 days. These groups served as the recovery groups.  At the end of each experimental period, the animals were scarified and their reproductive organs were removed and weighed immediately. There was no significant change in the body weight. There was a significant decrease (p <0.05) in the testicular and epididymal weight of rats for both treatments while the decrease in the seminal vesicle weight for both treatment groups was not significant. The prostate weight was not significantly increased in both groups. The recovery groups showed appreciable recovery in their organ weight. Serum level of testosterone of both groups was significantly decreased in a dose dependent manner when compared with those of the control rats. The histological section showed testicular degeneration and disorganization in the cytoarchitecture, as the observed changes were pronounced in the high dose group than the low dose group. However, there were both regeneration of the germinal epithelium and restructuring of the interstitum towards normal in the recovery groups. No lesion was observed in the epididymis of the rats. The results suggest that nicotine has deleterious effect on the male reproductive organ of albino rats ameliorated by nicotine cessation.     

The reproductive toxicity of yttrium nitrate in a two-generation study in Sprague-Dawley rats

ObjectiveTo evaluate the effects of yttrium nitrate on the development of the parent, offspring and third generation of Sprague-Dawley (SD) rats by using a two-generation reproductive toxicity test.MethodsThe SD rats were randomly divided into 0 mg/kg group, 10.0 mg/kg group, 30.0 mg/kg group and 90.0 mg/kg group according to the different doses of yttrium nitrate administration. The reproductive toxicity of parent, offspring and third generation SD rats were compared.ResultsThe weight gains of F1a female rats and F2a female rats in the low-dose groups were significantly lower than those of the control groups (p < 0.05), the weight gains of F1a male rats in the medium-dose and high-dose groups were significantly lower than those of the control groups (p < 0.05), and the weight gains of F2a male rats in the low-dose, medium-dose and high-dose groups were significantly lower than those of the control groups (p < 0.05). In F0 male rats, the absolute weight and relative weight of the liver in the low-dose, middle-dose, and high-dose groups were significantly lower than those of the control group (p < 0.05). In F1b male rats, the absolute and relative weights of the liver in the medium-dose and high-dose groups were significantly lower than those of the control group (p < 0.05). In F2b male rats, the absolute and relative weights of the liver and spleen of the medium-dose and high-dose groups were significantly lower than those of the control group (p < 0.05). In F2a female rats, the absolute weight and relative weight of oviduct in the high-dose group were significantly lower than those in the control group (p < 0.05). The absolute and relative weights of lung, spleen, brain and uterus of F2b female rats in the high-dose group were higher than those of the control group (p < 0.05). But the pathological test results showed no hepatotoxicity. There was no statistically significant difference in sperm count and sperm motility between male rats in the yttrium nitrate administration groups and the control group (p > 0.05). There was no significant correlation between F0, F1a, F1b, F2a, F2b SD rats' reproductive organ lesions and the dose of yttrium nitrate.ConclusionYttrium nitrate at a dose of 90 mg/kg has no reproductive toxicity to two generations of SD rats, but 30.0 mg/kg dose of yttrium nitrate is toxic to the liver weight of male two generations of SD rats, but no hepatotoxicity.     

Modulation of hepatic and renal drug metabolizing enzyme activities in rats by subchronic administration of farnesol

Farnesol demonstrates antitumor activity in several animal models for human cancer and was being considered for development as a cancer chemopreventive agent. This study was performed to characterize the effects of minimally toxic doses of farnesol on the activity of phase I and II drug metabolizing enzymes. CD((R)) rats (20/sex/group) received daily gavage exposure to farnesol doses of 0, 500, or 1000 mg/kg/day for 28 days; 10 rats/sex/group were necropsied at the termination of farnesol exposure; remaining animals were necropsied after a 28-day recovery period. No deaths occurred during the study, and farnesol had no significant effects on body weight, food consumption, clinical signs, or hematology/coagulation parameters. Modest but statistically significant alterations in several clinical chemistry parameters were observed at the termination of farnesol exposure; all clinical pathology effects were reversed during the recovery period. At the termination of dosing, the activities of CYP1A, CYP2A1-3, CYP2B1/2, CYP2C11/12, CYP2E1, CYP3A1/2, CYP4A1-3, CYP19, glutathione reductase, NADPH/quinone oxidoreductase and UDP-glucuronosyltransferase were significantly increased in the livers of farnesol-treated rats; farnesol also increased the activity of glutathione S-transferase in the kidney. The effects of farnesol on hepatic and renal enzymes were reversed during the recovery period. At the end of the dosing period, increases in absolute and relative liver and kidney weights were seen in farnesol-treated rats. These increases may be secondary to induction of drug metabolizing enzymes, since organ weight increases were not associated with histopathologic alterations and were reversed upon discontinuation of farnesol exposure. Administration of farnesol at doses of up to 1000 mg/kg/day induced reversible increases in the activities of several hepatic and renal drug metabolizing enzymes in rats, while inducing only minimal toxicity. It is concluded that non-toxic or minimally toxic doses of farnesol could alter the metabolism, efficacy, and/or toxicity of drugs with which it is co-administered.     

