Mice Of C57BL Strain Research Articles

Enhanced adhesion of blood platelets to intact endothelium of mesenteric vascular bed in mice with streptozotocin-induced diabetes is mediated by an up-regulated endothelial surface deposition of VWF – In vivo study

Numerous in vitro experiments have confirmed that a dysfunctional endothelium is characterized by, inter alia, a higher affinity for binding of platelets and leukocytes. However, there is still no direct evidence for greater interaction between platelets and intact endothelium in in vivo animal models of diabetes. Therefore, the present study examines the pro-adhesive properties of endothelium change in vivo as an effect of streptozotocin (STZ)-induced diabetes and the role of two key platelet receptors: GPIb-IX-V and GPIIb/IIIa.Mice of C57BL strain with streptozotocin-induced diabetes were used in the study. Flow cytometry was used to assess basal activation and reactivity of platelets. Adhesion of platelets to the vascular wall was visualized with the use of intravital microscopy in mesentery. The contribution of GPIIb/IIIa and GPIb-IX-V was evaluated by the injection of Fab fragments of respective antibodies. The integrity of the endothelium and vWf expression were evaluated histochemically.Basal activation and reactivity of platelets in streptozotocin-diabetic mice were elevated. Blood platelets adhered more often to the vascular wall of diabetic mice than nondiabetic animals: 11.9 (6.4; 32.8) plt/min/mm2 (median [IQR]) vs 2.7 (1.3; 6.4) plt/min/mm2. The injection of anti-GPIbα antibodies decreased the number of adhering platelets from 89.5 (34.0; 113.1) plt/min/mm2 (median [IQR]) in mice treated with isotype antibodies to 3.1 (1.7; 5.6) plt/min/mm2 in mice treated with blocking antibodies. The effect of GPIIb/IIIa blockage was not significant. Immunohistochemistry revealed a higher expression of vWF in the endothelium of STZ mice, but no substantial changes in endothelial morphology were detected.To conclude, the study shows that the platelets interact more frequently with the mesenteric vascular bed in mice with 1-month STZ-induced diabetes than in healthy mice. These interactions are mediated via platelet GPIb-IX-V and are driven by increased expression of vWF in endothelial cells.

Involvement of the Histaminergic System in Leptin-Induced Suppression of Food Intake

The ob gene product leptin is secreted from white adipose tissue, and may regulate food intake by acting on the hypothalamus in the central nervous system. But the mechanism of this effect is still unclear. The central histaminergic system has been suggested to participate in the control of various physiological functions, particularly in feeding behavior, as it mediates anorectic signals like leptin. Thus, we hypothesized that the central histaminergic system is a target for leptin in its control of feeding. To prove this, we first examined the effect of i.p. administration of α-fluoromethylhistidine (FMH), a specific and irreversible inhibitor of histidine decarboxylase, on leptin-induced suppression of food intake in normal C57BL strain mice. Leptin treatment (1.3 mg/kg, i.p.) significantly reduced food intake by 60% of that of control at 6 h and by 84% at 24 h compared with control. When mice were injected with FMH (100 mg/kg, i.p.) before being given leptin, leptin-induced suppression of food intake was abolished and there was no significant difference compared with that of control. Additionally, we further examined the effects of leptin on food intake in mutant mice lacking histamine H 1 receptors (H1R-KO mice). Leptin injection significantly reduced food intake by 56% of that of control at 6 h and by 79% at 24 h in wild-type mice (WT mice), but not in H1R-KO mice. This finding suggests that leptin affects the feeding behavior through activation of the central histaminergic system via histamine H 1 receptors.

Effects of Hemerocallis on sleep in mice.

Freeze-dried flowers of the Akinowasuregusa (Hemerocallis fulva L. var. sempervirona M. Hotta), a Hemerocallis genus of the lily family, were fed to C57BL strain mice. The slow wave sleep and paradoxical sleep of the Hemerocallis-treated group increased during the dark period. The differences between the control group and the Hemerocallis-treated group were significant (P < 0.05). The Hemerocallis feeding did not cause a change in sleep time during the light period. As a result, there was no significant change in the sleep-time percentage over a 24-h period.

