Action of N-isopropyl-α-(2-methylhydrazino)-p-toluamide hydrochloride (procarbazine hydrochloride) in the germ tissue of mice: dominant lethal effects

A study was carried out on the effects of N-isopropyl--(2-methylhydrazino)-p-toluamide (procarbazine, Natulan^®) in the dominant lethal test in the mouse. Male mice were dosed once and mated with fresh virgin females each week. The utilization of sperm, treated as spermatids or testicular sperm with 100–800 mg/kg, resulted in significant post-and pre-implantation death of embryos. Fertility was markedly reduced after the injection of 200 mg/kg of procarbazine and over. This is probably due to a cell killing effect, the most sensitive stages being differentiating spermatogonia, type A spermatogonia and resting primary spermatocytes. Total sterility was induced for several weeks with doses of 600 and 800 mg/kg. Up to 12 weeks after treatment the number of females with implants was still significantly lower than controls indicating a severe depletion of spermatogonial cells. The spectrum of effects correlates well with the drug's effect on nucleic acid and protein synthesis.     

Detection of dominant lethal mutation in mice after repeated low-dose administration of 6-mercaptopurine

Detection of dominant lethality after repeated low-dose administration was investigated, using the base analog 6-mercaptopurine (6-MP). The compound was administered to groups of 30 outbred CD-1 male mice by i.p. injection at dosage levels of 12.5, 25.0, or 50.0 mg/kg/day 5 days a week for 8 weeks. At the end of treatment, each male was cohoused for 1 week with two untreated females of different strains: one CD-1 and one (C3H x C57BL/10)F1. Negative (solvent) and positive (triethylenemelamine, TEM) control groups were included. Implant data were analyzed statistically. Exposure of male mice to 6-MP at 50 mg/kg/day resulted in 93% mortality and severe weight loss of the survivors. Body weights were also reduced in the group given 25 mg/kg/day. At the lowest dose level of 12.5 mg/kg/day, 6-MP had no noticeable toxic effect on the treated males. Dominant lethal analysis of the implant data showed that a statistically significant increase in dead implantations was induced in CD-1 but not in (C3H x C57BL/10)F1 females. The dominant lethal effect of TEM, the positive control, was detected in both strains of females tested.     

Chemoprotective effect of Spirulina (Arthrospira) against cyclophosphamide-induced mutagenicity in mice.

The aim of this study was to investigate the antimutagenic effects of Spirulina (SP) on male and female mice by the dominant lethal test using cyclophosphamide (CP) as a mutagen. Animals of both sex were given SP orally at 0, 200, 400 or 800 mg/kg body weight (b.w.) for 2 weeks prior to starting the CP treatment. CP was i.p. injected daily for 5 days at 40 mg/kg b.w. For the male-dominant lethal test, each male was caged with untreated females per week for 3 weeks. For the female-dominant lethal test the above doses and schedule treatments were used and treated females were caged for one week with untreated males (1-2). On days 13-15 after breeding was |started all the females were evaluated for incidence of pregnancy, total corpora lutea, total implants and pre- and post-implant losses. In the male-dominant lethal test, the CP induced pre- and post-implant losses in untreated females were inhibited at all SP doses. In the female-dominant lethal test only post-implantation losses were prevented at the same doses. Semen examination of a separate group of mice showed that SP improved its quality. Our results illustrate protective effects of SP in relation to CP-induced genetic damage to germ cells.     

Investigation of cyclohexylamine sulfate for dominant lethal effects in the mouse

Cyclohexylamine sulfate was studied for mutagenic effects in the dominant lethal test on mice. 20 male NMRI mice were treated with 150 mg cyclohexylamine sulfate (approx. 102 mg cyclohexylamine) per kg body weight (0.6% solution in demineralized water) orally per day for 5 successive days. A parallel control group of 20 male mice received demineralized water only.After the last treatment each male was mated with 3 untreated females. In order to study successive germ cell stages of the males, each male was placed with 3 other untreated females every week for mating. The total mating period was 8 weeks. The uterus of the females was examined on about the 14th day of pregnancy, when pre- and post-implantative losses were determined as assessment criteria from the number of corpora lutea, implantations, and live and dead embryos.The treatment did not damage the males and did not impair their mating capacity and fertility.The treatment also had no influence on pre- and post-implantative losses: The frequency of pre-implantative and post-implantative deaths was practically identical in the treatment group and the untreated control. Thus, we found no indication of a mutagenic action of orally administered cyclohexylamine sulfate (5 doses of 150 mg/kg) in the dominant lethal test on mice.     

