NIH Swiss Mice Research Articles

Effects of cocaine on fetal and postnatal development in mice

The goal of the current investigation was to study the effect of in utero exposure of cocaine on fetal and postnatal development. 48 adult female NIH Swiss mice were used as experimental animal models. Each of the 24 mice were injected intraperitoneally with cocaine HCl at a daily dose level of 45 mg/kg (body weight). Each of the 24 control animals were daily injected with saline. One week after the treatment started, one male was introduced into each female cage. The day the vaginal plug was found was recorded as day one of pregnancy. Both cocaine treated and saline treated animals were subdivided into three subgroups each with 8 animals in each subgroup. Subgroup one was used to obtain midgestational (11 day) fetuses, subgroup two was used to obtain full term fetuses (18 day) and subgroup three was used to obtain pups. Individual fetal weights were taken and each fetus was examined for developmental anomalies. Midgestational fetuses exposed to cocaine had lower body weights than those of the controls. The full term fetuses, however, had similar weight in both experimental and control groups. The pups were weighed every 2 days from day 2 to day 16. The pups showed a slightly wider range of weights in the cocaine treated group as they matured to 16 days. All fetuses and pups revealed no soft tissue anomaly which, along with the weight data, supported our earlier findings.

Synthesis and biological activity of N6-(p-sulfophenyl)alkyl and N6-sulfoalkyl derivatives of adenosine: water-soluble and peripherally selective adenosine agonists.

A series of N6-(p-sulfophenyl)alkyl and N6-sulfoalkyl derivatives of adenosine was synthesized, revealing that N6-(p-sulfophenyl)adenosine (10b) is a moderately potent (Ki vs [3H]PIA in rat cortical membranes was 74nM) and A1-selective (120-fold) adenosine agonist, of exceptional aqueous solubility of > 1.5 g/mL (approximately 3 M). Compound 10b was very potent in inhibiting synaptic potentials in gerbil hippocampal slices with an IC50 of 63 nM. At a dose of 0.1 mg/kg ip in rats, 10b inhibited lipolysis (a peripheral A1 effect) by 85% after 1 h. This in vivo effect was reversed using the peripherally selective A1-antagonist 1,3-dipropyl-8-[p-(carboxyethynyl)phenyl]xanthine (BW1433). The same dose of 10b in NIH Swiss mice (ip) was nearly inactive in locomotor depression, an effect that has been shown to be centrally mediated when elicited by lower doses of other potent adenosine agonists, such as N6-cyclohexyladenosine (CHA) (Nikodijevic et al. FEBS Lett. 1990, 261, 67). HPLC studies of biodistribution of a closely related and less potent homologue, N6-[4-(p-sulfophenyl)butyl]adenosine indicated that a 25 mg/kg ip dose in mice resulted in a plasma concentration after 30 min of 0.46 micrograms/mL and no detectable drug in the brain (detection limit < 0.1% of plasma level). Although 10b at doses > 0.1 mg/kg in mice depressed locomotor activity, this depression was unlike the effects of CHA and was reversible by BW1433. These data suggest that 10b is a potent adenosine agonist in vivo and shows poor CNS penetration.

Injection of vehicle is not a stressor in Porsolt's swim test

A single injection or chronic injections with vehicle are reported to induce physical changes in the brain, suggesting this treatment may be stressful. Furthermore, preliminary observations indicate that vehicle injections may interact with the behavioral effects of psychoactive compounds. We investigated the behavioral response to an injection in two tests sensitive to stress: Porsolt's swim test of depressive behavior and the resident-intruder test of aggression. Acute or repeated injections of vehicle did not alter immobility in the swim test in “normal” male NIH Swiss mice, isolated mice, or mice previously exposed to continuous fight stress. Behavior in the resident-intruder test was similar in injected and noninjected mice. The present data suggest that in male NIH Swiss mice a vehicle injection does not induce behavioral changes in tests sensitive to stress, although it is shown to alter various physiological parameters indicative of stress.

Effector molecules from antitumor macrophages induced with OK-432 and cyclophosphamide.

