Chromosome effect of cyclophosphamide in various strains of mice]

The chromosomes of four different mouse strains were examined after administration of a single dose of cyclophosphamide, 100 mg/kg. Chromosomal breaks and rearrangements were produced in C3H mice three to four times as frequently and in AKR mice twice as frequently as in C57 B1 and XLII Orl mice. This indicates that cytogenetic investigations in mutation research using mice as in vivo test systems may be variable depending on the mouse strain employed. Because the effect of the alkylating agent was not pronounced in the two strains having a high incidence of cancer and leukemia (C3H and AKR), the possibility of a relationship between chromosomal instability and cancer proneness is discussed.     

The infectivity of Plasmodium yoelii in different strains of mice

We evaluated the effect of using Medium 199 alone and Medium 199 supplemented with 5% normal mouse serum, 5% fetal calf serum, 5% bovine serum albumin or 5% Albumax on Plasmodium yoelii sporozoite yield from infected mosquitoes and infectivity in BALB/c mice. The sporozoites yield, as well as their infectivity, was statistically lower (P = 0.0031) when unsupplemented Medium 199 was used to separate sporozoites from infected mosquitoes. Although Medium 199 supplemented with Albumax led to lower sporozoite yield (P < 0.0009), infectivity of the sporozoites was similar to those obtained with the other medium supplements. Because normal mouse serum supports good sporozoite infections and is also the supplement that can be used repeatedly in mice during multiple sporozoite injections without inducing anaphylaxis, we selected it to evaluate the infectivity of P. yoelii sporozoites in different strains of mice. After injecting mice with serial dilutions of sporozoites and detecting patent infections, we determined that the infective dose 50 (ID50) for BALB/c, C57Bl/6, A/J, and B10BR mice ranged between 4.9 and 10.6 sporozoites. The ID50 obtained for CD-1 mice (147 sporozoites) was significantly higher.     

泼尼松龙致不同品系小鼠药源性证候的比较

目的研究糖皮质激素药物作用于不同品系小鼠后肾上腺皮质功能抑制程度及其诱导药源性证候的差异性。方法选用ICR、BALB/c、C57BL/6J、KM和裸小鼠5种小鼠为实验对象,采用泼尼松龙进行干预。每种小鼠16只,其中正常对照组8只,泼尼松龙组8只。以0.5 mg/(kg·d)泼尼松龙连续灌胃14 d,每日观测小鼠体重,在给药第14天,运用小鼠辨证论治实验方法学检测小鼠中医四诊信息,次日处死小鼠,取脾、胸腺称重并计算脏器指数;运用ELISA检测血清皮质酮和ACTH含量;采用实时荧光定量PCR技术检测肾上腺Star、Cyp11a1、Cyp21a1、Cyp11b1、Cyp11b2基因表达;运用Western blot方法检测肾上腺LDLR、SRBI、StAR蛋白表达。结果与各自对照组比较:1)0.5 mg/(kg·d)泼尼松龙给药后第7天起ICR小鼠体重显著下降(P<0.01);给药后第13天起BALB/c小鼠体重显著下降(P<0.01);给药后第5天起C57BL/6J小鼠体重显著下降(P<0.01);给药后第13天裸鼠体重显著下降(P<0.05)。2)泼尼松龙导致ICR小鼠抓力显著下降以及躯干平均温度显著降低(P<0.05)。3)泼尼松龙导致ICR小鼠和裸鼠脾重量显著下降(P<0.01)以及裸鼠脾指数下降(P<0.05),泼尼松龙导致ICR、C57BL/6J和KM小鼠胸腺重量和胸腺指数均显著下降(P<0.01)。4)泼尼松龙显著导致BALB/c与KM小鼠血清皮质酮下降(P<0.05),也显著引起BALB/c小鼠血清促肾上腺皮质激素(ACTH)含量下降(P<0.01)。5)泼尼松龙显著下调ICR小鼠肾上腺Cyp21a1基因表达(P<0.05),下调C57BL/6J小鼠Star基因表达(P<0.01),下调KM小鼠Cyp11a1、Cyp21a1基因表达(P<0.01),下调裸鼠Star与Cyp21a1基因表达(P<0.05);且泼尼松龙抑制ICR小鼠肾上腺LDLR蛋白表达以及KM小鼠肾上腺StAR蛋白表达。结论泼尼松龙造成的小鼠药源性虚证主要表现为"气虚",涉及中医"肾藏象"与"脾藏象",其物质基础以肾上腺皮质类固醇激素合成酶分子表达被抑制以及垂体-肾上腺皮质轴功能被抑制为主;开展糖皮质激素药源性虚证研究建议首选ICR小鼠。     

