Balance hypothesis of action of socially significant volatile chemosignals on reactivity of chromosome machinery of the bone marrow dividing cells in the house mouse Mus domesticus L

Volatile chemosignals released by female CBA laboratory mice have been shown to produce action of different direction, depending on conditions of performance of experiment, on chromosome machinery of bone marrow cells in syngenic adult males. Thus, chemosignals secreted into environment by isolated adult females decrease frequency of mitotic disturbances in bone marrow dividing cells in male recipients as compared with spontaneous level in control animals. At the same time, 2,5-dimethylpyrazine - pheronome released only by high density caged females - increases frequency of mitotic disturbances. Preliminary 24-h-long action of chemosignals of isolated females decreases effect of the subsequent action of 2,5-dimethylpyrazine, although the level of disturbances exceeds that in control animals. The simultaneous action of used chemosignals neutralizes completely the 2,5-dimethylpyrazine action, the frequency of mitotic disturbances being not different from that after chemosignals of isolated females. The hypothesis is put forward about dependence of the revealed cytogenetic effects in male recipients on zoosocial conditions of maintenance of female donors of chemocommunication signals.     

Chromosomal abnormalities and spleenocyte production in laboratory mouse males after exposure to stress chemosignals

Activity of antibody producing spleenocytes and chromosome stability in bone marrow cells from laboratory mouse males of CBA strain after exposure to different chemosignals excreted by stressed or irradiated syngeneic donors was studied. It has been shown that the exposure of the recipient males to volatiles from donor males (stressed by swimming) decreases quantity of antibody-producing cells in 1, 3 and 10 days after the treatment. The same exposure increased the chromosome aberrations level in dividing bone marrow cells from CBA recipients in 1 day after the treatment. Similar changes were observed in 24 h after exposure to volatiles of irradiated donors or to synthetic mouse pheromone, 2,5-dimethylpyrazine. Possible mechanisms of chemosignals effect on the immune system are discussed.     

Effect of the estrus cycle stage on sensitivity to pheromone 2,5-dimethylpyrazine in the house mouse <Emphasis Type="Italic">Mus musculus</Emphasis>

Frequency of cytogenetic disturbances was estimated in mitotically dividing bone marrow cells of CBA strain female mice after 24-h long action of pheromone 2,5-dimethylpyrazine (2,5-DMP). The stage of estrus cycle of each animal was taken into acount at the moment of the end of the pheromone action. The analysis was performed using the anatelophase method that allows evaluating frequencies of various types of disturbances—bridges, fragments, delayed chromosomes. The spontaneous level of the mitotic disturbances revealed by the anatelophase method in animals of the control group amounts to 5.4%. Action of pheromone 2,5-dimethylpyrazine induced the mitosis disturbances detected in the dividing bone marrow cells at the anaphase-telophase stage in the females at the di-+ postestrus stage. The corresponding frequency of disturbances after the pheromone action was equal to 9.2%. In the female in estrus, the mitotic disturbance level amounted 6.7%, which not differed statistically significantly from control. It is suggested that differences in female mouse hormonal state at different estrus cycle stages affect sensitivity to olfactory signals. Mechanisms of the revealed effect and significance of the differences in sensitivity to pheromone for reproductive processes are discussed.     

Effect of two pyrazine-containing chemosignals on cells of bone marrow and testes in male house mice (<Emphasis Type="Italic">Mus musculus</Emphasis> L.)

The evolutionarily conservative 2,5-dimethylpyrazine chemosignal, a pheromone released by female mice, has been shown to increase frequency of mitotic disturbances in bone marrow cells assessed by using metaphase and ana-telophase analyses. The substitution of methyl radical in the molecule of pheromone by carboxyl reveals specificity of the effect of the latter derivative: the frequency of disturbances revealed by the ana-telophase analysis alone increases, whereas no induction of disturbance is detected by the metaphase analysis. An increase of the anomalies induced by both compounds has been shown in a sperm head test. Possible mechanisms underlying specific action of the tested substances on stability of the genetic apparatus of bone marrow dividing cells in the house mouse are discussed.     