Preliminary screening study of reproductive outcomes after exposure to yarrow in the pregnant rat

BACKGROUND: Yarrow (Achillea millefolium) is used for the treatment of diarrhea, as a urinary antiseptic, hypotensive, and diuretic. Yarrow also has traditionally been used as an abortifacient, emmenagogue, contraceptive, and for stimulating uterine contractions. For this reason, it is contra‐indicated for use in pregnancy. There has, however, been little scientific research carried out to either confirm or refute this recommendation. METHODS: Female rats were dosed, orally by gavage using 56 times the human dose of yarrow daily on either gestation days (GD) 1–8 or GD 8–15. Two groups of controls were included; the first received water and the second received an equivalent dose of ethanol to that found in the yarrow preparation over the two gestation periods. On GD 20, rats were sacrificed, placentae were weighed, and corpora lutea counted. The fetuses were weighed and examined for signs of external, internal or skeletal malformations. RESULTS: The dose used was not materno‐toxic. There was no increase in pre‐ or post‐implantation losses suggesting that yarrow was neither an abortifacient nor a contraceptive. Placental weights were increased in rats treated with yarrow on GD 8–15 compared to water and ethanol controls and on GD 1–8 compared to water control fetuses. Body weight was reduced in fetuses exposed to yarrow on GD 8–15 compared to water control fetuses. There was no difference in incidence of external or internal malformations. CONCLUSIONS: In the present study it was found that yarrow, when administered to rats at 56 times the human dose, was associated with reduced fetal weight and increased placental weight. In the absence of a no observable effect level for these variables it must be concluded that the consumption of yarrow is contraindicated during pregnancy until further investigations have been carried out. Birth Defects Res B 68:416–420, 2003. © 2003 Wiley‐Liss, Inc.     

A 90-Day Feeding Study in Rats to Assess the Safety of Genetically Engineered Pork

Our laboratory recently produced genetically engineered (GE) Meishan pigs containing a ZFN-edited myostatin loss-of-function mutant. These GE pigs develop and grow as normal as wild type pigs but produce pork with greater lean yield and lower fat mass. To assess any potential subchronic toxicity risks of this GE pork, a 90-day feeding study was conducted in Sprague-Dawley rats. Rats were randomly divided into five groups, and fed for 90 days with basic diet and basic diets formulated with low dose and high dose pork prepared from wild type pigs and GE pigs, respectively. Animal behaviors and clinical signs were monitored twice daily, and body weight and food consumption were measured and recorded weekly. At days 45 and 90, blood tests (lipid panel, electrolytes, parameters related to liver and kidney functions, and complete blood counts) were performed. Additionally, gross pathology and histopathological analyses were performed for major organs in each group. Data analysis shows that there were no significant differences in growth rate, food consumption, and blood test parameters between rat groups fed with GE pork and wild type pork. Although differences in some liver function parameters (such as aspartate aminotransferase, total proteins, albumin, and alkaline phosphatase) and white blood cell counts (such as lymphocyte percentage and monocyte percentage) were observed between rats fed with high dose GE pork and basic diet, all test results in rats fed with GE pork are in the normal range. Additionally, there are no apparent lesions noted in all organs isolated from rats in all five feeding groups on days 45 and 90. Overall, our results clearly indicate that food consumption of GE pork produced by ZFN-edited myostatin loss-of-function mutant pigs did not have any long-term adverse effects on the health status in rats.     

