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PubMed1994

Rat T cell response to superantigens. I. V beta-restricted clonal deletion of rat T cells differentiating in rat-->mouse chimeras.

T cells of mice display V beta-specific reactivity for a spectrum of mouse mammary tumor virus (Mtv) antigens; confrontation with these antigens during ontogeny causes substantial "holes" in the T cell repertoire. Since endogenous Mtv antigens are rare in other species, the question arises whether V beta-specific recognition of Mtv antigens is unique to mice. To examine this question, rat T cells were allowed to differentiate from stem cells in severe combined immunodeficiency (SCID) mice. These rat-->mouse xenochimeras were prepared under a variety of conditions. The results show that rat T cells are strongly reactive to mouse Mtv antigens, both in terms of tolerogenicity and immunogenicity. In fact, the V beta specificity of rat and mouse T cells for Mtv antigens is almost indistinguishable.

Animals↗

PubMed1974

Levels of rat cellular RNA homologous to either Kirsten sarcoma virus or rat type-C virus in cell lines derived from Osborne-Mendel rats.

DNA transcripts from V-NRK and RT21c rat type-C viruses were found to differ in their sequence homology to Kirsten and Harvey sarcoma viruses. V-NRK DNA transcripts consistently had homology to Kirsten and Harvey sarcoma virus, whereas RT21c DNA transcripts did not. To explain the differences, the nucleic acids and structural proteins of the two type-C viruses, released from each of two cell lines derived from Osborne-Mendel rats, were analyzed by molecular hybridization and competition radioimmunoassays. The p30 and p12 structural proteins of the two viruses were found to be highly related immunologically. In the V-NRK virus preparation, two sets of distinct RNA sequences were found in approximately equal amounts. One set is homologous to Ki-SV, and the other homologous to RT21c. In contrast, the RT21c virus preparation was found to contain a different ratio of these sequences. In this case the RT21c-like RNA sequences are present in 100-fold excess as compared to the additional Ki-SV specific sequences. Both NRK and RT21c cells contain in their DNA the full complement of Ki-SV homologous sequences, but NRK cells express much higher levels of these Ki-SV sequences in their RNA. These additional sequences, not homologous to RT21c, which are detected in uninfected NRK cellular RNA or V-NRK rat virus, could also be detected in the 60-70S RNA from a Moloney mouse type-C virus released from the NRK cells infected with the Moloney type-C virus. The results suggest that type-C viruses released from NRK cells incorporate species of RNA present in NRK cells which are homologous to Kirsten and Harvey sarcoma viruses. Either these sequences are of cellular origin, or rat cells contain two endogenous viruses with completely distinct nucleic acid sequences.

Animals↗

PubMed1992

Changes in colonic mucins of germfree rats in response to the introduction of a "normal" rat microbial flora. Rat colonic mucin.

In order to determine the influence of bacterial colonization on amount and composition of colonic mucins, germfree male AS/Ztm rats were colonized with a rat specific intestinal flora for different times (2, 7, 14, 21, 28, 35, 120 days). The amount of colonic mucins was determined by gel filtration on Sepharose CL-4B; the relative amount of acidic mucins was calculated after ion exchange chromatography. In addition, cecal weight and dry matter of feces were monitored. While germfree and SPF rats revealed similar amounts of colonic mucins (7.0 vs. 7.2 mg mucin/300 g body weight), the initial phase of association was characterized by considerably decreasing values. After four weeks of association, the total amount of colonic mucins had almost equalized in the two groups. The amount of acidic mucins, having decreased during the first three weeks of colonization, rendered values comparable to the SPF mucins after four months of adaptation. Cecomegaly in germfree rats disappeared within the first two days, while solidification of the intestinal content occurred within four months. Mucin losses during initial phase of association are attributed 1. to the disappearance of the cecal mucin pool, and 2. to the mucin degrading activity of some bacterial strains known to be present in the intestinal flora. Further development is conducted by a stimulation of mucin secretion, described to follow the colonization. The initially increased secretion of neutral mucins is attributed to a pronounced release of immature mucin glycoproteins, while the shift to more acidic mucins is considered to result from stimulated secretion as well as from a selective bacterial degradation of neutral mucin components.