The role of metabolic activation of promutagens in the genome destabilization under pheromonal stress in the house mouse (<Emphasis Type="Italic">Mus musculus</Emphasis>)

The hypothesis on a relationship between the high frequency of mitotic disturbances in bone marrow cells and the change in the activity of the S9 liver fraction containing promutagen-activating enzymes under olfactory stress in the house mouse Mus musculus has been tested. For this purpose, the effect of the pheromone 2,5-dimethylpyrazine on the frequency of mitotic disturbances in mouse bone marrow cells has been measured by the anaphase-telophase assay. In paralled, we compared the capacities of the S9 liver fractions from stressed and intact mice for activating the promutagen 2-aminofluorene in the Ames test utilizing Salmonella typhimurium. It has been demonstrated that the increased frequency of mitotic disturbances in bone marrow cells induced by the pheromonal stressor in male house mice is accompanied by an increased ability of the S9 liver fraction to activate the promutagen. The model system used in the study allowed the genetic consequences of the exposure to the olfactory stressor to be estimated and the possible mechanisms of genome destabilization to be assumed.     

Chemosignals from isolated females have antimutagenic effect in dividing the cells of bone marrow from male mice of the CBA strain

A level of X-ray induced mitotic disturbances in the cells of the bone marrow of male mice was studied under the modifying influence of chemosignals from isolated adult female mice of the CBA strain. It has been shown that the frequency of chromosomal aberrations in irradiated (4 Gr) males after exposing them for 24 hours on bedding soiled with female chemosignals is lower than in irradiated males in cages with clean bedding. The mechanisms and importance of the antimutagenic effect of female house mouse chemosignals are discussed.     

The role of metabolic activation of promutagens in the genome destabilization under pheromonal stress in the house mouse (Mus musculus)

The hypothesis on a relationship between the high frequency of mitotic disturbances in bone marrow cells and the change in the activity of the S9 liver fraction containing promutagen-activating enzymes under olfactory stress in the house mouse Mus musculus has been tested. For this purpose, the effect of the pheromone 2,5-dimethylpyrazine on the frequency of mitotic disturbances in mouse bone marrow cells has been measured by the anaphase-telophase assay. The Ames test using Salmonella typhimurium has been employed to compare the capacities of the S9 liver fractions from stressed and intact mice for activating the promutagen 2-aminofluorene. It has been demonstrated that the increased frequency of mitotic disturbances in bone marrow cells induced by the pheromonal stressor in male house mice is accompanied by an increased promutagen-activating capacity of the S9 liver fraction. The model system used in the study allowed the genetic consequences of the exposure to the olfactory stressor to be estimated and the possible mechanisms of genome destabilization to be assumed.     

DNA damage in bone marrow cells of mouse males in vivo after exposure to the pheromone: Comet assay

It is shown by single-cell gel electrophoresis that the exposure of CBA mouse males with pheromone 2,5-dimethylpyrazine for 4 or 24 h increases DNA damage level in interphase nuclei of bone marrow cells. The results may reflect the work of a mechanism of formation of chromosomal aberrations and other mitotic disturbances, detected at the stage of ana-telophase, the frequency of which in dividing bone marrow cells increased after similar pheromonal exposure. The comparison of the damaged cell distribution types is proposed as an approach to analysis of comet assay data. The significance of the revealed effects on the immune system in the recipient organism is discussed.     

Effect of the estrous cycle stage on sensitivity to pheromone 2,5-dimethylpyrazine in the house mouse Mus musculus

Frequency of cytogenetic disturbances was estimated in mitotically dividing bone marrow cells of CBA strain female mice after the 24-h long action of pheromone 2,5-dimethylpyrazine (2,5-DMP). The stage of the estrous cycle of each animal was taken into account at the moment of the end of the pheromone action. The analysis was performed using the anatelophase method that allows evaluating frequencies of various types of disturbances--bridges, fragments, delayed chromosomes. The spontaneous level of the mitotic disturbances revealed by the anatelophase method in animals of the control group amounts to 5.4 %. Action of pheromone 2,5-dimethylpyrasine induced the mitosis disturbances detected in the dividing bone marrow cells at the anaphase-telophase stage in the females at the di- + postestrus stage. The corresponding frequency of disturbances after the pheromone action was equal to 9.2%. In the female in estrus, the mitotic disturbance level amounted 6.7%, which did not differ statistically significantly from control. It is suggested that differences in the female mouse hormonal state at different estrous cycle stages affect sensitivity to olfactory signals. Mechanisms of the revealed effect and significance of the differences in sensitivity to pheromone for reproductive processes are discussed.     

Antimutagenic effect of chemosignals from isolated female house mouse on male germ cells (Mus musculus L.)