Use of oral buprenorphine ('buprenorphine jello') for postoperative analgesia in rats--a clinical trial

Buprenorphine (0.1, 0.2, 0.3 or 0.4 mg/kg) in a flavoured gelatin base was administered preoperatively to rats undergoing a flank laparotomy. A control group of animals underwent surgery and received only flavoured gelatin. Body weight loss was significantly greater in the group which received no analgesia than in any of the analgesic-treated groups (P < 0.01). Food consumption was reduced significantly in all groups except in those animals which received 0.3 mg/kg buprenorphine. Water consumption was significantly reduced in the control (no analgesia) group (P < 0.001), but was not significantly depressed in the analgesic-treated groups (P > 0.05). Between-group comparisons did not show any significant difference between the different dose rates of analgesia used on either the change in body weight or the reduction in food or water consumption. The results of this study support the use of buprenorphine jelly for post-surgical analgesia in rats. This route of delivery is easy to use, and causes a minimum of stress to the rats.     

Fat Intake Affects Adiposity,Comorbidity Factors,and Energy Metabolism of Sprague‐Dawley Rats

Objective: Childhood obesity is an emerging health problem. This study assesses the effects of three levels of dietary fat (10%, 32%, and 45% measured by kilocalories) on weight gain, body composition, energy metabolism, and comorbidity factors in rats from weaning through maturation. Research Methods and Procedures: The role of dietary fat on the susceptibility to obesity was assessed by feeding diets containing three levels of dietary fat to rats from weaning through 7 months of age. Body composition was analyzed by DXA after 6 and 12 weeks of dietary treatment. Energy metabolism was measured by indirect calorimetry. Results: Energy intake, weight gain, fat mass, and plasma glucose, cholesterol, triglyceride, free fatty acid, leptin, and insulin levels increased dose‐dependently with increased dietary fat. No difference in absolute lean mass among the three groups was observed. Therefore, the differences in weight gain are accounted for primarily by increased fat accretion. Compared with rats that were relatively resistant to obesity when on a 45% fat diet, diet‐induced obesity‐prone rats were in positive energy balance and had an elevated respiratory quotient, indicating a switch in energy substrate use from fat to carbohydrate, which promotes body‐fat accretion. Discussion: Our data support the hypothesis that administration of increasing amount of dietary fat to very young rats enhances susceptibility to diet‐induced obesity and its comorbidities.     

Persistent alterations in biomarkers of oxidative stress resulting from combined in Utero and neonatal manganese inhalation

Neonatal female and male rats were exposed to airborne manganese sulfate (MnSO₄) during gestation and postnatal d 1–18. Three weeks post-exposure, rats were killed and we assessed biochemical end points indicative of oxidative stress in five brain regions: cerebellum, hippocampus, hypothalamus, olfactory bulb, and striatum. Glutamine synthetase (GS) protein levels, metallothionein (MT) and GS mRNA levels, and total glutathione (GSH) levels were determined for all five regions. Overall, there was a statistically significant effect of manganese exposure on decreasing brain GS protein levels (p=0.0061), although only the highest dose of manganese (1 mg Mn/m³) caused a significant increase in GS messenger RNA (mRNA) in both the hypothalamus and olfactory bulb of male rats and a significant decrease in GS mRNA in the striatum of female rats. This highest dose of manganese had no effect on MT mRNA in either males or females; however, the lowest dose (0.05 mg Mn/m³) decreased MT mRNA in the hippocampus, hypothalamus, and striatum in males. The median dose (0.5 mg Mn/m³) led to decreased MT mRNA in the hippocampus and hypothalamus of the males and olfactory bulb of the females. Overall, manganese exposure did not affect total GSH levels, a finding that is contrary to those in our previous studies. Only the cerebellum of manganese-exposed young male rats showed a significant reduction (p<0.05) in total GSH levels compared to control levels. These data reveal that alterations in biomarkers of oxidative stress resulting from in utero and neonatal exposures of airborne managanese remain despite 3 wk of recovery; however, it is important to note that the doses of manganese utilized represent levels that are 100-fold to a 1000-fold higher than the inhalation reference concentration set by the US Environmental Protection Agency.     