Ultrastructural morphometric study of efferent nerve terminals on murine bone marrow stromal cells, and the recognition of a novel anatomical unit: The “neuro‐reticular complex”

In order to extend our understanding of the role of nerve fibers in the structure and function of bone marrow stroma, we have examined nerve terminals, arterioles, and capillaries in femoral bone marrow tissues of 50 C57BL strain mice, using electron microscopy and morphometric methods. Within the adventitia of arterioles, a particular type of cell, termed periarterial adventitial (PAA) cell, is characterized by a thin veil-like cytoplasm which concentrically surrounds both nerves and arterioles. Nerve fibers containing both unmyelinated and myelinated axons are distributed mainly between the layers of PAA cells, but are found rarely on the sinus walls or within the hematopoietic parenchyma. Quantitatively, the efferent nerve terminals with many synaptic vesicles are distributed mainly beside arterial smooth muscle cells (Type I: 58.8%) or between the layers of PAA cells (Type III: 33.2%), and rarely in hematopoietic parenchyma (Type II: 5.3%) or on sinus walls (Type IV: 2.7%). In the case of Type II-IV nerve terminals, efferent (autonomic) nerves and bone marrow stromal cells which are connected by gap junctions (sinus adventitial reticular cells, intersinusoidal reticular cells, and PAA cells) appear to constitute a potential functional unit for signal conduction. We would like to propose a new term for this anatomical unit in marrow, the "neuro-reticular complex."

Excess dietary vitamin B6 alters water maze performance in two strains of mice

The effects of excess vitamin B6 on learning performance in a water maze were studied in progeny of two strains of mice, I strain mice which demonstrate acute sensitivity to pyridoxine depletion, and C57BL strain mice, a control strain. I strain mice fed 12 mg pyridoxine (PN)/kg diet made more errors to complete the maze than C57BL mice. When fed diets with vitamin B6 410 or 1230 times the recommended amount, water maze error scores of I strain mice decreased; but for C57BL strain mice, increased. Significant differences between dietary treatment for both strains were found, however, only when scores from third and later litters were included in the analysis. This suggests that a cumulative effect of diet was necessary in order to see an effect on water maze learning. The improvement in water maze performance demonstrated by the I strain mice with vitamin B6 intakes 410 times recommended amounts indicates that the pyridoxine requirement of the I strain is between 12 and 410 mg PN/kg diet. The detrimental effects found on learning performance of C57BL strain mice, a control strain, provides evidence of neurotoxicity with ingestion of megadose amounts of vitamin B6. In parent mice, final body weight and organ weights tended to increase in the I strain and decrease in the C57BL mice with the higher PN diets, but body weight gain was less in both strains in mice fed the higher amounts of PN. In the offspring mice, dietary PN had no effect on body weight and brain pyridoxal phosphate content.

Tissue and organ distribution of mammary tumor virus antigens in low and high mammary cancer strain mice

Expression of mammary tumor virus (MTV) antigen was measured in a wide variety of organs and tissues of a series of high (GR, SHN, SHNf, DD, SLN, SLNf) and low (DDf, DDD, DDDf, KF, KFf, ddY, C57BL, BALB/c) mammary cancer strain mice. Tests were carried out by microimmunodiffusion (micro-ID) and immunoperoxidase tests on formalin-fixed tissues and radioimmunoassays in extracts for 2 viral proteins, MTVp27 from the viral core and MTVgp52 from the viral envelope. Organs with exocrine function, i.e. the mammary gland, salivary gland, coagulating gland and prostate, were mostly positive. The secretory epithelial cells of these organs showed viral antigen expression. Less positivity was encountered in brain, pancreas, stomach, urinary bladder, epididymis, uterus, thymus, spleen, lymph nodes and kidney, plasma and blood cell pools. Unexpectedly the uterus extracts showed MTV antigen expression, occasionally even by immunodiffusion, especially in mice of various DD stocks, but also in the GR strain. Another striking observation was the detection of MTV antigen expression in salivary glands in C57BL strain mice; most other organs of this strain (including the mammary glands) were negative. The implications of results of this extensive survey for MTV antigen expression are discussed for tumorigenesis by MTV of mammary gland and perhaps other tissues in the mouse.