Prednisone in MOPP chemotherapy for Hodgkin's disease.

High remission rates have been produced by MOPP (mustine, vincristine, procarbazine, and prednisone) chemotherapy in patients with advanced Hodgkin's disease, but the prednisone component has caused adverse effects in patients who have undergone radiotherapy. The remission rates and length of remission were reviewed in 211 patients with Hodgkin's disease who received chemotherapy either with or without prednisone. In contrast to the findings of a British study, there were no significant differences in remission rates or length of remission between patients who had received prednisone and patients who had not. There were differences between the British prospective study and this retrospective one, but it is difficult to know what accounted for the substantial differences in the findings.     

Toxic responses to acute, subchronic, and chronic oral administrations of monochlorobenzene to rodents

Acute (single exposure), 14-d repeated exposure, 91-d subchronic, and 103-wk chronic toxicity studies of orally administered (gavage, in corn oil) monochlorobenzene were conducted in male and female Fischer-344 rats and B6C3F1 hybrid mice. A single exposure to 4000 mg/kg was lethal to male and female rats, while a single exposure to a dose as low as 1000 mg/kg was lethal to mice. Fourteen daily exposures to 1000 mg/kg caused death in rats of both sexes, but neither survival nor clinical health were compromised at 500 mg/kg in rats or mice. In the 91-d studies, wherein monochlorobenzene was administered once daily, 5 d/wk, survival was reduced by doses of 500 mg/kg and higher in rats, and by doses of 250 mg/kg and higher in mice. Dose-dependent necrosis of the liver (hepatocytes), degeneration or focal necrosis of the renal proximal tubules, and lymphoid or myeloid depletion of the spleen, bone marrow, and thymus (mild to severe) were produced by doses of 250 mg/kg or greater of monochlorobenzene in both sexes of rats and mice, although the incidences of these lesions varied considerably by sex and species. Consistent changes in the circulating blood components were not observed, but a mild porphyrinuria was detected at the higher doses. No toxic effects were observed at doses of 125 mg/kg or less. In the 2-yr studies, wherein monochlorobenzene was administered once daily, 5 d/wk, doses of 30 or 60 mg/kg in male mice and 60 or 120 mg/kg in female mice and male and female rats did not produce any evidence of toxicity. Doses of 60 or 120 mg/kg caused slight (statistically significant at 120 mg/kg; p less than 0.05) increases in the frequencies of male rats with neoplastic nodules of the liver. Increased tumor frequencies were not observed in female rats or in male or female mice receiving monochlorobenzene.     

Comparison of behavioral and radioprotective effects of WR-2721 and WR-3689.

The behavioral effects of the radioprotectant agents ethiofos, S-2-(3-aminopropylamino)ethylphosphorothioic acid (WR-2721) and S-2-(3-methylaminopropyl)aminoethylphosphorothioic acid (WR-3689) were evaluated in rats trained to respond under a multiple fixed-interval 120-s, fixed-ratio 50-response (mult FI FR) schedule of milk reinforcement. Each compound produced dose-dependent reductions in responding under both schedules over the same dose range (100-180 mg/kg, IP); ED50s indicated that WR-3689 was slightly more potent than WR-2721. On several performance measures, WR-3689 produced greater decrements during a second dose-effect determination, whereas WR-2721 had more pronounced effects during the initial one. In a second series of studies, low (56 mg/kg) and high (180 mg/kg) doses of both drugs were tested for radioprotective effects in rats responding under an FR-50 schedule of milk reinforcement and exposed to a nonlethal (5 gray, Gy) or lethal (10 Gy) dose of ionizing radiation (60Co gamma rays). Neither dose of radiation altered FR response rates on the day of exposure (day 1). Five Gy of gamma radiation produced a 25-40% reduction in response rates on days 2-5 (24-72 h) after exposure. Neither dose of WR-2721 or WR-3689 provided significant protection against these performance decrements. All groups exposed to 10 Gy experienced a progressive decline in FR responding on days 2-5 after exposure. Performance of groups that received pretreatment with the 180-mg/kg dose of either drug or the 56-mg/kg dose of WR-3689 was maintained at significantly higher levels than saline-treated controls on days 4-5 after exposure to 10 Gy; however, even at these higher levels of performance response rates remained below 50% of preirradiation control levels. Subsequently, 56 and 180 mg/kg WR-3689 and 180 mg/kg WR-2721 were found to provide protection against the lethal consequences of the 10-Gy exposure. Thus, neither WR-2721 nor WR-3689 afforded any significant short-term protection against radiation-induced performance decrements when these drugs were administered at either behaviorally ineffective or behaviorally disruptive doses. Rather, the beneficial effects of these drugs paralleled their ability to antagonize radiation-induced lethality.     