Developmental toxicity evaluation of sodium thioglycolate administered topically to Sprague-Dawley (CD) rats and New Zealand White rabbits

BACKGROUND: Sodium thioglycolate, which has widespread occupational and consumer exposure to women from cosmetics and hair‐care products, was evaluated for developmental toxicity by topical exposure during the embryonic and fetal periods of pregnancy METHODS: Timed‐mated Sprague–Dawley rats (25/group) and New Zealand White (NZW) rabbits (24/group) were exposed to sodium thioglycolate in vehicle (95% ethanol:distilled water, 1:1) by unoccluded topical application on gestational days (GD) 6–19 (rats) or 6–29 (rabbits) for 6 hr/day, at 0, 50, 100, or 200 mg/kg body weight/day (rats) and 0, 10, 15, 25, or 65 mg/kg/day (rabbits). At termination (GD 20 rats; GD 30 rabbits), fetuses were examined for external, visceral, and skeletal malformations and variations. RESULTS: In rats, maternal topical exposure to sodium thioglycolate, at 200 mg/kg/day (the highest dose tested) on GD 6–19, resulted in maternal toxicity, including reduced body weights and weight gain, increased relative water consumption and one death. Treatment‐related increases in feed consumption and changes at the application site occurred at all doses, in the absence of increased body weights or body weight change. Fetal body weights/litter were decreased at 200 mg/kg/day, with no other embryo/fetal toxicity and no treatment‐related teratogenicity in any group. In rabbits, maternal topical exposure to sodium thioglycolate on GD 6–29 resulted in maternal dose‐related toxicity at the dosing site in all groups; no maternal systemic toxicity, embryo/fetal toxicity, or treatment‐related teratogenicity were observed in any group. CONCLUSIONS: A no observed adverse effect level (NOAEL) was not identified for maternal toxicity in either species with the dosages tested. The developmental toxicity NOAEL was 100 mg/kg/day (rats) and ≥65 mg/kg/day (rabbits; the highest dose tested). The clinical relevance of theses study results is uncertain because no data were available for levels, frequency, or duration of exposures in female workers or end users. Birth Defects Research Part B 68:144–161, 2003. © 2003 Wiley‐Liss, Inc.     

Effect of Himatanthus sucuuba in Maternal Reproductive Outcome and Fetal Anomaly Frequency in Rats

The aim of this study was to evaluate the effect of Himatanthus sucuuba on the maternal reproductive outcome and fetal anomaly incidence in rats. Pregnant rats were randomly divided into three experimental groups as follows: Control = treated with water (vehicle), treated 250 = treated with H. sucuuba at dose 250 mg/kg, and treated 500 = treated with H. sucuuba at dose 500 mg/kg. The rats were orally treated, by gavage, with H. sucuuba or vehicle (water) during preimplantation and organogenic period (from gestational day 0–14). At day 21 of pregnancy, all rats were killed to obtain maternal–fetal data. The treatment with H. sucuuba at dose of 250 mg/kg caused reduction in placental efficiency and an increase preimplantation loss rate and placenta weight compared with the control. The treated 500 group presented a significant decrease in maternal weight gain, maternal weight gain minus gravid uterus weight, fetal weight, and placental efficiency compared with the control. In this group, there was a decrease in body weight at day 20 of pregnancy and metacarpus ossification and an increase in the preimplantation loss rate and skeletal anomalies compared with other groups. Himatanthus sucuuba extract caused intrauterine growth restriction, preimplantation loss, and developmental delay in the high doses tested     

Conduct and interpretation of a dermal developmental toxicity study with KBR 3023 (a prospective insect repellent) in the Sprague-Dawley rat and Himalayan rabbit

