Lipid-lowering properties of 6-benzoyl-2(3H)-benzothiazolone and structurally related compounds

Fifteen compounds derived from the 2(3H)-benzothiazolone template with an acyl side-chain in position-6 were evaluated for their lipid-lowering action in mice. Among these compounds, 6-benzoyl-2(3H)-benzothiazolone was found to be the most potent one both in mice models receiving a hypercholesterolemic diet (for 15 days) or a standard diet (for 21 days). 6-Benzoyl-2(3H)-benzothiazolone compares favorably with fenofibrate, the standard drug, both in terms of HDL-C/Chol (High Density Lipoprotein-Cholesterol/Total Cholesterol) ratio and absence of liver hepatomegaly.     

Novel 1,3-dicarbonyl compounds having 2(3H)-benzazolonic heterocycles as PPARgamma agonists

A series of 1,3-dicarbonyl compounds having 2(3H)-benzazolonic heterocycles has been synthesized and tested for PPARgamma agonist activity. SAR were developed and revealed that 6-acyl-2(3H)-benzothiazolone derivatives with 1,3-dicarbonyl group were the most potent. IP administration of compound 22 exhibited comparable levels of glucose and triglyceride correction to PO administration of rosiglitazone in the ob/ob mouse studies.     

Characterization of Bglu3, a mouse fasting glucose locus, and identification of Apcs as an underlying candidate gene

Bglu3 is a quantitative trait locus for fasting glucose on distal chromosome 1 identified in an intercross between C57BL/6 (B6) and C3H/HeJ (C3H) apolipoprotein E-deficient (apoE(-/-)) mice. This locus was subsequently replicated in two separate mouse intercrosses. The objective of this study was to characterize Bglu3 through construction and analysis of a congenic strain and identify underlying candidate genes. Congenic mice were constructed by introgressing a genomic region harboring Bglu3 from C3H.apoE(-/-) into B6.apoE(-/-) mice. Mice were started with a Western diet at 6 wk of age and maintained on the diet for 12 wk. Gene expression in the liver was analyzed by microarrays. Congenic mice had significantly higher fasting glucose levels and developed more significant glucose intolerance compared with B6.apoE(-/-) mice on the Western diet. Microarray analysis revealed 336 genes to be differentially expressed in the liver of congenic mice. Further pathway analysis suggested a role for acute phase response signaling in regulating glucose intolerance. Apcs, encoding an acute phase response protein serum amyloid P (SAP), is located underneath the linkage peak of Bglu3. Multiple single nucleotide polymorphisms between B6 and C3H mice were detected within and surrounding Apcs. Apcs expression in the liver was significantly higher in congenic and C3H mice compared with B6 mice. The Western diet consumption led to a gradual rise in plasma SAP levels, which was accompanied by rising fasting glucose in both B6 and C3H apoE(-/-) mice. Expression of C3H Apcs in B6.apoE(-/-) mice aggravated glucose intolerance. Bglu3 is confirmed to be a locus affecting diabetes susceptibility, and Apcs is a probable candidate gene.     

Effects of atherogenic diet consumption on lipoproteins in mouse strains C57BL/6 and C3H

Inbred mouse strains C57BL/6J (B6) (susceptible) and C3H/HeJ (C3H) (resistant) differ in atherosclerosis susceptibility due to a single gene, Ath-1. Plasma lipoproteins from female mice fed chow or an atherogenic diet displayed strain differences in lipoprotein particle sizes and apolipoprotein (apo) composition. High density lipoprotein (HDL) particle sizes were 9.5 +/- 0.1 nm for B6 and 10.2 +/- 0.1 nm for C3H. No major HDL particle size subclasses were observed. Plasma HDL level in the B6 strain was reduced by the atherogenic diet consumption while the HDL level in the resistant C3H mice was unaffected. The reduction in HDL in the B6 strain was associated with decreases in HDL apolipoproteins A-I(-34%) and A-II(-60%). The HDL apoC content in mice fed chow was two-fold higher in C3H than B6. Lipoproteins containing apolipoprotein B (VLDL, IDL, LDL) shifted from a preponderance of the B-100 (chow diet) to a preponderance of the B-48 (atherogenic diet). The LDL-particle size distribution was strain-specific with the chow diet but not genetically associated with the Ath-1 gene. In both strains on each diet, apolipoprotein E was largely distributed in the VLDL, LDL, and HDL fractions. The B6 strain became sixfold elevated in total lipoprotein E content which in the C3H strain was not significantly affected by diet. However, the C3H LDL apoE content was reduced. On both diets, the C3H strain exhibited apolipoprotein E levels comparable to the atherogenic diet-induced levels of the B6 mice.     