Animals↗

PubMed1987

The primary structure of rat ribosomal protein S12. The relationship of rat S12 to other ribosomal proteins and a correlation of the amino acid sequences of rat and yeast ribosomal proteins.

The covalent structure of the rat 40 S ribosomal subunit protein S12 was determined from the sequence of amino acids in tryptic, chymotryptic, thermolytic, and cyanogen bromide peptides and inferred from the sequence of nucleotides in a recombinant cDNA. Rat ribosomal protein S12 contains 129 amino acids and has a molecular weight of 14,120. The amino acid sequences of a number of ribosomal proteins appear to be related to rat S12. These include spinach chloroplast L7, Escherichia coli S5, Nicotiana tabacum chloroplast S18, and Bacillus stearothermophilus S12, and perhaps others. In addition, there are two sequences, 26 and 18 amino acids in length, in rat S12 that may be related to segments of the same number of residues in ribosomal proteins from a number of species. These, and other results, reinforce the suggestion that ribosomal proteins form an extended family.

Amino Acid Sequence↗

PubMed1980

Age and blood pressure related changes in cholesterol esterase activity and cholesterol content in aortas of stroke prone spontaneously hypertensive rats, spontaneously hypertensive rats and normotensive Wistar Kyoto rats.

Changes in aortic lipolytic enzyme activities (cholesterol esterase and lipoprotein lipase) and acid phosphatase activity during aging were investigated in three strains of rats with different blood pressures; stroke prone spontaneously hypertensive rats (SHRSP), spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto (WKR). The blood pressures of male, 7 month old animals, was 234 (SHRSP), 173 (SHR) and 128 (WKR) mmHg. The cholesterol esterase activity markedly decreased with age in the aortas of SHRSP, SHR and normotensive WKR rats, while acid phosphatase activity decreased only slightly, if at all, and lipoprotein lipase activity remained unchanged. This effect was enhanced by increasing blood pressure in SHRSP, SHR and WKR. The total aortic cholesterol content increased significantly with hypertension in a inverse relation with cholesterol esterase activity. These results suggest that cholesterol deposition in aged arteries is, at least partialy, ascribable to an age-related decrease in cholesterol esterase, and that hypertension aggravates the deposition of arterial cholesterol by accelerating the age-related decrease in aortic cholesterol esterase activity.

Acid Phosphatase↗

PubMed2004

Effect of sarpogrelate hydrochloride, a 5-HT2 blocker, on insulin resistance in Otsuka Long-Evans Tokushima fatty rats (OLETF rats), a type 2 diabetic rat model.

5-hydroxytryptamine (5-HT) is closely related to pathogenesis of angiopathy in type 2 diabetes. Acute and chronic effects of sarpogrelate hydrochloride (sarpogrelate), a 5-HT2 blocker, on glucose tolerance and insulin resistance were examined. Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type 2 diabetes, were randomly assigned to 2 groups; those with 30 mg/kg BW/d sarpogrelate treatment of 4 weeks (HTB group) and without (control group). The glucose infusion rate was significantly increased in the HTB group compared with the control group. The blood glucose levels after oral glucose tolerance test and levels of plasma insulin and lipids were significantly lower in the HTB group than in the control group. To investigate mechanism of the improvement by sarpogrelate, acute effect of 5-HT and its blocking effect by sarpogrelate on blood levels of glucose were examined in 25-week-old Sprague-Dawley rats. Blood glucose levels were significantly increased by administration of 5-HT. This increase was reversed by pretreatment of sarpogrelate. A plasma adrenaline level also rose significantly by injection of the 5-HT and was prevented by pretreatment of sarpogrelate. These results indicate that sarpogrelate improves insulin resistance in type 2 diabetic rats.