Morphogenesis of the mouse coronal suture.

The morphogenesis and maturation of the coronal suture in C57Bl-strain mice was studied histologically using light microscopy from day 15 postconception through day 71 postpartum. Early differentiation of the osteoid precursors proceeds centrally within the 7- to 8-cell-thick fibrous ectomeninx beginning in the regions of the ossification centers and extends peripherally toward the future sutural margin. Differentiation into osteogenic cellular elements is marked morphologically by an increased nuclear:cytoplasmic ratio, dark-staining nucleoli and a granular chromatin pattern. This zone of cells, designated the osteogenic induction front (OIF), extends in advance of any identifiable accumulation of osteoid matrix or biomineralization. As the OIFs of the parietal and frontal bones approach, but prior to any physical overlap, they lie in different planes dorsoventrally; the parietal OIF located dorsal to the frontal OIF, a pattern maintained throughout subsequent sutural morphogenesis. Upon physical overlapping of the parietal and frontal OIFs, the fibrous capsule thickens dorsoventrally assuming a 'fusiform' configuration. This morphological event, referred to as the 'fusiform blastema', has been suggested to presage sutural location and determine the relative vertical position of the bony plates comprising the suture. Our results suggest that this is actually a secondary event, the structure of the suture having already been established with the relative physical overlapping of the respective OIFs.

Effect of sodium selenite on methylmercury-induced cleft palate in the mouse

The effects of simultaneous administration of sodium selenite on the teratogenic action of methylmercury was examined. Methylmercury, or sodium selenite, or a mixture of methylmercury and sodium selenite was administered subcutaneously to pregnant ICR-strain mice on Days 9 through 12 or Days 7 through 12 of gestation, and intraperitoneally to pregnant C57BL-strain mice on Days 7 through 12 of gestation. On Day 17 of gestation the fetuses were removed and examined for cleft palates. Although the incidence of cleft palate in the fetuses, on Day 17, differed according to the concentration of methylmercury (3 or 5 mg/kg/day) and the duration of administration (1 injection per day for 4 or 6 days), the simultaneous administration of selenium at concentrations of 0.0625 to 3.5 mg/kg/day did not reduce the incidence of cleft palate. At the higher concentrations (0.5 to 3.5 mg/kg/day) selenium appeared to increase the maternal toxicity and the teratogenicity of methylmercury. Analysis of fetal body weights on Day 17 of gestation indicated that in those groups in which methylmercury alone resulted in a significant decrease in body weight, the simultaneous administration of selenium did not prevent this growth suppression. It is suggested that cleft palate induction by methylmercury is the result of suppression of growth, rather than a tissue-specific teratogenic action. The effects of methylmercury and selenium on other parameters of maternal and fetal health are also discussed.

Estrogen receptor in the thymus of the castrated mice.

Sucrose density gradient ultracentrifugation and dextran-coated charcoal adsorption permitted us to characterize the estrogen-binding proteins in cytosols obtained from the thymus, spleen and mesenteric lymph node of the castrated male and female mice of C57BL strain. The thymic cytosol from both sexes incubated with 3H-estradiol-17 beta in the presence of excess unlabeled steroids showed a specific estrogenbinding 4 S protein with its binding capacity of 10(-14) moles/mg protein for males and 4 x 10(-15) moles/mg protein for females, respectively. The dissociation constant was of 4 x 10(-10) M for males and 3 x 10(-10) M for females, respectively. No specific binding was, however, found in the cytosols of the spleen and mesenteric lymph node. Steroid analysis by thin-layer chromatography of the thymic cytosols after incubation of them with 3H-estradiol-17 beta showed that a fair amount (around 60%) of radioactivity was from the undegradated radioactive steroid still bound to 4 S binder in both sexes. Enzyme study and heat experiment revealed that the estrogen specific 4 S binding component in the thymic cytosols bears at least protein in nature and is of heat-labile nature. These results strongly suggest that the thymus of the castrated mice contain a specific estrogen receptor, the nature of which is in part protein and heat-labile.