Proteomic analysis of diet-induced hypercholesterolemic mice

We report here a proteomic analysis of differentially expressed liver proteins of both C57BL/6J (B6, atherosclerosis-susceptible strain) and C3H/HeJ mice (C3H, atherosclerosis-resistant strain), which were fed either control or a high-fat enriched atherogenic diet for eight weeks. We observed differential patterns of plasma lipids between the two strains when both were fed atherogenic diets. That is, although low density lipoprotein cholesterol level was highly elevated in both, the levels of total cholesterol and triglyceride in B6 mice were much lower than those in C3H mice when they were fed atherogenic diets. However, the high density lipoprotein cholesterol level was increased in the latter but decreased in the former. Histopathological observation revealed that more prominent lipid droplets were present in B6 mice than in C3H mice, when they were maintained on the atherogenic diets. Proteomic analysis of liver tissues of these two strains showed that a total of 30 proteins were significantly changed in the livers obtained from both strains after being fed the atherogenic diet. Of these, 14 protein spots including carbonic anhydrase III, senescence marker protein 30 and selenium binding protein 2 were differentially changed only in B6 mice, which was also confirmed in part by Western blotting. An additional 16 protein spots including glutathione S-transferase subclass, apolipoprotein E and chaperonin proteins were changed in both strains. We also identified 28 proteins that were differentially expressed in the livers of both B6 and C3H mice, regardless of diet feeding condition. Of these, 4 protein spots in B6 mice and 11 protein spots in C3H mice were up-regulated. Thirteen strain specific protein spots including antioxidant protein 2, apolipoprotein E and apolipoprotein A-I were also detected in different positions in two-dimensional electrophoresis. These results suggest a clear distinction in differential expression of oxidative stress proteins and lipid metabolism related proteins between the two strains in response to atherogenic diet feeding, which might account for their difference in susceptibility to atherogenesis.     

Neointimal formation in two apolipoprotein E-deficient mouse strains with different atherosclerosis susceptibility

C57BL/6 (B6) and C3H/HeJ (C3H) are two commonly used mouse strains that differ markedly in atherosclerosis susceptibility. In this study, we determined plaque formation after removal of the endothelium in the two strains carrying the mutant apolipoprotein E gene (apoE(-/-)). At 10 weeks of age, male B6.apoE(-/-) and C3H.apoE(-/-) mice underwent endothelial denudation of the left common carotid artery. Two weeks after injury, B6.apoE(-/-) mice developed significantly larger neointimal lesions in the vessel than their C3H.apoE(-/-) counterparts, although they had comparable plasma cholesterol levels on a chow diet. Feeding of a Western diet aggravated lesion formation in both strains, but the increase was more dramatic in B6.apoE(-/-) mice than in C3H.apoE(-/-) mice. Immunohistochemical and histological analyses demonstrated the presence of macrophage foam cells in neointimal lesions. We then compared neointimal growth in F1 mice reconstituted with bone marrow from B6.apoE(-/-) and C3H.apoE(-/-) mice. No significant lesions were observed 2 weeks after endothelial denudation in the mice reconstituted with bone marrow from either donor. Thus, these data indicate that foam cell formation contributes to neointimal growth in the hyperlipidemic apoE(-/-) model and that neither endothelial cells nor blood cells alone explain the dramatic difference between B6 and C3H mice in plaque formation.     