Characterization of Nippostrongylus brasiliensis infection in different strains of mice

Five mouse strains, CBA/J, BALB/c, C3H/HeJ, A/J, and C57Bl/6J-bg-bg, all showed similar expulsion kinetics for Nippostrongylus brasiliensis (infective dose = 500 L3). Typically, parasite recovery was maximal on day 2 in the lungs and by day 4 in the small intestine. Few worms (less than 5% infective dose) were recovered on day 14 in all strains. These same mouse strains exhibited immune depression on day 5 of infection with mesenteric lymph node cells (MLN) showing reduced (10-30% normal) IgM, IgG, and IgA responses against heterologous antigen. The intestinal mast cell numbers and tissue histamine levels were examined in CBA/J mice. Mast cell numbers increased (normal = less than 1/villous crypt unit; VCU) from day 5 and peaked on day 12 (greater than 15/VCU). Intestinal histamine levels did not completely correlate with mast cell numbers with maximum concentrations (240 +/- 73 ng/g, 2-fold over normal) reached by day 8. Histamine concentrations in the intestine returned to normal levels by day 20.     

In vivo release of lymphokines in different strains of mice

Attempts were made to induce the two lymphokines, migration inhibitory factor and interferon II, in vivo with antigens from the tubercle bacillus. Of 11 strains of mice assayed, marked variations occurred in the capacity to release these lymphokines. This capacity to respond, however, was altered by the mode of presentation of the antigen. The migration inhibitory factor and interferon II appeared together in the responding strains, and both were absent in the nonresponding strains.     

Gamma aminobutyric acid in different strains of mice effect of ethanol

Four strains of mice (C57BL/6J, DBA/2J, LS and SS), which differ in their voluntary intake and/or neural sensitivity to ethanol, were examined for the contents of γ-aminobutyric acid (GABA) in various brain regions. The effect of an acute dose of ethanol (4 g/kg) on the contents of this amino acid neurotransmitter in these mice were studied. The objective is to determine if the differences in sensitivity to ethanol may be reflected in differences in brain GABA contents in these animals.Results indicate that a previously documented ethanol-induced elevation of GABA in the whole mouse brain is a phenomenon observed in a variety of brain regions. No correlation was observed between GABA contents in the brain and neural sensitivity to ethanol.     

Persistence of Mycoplasma arthritidis in the body of mice of different strains

Mice belonging to 3 strains were shown to differ greatly in their sensitivity to M. arthritidis. This organism persisted for a year in (C57BL/6 X A/Sn)F1 mice, for 6 weeks in BALB/c mice and for 1-3 weeks in C57BL/6 mice. The sensitivity of mice to M. arthritidis infection and the persistence of the infective agent in the organs of the animals were found to depend on the state of their cell-mediated immunity.     

Egg production of Clonorchis sinensis in different strains of inbred mice.

In order to compare the intraspecific variation in host-parasite relationship of Clonorchis sinensis, six strains of inbred mice, ICR, DDY, GPC, BALB/c, nude and DS, were infected orally with 20 metacercariae of C. sinensis. The biologic incubation period of C. sinensis was the shortest in DDY mice, 21.2 days in average, followed by GPC 21.4, BALB/c and DS 23.2, ICR and nude 23.4 days, respectively. The fertile period of the fluke was also the longest in the DDY strain, 164 days on average, followed by GPC 132, BALB/c 97, nude 37, DS 32 and ICR 28 days. The egg-laying capacity of the fluke in DDY and GPC was relatively high and stable compared with the other four strains of mice. It was found that there are intraspecific variations in biologic incubation period, fertile period, and fecundity of C. sinensis. The DDY mouse is likely to be the most suitable experimental animal among the six strains of the mice tested.