Evaluation of the co-mutagenicity of ethanol and delta 9-tetrahydrocannabinol with Trenimon.

The mutagenic potential of chronic treatments of male CF-1 mice with ethanol and delta 9-tetrahydrocannibinol (THC), and their comutagenic potential with a known mutagenic agent, Trenimon, were examined. This was accomplished by measuring the frequency of dominant lethal mutations arising from mating of treated males with nontreated females. Adult male mice were treated with 5% (v/v) ethanol as part of a liquid diet (28% ethanol-derived calories) for five weeks; 10 mg/kg body weight (p.o.) THC every two days for five weeks; a single injection of Trenimon (0.125 mg/kg, i.p.) on day 28 of diet treatment; and all combinations of treatments. The control group was pair-fed a liquid diet in which isocaloric sucrose replaced ethanol; these males were also given sesame oil (vehicle for THC) and saline (vehicle for Trenimon) on the same schedule as that for the treated males. Neither body weights nor hematocrits were adversely affected by any treatment. Both ethanol and Trenimon treatments resulted in a small (8-9%; p less than 0.05) decrease in testicular weight. The effect of combined treatment with ethanol and Trenimon was roughly additive. Treatment with THC had no effect on testicular weight. Seminal vesicle weights were not affected by any treatment. Treatments were without significant effect on fertility, as measured by the frequency of males producing pregnancies. Ethanol and Trenimon treatments produced approximately 3- and 7-fold increases, respectively in the frequencies of preimplantational loss over that seen for the control group (7.3%), resulting in significant ethanol and Trenimon effects (p less than 0.001). No interactive effects of ethanol and Trenimon treatments were noted. Frequencies of dead fetuses per pregnancy in the ethanol- and Trenimon-treated groups were increased approximately 2.5- and 4-fold, respectively, over the control value of approximately 16%. However, the effect of combined treatments was not greater than that due to Trenimon alone, resulting in Trenimon and ethanol effects (p less than 0.001) and ethanol-Trenimon interaction (p less than 0.001). The calculated mutation index resulting from each treatment yielded significant (p less than 0.001) ethanol- and Trenimon-induced effects. In contrast to effects of ethanol and Trenimon treatments, THC, given alone, or in combination with ethanol and/or Trenimon, had no effect on either preimplantational loss, fetal mortality or the resulting mutation index. The data suggest that chronic ethanol treatment, at levels resulting in minimal fertility impairment, increases the frequency of dominant lethal mutations. In contrast, chronic treatment with THC, as administered in the present study, appears to be without effect.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of 50-hertz electromagnetic fields on proliferation and on chromosomal alterations in human peripheral lymphocytes untreated or pretreated with chemical mutagens.

Cultivation of human peripheral lymphocytes (HPL) in the presence of 50-Hz electromagnetic fields (EMFs) does not alter the spontaneous frequencies of sister-chromatid exchanges (SCE) and of chromosomal aberrations (CA), but leads to an enhancement of the cell cycle progression of HPLs in vitro. Pretreatment of HPLs with trenimon (TRN), diepoxybutane (DEB), or methylnitrosourea (MNU) in the G0 phase of the cell cycle results in dose-dependent elevations of the SCE frequencies. In some cases culturing of HPLs pretreated with MNU or TRN in the presence of EMFs led to significantly higher frequencies of SCEs when compared to cells cultivated in the absence of EMFs. Since we did not use multiple fixation times these data may rather result from differential influences on HPL subsets than from EMF exposure.

Transplacental genetic and cytogenetic effects of alkylating agents in the mouse. II. Induction of chromosomal aberrations.

Six monofunctional alkylating agents, trenimon, cyclophosphamide, and isoniazid were proven for transplacental cytogenetic activity in mouse embryos at day 10 of gestational age under the same conditions as used in the mammalian spot test. With the exception of isoniazid, all compounds led to an increase in the aberration frequencies in embryonal cells. The results were statistically not significant in the case of EMS, while all other chemicals showed a dose-dependent clastogenic activity. After treatment with monofunctional alkylants, chromatid breaks were dominating, while polyfunctional compounds also produced chromatid exchanges, especially in the case of trenimon. ENU and DMS showed a very early aberration maximum 6 hr after injection. For both compounds, very similar dose-response curves were found for induction of chromatid breaks in the dose range 10-75 mg/kg. There is no correlation between the Swain-Scott factors of monofunctional alkylants and their ability to induce chromosomal damage when compared in terms of pharmacological doses. A quantitative comparison of data found in the cytogenetic test in embryonal cells with those obtained in the mammalian spot test led to the conclusion that chromosomal mutations are of minor relevancy for the expression of recessive alleles in heterozygous mouse embryos. With this respect, the mammalian spot test must be considered as an in vivo test for the detection of gene mutations in somatic cells of the mouse.