Synthetic low and high fat diets for the study of atherosclerosis in the mouse

Diets currently used to produce atherosclerotic lesions in mice are often undefined and cause accumulation of fat in the liver and gallstone formation. Therefore, synthetic low and high fat diets of known composition were formulated in this study. A synthetic diet containing 50% sucrose, 15% cocoa butter, 1% cholesterol, and 0.5% sodium cholate was found to produce a depression in high density lipoprotein cholesterol (HDL-C) and an elevation of very low density lipoprotein (VLDL) and low density lipoprotein cholesterol (LDL-C) in the atherosclerosis-susceptible strain, C57BL/6J. This diet was able to consistently produce aortic lesions and led to a decrease in liver damage and gallstone formation. The synthetic low fat diet did not produce HDL-C levels as high as those found in mice fed chow, but resulted in similar VLDL/LDL-C levels. Lipoprotein and apolipoprotein parameters were compared in C57BL/6J and the atherosclerosis-resistant strain, C3H/HeJ, consuming the synthetic low fat or high fat diets. As reported earlier, when consuming a high fat diet C57BL/6J mice have significantly lower HDL-C and apoA-I levels than C3H/HeJ mice. Further analysis shows that the molar ratio of plasma HDL-C to apoA-I is significantly lower in C57BL/6J mice, suggesting that HDL in the susceptible strain has a lower cholesterol-carrying capacity. This conclusion is consistent with the observation that the HDL particle size is smaller for C57BL/6J mice than for C3H/HeJ. Both strains increased their apoE levels when fed the synthetic high fat diet, but C3H/HeJ mice had higher levels of apoE on both diets. The major response to consumption of the high fat diet for both strains was an increase in apoB-48 from 5 micrograms/ml on a low fat diet to 54 and 109 micrograms/ml for C57BL/6J and C3H/HeJ, respectively. ApoB-100 showed minimal response to the high fat diet. The defined high fat diet can be used to study atherosclerosis in the mouse since it produces aortic lesions but reduces or eliminates other pathological changes such as gallstone formation and liver damage.     

Dietary fat saturation produces lipid modifications in peritoneal macrophages of mouse

We investigated the effects of a saturated fat diet on mice lipid metabolism in resident peritoneal macrophages. Male C57BL/6 mice were weaned at 21 days of age and assigned to either the experimental diet, containing coconut oil (COCO diet), or the control diet, containing soybean oil as fat source. Fat content of each diet was 15% (w/w). Mice were fed for 6 weeks until sacrifice. In plasma of mice fed the COCO diet, the concentration of triglyceride, total cholesterol, HLD- and (LDL+VLDL)-cholesterol, and thiobarbituric acid-reactive substances (TBARS) increased, without changes in phospholipid concentration, compared with the controls. In macrophages of COCO-fed mice, the concentration of total (TC), free and esterified cholesterol, triglyceride, phospholipid (P) and TBARS increased, while the TC/P ratio did not change. The phospholipid compositions showed an increase of phosphatidylcholine and phosphatidylserine + phosphadytilinositol, a decrease of phosphatidylethanolamine, and no change in phosphatidylglycerol. (3)H(2)O incorporation into triglyceride and phospholipid fractions of macrophages increased, while its incorporation into free cholesterol decreased. Incorporation of [(3)H]cholesterol into macrophages of COCO-fed mice and the fraction of [(3)H]cholesterol ester increased. COCO diet produced an increase in myrystic, palmitic and palmitoleic acids proportion, a decrease in linoleic and arachidonic acids and no changes in stearic and oleic acids, compared with the control. Also, a higher relative percentage of saturated fatty acid and a decrease in unsaturation index (p <0.001) were observed in macrophages of COCO-fed mice. These results indicate that the COCO-diet, high in saturated fatty acids, alters the lipid metabolism and fatty acid composition of macrophages and produces a significant degree of oxidative stress.     

Comparison of immune responsiveness in mice after single or multiple donor-specific transfusions

Immune responsiveness was compared in B6AF1 mice after one, two, three, or four donor-specific DBA/2 blood transfusions (DST). Ten days after the last transfusion, the spleen cells of transfused mice were assayed for direct lymphocyte-mediated cytotoxicity, for the ability to respond in mixed lymphocyte culture (MLC) and cell-mediated lymphocytotoxic (CML) assays to DBA/2 and C3H/He antigens, and for the ability to inhibit the MLC and CML response of normal B6AF1 to DBA/2 and C3H/He antigens. Immune responsiveness was also tested in B6AF1 2 to 80 days after a single DBA/2 DST. The MLC response of transfused mice was specifically suppressed to the blood donor after both single and multiple transfusions. The CML response to DBA/2 was suppressed after a single DST, but returned to normal after multiple transfusions. Spleen cells from transfused mice did not inhibit the MLC response of normal B6AF1 mice to DBA/2 or C3H/He antigens after one or two transfusions regardless of time tested, but were able to inhibit the response to both stimulators after three or more transfusions. The MLC response remained specifically suppressed to the blood donor for as long as 80 days after a single DST, while the CML response was suppressed up to 50 days after transfusion, but had returned to normal by 80 days.     