Animals↗

PubMed1985

Characterization of a growth-inhibiting protein present in rat serum that exerts a differential effect on in vitro growth of nonmalignant rat liver cells when compared with Rous sarcoma virus-transformed rat liver cells.

We have previously reported the transformation by Rous sarcoma virus of a cloned epithelial cell line (BRL) established from Buffalo rat liver by H. Coon. The nontransformed (BRL) and transformed (RSV-BRL) cells grew at comparable rates in culture, whereas only the transformed cells were tumorigenic in vivo. We report here on the existence in rat and mouse sera of a growth inhibitor for the nontransformed BRL cells. The transformed BRL cells (RSV-BRL) were insensitive to this inhibitor. The inhibitory activity was not prominent in sera from other species of animals tested except for rabbit; this serum inhibited the growth of RSV-BRL cells more strongly than that of BRL cells. The growth inhibitor was partially purified from rat serum. It is a protein free of lipid and has a molecular weight of about 220 000. The inhibitor could be separated into three components of pI 4.6, 5.2 (major) and 5.6 by isoelectric electrophoresis.

Animals↗

PubMed1989

Binding of bovine, ovine, porcine, canine, and rat plasminogen to rat hepatocytes and rat C6 glioma cells in vitro.

Plasminogens were purified by affinity chromatography from bovine, ovine, porcine, canine, and rat plasma. The binding of each plasminogen to rat hepatocytes in primary culture and to rat C6 glioma cells was studied by radiodisplacement experiments. All of the plasminogens inhibited human 125I-[Glu1]plasminogen type 2 binding to specific cell surface receptors. The IC50 values were similar. These studies suggest conservation of the receptor recognition site in plasminogens across species lines.

Animals↗

PubMed1998

Regulation of rat hepatic cytochrome P450 expression by sterol biosynthesis inhibition: inhibitors of squalene synthase are potent inducers of CYP2B expression in primary cultured rat hepatocytes and rat liver.

The effects of treatment with squalestatin 1, a potent inhibitor of squalene synthase, the first committed enzyme of sterol biosynthesis, were examined on cytochrome P450 expression in primary cultured rat hepatocytes and rat liver. Incubation of cultured hepatocytes with squalestatin 1 caused marked accumulations (maximal elevations that were approximately 25-100% of phenobarbital-elicited increases) of CYP2B mRNA and immunoreactive protein but not of CYP1A, CYP3A, or CYP4A. Squalestatin 1 treatment increased CYP2B and 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA content in hepatocyte cultures with comparable potencies (ED50 = 5.0 and 18 nM, respectively), and significantly induced CYP2B (mRNA, immunoreactive protein, and pentoxyresorufin O-dealkylase activity) in the livers of treated rats, producing maximal increases at a dose of 25 mg/kg/day that were approximately 32-87% of phenobarbital-induced increases. Squalestatin 1 treatment induced both CYP2B1 and CYP2B2 and activated reporter gene expression in cultured hepatocytes transiently transfected with a plasmid containing approximately 2.4 kb of CYP2B1 gene 5'-flanking region or containing a previously described phenobarbital-responsive region. Coincubation of cultured hepatocytes with 25-hydroxycholesterol suppressed squalestatin 1-mediated CYP2B and 3-hydroxy-3-methylglutaryl coenzyme A mRNA induction with approximately the same potency. Treatment of cultures with SQ-34919, a structurally distinct squalene synthase inhibitor, produced the same selective CYP2B mRNA induction as did squalestatin 1. These results suggest that inhibition of hepatic sterol synthesis activates processes that culminate in increased CYP2B gene transcription.

Animals↗

PubMed1997

Expression of adrenomedullin (ADM) and its binding sites in the rat uterus: increased number of binding sites and ADM messenger ribonucleic acid in 20-day pregnant rats compared with nonpregnant rats.