The present study was designed to determine whether antitumor activity of macrophages induced with OK-432 and cyclophosphamide was mainly dependent on their ability to produce a soluble factor, that is, L-arginine-dependent nitric oxide as measured by nitrite concentration. Nitrite production by peritoneal macrophages from NIH Swiss mice pretreated with OK-432 (125 KE/kg) i.p. twice at 1-week intervals and with cyclophosphamide (200 mg/kg) i.p. 2 days before the second OK-432 treatment, increased with time for 24 h, and proportionally depended on macrophage numbers. Nitrite production was inhibited by actinomycin D and puromycin but not by mitomycin C. NG-Monomethyl-L-arginine, a specific competitive inhibitor of L-arginine-dependent nitric oxide synthesis, also inhibited production. There was a close correlation between nitrite production and antitumor activity in macrophages from mice pretreated with either OK-432 and cyclophosphamide, OK-432, or thioglycolate broth. OK-432 increased both nitrite production and antitumor activities when added to the macrophage from mice pretreated with OK-432 but not with thioglycolate broth. Both activities of macrophages from mice pretreated with OK-432 and cyclophosphamide were enhanced with increasing concentrations of L-arginine (0.125-1 mM) in the culture medium. D-Arginine, however, did not substitute for L-arginine. Neither activity was affected by contact between the macrophage and the EL4 cell. The macrophage showed antitumor activity through a membrane filter though the activity was greatly reduced. This antitumor activity of macrophages through a membrane was also inhibited by NG-Monomethyl-L-arginine, and increased by OK-432. However, conditioned media, obtained by culturing macrophages induced with OK-432 and cyclophosphamide, inhibited growth of EL4 cells. This activity was carried out by dialysable and non-dialysable factors. One of the dialysable factors was nitrite, an oxidized product of nitric oxide. The antitumor activity of non-dialysable factors was heat-stable and production of factors was increased by NG-Monomethyl-L-arginine and OK-432. Also, non-dialysable factors increased both antitumor and nitrite production activities of OK-432-elicited macrophages, when incubated with factors. Such activity of factors was also heat-stable. The production of factors increased with incubation time of macrophages, and was not inhibited by NG-Monomethyl-L-arginine. These results indicate that in vitro antitumor activity of macrophages induced with OK-432 and cyclophosphamide was mainly dependent on L-arginine-dependent nitric oxide, and that macrophage-associated soluble factors other than nitric oxide were also needed to inhibit fully tumor growth in vitro.

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.

Synthetic peptides of venezuelan equine encephalomyelitis virus E2 glycoprotein. III. Identification of a protective peptide derived from the carboxy-terminal extramembranal one-third of the protein

To complete our analysis of the E2 glycoprotein of Venezuelan equine encephalomyelitis (VEE) virus, we prepared six synthetic peptides corresponding to the extramembranal carboxy-terminal one-third of the protein. NIH-Swiss mice were immunized with the peptides, and antipeptide and antiviral titers were determined by enzyme-linked immunosorbent assay (ELISA). Challenge studies revealed that peptide 13 (amino acids 241–265) protected 60–70% of virus-challenged mice. Although the other peptides generally elicited antipeptide ELISA titers but no or low antiviral titers and did not protect mice, significant E2 reactivity was found in immunoblots. These results provide the first direct evidence that much of the E2 carboxy-terminal domain is cryptic in the VEE virion, even when virus was bound to polystyrene ELISA plates.

Acetaminophen-induced cytotoxicity in cultured mouse hepatocytes: Correlation of nuclear Ca 2+ accumulation and early DNA fragmentation with cell death