cis-acting determinants of basal and lipid-regulated apolipoprotein A-IV expression in mice

The levels of apolipoprotein A-IV (apoA-IV) mRNA are regulated by dietary lipid in the liver of both the mouse and rat. Thirteen different inbred mouse strains were fed a high lipid diet, and the effect on apoA-IV liver mRNA levels was examined. It was found that each strain responded in one of two ways. Mice of four strains had higher liver apoA-IV mRNA levels as compared with syngeneic mice fed a normal chow diet. Mice of the other nine strains had decreased liver apoA-IV mRNA levels as compared with syngeneic mice fed a normal chow diet. Using F1 hybrids between mice from BALB/c, C3H, and C57BL/6 and between 129 and C57BL/6, as well as recombinant inbred strains derived from a cross between BALB/c and C57BL/6, we have shown that both the normal level of liver apoA-IV mRNA in the chow-fed mice and the lipid-dependent regulation of apoA-IV mRNA levels are controlled by cis-acting genetic elements. The apoA-IV mRNA levels in mice fed a normal diet varied dramatically among strains, with the largest difference (90-fold) being between the 129/J inbred strain and the C57BL/6J strain. In addition, we have examined the expression of apoA-IV during mouse development. ApoA-IV mRNA is expressed early in mouse liver (16 days postcoitum), whereas others have shown previously that rat liver apoA-IV mRNA is undetectable until 14 days after birth. ApoA-IV mRNA levels in the intestine and apoA-I mRNA levels in the liver and intestine, by contrast, mirror the pattern seen in the rat.     

Single-bulb garlic oil regulates toll-like receptors and Nrf2 cross-talk and IL-17 production in mice fed with high-fat diet

The present study aimed to evaluate the effect of single-bulb garlic oil (SGO) on toll-like receptors 3 and 4 (TLR3 and TLR 4) and nuclear erythroid factor-like 2 (Nrf2) signaling pathway resulted from a high-fat diet and its underlying mechanism. Twenty-four Balb/c mice allocated into six groups: 1) N: mice fed with standard chow; 2) HFD: mice fed a high-fat diet for 45 days without any treatment; 3) HFD + Simv: mice fed a high-fat diet for 45 days and treated with simvastatin; 4–6) HFD + SGO 100, 200, 400 (mice fed a high-fat diet for 45 days and treated with single-bulb garlic oil at dose: 100, 200, and 400 mg/kg body weight for 30 days), respectively. At the end of treatment, spleen and hepar were isolated. The flow cytometry analysis was performed to analyze the relative number of nrf2, superoxide dismutase (SOD), malondialdehyde (MDA), TLR3, TLR4 and interleukin (IL-17). The results showed that HFD induction significantly reduced Nrf-2 and antioxidant enzyme levels. Furthermore, HFD induction increased TLR3 and TLR4 signaling and IL-17 production. Interestingly, 200 mg/kg BW of SGO increased the relative number Nrf-2 followed by SOD and HO-1 elevation at a dose of 100 mg/kg BW. SGO100 notably decrease the relative number of TLR3 (CD11b⁺TLR3⁺) and TLR4 (CD11b⁺TLR4⁺). The production of IL-17 by CD4 and CD8 were also reduced after receiving SGO at 200 mg/kg BW. This study suggests that the protective effect of SGO treatment on HFD mice was achieved by modulating TLR-Nrf2 cross-talks and decreasing IL-17 production. Our findings support a potential beneficial role of SGO for treating metabolic disease caused by a high-fat diet.     