KBR 3023, 1-(1-methyl-propoxycarbonyl)-2-(2-hydroxyethyl)piperidine, a prospective insect repellent being developed by Bayer Corporation, was evaluated for developmental toxicity in the Sprague-Dawley rat and Himalayan rabbit. As the intended human usage of the test compound is topical, the test systems were exposed to the compound via the dermal route. Specifically, the animals were fitted with Elizabethan collars, to reduce the likelihood of oral ingestion, and dermally administered either 0, 50, 200, or 400 mg KBR 3023/kg (rat), and 0, 50, 100, or 200 mg KBR 3023/kg (rabbit) on gestation days 0-19 (rat) and 0-28 (rabbit). Maternal toxicity, as demonstrated by clinical signs and changes in body weight gain and food consumption during gestation, was characterized. Animals were sacrificed on gestation day 20 (rat) and 29 (rabbit), at which time fetuses were removed by cesarean section and a gross maternal necropsy was performed. All fetuses were evaluated for external anomalies. With rats, approximately half of each litter was examined for visceral effects; the other half underwent a skeletal examination. With rabbits, all fetuses underwent both visceral and skeletal examinations. No effects were observed on maternal body weight gain or food consumption in either the rat or rabbit. In the rat, dermal effects (scaling/sloughing), were observed at the dose site of all test substance-treated groups from approximately gestation day 7 until termination of the study. Also noted were an increase in both absolute and relative liver weights in rats in the 400-mg/kg dose group. In the rabbit, dermal effects (slight erythema, squamous and cracked skin) were noted at the dose site of virtually all does administered the test compound, from approximately gestation day 7 until termination. Also observed in the rabbits was a potentially compound-related increase in soft stool, particularly at the highest dose level. In both species, there were no statistically significant effects on any reproductive parameters, or any embryonic endpoints, including pre/post-implantation loss and resorptions. There were no statistically significant effects on litter size or fetal or placental weights. No test compound-related external, visceral, or skeletal findings were observed. No effect on the individual fetal or litter incidence of total malformations or variations was observed and there was no difference in the incidence of malformations between males and females. KBR 3023 Technical, administered as described in these studies, produced maternal effects in the rat (liver weight) at a dose of 400 mg/kg, and in the rabbit (soft stool) in the 200-mg/kg dose group. No developmental toxicity was observed at any dose level.     

Maternal exposure to multi-wall carbon nanotubes does not induce embryo-fetal developmental toxicity in rats

BACKGROUND: Although the potential risk of carbon nanotubes (CNTs) to humans has recently increased due to expanding production and widespread use, the potential adverse effects of CNTs on embryo–fetal development have not yet been determined. METHODS: This study investigated the potential effects of multi‐wall CNTs (MWCNTs) on pregnant dams and embryo–fetal development in rats. MWCNTs were administered to pregnant rats by gavage at 0, 40, 200, and 1,000 mg/kg/day. All dams were subjected to Cesarean section on day 20 of gestation, and the fetuses were examined for any morphological abnormalities. RESULTS: All animals survived to the end of the study. A decrease in thymus weight was observed in the high dose group in a dose‐dependent manner. However, maternal body weight, food consumption, and oxidant–antioxidant balance in the liver were not affected by treatment with MWCNTs. No treatment‐related differences in gestation index, fetal deaths, fetal and placental weights, or sex ratio were observed between the groups. Morphological examinations of the fetuses demonstrated no significant difference in incidences of abnormalities between the groups. CONCLUSIONS: The results show that repeated oral doses of MWCNTs during pregnancy induces minimal maternal toxicity and no embryo–fetal toxicity at 1,000 mg/kg/day in rats. The no‐observed‐adverse‐effect level of MWCNTs is considered to be 200 mg/kg/day for dams and 1,000 mg/kg/day for embryo–fetal development. In this study, the dosing formulation was not analyzed to determine the degree of reaggregation (or not), nor were blood levels of CNT's measured in the dosed animals to verify or characterize absorption. Birth Defects Res (Part B) 92:69–76, 2011. © 2011 Wiley‐Liss, Inc.     

The Effect of Eimeria nieschulzi Infection on Leukocyte Levels in the Rat*

SYNOPSIS. Rats inoculated with 10,000 sporulated oocysts of Eimeria nieschulzi had significantly higher total leukocyte counts on postinoculation days (PI) 1, 5, 6 and 7 when compared to control rats. Relative and absolute neutrophil counts increased concomitantly with a decrease in the relative lymphocyte levels in E. nieschulzi-infected rats on PI day 7. Absolute and relative neutrophil counts in infected rats on PI days 7 and 8 were closely correlated with the host's total oocyst discharge. The E. nieschulzi infection had no significant effect on the relative or absolute levels of monocytes or eosinophils. The described changes in leukocyte levels were not paralleled by a significant change in the erythrocyte count.     