Failure of hexachlorobenzene to induce dominant lethal mutations in the rat.

Three groups of 10 male rats each were gavaged with 0, 70, or 221 mg hexachlorobenzene (HCB)/kg daily for 5 consecutive days. Ten other male rats received a single oral dose of 0.5 mg triethylenemelamine (TEM)/kg. Both compounds were dissolved in corn oil. Following the last administration, each male rat was allowed to mate with two naive, nulliparous females per week for 14 consecutive weeks. Females were sacrificed on Day 14 of gestation. Their ovaries and uteri were exposed and examined for numbers of corpora lutea and total, living and dead implantations. Mating and fertility frequencies were calculated. TEM elicited typical dominant lethal events. HCB did not. Dose-dependent decreases in the numbers of females inseminated and impregnated were observed.     

Dominant lethal mutations in male mice

Dominant lethal mutations are due to chromosome aberrations as demonstrated by analysis of first cleavage. With a sample size of 40–45 mice per dose the induction of dominant lethal mutations by 10 mg/kg of methyl methanesulfonat (MMS) can be detected in spermatids in the mating interval 9–12 days posttreatment (6–11%). In the same mating interval a dose of 150 mg/kg of MMS induces 100% dominant lethal mutations. MMS and other chemical mutagens can be characterized by their different spermatogenic response. The germ cell stage specific induction of dominant lethal mutations by chemical agents is very likely due to their different pathways and therefore, to different effects on the structural and macromolecular changes during spermatogenesis. The feasibility of standardizing test protocol for the dominant lethal assay in mice, based on collaborative studies, is discussed. The reproducibility of results and the sensitivity of the induction of dominant lethal mutations in the collaborative studies demonstrate the usefullness of the method for mutagenicity screening.Presented at the 3rd Meeting of the Gesellschaft für Umwelt-Mutationsforschung, D-8042 Neuherberg, July 1–2, 1976     

Combined effects of low-level methylmercury and x-radiation on the developing mouse cerebellum

The effects of low-level methylmercury and x-radiation in combination on the developing mouse cerebellum were studied. Pregnant BALB/cJcl mice were divided into two groups. Dams of a group were orally given 9 micrograms Hg/g body weight of methylmercuric chloride on d 17 of pregnancy. The other dams were not treated. They were allowed to give birth, and the male pups were exposed to a single x-radiation at doses of 0.125 or 0.5 Gy on the day following birth. Sham-exposed pups were also prepared. The pups were killed at various postexposure periods, and their cerebella were removed and processed for microscopy and mercury analysis. Mercury was retained in the pup cerebellum at levels of 4-8 micrograms/g for 4 d and then lowered. Appearance and incidence of cell death in the external granular layer (EGL) were similar in groups exposed to 0.125 Gy alone or 0.125 Gy and methylmercury in combination. Fourteen percent of cells in the EGL were killed by exposure to 0.5 Gy with or without methylmercury. Restoration of the EGL from the damage was slightly retarded by methylmercury, but by 10 d of age these cerebella overtook the normal ones in development. These findings indicate that methylmercury does not modify the apoptotic cell death caused by x-radiation in the EGL but retards the tissue restoration from the damage.     

Induction of dominant lethal mutations in male mice by fosfestrol.

Using the dominant lethal assay, the ability of fosfestrol, a diethylstilboestrol derivate, to induce mutations in male mice was tested and confirmed. Up to 300 mg/kg of fosfestrol the induction of mutations occurs exclusively in spermatozoa. A dose of 600 mg/kg of fosfestrol induces dominant lethal mutations up to 10 days posttreatment. The majority of induced dominant lethal mutations in all dose groups are expressed as loss after implantation.     

Mutagenicity test of antithyroid agent, methimazole--dominant lethal mutation test on male mice (author's transl)]

Mutagenicity test of Methimazole (MMI) was performed by means of dominant lethal mutation test in the male mice. Male mice were treated with a single s.c. injection of 45 mg/kg or 90 mg/kg MMI. Mean body weights were slightly decreased and mating rates were low immediately after treatment of MMI. Mean numbers of living implants at any periods examination up to 6 weeks after the treatment were compared with Salin Control, indicating lack of dominant lethality of MMI. On the other hand, EMS and MMC known mutagens and reference agents used in the present study, induced dominant lethalities at a single s.c. injection respectively.     