Hepatotoxic doses of acetaminophen cause widespread alkylation of liver and early loss of cytosolic Ca 2+ regulation. Although the precise location and target of lethal alkylation are not known, Ca 2+ accumulation is viewed as a possible link between cell alkylation and cell death. We have recently shown that Ca 2+ accumulates in the nucleus and that DNA fragments in vivo before the development of acetaminophen-induced necrosis in mice. The present study examined cultured hepatocytes for nuclear damage and its association with cell death in vitro. Positive results would argue for two key points. (1) Nonparenchymal cell damage does not explain DNA fragmentation induced by acetaminophen in vivo. (2) A chemical that causes necrosis can produce DNA damage considered characteristic of apoptosis. Hepatocytes from NIH Swiss mice were isolated by collagenase perfusion, cultured in Williams' E medium for 24 hr, and exposed to acetaminophen. Cytotoxicity was assessed by lactate dehydrogenase leakage and release of [ 3H]adenine from a prelabeled nucleotide pool. Genomic DNA fragmentation was assessed quantitatively by colorimetric analysis and qualitatively by agarose gel electrophoresis. Acetaminophen caused DNA damage from 1–4 hr onward and produced significant release of lactate dehydrogenase and [ 3H]adenine nucleotides at later times. Agarose gel electrophoresis revealed a “ladder” of DNA fragments characteristic of Ca 2+-mediated endonuclease activation. Cytotoxicity correlated with nuclear Ca 2+ accumulation ( r > 0.895, p < 0.05) and with percentage DNA fragmentation ( r > 0.835, p < 0.05). Nuclear changes in vitro generally reproduced those observed in vivo. Collectively, these findings demonstrate that nuclear Ca 2+ accumulation and DNA fragmentation appear as early events that correlate directly with later cytotoxicity. These changes may contribute to acetaminophen-induced injury leading to cell death in vitro and necrosis in vivo.

The ultrastructural diversity of scrapie-associated fibrils isolated from experimental scrapie and Creutzfeldt-Jakob disease

Several different samples of scrapie-associated fibrils (SAF) were extracted in identical fashion from the brains of golden Syrian hamsters infected with the 263K strain of scrapie agent and NIH Swiss mice infected with the Fujisaki strain of Creutzfeldt-Jakob disease (CJD) agent. Based on a total of over 500 measurements in individual fibrils in different extracts, hamster fibrils were more abundant, thicker and had better defined substructure than mouse fibrils. Hamster protofibrils were usually either twisted helically or in parallel arrays, whereas mouse protofibrils were often twisted, occasionally parallel, or could not be morphologically defined. Thus, SAF preparations from scrapie-affected hamsters can be ultrastructurally distinguished from those of CJD-affected mice, an observation that presumably reflects differences in their respective host-encoded amyloid protein subunits.

Deletion of a GC-rich region flanking the enhancer element within the long terminal repeat sequences alters the disease specificity of Moloney murine leukemia virus

Moloney murine leukemia virus (M-MuLV) is a replication-competent retrovirus which induces T-lymphoblastic lymphoma 2 to 4 months after inoculation. Enhancer sequences in the U3 region of the M-MuLV long terminal repeat, primarily the 75-bp tandem repeats, strongly influence the disease specificity and latency of M-MuLV. We investigated the role of GC-rich sequences downstream of the tandem repeats in the disease specificity of M-MuLV. A recombinant M-MuLV lacking 23 bases of a GC-rich sequence (-174 to -151), Delta 27A M-MuLV, was tested for pathogenesis in neonatal NIH Swiss mice. Delta 27A M-MuLV induced disease with a longer latency than did M-MuLV (7 versus 3 months) in greater than 85% of inoculated mice. More interestingly, this virus showed an expanded repertoire of hematopoietic diseases. Molecular analyses and histopathologic examinations indicated that while 39% of mice inoculated with Delta 27A M-MuLV developed T-cell lymphoblastic lymphoma typical of wild-type M-MuLV, the majority developed acute myeloid leukemia, erythroleukemia, or B-cell lymphoma. Viral DNA corresponding to Delta 27A M-MuLV was detectable in most of the tumors analyzed. These findings indicate that the GC-rich region significantly influences the disease specificity and latency of M-MuLV.