RIA of nonpregnant rat uterus extracts showed 0.68 +/- 0.08 pmol/g adrenomedullin (ADM) and 3.23 +/- 0.08 pmol/g calcitonin gene-related peptide (CGRP). In the pregnant (20 days gestation) uterus, the ADM content was 0.90 +/- 0.17 pmol/g, and CGRP could not be detected. ADM messenger RNA was detected at high levels in the uterus, with a 1.8-fold increase in expression in pregnancy. Pharmacologically distinct binding sites for ADM (Bmax = 21 +/- 2 fmol/mg protein, dissociation constant = 80 +/- 6 pM), and CGRP (Bmax = 101 +/- 18 fmol/mg protein, dissociation constant = 140 +/- 20 pM) were identified in nonpregnant uterus. Competition for 125I[Tyr0]alphaCGRP binding was shown by both ADM and CGRP (8-37), whereas CGRP and CGRP (8-37) did not compete for 125I-ADM-binding sites. The density of the ADM-binding sites was 10 times greater in pregnant uterus (Bmax = 211 +/- 39 fmol/mg protein, P < 0.01) than nonpregnant uterus. CGRP receptor messenger RNA was identified in both nonpregnant and pregnant uteri. In isolated nonpregnant rat uteri, CGRP and ADM attenuated the contractile response to galanin by 77 +/- 10% and 57 +/- 10%, respectively. The responses to both CGRP and ADM were abolished by CGRP (8-37). These results demonstrate, for the first time, the presence of ADM and specific binding sites for both ADM and CGRP in the rat uterus.

Adrenomedullin↗

PubMed1986

Asialogangliosides as differentiation markers of rat erythropoietic and granulopoietic cells in rat bone marrow. Flow cytometric analysis of rat bone marrow cells using anti-asialoganglioside antibodies.

Flow cytometric analysis using anti-glycolipid antiserum was used on rat bone marrow cells to determine the relation between the glycolipid species expressed on cell surfaces and cell differentiation. Four kinds of antibodies against gangliotriaosylceramide (Gg3Cer), gangliotetraosylceramide (Gg4Cer), fucogangliotetraosylceramide (IV2 alpha Fuc-Gg4Cer) and IV3 alpha Gal-fucogangliotetraosylceramide (IV3 alpha GalIV2 alpha Fuc-Gg4Cer, blood group B lipid) were used. The cells sorted out by each anti-glycolipid antiserum were stained with May-Grünwald-Giemsa reagent and identified by microscopy. In the erythropoietic group, only polychromatic erythroblasts had these four glycolipids on their cell surfaces; none appeared on differentiated erythrocytes. These glycolipids were expressed during the early stages of immature granulocytes, especially in the promyelocyte and myelocyte stages of eosinophilic and neutrophilic granulocytes. Very limited populations of lymphocytes were sorted out as asialoganglioside-expressing cells. We concluded that asialogangliosides are useful differentiation markers for the erythropoietic and granulopoietic cells of rat bone marrow, and that anti-asialoganglioside antibody-flow cytometry is a very useful technique with which to isolate immature granulocytes and erythropoietic cells from rat bone marrow cells.

Animals↗

PubMed1985

Rat cytomegalovirus induces cellular purine and pyrimidine nucleoside kinases in rat embryo fibroblasts and TK- rat-2 cells. Correlations with the antiviral activity of Acyclovir.

Rat cytomegalovirus (RCMV) induces a cytosol thymidine kinase (TK) in G0-phase rat embryo fibroblasts (REF), but not in a TK deficient rat cell line (R-2), though virus titers in both cell types reached comparable levels. The results indicate that TK is neither virus-coded nor is required for a productive infection in R-2 cells. A deoxycytidine kinase (dCK) is induced in either growing or RCMV-infected REF and R-2 cells, suggesting that dCK is essential for both host-cell and viral DNA synthesis. A deoxyguanosine kinase (dGK) is detectable in low concentrations in either growing or G0-phase REF and R-2 cells suggesting that this enzyme is cell-cycle independent. In contrast, RCMV induces high persisting levels of dGK, particularly in R-2 cells, indicating that this enzyme is of crucial importance for viral DNA synthesis. By comparison of thermostabilities and electrophoretic mobilities (Rf for TK, dCK and dGK were 0.12; 0.97; and 0.54, respectively) the enzymes were found to be substrate specific but of cellular origin. In contrast to TK and dCK, only dGK is inhibited by Acyclovir (Ki = 320 microM). It is suggested that RCMV inducable dGK is an important enzyme determining the in vitro anti-CMV activity of Acyclovir.