The influence of chemosignals from isolated mature females of the CBA strain on level of spontaneous and radiation-induced meiotic disturbances in spermatocytes I of males of the same strain was studied. Using an ana-telophase method, 24-hour exposure of males to soiled bedding containing isolated females’ chemosignals was shown to lead to a significantly lower frequency of chromosomal aberrations and other meiotic disturbances in spermatocytes I as compared to males kept on clean bedding. The same effect of female chemosignals was found in the germ cells of irradiated males (4 Gr). The mechanisms and importance of the revealed antimutagenic effect of mouse female chemosignals on the male reproductive cells in the reproduction process are discussed.     

Induction of dominant lethals in progeny of male CBA mice after pheromonal action

The inhibiting effect of pheromone 2,5-dimethylpyrazine of house mouse females on the reproductive function of the CBA male mice was studied. The mutagenic effect of six-day pheromonal effect was assessed by dominant lethal test. Analysis for the frequency of dominant lethals showed that the pheromonal effect results in an increased death rate of the progeny of the treated males. This is probably explained by implantation failure and is expressed in a reduced average number of the implantation sites and low live embryos per female. The proportion of females with live embryos decreased significantly. The implication of the effect of female mouse pheromone 2,5-dimethylpyrazine on the genetic processes in germ cells of male mice is discussed.     

Effects of “Pheromone-Like” pyrazine-containing compounds on stability of genetic apparatus in bone marrow cells of the male house mouse <Emphasis Type="Italic">Mus musculus</Emphasis> L.

There was studied effect of female house mouse pheromone 2,5-dimethylpyrasine and other pyrazine-containing substances on the genetic apparatus stability of dividing bone marrow cells of male mice of the strain CBA. Differences in action of the used chemosignals are revealed. Role of the method of action on induction of analyzed mitotic aberrations is shown. Spectrum of the aberrations is analyzed. Dependence of cytogenetic activity of the used substances on their structural peculiarities and significance of the revealed effects are discussed.     

Induction of Dominant Lethals in Progeny of CBA Male Mice after Pheromonal Action

The inhibiting effect of pheromone 2,5-dimethylpyrazine of house mouse females on the reproductive function of the CBA male mice was studied. The mutagenic effect of six-day pheromonal treatment was assessed by dominant lethal test. Analysis for the frequency of dominant lethals showed that the pheromonal effect results in an increased death rate of the progeny of the treated males. This is probably explained by implantation failure and is expressed in a reduced average number of the implants and low live embryos per female. The proportion of females with live embryos decreased significantly. The implication of the effect of female mouse pheromone 2,5- dimethylpyrazine on the genetic processes in germ cells of male mice is discussed.     

The alteration of attractiveness of intact males mice to females chemosignals, subjected of ionizing radiation in sublethal dose

After irradiation in a dose 4 Gy female mice of CBA and C57Bl/6 (female CBA during 18-23 days, female C57Bl/6 - 4-10 days) secretes with urine volatile components (chemosignals) which possess higher, than secretes intact females, attractiveness for intact males the same strains irrespective of a genotype. When estimation relative attractiveness postradiation secretes female mice CBA and C57Bl/6 intact males prefer chemosignals singenic (genetically identical) females during 1-23 day after irradiation. Observed olfactorial reaction male mice more differ from norm. In which males prefer chemosignals of allogenic (with a strange genotype) females. This disturbances identifed as postradiation reversion attractiving males of chemosignals, dependent on the genotype of females. Typical for norm chemosignalisation at females restored for 43 days after the irradiation. The mechanism and biological advisability of this phenomenon are discussed.     

Olfactory stress and modification of phagocytosis in peripheral blood cells of adult male mice]

Data on pheromonal influence on phagocytic activity of leukocytes in peripheral blood of adult randombred and CBA male mice have been obtained. The identified mouse pheromone 2,5-dimethylpyrazine was used, which induces some physiological effects associated with reproduction in both mouse males and females. Significant differences in spontaneous level of phagocytosis were between inbred CBA and randombred animals: the frequency of phagocytic cells was lower in CBA males by 1.4 times. The substance tested here induces phagocytosis in randombred (by 1.7 times) males. A low dose of 2,5-dimethylpyrazine (similar to the natural pheromone concentration) induces a higher increase in phagocytic activity by leukocytes. Possible mechanisms of pheromonal action on phagocytosis are discussed with the perspectives of finding highly effective immunomodulators among mammalian pheromones.     