Immunogenicity of hepatitis B surface antigen derived from the baculovirus expression vector system: a mouse potency study

A standard mouse potency test was performed to evaluate the immunogenicity of recombinant hepatitis B surface antigen (HBsAg) produced in the baculovirus/insect cell expression system. Groups of NIH Swiss mice were immunized with serial four-fold amounts of either baculovirus-derived HBsAg adsorbed to aluminum sulfate or a commercially available yeast-derived recombinant HBsAg vaccine preparation. Results from these experiments showed that the effective dose of baculovirus-and yeast-derived HBsAg vaccine preparations necessary to seroconvert 50% of the animals were similar. The duration of the antibody response to HBsAg was studied in mice immunized with the highest doses of the two recombinant vaccine preparations 3 and 6 months after injection. No decrease in the anti-HBs response was observed 6 months after injection. No decrease in the anti-HBs response was observed 6 months after immunization with either of the two vaccine preparations. These results indicate that the baculovirus-derived recombinant HBsAg could serve as an alternative vaccine candidate for hepatitis B virus.

Bone marrow depletion by 89Sr complements a preleukemic defect in a long terminal repeat variant of Moloney murine leukemia virus.

We previously described a preleukemic state induced by Moloney murine leukemia virus (Mo-MuLV) characterized by hematopoietic hyperplasia in the spleen. Further experiments suggested that splenic hyperplasia results from inhibitory effects in the bone marrow, leading to compensatory extramedullary hematopoiesis. An enhancer variant of Mo-MuLV, Mo + PyF101 Mo-MuLV, fails to induce preleukemic hyperplasia and has greatly reduced leukemogenicity, indicating the importance of this state to efficient leukemogenesis. An alternative method for induction of preleukemic hyperplasia was sought. Treatment of mice with 89Sr causes specific ablation of bone marrow hematopoiesis and compensatory extramedullary hematopoiesis in spleen and nodes. NIH Swiss mice were inoculated neonatally with Mo + PyF101 Mo-MuLV and treated with 89Sr at 6 weeks of age. Approximately 85% developed lymphoid leukemia with a time course resembling that caused by wild-type Mo-MuLV. In contrast, very few animals treated with Mo + PyF101 Mo-MuLV or 89Sr alone developed disease. In approximately one-third of cases, the Mo + PyF101 Mo-MuLV proviruses were found at common sites for wild-type Mo-MuLV-induced tumors (c-myc, pvt-1, and pim-1), indicating that this virus is capable of performing insertional activation in T-lymphoid cells. These results support the proposal that splenic hyperplasia results from inhibitory effects in the bone marrow. They also indicate that Mo + PyF101 Mo-MuLV is blocked in early and not late events in leukemogenesis.

Amino acid sequence and characterization of a heparin-binding neurite-promoting factor (p18) from bovine brain.

A neurite-promoting factor (p18) was isolated from bovine brain using ammonium sulfate fractionation, sulfated Sephadex G-50 chromatography, heparin-Sepharose gel chromatography, and reverse phase high performance liquid chromatography. The complete amino acid sequence of p18 was determined by automated Edman degradation of S-pyridylethylated p18, and its peptide fragments produced by cyanogen bromide cleavage and by digestion with specific endoproteinases. Alignment of the amino acid sequences of these peptides revealed that p18 consists of 119 amino acid residues with a calculated molecular weight of 14,200. p18 appears to possess five disulfide bonds per molecule. A region of amino acid sequence at the C terminus of p18 shows a structural feature homologous to that around the reactive sites of Kazal-type protease inhibitors. However, p18 did not exhibit anti-trypsin activity. p18 showed very little, if any, mitogenic activity toward NIH 3T3 cells and Swiss mouse 3T3 cells. p18 was found to bind to a specific receptor with an apparent Kd of approximately 8 nM and receptor numbers 1.7 x 10(5) and 1.0 x 10(4) for NIH 3T3 cells and PC12 cells (rat pheochromocytoma cells), respectively.

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.