Genetic loci for spleen weight and blood pressure in ISIAH rats with inherited stress-induced arterial hypertension

Recently, the important role of the spleen’s function in hypertension development was demonstrated. In this study, the genetic control of absolute and relative spleen weight was investigated to reveal the genetic loci common for spleen traits and for arterial blood pressure at rest and under the emotional stress conditions in ISIAH rats with inherited stress-induced arterial hypertension. The search for genetic loci for absolute and relative spleen weight was performed on 6-month-old F₂ (ISIAH × WAG) hybrid males derived from a cross of hypertensive ISIAH and normotensive WAG rats. One significant QTL mapped on chromosome 1 and 5 suggestive loci were found for relative spleen weight. Four suggestive loci were detected for absolute spleen weight. All detected loci were novel. The significant QTL on chromosome 1 was common for relative spleen weight and arterial blood pressure at rest and under the emotional stress conditions in ISIAH rats. The results suggest that the manifestation of the stress-sensitive arterial hypertension in ISIAH rats may be related to the changes in genetic control of the spleen function.     

LY226936 Administered Orally and Centrally to Obese Zucker Rats Suppresses Food Intake and Body Weight Gain

LY226936, methylcarbamothoic acid-S-(4,5-dihydro-2-thiazolyl) ester, is a new compound that, when administered to obese Zucker rats, caused reduced food intake. LY226936 reduced the food consumption after a single oral dose of 50 and 100 mg/kg. On chronic oral administration to meal-fed obese (5 to 35 mg/kg. once daily) and to fed obese and lean (15 mg/kg. twice daily) Zucker rats, LY226936 reduced food intake and body weight gain for periods ranging from 40 to 48 days. The effect on both parameters was statistically significant. There is no evidence in our studies that tolerance to the actions of LY226936 developed. LY226936 decreased the consumption of both high carbohydrate and high fat diets. Food consumption of meal-fed obese Zucker rats was reduced significantly each time a single dose of 10 ugm LY226936 per rat was infused intracerebroventricularly. None of the receptors studied (mu and kappa opioid, CCK, serotonin, neuropeptide Y, galinin, N-methyl-D-aspartic acid) appeared to bind LY226936 and therefore, appear not to be involved in the depression of food intake by the obese Zucker rat.     

腹腔注射乙酰唑胺对大鼠氧惊厥潜伏期的影响

为探讨脑血流调节与氧惊厥的关系,本研究在复制大鼠氧惊厥模型的基础上,采用行为学方法测定氧惊厥潜伏期,并测定脑皮质氧化指标内二醛（maleic dialdehyde,MDA）含量,采用腹腔注射不同剂量脑血管扩张药物乙酰唑胺（acetazolamide,ACZ）,以及联合注射ACZ及其拈抗刺吲哚美辛（indomethacin,IND）后,观察脑血管扩张对氧化状态以及氧惊厥潜伏期的影响。结果观察到：（1）腹腔注射ACZ（不小于7．5mg／kg体重）后,氧惊厥潜伏期明显缩短（P〈0．05）,剂量越大,缩短越明显。腹腔注射IND对氧惊厥潜伏期无显著影响。腹腔注射IND（20mg／kg体重）,30min后再注射ACZ（7．5mg／kg体重）,ACZ的氧惊厥潜伏期缩短作川被对抗（P〈0．05）。（2）腹腔注射ACZ7．5mg／kg后,与各组相比,6及16min暴露后,脑组织MDA含量明显增多（P〈0．01,P〈0．05）;腹腔注射IND对脑皮质MDA含量无显著影响;在预注射IND,再注射ACZ后,MDA含量显著降低（P〈0．01,P〈0．05）。结果表明,ACZ外周注射加重氧化损伤,缩短氧惊厥潜伏期;而IND可以对抗其氧惊厥潜伏期缩短作用以及氧化损伤加重作用,碳酸酐酶活力变化很可能是通过影响脑血管状态而影响氧化损伤以及氧惊厥潜伏期。     