Comparative study on high fat diet-induced 4-hydroxy-2E-nonenal adducts in the hippocampal CA1 region of C57BL/6N and C3H/HeN mice

In the present study, we investigated the influences of a high fat diet (HD) fed for 12 weeks, on lipid peroxidation and antioxidant enzyme using 4-hydroxy-2E-nonenal (HNE)-modified proteins (HNE-mp) and Cu,Zn-superoxide dismutase (SOD1) in the hippocampal CA1 region (CA1) in C57BL/6N and C3H/HeN mice. Body weights and body weight gains were significantly higher in HD fed C57BL/6N mice than in low fat diet (LD) fed C57BL/6N and LD or HD fed C3H/HeN mice. In the HD fed C57BL/6N and C3H/HeN mice, HNE-mp immunoreactivity and protein levels were much higher than in the LD fed C57BL/6N or C3H/HeN mice. In particular, HNE-mp immunoreactivity and protein levels in HD fed C57BL/6N mice was higher than that in the HD fed C3H/HeN mice. SOD1 immunoreaction was detected in the non-pyramidal cells of C57BL/6N mice, while in the C3H/HeN mice SOD1 immunoreaction was observed in CA1 pyramidal cells. The SOD1 immunoreactivity in the LD fed C57BL/6N and C3H/HeN mice was slightly, but not significantly decreased compared to that in the HD fed C57BL/6N and C3H/HeN mice, respectively. In addition, ionized calcium-binding adapter molecule 1 (Iba-1) immunoreactive microglia in the HD fed C57BL/6N showed hypertrophy of cytoplasm, which is the characteristics of activated microglia. These results suggest that HD fed C57BL/6N mice are more susceptible to lipid peroxidation in the CA1 than in LD fed C57BL/6N and LD or HD fed C3H/HeN mice without any differences of SOD1 expression. In Koo Hwang and Il Yong Kim have contributed equally to this article.     

A common polygenic basis for quinine and PROP avoidance in mice

Inbred strains of mice (Mus musculus) differ greatly in ability to taste various bitter compounds. For some compounds, the differences result from allelic variation at a single locus. However, segregation patterns incompatible with monogenic inheritance have been found for quinine avoidance. The Soa bitter sensitivity locus exerts some influence on this phenotype, but an unknown number of other loci also contribute. Relative avoidance patterns for quinine sulfate in panels of naive inbred strains resembled avoidance patterns for 6-n-propyl-2- thiouracil (PROP), suggesting a common genetic basis. In particular, C57BL/6J mice strongly avoided both 0.1 mM quinine sulfate and 1 mM PROP in two-bottle preference tests, whereas C3H/HeJ mice were indifferent to both. Therefore, 12 BXH/Ty recombinant inbred strains, derived from these strains, were tested with both solutions to begin identification of the unknown bitter loci. Naive mice were tested for four consecutive days with each compound (order counterbalanced). Some BXH/Ty strain means resembled those of the parent strains, but others were intermediate. This indicated recombination among loci affecting avoidance, and therefore polygenic inheritance. The strain means were highly correlated across compounds (r = 0.98), suggesting that the same polygenes controlled both phenotypes. The BXH/Ty means for both compounds were then compared with the strain genotypes at 212 chromosome position markers distributed throughout the genome. Eight markers on five chromosomes (3, 6, 7, 8 and 9) yielded significant correlations. Six of the markers were correlated with both phenotypes, again suggesting common polygenic inheritance. The marker with the highest correlation was Prp, tightly linked to Soa on chromosome 6. The correlated marker regions likely contain quantitative trait loci affecting bitter avoidance. The phenotypic similarity of PROP to quinine, rather than to phenylthiourea, apparently stemming from a common polygenic basis, indicates a difference between mice and humans in gustatory organization related to bitters.      

