Male NIH Swiss Mice Research Articles

Are there preexisting behavioral characteristics that predict the dominant status of male NIH Swiss mice (Mus musculus)?

The behavior of isolated Cr:NIH(S) mice (Mus musculus) was studied in a holeboard test of exploration, in a plus-maze test of anxiety, in the resident-intruder paradigm of aggression, and in the swim test. Thereafter, mice that were matched for body weight were housed together in groups of 4-5. Within a week, 1 mouse per cage (the alpha) had attacked all its subordinate cagemates but lacked any signs of attack itself. Subordinate mice had bite marks on their tails and backs. When mice were isolated, no differences were found between the behavior of those that later became alphas and those that became subordinates. In contrast, after the establishment of the social hierarchy, alpha mice spent less time immobile in the swim test and had higher locomotor activities than did the subordinate mice. The results suggest that the differences in behavior between the alpha and subordinate mice result from aggressive social interactions in the home cage.

Are there preexisting behavioral characteristics that predict the dominant status of male NIH Swiss mice (Mus musculus)?

Are there preexisting behavioral characteristics that predict the dominant status of male NIH Swiss mice (Mus musculus)?

The role of body weight in resident-intruder aggression

The behavior of male NIH Swiss mice of various body weights in the resident-intruder test of aggression was investigated. Mice were housed individually for 10 days prior to the test, and allocated to six groups. In the first three groups body weights of residents and group-housed intruders were matched, and the animals were divided into light, average, or heavy groups. In the last three groups weights of the intruder mice were either matched with the residents, or intruders were lighter or heavier than the residents. We found that light residents spent significantly less time in aggressive behaviors and longer time in defensive behaviors than the other two groups. The heavy mice showed most social investigation. The body weights of intruders were also shown to affect the behavior in the test: those residents which had light opponents spent a longer time in aggressive behavior than those which had matched or heavy opponents. The resident mice with heavy opponents showed most defensive behaviors. To study whether pharmacological manipulation may have different effects on behavior in the resident-intruder test in mice having different weights, animals of light, average, and heavy body weight received a low dose (0.8 g/kg) of ethanol 30 min prior to the test. We did not note any effect of ethanol on aggressive behavior in the three groups. The results suggest that body weight plays a significant role in determining the level of aggression and defensive behaviors in the resident-intruder test.

Effect of tryptophan on the behavior of nonstressed and stressed mice in Porsolt's swim test

The effect of tryptophan on immobility in Porsolt's swim test was studied in male NIH Swiss mice. Preexposure to a swim or fight-stressor was included in the design. Doses of tryptophan (0, 12.5, 50, 75, 100, 125 and 200 mg/kg) were administered intraperitoneally 60 min prior to the swim test. In the nonstressed mice tryptophan had an U-shaped dose-response relationship: immobility in the water was dose-dependently shortened after doses from 0 to 100 mg/kg, whereas after 125 and 200 mg/kg tryptophan the immobility times did not differ from the values obtained after a saline injection. Preexposure to a swim- or fight-stressor did not make mice more sensitive to the effects of tryptophan. Tryptophan (0–300 mg/kg) had no effect on exploratory behavior or locomotor activity in the holeboard, suggesting that sedation was not a factor in the swim test results. The findings suggest that tryptophan has antidepressant -like properties in Porsolt's swim test.

Behavior of streptozotocin-diabetic mice in tests of exploration, locomotion, anxiety, depression and aggression

The present study examined behavior of streptozotocin-diabetic mice in Porsolt's swim test, a putative animal model of depression, in the holeboard test of exploration and locomotor activity, in the plus maze test of anxiety, and in the resident-intruder paradigm of aggression. Two weeks after an IP injection of 200 mg/kg streptozotocin, which caused a 20% weight loss and increased fluid consumption and urination, male NIH Swiss mice were found to show lengthened duration of immobility in the swim test. One week of insulin treatment (0.1 IU/g/day) partially antagonized this change. The locomotor activity scores in the streptozotocin-treated mice were lower in the holeboard but higher in the plus maze than in the controls; therefore, the lengthened immobility was not likely to be due to a general motor impairment. No significant changes in the time spent in social interaction or aggressive behavior were found in the streptozotocin-treated mice. The results indicate that streptozotocin-treated mice show lengthened immobility in the swim test.

Correlations between behavior of mice in Porsolt's swim test and in tests of anxiety, locomotion, and exploration

This study examined whether the behavior of male NIH Swiss mice in a putative animal model of depression, Porsolt's swim test, is related to that in other behavioral tests. The other tests were the plus-maze test of anxiety, the holeboard test of exploration and locomotor activity, and a test of seizure threshold to bicuculline. The immobility of the mice in the swim test did not correlate with their behavior in any of the other tests used. The only significant correlations found occurred between individual measures in the holeboard and plus-maze tests. The data suggest that immobility in the swim test is not related to behavior in the tests of anxiety, directed exploration, locomotor activity, or seizure threshold.

The effects of novelty, isolation, light and ethanol on the social behavior of mice.

The social behavior of pairs of male NIH Swiss mice was assessed under a variety of experimental conditions. Increasing periods of isolation increased both the total time spent in social interaction and also increased the incidence of aggressive behavior. Familiarity with the testing arena tended to increase social behavior, but the magnitude of this effect was considerably less than that previously observed in rats. High light levels reduced social interaction. Ethanol (0.8-2.4 g/kg) caused a dose-related decrease in the total time spent in social interaction, a biphasic effect on aggressive behavior and a dose-related increase in locomotor activity. While the social interaction test in this form may not be a suitable model of anxiety in NIH Swiss mice, it should provide a useful method of assessing drug effects and investigating genetic influences on social and aggressive behavior.

Macrocytic-megaloblastic anemia in male NIH Swiss mice following repeated exposure to 1,3-butadiene

Thymic lymphoma/leukemia is the major cause of death in B6C3F1 mice chronically exposed to 1,3-butadiene (BD). Similar to radiation-induced murine thymic lymphoma, the bone marrow is also a major target organ. Because of the association of murine thymic lymphoma with endogenous type-C murine leukemia retroviruses (MuLV) present in the germ line of most strains of laboratory mice, including B6C3F1 and its parent strains, we examined the effects of BD exposure on NIH Swiss mice which do not possess intact endogenous ecotropic MuLV. Male NIH Swiss mice exhibited a macrocytic-megaloblastic anemia following inhalation of 1250 ppm BD for 6 weeks. Treatment-related changes included decreases in circulating erythrocytes, total hemoglobin, and hematocrit and an increase in mean corpuscular volume. An eightfold increase in circulating micronuclei was also observed. The anemia was not accompanied by a significant alteration in mean corpuscular hemoglobin concentration, an increase in circulating reticulocytes, or an increase in circulating nucleated erythrocytes. These findings are consistent with a treatment-related macrocytic-megaloblastic anemia and indicate that the bone marrow is an important target for BD toxicity in mice independent of MuLV background and expression.