Antibodies to dengue 2 virus E-glycoprotein synthetic peptides identify antigenic conformation

Eighteen synthetic peptides have now been prepared from dengue (DEN) 2 virus, representing 80% of the extramembranal domain of the DEN envelope (E)-glycoprotein. These peptides were selected based upon our previous results with Murray Valley encephalitis (MVE) virus, computer analysis of the DEN virus sequence, and the predicted E-glycoprotein secondary structure. Six of these peptides were “structural” peptides derived from either nonlinear amino acid sequences or predicted disulfide bridge-stabilized loop structures. As with MVE virus, some peptides could be recognized by antivirus hyperimmune ascitic fluids, but monoclonal antiflavivirus antibodies failed to react with any peptide. Immunogenicity of these peptides was tested in BALB/c or NIH-Swiss mice. Fourteen of these peptides elicited antipeptide antibody in one or both mouse strains. Eleven of these antipeptides reacted with virus. Peptides 35 (amino acids 35–55) and 17 (amino acids 352–368) elicited virus-neutralizing antibody. Four antipeptides were more efficient at binding to pH 5.0-treated virus. These antipeptides precisely defined a flavivirus group common sequence (amino acids 98–110) that has biochemical characteristics similar to previously defined viral fusion sequences.

Studies on the mechanism of 1,3-butadiene-induced leukemogenesis: the potential role of endogenous murine leukemia virus.

Previous studies have revealed marked differences in the incidence of leukemia between rats and mice exposed to 1,3-butadiene that do not appear to be readily explained on the basis of pharmacokinetics or metabolism. Chronic exposure to 1,3-butadiene results in a high incidence of thymic lymphoma in B6C3F1 mice that is not observed in Sprague-Dawley rats. Studies at the Chemical Industry Institute of Toxicology have focused on evaluating the potential of endogenous ecotropic retroviral background to influence susceptibility to 1,3-butadiene leukemogenesis. These studies have compared the pathogenesis and incidence of thymic lymphoma between B6C3F1 and NIH Swiss mice. Proviral ecotropic sequences are truncated in the NIH Swiss mouse, and the virus is not expressed. Chronic exposure to 1,3-butadiene (1250 ppm) for up to 1 year resulted in a fourfold difference in the incidence of thymic lymphoma between B6C3F1 and NIH Swiss mice. These results provide presumptive evidence for retrovirus involvement since NIH Swiss mice lack ecotropic viruses and appear to be relatively resistant to induction of lymphoma by 1,3-butadiene. Other explanations appear to be less likely in light of the fact that target organ toxicity has been determined to be virtually identical between the two strains during the preleukemic phase of 1,3-butadiene exposure.

Studies on the Mechanism of 1,3-Butadiene-Induced Leukemogenesis: The Potential Role of Endogenous Murine Leukemia Virus

Previous studies have revealed marked differences in the incidence of leukemia between rats and mice exposed to 1,3-butadiene that do not appear to be readily explained on the basis of pharmacokinetics or metabolism. Chronic exposure to 1,3-butadiene results in a high incidence of thymic lymphoma in B6C3F1 mice that is not observed in Sprague-Dawley rats. Studies at the Chemical Industry Institute of Toxicology have focused on evaluating the potential of endogenous ecotropic retroviral background to influence susceptibility to 1,3-butadiene leukemogenesis. These studies have compared the pathogenesis and incidence of thymic lymphoma between B6C3F1 and NIH Swiss mice. Proviral ecotropic sequences are truncated in the NIH Swiss mouse, and the virus is not expressed. Chronic exposure to 1,3-butadiene (1250 ppm) for up to 1 year resulted in a fourfold difference in the incidence of thymic lymphoma between B6C3F1 and NIH Swiss mice. These results provide presumptive evidence for retrovirus involvement since NIH Swiss mice lack ecotropic viruses and appear to be relatively resistant to induction of lymphoma by 1,3-butadiene. Other explanations appear to be less likely in light of the fact that target organ toxicity has been determined to be virtually identical between the two strains during the preleukemic phase of 1,3-butadiene exposure.

Effect of castanospermine on virus titers and rauscher MuLV infected NIH swiss mice : L. Allen, L. Westbrook, B. Toyer, and M. Hollingshead. Southern Research Institute, Birmingham, AL 35255 USA

Effect of castanospermine on virus titers and rauscher MuLV infected NIH swiss mice : L. Allen, L. Westbrook, B. Toyer, and M. Hollingshead. Southern Research Institute, Birmingham, AL 35255 USA