Toxicity of intraperitoneally administered antitumour drugs in athymic rats

The toxicity of eight anticancer drugs given intraperitoneally to athymic rats was investigated to define the maximum tolerable doses (MTD). Drugs were given once weekly. Toxicity was assessed as percentage loss of body weight (LBW%) or percentage toxic death rate (TDR%) during the first week after drug administration. LBW% and TDR% were significantly correlated, r = 0.58 p less than 0.00001. From the regression equation for the relationship between LBW% and TDR%, 10 percent TDR (LD10), usually regarded as equivalent to MTD in animals, was found to correspond to 14 percent LBW. From the individual regression equations for LBW% and dose for each of six drugs, MTDs were calculated to be as follows; doxorubicin 7 mg/kg, cyclophosphamide 100 mg/kg, mitomycin C 1.8 mg/kg, cisplatin 8 mg/kg, vindesine 0.8 mg/kg and vincristine 0.9 mg/kg. LD10 was found to be 40 mg/kg for both carmustine (BCNU) and etoposide.     

维拉帕米及艾灸对长春新碱耐药胃癌细胞株SGC7901逆转增效作用

目的 观察维拉帕米(VPM)及艾灸对小鼠长春新碱(VCR)耐药SGC7901胃癌移植后的瘤体重量、抑瘤率及P-糖蛋白(P-gp)表达的影响,以了解两者对长春新碱耐药逆转增效作用.方法 分别进行不同剂量维拉帕米及艾灸联合不同剂量维拉帕米抗肿瘤耐药的实验.第一组实验将SD小鼠分成等渗盐水组、VCR对照组、VPM对照组、0.5 mg/kg VPM+VCR组、1.0 mg/kg VPM+VCR组、1.5 mg/kg VPM+VCR组、2.0 mg/kg VPM+VCR组,,每组16只,雌雄各半,所有模型组小鼠在左前肢腋下接种瘤组织,按组给予等渗盐水和不同剂量药物,15 d后,取出瘤体称重,计算抑瘤率,同时留取瘤体标本,检测多药耐药(MDR)相关蛋白P-gp的变化.第二组实验将SD小鼠分成等渗盐水组、VCR对照组、VPM对照组、艾灸对照组、0.5 mg/kg VPM+VCR+艾灸组、1.0 mg/kg VPM+VCR+艾灸组、1.5 mg/kg VPM+VCR+艾灸组、2.0 mg/kg VPM+VCR+艾灸组,每组16只,雌雄各半,所有模型组小鼠在左前肢腋下接种瘤组织,按组给予等渗盐水和不同剂量药物及艾灸,15 d后,取出瘤体称重,计算抑瘤率,同时留取瘤体标本,检测MDR相关蛋白P-gp的变化.结果 第一组实验中给予维拉帕米时,等渗盐水组与不同剂量药物组间差异有统计学意义(P<0.05),随剂量增加瘤体重量下降、抑瘤率增加和蛋白P-gp表达下降,但1.5 mg/kg和2.0 mg/kg时,蛋白P-gp值差异无统计学意义.第二组实验中给予维拉帕米和艾灸时,等渗盐水组与不同剂量药物组间差异也有统计学意义(P<0.05),随剂量增加瘤体重量下降、抑瘤率增加和蛋白P-gp表达下降,其中剂量组:1.5 mg/kg和2.0 mg/kg与仅给予维拉帕米组相比差异有统计学意义(P<0.05).结论 维拉帕米和艾灸对小鼠长春新碱耐药SGC7901胃癌耐药具有逆转增效作用,在2.0 mg/kg维拉帕米、0.5 mg/kg长春新碱、艾灸联合用药时可达到单用1.0 mg/kg长春新碱用药效果.     

Lack of induction of dominant lethal mutations in male mice by nalidixic acid

Nalidixic acid (NA) in single or in 5 consecutive daily doses of 100 or 1000 mg/kg produced no dominant lethal mutational effects in male ddY strain mice during an 8-week mating schedule. Ethylmethanesulfonate (EMS), used as a positive control, produced dominant lethal mutations in the first and second weeks.     