Acyclovir↗

PubMed1984

Studies on the action of nystatin on cultured rat myocardial cells and cell membranes, isolated rat hearts, and intact rats.

The action of nystatin, a polyene antibiotic, was studied in rat myocardial cells, isolated rat hearts, and intact rats. Myocardial cells responded to 10 and 25 micrograms nystatin/ml with arrhythmias that could be minimized by elevated concentrations of K+ and Mg2+ or reversed by washing the cells. Similarly, the isolated heart responded to 100 micrograms nystatin/ml with arrhythmias that could be tempered by addition of elevated concentrations of K+ and Mg2+. The i.v. injection of the drug caused heart failure in intact animals at the 4-mg/kg dose level. At the subcellular level, nystatin made the myocardial cell membranes more rigid, as measured by electron spin resonance spectrometry. These findings indicate a parallel between physiocochemical changes caused by nystatin in the myocardial cell membrane and the biological changes caused by this drug in myocardial cells, isolated heart, and heart of the intact animal.

Animals↗

PubMed1991

CD4 rat x rat and mouse x rat T cell hybridomas produced by fusion of established T cell lines and clones to W/Fu (C58NT)D.

Previously, fusion of established T cell lines or clones has been claimed to be difficult. We now report our experiences in the fusion of both long term cultures of rat T cell clones and mouse T cell lines to rat W/Fu (C58NT)D. Upon fusion of rat T cell clones the hybrids obtained expressed antigen specificities identical to those of the parent clones. In addition, C58 was used for interspecies hybridisation of murine T cell lines. The specificity of intra- and inter-species hybrids was maintained by subcloning. We conclude that the C58 cell line can be used to generate continuously growing monoclonal T-cell reagents of sufficient stability using both intra- and inter-species hybridisation.

Animals↗

PubMed1977

Deoxyribonucleic acid and polyamine synthesis in rat ventral prostrate. Effects of age of the intact rat and androgen stimulation of the castrated rat with testosterone, 5 alpha-dihydrotestosterone and 5 alpha-androstane-3 beta, 17 beta-diol.

The relationship between polyamine synthesis, growth and secretion in vivo was examined in ventral prostates from: (a) intact rats aged 3-60 weeks; (b) animals castrated for 7 days before injection with 5 alpha-dihydrotestosterone (17 beta-hydroxy-5-alpha-androstan-3-one), testosterone and 5 alpha-androstane-3 beta, 17 beta-diol for up to 10 days; (c) rats injected with the 3 beta, 17 beta-diol immediately after castration. Ornithine decarboxylase activity and the concentrations of putrescine, spermidine and spermine were measured. DNA-synthetic activity was monitored by measuring [125I]iododoxyuridine incorporation. An enhanced spermidine/spermine molar ratio reflected increased activity of the prostate. The ratio was higher (greater than 2) in prostates from sexually immature animals, than in the intact adult (1.5), suggesting that the ratio was indicative of the proliferative activity of the tissue. However, in the androgen-stimulated castrated rat, enhanced spermidine/spermine ratios tended to correlate with hypertrophy and secretion. In both sets of experiments there was a linear relationship between protein and spermidine content. High spermidine/spermine molar ratios were the consequence of a relatively low rate of accumulation of spermine relative to spermidine and protein. The relationship between polyamine synthesis and DNA-synthetic activity was investigated in cultured prostate. A combination of insulin (3 mug/ml) and testosterone (0.1 muM caused a stimulatory response in the incorporation of [125I]iododeoxyuridine and in cell division, despite a depleted polyamine content and low ornithine decarboxylase activity in the cultured tissue.