Peroxide sensitivity of endothelin responses in coronary artery smooth muscle: ETA vs. ETB pathways

The aim of this study was to investigate the effect of pyridoxine (Vitamine B6) deficiency on the immunological response of BALB/c mice infected with the parasite T. spiralis. Specific anti-parasite IgM and IgG immunoglobulins were detected by ELISA method in the serum of treated animals at different periods for 60 days post infection.Vitamin B6-deficiency was induced in two separate groups of mice by either (1) maintaining the mice on a Vitamin B6-deficient synthetic pellet diet for 40 days before infection, or (2) by daily intraperitoneal injection of 8 ×105 M/100 g of 4-Deoxypyridoxine (4-DPD), a potent antagonist of Vitamin B6 for 20 days prior to infection. These two groups of mice were then injected with 100 larvae (L1-T. spiralis) per os.Parasite burdens in the mice were observed by light microscopy. Cysts were present in the diaphragms of the mice after 60 days post-infection. Parasite specific IgG, as well as IgG. levels were determined in the sera of infected mice fed a normal diet. These levels were found to be lower in the 4-DPD-treated mice compared to the untreated mice. The inhibition started from the 10th day and continued to the 60th day, and in the 4-DPD treated group the inhibition initiated after 24 h to 60 days. IgM level also was depressed by 4-DPD, starting from 24 h after injection of the compound. In mice fed Vitamin B6-deficient diets the levels of IgG were lower than in mice fed normal diets.These results show that BALB/c mice infected with T. spiralis and fed either a Vitamin B6-deficient diet or a diet which included the Vitamin B6-antagonist, 4-DPD, both influence the course of IgG, IgGI and IgM production.     

Methionine excess in diet induces acute lethal hepatitis in mice lacking cystathionine γ-lyase, an animal model of cystathioninuria

Physiological roles of the transsulfuration pathway have been recognized by its contribution to the synthesis of cytoprotective cysteine metabolites, such as glutathione, taurine/hypotaurine, and hydrogen sulfide (H(2)S), whereas its roles in protecting against methionine toxicity remained to be clarified. This study aimed at revealing these roles by analyzing high-methionine diet-fed transsulfuration-defective cystathionine γ-lyase-deficient (Cth(-/-)) mice. Wild-type and Cth(-/-) mice were fed a standard diet (1 × Met: 0.44%) or a high-methionine diet (3 × Met or 6 × Met), and hepatic conditions were monitored by serum biochemistry and histology. Metabolome analysis was performed for methionine derivatives using capillary electrophoresis- or liquid chromatography-mass spectrometry and sulfur-detecting gas chromatography. The 6 × Met-fed Cth(-/-) (not 1 × Met-fed Cth(-/-) or 6 × Met-fed wild type) mice displayed acute hepatitis, which was characterized by markedly elevated levels of serum alanine/aspartate aminotransferases and serum/hepatic lipid peroxidation, inflammatory cell infiltration, and hepatocyte ballooning; thereafter, they died of gastrointestinal bleeding due to coagulation factor deficiency. After 1 week on 6 × Met, blood levels of ammonia/homocysteine and hepatic levels of methanethiol/3-methylthiopropionate (a methionine transamination product/methanethiol precursor) became significantly higher in Cth(-/-) mice than in wild-type mice. Although hepatic levels of methionine sulfoxide became higher in 6 × Met-fed wild-type mice and Cth(-/-) mice, those of glutathione, taurine/hypotaurine, and H(2)S became lower and serum levels of homocysteine became much higher in 6 × Met-fed Cth(-/-) mice than in wild-type mice. Thus, transsulfuration plays a critical role in the detoxification of excessive methionine by circumventing aberrant accumulation of its toxic transamination metabolites, including ammonia, methanethiol, and 3-methylthiopropionate, in addition to synthesizing cysteine-derived antioxidants to counteract accumulated pro-oxidants such as methionine sulfoxide and homocysteine.     

Taenia taeniaeformis: early inflammatory response around developing metacestodes in the liver of resistant and susceptible mice I. Identification of leukocyte response with monoclonal antibodies