Accumulation and binding of 3H-estradiol-17beta by lymphoid tissues of castrated mice.

The in vivo uptake of 3H-estradiol-17beta by the various lymphoid tissues, fat tissue, skeletal muscle and circulating blood of castrated male and female mice of C57BL strain was studied after an intravenous injection of the hormone. In both sexes the highest uptake was by the bone marrow and fat tissue, followed by the spleen, thymus and mesenteric lymph node. The lowest was by the muscle and the blood serum. The lymphoid tissues in the female took up a slightly more amount of radioactivity than those in the male until 1 hr after the injection, but thereafter the uptake was at almost the same level between both sexes. The lymphoid tissues showed a relative and long-term retention of the radioactivity, as compared with that in the muscle and blood serum. The binding of 3H-estradiol-17beta by the lymphoid tissue cytosol and their binding specificity for the hormone were examined in vitro by Sephadex G-100 column analysis. All the tissue cytosols tested contained estradiol-binding component(-s). Among those the thymic cytosol showed to contain the component(-s) which is fairly specific to this hormone. These results suggest that there is a relatively high uptake and retention of estrogen in the lymphoid tissues in which it is bound to cytoplasmic binding component(-s).

Length of gestation in mice under a 21-hour day.

Experiments were conducted to determine whether gestation length in mice was determined by the number of daylight/darkness cycles or by an absolute length of time. C57BL strain mice were bred and raised under a 10 1/2-hour light (L):10 1/2-hour dark (D) cycle. Inurement to the cycle was demonstrated by measuring running activity. The animals were 1st bred (Period 1) under the 10 1/2 L:10 1/2 D cycle (21 pregnancies) then for about 3 weeks (Period 2) under a 12 L:12 D cycle (10 pregnancies) followed again (Period 3) by breeding under the 10 1/2 L:10 1/2 D cycle (9 pregnancies). The mode of gestation lengths was 20 days for Period 1 (range: 19-20 days) 20 days for Period 2 (range: 20-21 days) and 21 days for Period 3 (range: 20-22 days). In terms of absolute time the gestation length remained approximately constant in mice inured to a shortened light-dark cycle.

Necessity of the spleen for balanced secondary sex ratios following maternal immunization with male antigen.

A study testing the hypothesis of Hellstrom that the success of allogeneic matings in the mouse is due to the passive protection of antigenically dissimilar embryos by factors in the maternal serum is presented. Female mice were splenectomized and grafted with isogenic male skin 2-3 weeks later. The animals were then inoculated with male spleen cells and mated with isogenic males. Sham splenectomized animals treated in otherwise the same manner and untreated animals served as controls. The splenectomized animals had an unusually high number of male offspring (70.5%), though the sham group did not (55.2%). This result was corroborated in a repeat experiment with C57BL strain mice. The difference in sex ratios in litters born to splenectomized females (59.4%) and sham splenectomized females (49%) was highly significant (p less than .005). The increased sex ratio in litters born to females is related to the immunological status of the animals. The shorter the time it took to reject the male skin grafts, the higher was the sex ratio. It is suggested that a spleen-associated factor and maternal recognition of male antigens could be invlolved in the maintenance of a balanced sex ratio in most mice strains. Because of the splenetic activity and the higher sex ratios, the Hellstrom hypothesis is refuted.

Carcinogenic effect of egg yolk in mice of the C57 B1 strain.

SummaryMice of the C57 Bl strain maintained on a diet supplemented with raw egg yolk, like those of the T.M. strain, developed a high incidence of neoplasms. The most frequent neoplasms were lung tumors and lymphosarcomas. Liver hepatoma, which occurred rarely in mice of the T.M. strain, was found in 6.5% of the experimental C57 Bl strain mice. The incidence of mammary cancer in these mice was only 9.6%, as compared with the 33% found among the breeding females of the T.M. mice on the diet supplemented with yolk; a difference which may probably be due to a difference in genetic constitution of these two strains of mice. Finally, many of the mice of the C57 Bl. strain on the diet supplemented with egg yolk developed pituitary tumors, the majority of which appeared to originate from the intermediate lobe.