Age Factors↗

PubMed1986

Differential implication of deoxyribonucleic acid methylation in rat prolactin and rat growth hormone gene expressions: a comparison between rat pituitary cell strains.

In order to assess the potential role of DNA methylation in the expression of rat PRL (rPRL) as compared to rat GH (rGH) gene, the cleavage patterns generated by the isoschizomeric restriction enzymes HpaII and MspI were examined in DNA isolated from rat pituitary cell lines producing either high levels of rPRL (GH3B6) or of rGH (GC) and in a stable variant cell strain which produces minute amounts of both hormones (GH3CDL cells). The rPRL and the rGH genes were found hypomethylated in GH3B6 and GC cells, respectively, whereas in GH3CDL cells both genes were methylated, indicating a correlation between the extent of gene methylation and the level of expression. However the use of 5-azacytidine (5-azaC), which decreases DNA methylation, suggested a variable importance of gene methylation in the control of rPRL and rGH gene expression. 5-AzaC was unable to increase rPRL production to a detectable level in GC cells, whereas the cytidine analog markedly increased rPRL production and rGH production in GH3CDL cells. Further analysis using GH3CDL cells showed that the extent of the 5-azaC-induced rPRL and rGH gene demethylation was consistent with the 5-azaC-induced increase of gene expressions. However, in these cells, the stimulation of rPRL and rGH production unexpectedly increased as a function of time elapsed after drug withdrawal. The maximal stimulation, 30-fold and 7-fold, respectively, was observed 3 weeks after a 60-h exposure to 5-azaC. This pattern suggests that other events are required for the full expression of rPRL and rGH genes in addition to their own demethylation.

Animals↗

PubMed1984

[Distribution, metabolism and excretion of 14C-MT-141 in rats. II. Distribution and excretion after multiple intravenous administration in male rats and after single intravenous administration in female rats].

The distribution and tissue accumulation of the radioactivity were studied in male rats after the multiple intravenous administration of 14C-MT-141. The distribution and the placental transfer were also studied using pregnant rats or lactating rats after the single intravenous administration of 14C-MT-141. The radioactive concentration in the fetus was low and the radioactivity was distributed almost uniformly through the fetus body. The peak time of the milk level was 2 hours after the administration and the radioactivity in milk decreased gradually thereafter. The milk levels decreased more slowly than the blood levels did. The blood level after the last dose administered daily for 7 days tended to decrease more slowly, when compared with the single administration. However the blood concentration at 48 hours after the last administration was less than 3 times as high as that after the single administration.

Animals↗

PubMed1983

Development of cerebral methionine-enkephalinergic neurons in rats: some difference in Wistar-Kyoto rats and spontaneously hypertensive rats.

Development of methionine-enkephalin (ME) and ME receptor binding in the embryonic and neonatal rat cerebral nuclei was defined quantitatively by immunocytofluorescent and microautoradiographic methods. On embryonic days 14 and 18, ME was localized in 10 of 83 nuclei particularly in the n. amygdaloideus centralis, n. periventricularis, n. supraopticus, n. interpeduncularis, n. suprachiasmaticus, n. arcuatus and n. ambiguus. ME receptor binding was distributed in the former 4 nuclei on embryonic day 14 and additional 5 nuclei on embryonic day 18. At the day of birth both levels markedly increased in these nuclei (2-3 times) and abruptly emerged in 65 out of 73 nuclei in which ME neurons were not detectable in embryonic nuclei. The abrupt appearance in most nuclei at birth probably regulates nociceptive and non-nociceptive stimuli at birth and in the neonatal period. Both levels attained their maximum at the postnatal day 7 and gradually declined thereafter. Among the perinatal period examined, ME immunoreactivity in the tractus spinalis nervi trigemini and ME receptor binding in the n. tractus spinalis nervi trigemini were markedly lower in both SHR neonates than in corresponding Wistar-Kyoto rats. Lowered levels in both areas of neonatal SHR may be involved in central hyperreactivity and preganglionic sympathetic activation of young SHR.

Aging↗