An ethological analysis of the effects of diazepam and nitrazepam on the responses of female mice to anosmic males encountered in a novel arena

The effects of acutely administered benzodiazepines have largely been validated in male animals, in spite of the fact that the majority of anti-anxiety drugs are prescribed for female patients. A study was carried out assessing the potential of female mice in the testing of the anxiolytic properties of drugs. Three doses (0.5, 1.0 and 2.0mg/kg) of the benzodiazepines diazepam and nitrazepam were given to individually-housed female Swiss mice before dyadic encounters with anosmic, group-housed males. Videotape analysis of the encounters, using an ethopharmacological technique, revealed suppressive effects of diazepam (1.0 and 2.0mg/kg) and nitrazepam (all doses) on avoidance/flee, confirming the anxiolytic properties of these drugs. However, some doses of diazepam (2.0mg/kg) and nitrazepam (1.0mg/kg), greatly increased immobility with little effect on active behavioural elements. It is suggested that "immobility" does not simply measure sedation.     

Effects of haloperidol, clozapine, and quetiapine on sensorimotor gating in a genetic model of reduced NMDA receptor function

Rationale Reduced N-methyl d-aspartate (NMDA) receptor function is hypothesized to contribute to the pathophysiology of schizophrenia. In order to model chronic and developmental NMDA receptor hypofunction, a mouse line was developed that expresses low levels of the NMDA R1 (NR1) subunit of the NMDA receptor. These mice show increased acoustic startle reactivity and deficits in prepulse inhibition (PPI) of acoustic startle. Objectives The present study tested the hypothesis that these altered acoustic startle responses in the NR1 hypomorphic (NR1−/−) mice would be affected by antipsychotic drug treatment. Methods Mice were injected with drugs 30 min before assessment of acoustic startle responses with and without prepulse stimuli. Results Haloperidol (0.5 or 1.0 mg/kg) did not reduce the increased startle reactivity in the NR1−/− mice, but did increase PPI in both the mutant and wild type mice. Clozapine (3 mg/kg) and quetiapine (20 mg/kg) reduced startle magnitude and increased PPI in both the wild type and mutant mice. The antidepressant drug imipramine (10 and 20 mg/kg) had minimal effects on startle amplitude in NR1−/− or wild type mice. However, for the 20-mg/kg dose of imipramine, a significant increase in PPI was observed in the wild type animals, but not in the mutant mice. Conclusions The results demonstrate that PPI can be increased in a mouse model of chronic NMDA receptor hypofunction by typical and atypical antipsychotic drugs. The similar effects of typical and atypical antipsychotic drugs to increase PPI in the wild type and mutant mice indicates that the assessment of behavior of the NR1 hypomorphic mice in the PPI paradigm offers no advantage over the wild type controls for identifying new clozapine-like drugs.     

Prevention of memory loss following puromycin treatment.

Female C57BL/6J mice were trained on a one trial passive avoidance response. Twenty-four hours later, they were treated with puromycin in combination with either 2.0 or 10.0 mg/kg of amphetamine, 0.3 mg/kg of strychnine, or 20.0 or 50.0 mg/kg of pentylenetetrazol. Tests one week after training revealed that treatment with these stimulant drugs prevented the memory loss characteristic of puromycin; an exception being those animals injected with the low dose of amphetamine. Biochemical determination of amino acid incorporation into protein revealed that none of the stimulant drugs used significantly altered the extent or the duration of protein synthesis inhibition induced by puromycin. These results are interpreted as showing that the amnesic effects of puromycin can be counteracted by a state of heightened nervous system excitation.     

Investigation of hexachlorophene for dominant lethal effects in the mouse.

Hexachlorophene (HCP) was studied for mutagenic effects in the dominant lethal test on mice. Groups of male mice were treated with either 2.5 or 5.0 mg hexachlorophene per kg body weight as a single intraperitoneal injection. Control animals were treated with the propylene glycol vehicle. Each male was mated with 3 untreated females for each of 8 consecutive weeks with the uterus of the females examined at mid-pregnancy for signs of early embryonic death. Treatment did not alter mating capacity and fertility of the males. The administration of hexachlorophene had no influence on pre- or post-implantation losses. An increase in early resorptions among female mice bred to males treated with the reference compound, methyl methanesulfonate (MMS) given a single i.p. injection of 100 mg/kg, indicated the susceptibility of the mouse strain used to a known mutagen. It is concluded that hexachlorophene at maximally tolerated doses is not mutagenic in the dominant lethal test in mice.