Influence of Neurospora endonuclease on trenimon-induced structural chromosomal aberrations and sister-chromatid exchanges in human peripheral lymphocytes and Chinese hamster ovary cells.

Human peripheral lymphocytes and Chinese hamster ovary cells were treated in the G1 phase of the cell cycle with the trifunctional alkylating agent trenimon (TRN) and post-treated with a single-strand specific endonuclease from Neurospora crassa (NE). TRN induces chromosomal aberrations of the chromatid type (CA) and sister-chromatid exchanges (SCE). NE post-treatment leads to an elevation of the frequencies of CA but not of SCEs. This indicates that TRN induced CA are the result of DNA double-strand breaks and that the SCEs originate from other types of lesions, most probably base damage.

Trenimon-induced sex chromosome loss in Drosophila: different dose-responses for ring-X loss as compared to rod-X loss and Y-marker loss.

Drosophila melanogaster males carrying either a ring- or a rod-shaped X-chromosome were injected or fed with Trenimon (triaziquone) at concentrations ranging from 5 X 10(-5) to 2 X 10(-2) mM. The F1 generation was assayed for the occurrence of total sex chromosome loss and of Y-chromosome markers. Sex-linked recessive lethal tests were carried out simultaneously. The data show that significant induction of ring-X loss occurs already at very low treatment concentrations (5 X 10(-5) -10(-4) mM) whereas rod-X loss or Y-marker loss is only seen at 2-5 X 10(-3) mM and higher. Induction of sex-linked recessive lethals is observed from 10(-4) -10(-3) mM on. These results add to existing evidence that loss of ring-X chromosomes, induced by some chemicals, may proceed by a mechanism different from the kind of events leading to chromosome breakage, as measured by rod-X loss and Y-marker loss.

Depression of histone acetylation by alkylating antitumor agents in murine cells.

Treatment of Ehrlich ascites tumor cells with the alkylating agent triaziquone [2,3,5-tris(ethyleneimino)benzoquinone-1,4] and nitrogen mustard leads to a reduction of the posttranslational acetylation of histones. Acetylation of all core histones is affected. The reduction of labeling of acetylated sites is accompanied by a dose-dependent decrease in the extent of acetylation as indicated by the level of acetylation of H4. The depression of histone acetylation is expressed at all concentrations of the alkylating agents which cause significant inhibition of tumor cell proliferation. It could be excluded that the observed effects are caused by an impairment of acetyl coenzyme A synthesis.

Pre-implantation embryos of Chinese hamster. II incidence and type of karyotype anomalies after treatment of the paternal post-meiotic germ cells with an alkylating mutagen.

Ninety-two male Chinese hamsters were treated with a single, sub-lethal dose of the alkylating cytostatic drug Trenimon. After 3--23 days they were mated with untreated females. The great majority of the male germ cells had been exposed to the mutagen while they were in the highly sensitive post-meiotic spermatid stage. The karyotypes of the resulting embryos were studied in the 4--8-cell stage. Out of 221 analysable embryos, 24.4% had aberrant karyotypes. Ploidy and genome mutations were, at 0.9% each, within control limits. Structural aberrations, involving one or several chromosomes, were present in 23.6% of the embryos (control 1.8%). 51% had a single aberrant centric element. The most frequent aberration types were deletions (54%), dicentrics (16%), translocations inversions and complex rearrangements with 22% and rings with 7%. About one-third of the cells, in addition, contained acentric fragments.

Experiences with the dominant lethal test in female mice: effects of alkylating agents and artificial sweeteners on pre-ovulatory oocyte stages.

Pre-ovulatory oocytes are especially sensitive to mutagenic influences. Since post-dictyotene oocytes are not subject to selection and elimination before fertilization, they may reveal mutagenic effects directly and unrestrictedly. Presuming that a chemical is administered at pro-estrus to female mice one can conclude that the substance or its active metabolite has the chance to reach the gamete during the sensitive pre-fertilization stages. We proved the usefulness of the test system by investigating the effects of alkylating agents. A second step was to investigate other substances. The following treatments induced dominant lethal effects: methyl methanesulfonate 100 mg/kg i.m., cyclophosphamide 200 mg/kg per os, triaziquone 0.25 mg/kg i.p. In contrast, the following agents were ineffective and can be classified as not mutagenic in this method: sodium cyclamate 10 000 mg/kg per os, saccharine sodium, 10 000 mg/kg per os, cyclohexamine sulfate 150 mg/kg per os, ethanol 5 ml/kg per os.