Female BALB/cJ (resistant), C3H/HeJ (intermediate resistant), and C3H/HeDub (susceptible) inbred mice, 4-5 wk old, were infected with Taenia taeniaeformis. Liver sections were stained by an immunoperoxidase technique (avidin-biotin complex, ABC) for the differentiation antigens Lyt-1, Lyt-2, Mac-1, Mac-2, Mac-3, and B220. Binding of ABC to the cytoplasm of hepatocytes around the developing parasite was observed at 4 days postinfection (PI) in all 3 strains of mice, persisting in BALB/cJ and C3H/HeJ liver sections at 5 and 6 days PI, suggesting the presence of high concentrations of biotin, a fatty acid synthesis mediator. Two cell populations were labeled with B220 monoclonal antibodies: lymphocytes and polymorphonuclear (PMN) cells. At 4 days PI the number of labeled PMN cells peaked in infected C3H/HeJ and BALB/cJ mice; however a low number of PMN cells were labeled in infected C3H/HeDub mice. Few lymphocytes bound the B220 antibody in either BALB/cJ, C3H/HeJ, or C3H/HeDub infected mice. The number of Mac-1+ cells detected in infected C3H/HeJ and BALB/cJ liver sections were similar whereas fewer Mac-1+ cells were present in infected C3H/HeDub mice. Mac-2+ cells appeared in high numbers around the growing parasite at 5 and 6 days PI in the liver of C3H/HeDub mice, but not in the liver of BALB/cJ mice. Mac-3+ cells followed a similar pattern to that of the cell population defined by Mac-2. Few Lyt-1+ and Lyt-2+ cells were detected around the parasite site in the 3 strains of mice.(ABSTRACT TRUNCATED AT 250 WORDS)     

Prevention of Cyclophosphamide-induced Accelerated Diabetes in the NOD Mouse by Nicotinamide or a Soy Protein-based Infant Formula

Spontaneous diabetes in the NOD mouse can be prevented by nicotinamide or by an infant formula diet in which the protein source is replaced with casein hydrolysate (Pregestimil) or soy protein (Prosobee). NOD mice maintained on the standard diet (chow and water) and given cyclophosphamide (Cy) at day 95 develop accelerated and synchronised diabetes within 14 days. Here, we compared the ability of oral nicotinamide or Prosobee, either given alone or concurrently, from weaning, in preventing diabetes in the Cy model. The resulting insulitis and the expression of intra-islet inducible nitric oxide synthase (iNOS) were examined at days 0, 4, 7, 11 and 14 following Cy administration. Intra-islet CD4 and CD8 cells and macrophages were also enumerated at day 11. In mice given the standard diet and injected with Cy at day 95 (group 5), diabetes developed in 7/11 mice, 14 days later. Mice exposed to oral nicotinamide (group 2), Prosobee (group 3) or both (group 4), did not develop the disease during this period and until a further 30 days (p = 0.03). In mice exposed to the standard diet and without Cy treatment (group 1) the insulitis scores increased slowly until day 11 and then declined slightly at day 14 whereas mice exposed to the same diet but given Cy at day 95, showed a sharp decline at day 4 followed by a rapid increase between day 7–14. However, in mice given either nicotinamide, Prosobee or both, the insulitis scores at most time-points were generally lower than in Cy-teated animals on the standard diet. In the latter group, CD4 and CD8 cells and macrophages were also higher at day 11 than all other 4 groups (CD4: p < 0.05; CD8: p < 0.05; macrophages: p < 0.0001). The number of iNOS labelled cells increased progressively in mice on the standard diet and given Cy and were significantly higher at days 4, 7 and 11 than in the 3 dietary groups. Thus, oral nicotinamide or Prosobee, either alone or together, prevents Cy induced diabetes in the NOD mouse. The protective diets suppress Cyinduced intra-islet immune cell influx and iNOS expression.     

C57BL/6J小鼠在构建2型糖尿病模型中体重和非空腹血糖浓度的异常变化

由北京市一实验动物生产单位购入近交系C57BL/6J(B6)和封闭群ICR(3周龄)小鼠,分别以高脂饲料、高脂饲料-3%果糖饮水(实验组)和常规饲料(对照组)喂养6周,实验组腹腔注射链脲佐菌素(STZ,100mg/kg体重),然后以相应饲料继续喂养4周。每周测定小鼠体重,于注射STZ前和注射后每周测定非空腹血糖浓度。研究显示,无论是否补充果糖饮水,B6对照组体重显著高于实验组,而相应周龄的ICR小鼠,实验组体重显著高于对照组。两品系小鼠实验组间体重无差异。注射STZ后,B6实验组血糖浓度均没有达到糖尿病小鼠非空腹血糖浓度的成模标准(11mmol/L),而ICR实验组血糖浓度均达到并超过糖尿病小鼠非空腹血糖浓度的成模标准。研究表明,无论补充果糖与否,ICR小鼠均能成功建模,而B6小鼠建模均失败。因此,ICR小鼠仍是目前应用高脂饲料-STZ联合诱导2型糖尿病模型中经济、有效的候选动物,而B6小鼠在体重和血糖浓度上的异常表现很可能是其遗传背景变化的结果,这尚需进一步研究证实。     