Juvenile toxicity assessment of d,l-methylphenidate in rats

BACKGROUND: The oral administration of d,l‐methylphenidate (MPH) was designed to encompass the major part of postnatal development in the rat and to evaluate potential chronic effects. METHODS: Wistar Hannover rats were cross‐fostered on postpartum day 0 (day of birth) and were administered MPH at doses of 5, 50, and 100 mg/kg/day (mpkd) on postpartum days 7 to 70. Clinical signs, body weight, food consumption, developmental, behavioral, clinical/anatomic pathology, toxicokinetic, and fertility evaluations were conducted. RESULTS: MPH‐related effects on clinical signs, body weight, and behavior tests were noted. Increased locomotor activity and cage biting/chewing occurred at ≥5 mpkd (females) and ≥50 mpkd (males) and were absent after dosing ceased. Body weight parameters were decreased at ≥50 mpkd and were comparable to controls at 5 weeks' recovery. Open field motor activity tests conducted 2 weeks after dosing ceased revealed decreased peripheral beam breaks at ≥50 mpkd. Passive avoidance tests conducted 3 weeks after dosing ceased indicated decreased females reaching learning criterion at 100 mpkd. This is considered of nominal significance as there were no effects in the water maze test or retention in passive avoidance test. After multiple doses, females exhibited higher exposures than males and exposures were reduced in all groups in comparison to those after a single dose. CONCLUSIONS: These results suggest that MPH can produce enduring behavioral effects in rats. The no‐toxicologic‐effect‐level was 5 mpkd, associated with AUC_{(0–24 h)} racemate values in males and females, respectively, of 101 and 153 ng.h/mL after chronic dosing. Birth Defects Res (Part B) © 2008 Wiley‐Liss, Inc.     

Comparison of the developmental toxicity of aspirin in rabbits when administered throughout organogenesis or during sensitive windows of development

BACKGROUND: A review of the nonsteroidal anti‐inflammatory drug (NSAID) literature suggested occurrences of low‐level incidences of cardiovascular and midline defects in rabbit fetuses exposed in utero. Aspirin (acetylsalicylic acid, ASA) is a widely used NSAID that irreversibly inhibits cyclooxygenases (COXs) 1 and 2. ASA has been studied extensively in rats and has consistently increased low‐incidence cardiovascular malformations and defects in midline closure. The objectives of the current study were to comprehensively define the developmental toxicology profile of ASA in rabbits by using a dosing paradigm encompassing the period of organogenesis and to test the hypothesis that maternal gastrointestinal toxicity after repeated dose administrations hampers the detection of low‐incidence malformations with ASA in rabbits by limiting ASA administration to sensitive windows for cardiovascular development and midline closure. METHODS: ASA was administered to pregnant New Zealand White rabbits from gestation days (GDs) 7 to 19 at dose levels of 125, 250, and 350 mg/kg per day and as single doses of 500, 750, or 1000 mg/kg on GD 9, 10, or 11. Cesarean sections were performed on GD 29, and the fetuses were examined for external, visceral, and skeletal development. RESULTS: In the repeated dose study, maternal toxicity was exhibited in the 250‐ and 350‐mg/kg per day groups by mortality and decreased food consumption and body weight gain. In the single dose studies, maternal toxicity was exhibited at all doses by reductions in body weight gain and food consumption for 3 days after treatment. Fetal body weight was significantly reduced in the repeated dose study at 350 mg/kg per day. Fetal weights were not affected by single doses of ASA on GD 9, 10, or 11. There were no treatment‐related external, visceral, or skeletal malformations associated with ASA administration throughout organogenesis or with single doses administered during critical developmental windows. CONCLUSION: These findings supported previous work demonstrating that ASA is not teratogenic in rabbits, as opposed to rats, even when large doses are administered on single days during specific windows of development. Birth Defects Research (Part B) 68:38–46, 2003. © 2003 Wiley‐Liss, Inc.     

Effects of long-term ingestion of white tea on oxidation produced by aging and acute oxidative damage in rats

The infusion tea extracted from the leaves of the plant Camellia sinensis can be used in the prevention of cancer, cardiovascular and neurodegenerative diseases, and aging, while adriamycin (ADR) is an anticancer drug that increases oxidative stress in cells. The present study evaluated the protective effect of the long-term consumption of white tea used at two different doses against the oxidative stress produced by aging and acute oxidation caused ADR treatment. At wearing, rats received distilled water (control), or 0.15 (dose 1) or 0.45 mg (dose 2) of solid tea extract/kilogram body weight in their drink. At 12 months, about half of the rats of each group were injected with a bolus of ADR, and six rats of the control group with an injection of saline solution and sacrificed. The rest of the animals continued in their cages until 24 months of age, when they were sacrificed. Lipid and protein oxidation of liver and brain microsomes was analyzed by measuring hydroperoxide and carbonyl levels. White tea consumption for 12 months at a non-pharmacological dose was seen to reverse the oxidative damage caused by ADR in both liver and brain, while the consumption of white tea for 20 months at a non-pharmacological dose had no effect on carbonyl or hydroperoxides in these tissues. The long-term ingestion of white tea protected tissues from acute oxidative stress but did not affect chronic oxidative agents such aging.