Action of two pyrazine-containing chemosignals on cells of bone marrow and testes in male house mouse Mus musculus L

Evolutionary conservative chemosignal 2,5-dimethylpyrazin that is pheromone in female mice has been shown to increase frequency of mitotic aberrations analyzed with aid of metaphasic and ana-telophasic analysis in bone marrow cells. Replacement of one of methyl radicals in the pheromone molecule by the carboxyl radical reveals specificity of action of the used derivative: the frequency of disturbances revealed only by the ana-telophasic analysis increases, whereas by the metaphasic analysis, no induction of disturbance is detected. In the sperm head abnormality test there is shown a rise of the anomalies by both compounds. Possible mechanisms of specific action of the tested substances on stability of genetic apparatus of the bone marrow dividing cells in the house mouse are discussed.     

The female pheromone 2,5-dimethylpyrazine induces sperm head abnormalities in male CBA mice

The effect of the house mouse female pheromone 2,5-dimethylpyrazine (2,5-DMP) on sperm differentiation in male CBA mice has been studied. For this purpose, mature males were treated with a 0.01% aqueous solution of the pheromone for six days. Control mice were similarly treated with physiologic saline. The mice were sacrificed 23 days after the treatment, and material for the analysis of sperm-head abnormalities was sampled from the caudal portion of the epididymis. Analysis of the frequency of abnormal sperms has demonstrated that the pheromonal treatment significantly increases the frequencies of various sperm-head abnormalities. Apparently, this results from disturbances in sex-cell differentiation germline cells caused by the induction of genetic damage at stages immediately preceding meiosis, as well as during the first and second meiotic divisions. The relationship between the effect of 2,5-DMP and the decrease in the fertility of male CBA mice that was earlier observed after a similar treatment is discussed.     

Analysis for Pheromone-Induced Cytogenetic Disturbances Depending on Major Urinary Proteins of Laboratory Mouse Males

Young male CBA/LacStoRap mice for 2 h were exposed to pheromones that are transferred by major urinary proteins of sexually mature males of the same strain. The treatment was conducted using either a complete set of the major urinary proteins typical of the CBA mice or incomplete set of protein fractions detected in some animals. The effect of pheromones was estimated 24 h after treatment by cytogenetic analysis for disturbances in dividing bone marrow cells at anaphase–telophase and in germ cells at metaphase I. The frequency of both mitotic and meiotic disturbances was significantly increased after exposure to pheromones associated with the complete spectrum of the major urinary proteins. Conversely, no cytogenetic effect was observed in the absence of particular protein fractions. Possible consequences of the pheromonal effect on the genomes of somatic and germ cells are discussed as well as the relationships between pheromones and the major urinary proteins.     

The Female Pheromone 2,5-Dimethylpyrazine Induces Sperm-Head Abnormalities in Male CBA Mice

The effect of the house mouse female pheromone 2,5-dimethylpyrazine (2,5-DMP) on sperm differentiation in male CBA mice has been studied. For this purpose, mature males were treated with a 0.01% aqueous solution of the pheromone for six days. Control mice were similarly treated with physiologic saline. The mice were sacrificed 23 days after the treatment, and material for the analysis of sperm-head abnormalities was sampled from the caudal portion of the epididymis. Analysis of the frequency of abnormal sperms has demonstrated that the pheromonal treatment significantly increases the frequencies of various sperm-head abnormalities. Apparently, this results from disturbances in germ cell differentiation caused by the induction of genetic damage at stages immediately preceding meiosis, as well as during the first and second meiotic divisions. The relationship between the effect of 2,5-DMP and the decrease in the fertility of male CBA mice that was earlier observed after a similar treatment is discussed.     

Primer effects by conspecific odors in house mice: a new perspective in the study of primer effects on reproductive activities

Half a century has passed since the first report of the influence of odors on mice. Odors are known to influence behavior (signaling effect) and affect the physiology (primer effect) of mice. This review focuses on summarizing the primer effects found so far in female and male mice. Odors from conspecifics of the opposite sex had the tendency to enhance reproductive activities, whereas odors from conspecifics of the same sex diminish them. Only 2,5-dimethylpyrazine, one of the odor components identified in group-housed females, has been reported to have a suppressive influence on both males and females by lowering reproductive activities. Studies showed progress from the discovery of phenomena to the identification of odor components that cause such changes in reproductive organs and related neuroendocrinological changes. Compared to studies on the mechanisms of primer effects in females, the mechanisms in males are not yet clarified, and detailed studies on effects on the reproductive organs are still in primitive stages especially for males. Hypotheses on the influence of changes in the concentration of testosterone, estrogen, and prolactin on spermatogenesis and sperm maturation after exposure to odors are discussed.