Preservation of liver protein synthesis during dietary leucine deprivation occurs at the expense of skeletal muscle mass in mice deleted for eIF2 kinase GCN2

In eukaryotic cells, amino acid depletion reduces translation by a mechanism involving phosphorylation of eukaryotic initiation factor-2 (eIF2). Herein we describe that mice lacking the eIF2 kinase, general control nonderepressible 2 (GCN2) fail to alter the phosphorylation of this initiation factor in liver, and are moribund in response to dietary leucine restriction. Wild-type (GCN2(+/+)) and two strains of GCN2 null (GCN2(-/-)) mice were provided a nutritionally complete diet or a diet devoid of leucine or glycine for 1 h or 6 days. In wild-type mice, dietary leucine restriction resulted in loss of body weight and liver mass, yet mice remained healthy. In contrast, a significant proportion of GCN2(-/-) mice died within 6 days of the leucine-deficient diet. Protein synthesis in wild-type livers was decreased concomitant with increased phosphorylation of eIF2 and decreased phosphorylation of 4E-BP1 and S6K1, translation regulators controlled nutritionally by mammalian target of rapamycin. Whereas translation in the liver was decreased independent of GCN2 activity in mice fed a leucine-free diet for 1 h, protein synthesis in GCN2(-/-) mice at day 6 was enhanced to levels measured in mice fed the complete diet. Interestingly, in addition to a block in eIF2 phosphorylation, phosphorylation of 4E-BP1 and S6K1 was not decreased in GCN2(-/-) mice deprived of leucine for 6 days. This suggests that GCN2 activity can also contribute to nutritional regulation of the mammalian target of rapamycin pathway. As a result of the absence of these translation inhibitory signals, liver weights were preserved and instead, skeletal muscle mass was reduced in GCN2(-/-) mice fed a leucine-free diet. This study indicates that loss of GCN2 eIF2 kinase activity shifts the normal maintenance of protein mass away from skeletal muscle to provide substrate for continued hepatic translation.     

Variation in Type 2 Diabetes-Related Phenotypes among Apolipoprotein E-Deficient Mouse Strains

We recently have found that apolipoprotein E-deficient (Apoe^-/-) mice with the C57BL/6 background develop type 2 diabetes when fed a Western diet for 12 weeks. In the present study we constructed multiple Apoe^-/- mouse strains to find diabetes-related phenotyptic variations that might be linked to atherosclerosis development. Evaluation of both early and advanced lesion formation in aortic root revealed that C57BL/6, SWR/J, and SM/J Apoe^-/- mice were susceptible to atherosclerosis and that C3H/HeJ and BALB/cJ Apoe^-/- mice were relatively resistant. On a chow diet, fasting plasma glucose varied among strains with C3H/HeJ having the highest (171.1 ± 9.7 mg/dl) and BALB/cJ the lowest level (104.0 ± 6.6 mg/dl). On a Western diet, fasting plasma glucose rose significantly in all strains, with C57BL/6, C3H/HeJ and SWR/J exceeding 250 mg/dl. BALB/cJ and C3H/HeJ were more tolerant to glucose loading than the other 3 strains. C57BL/6 was sensitive to insulin while other strains were not. Non-fasting blood glucose was significantly lower in C3H/HeJ and BALB/cJ than C57BL/6, SM/J, and SWR/J. Glucose loading induced the 1st and the 2nd phase of insulin secretion in BALB/cJ, but the 2nd phase was not observed in other strains. Morphological analysis showed that BALB/cJ had the largest islet area (1,421,493 ± 61,244 μm²) and C57BL/6 had the smallest one (747,635 ± 41,798 μm²). This study has demonstrated strain-specific variations in the metabolic and atherosclerotic phenotypes, thus laying the basis for future genetic characterization.