Buffalo Strain Rats Research Articles

Effects of massage on the expression of proangiogenic markers in rat skin.

Massage is a physiotherapeutic treatment, commonly used in both therapy and restoration of normal body functions. The aim of this work was to determine the effects of skin massage on stimulating the expression of angiogenesis-initiating factors, i.e. VEGF-A, FGF-2 (bFGF) and CD34 and on skin regeneration processes. The study was conducted on 48 Buffalo strain rats, randomly divided into two groups. In the first group (M, the massaged group), massage was applied five times a week for 7 weeks. In the second study group (C, the control group), the massage was omitted. Massage consisted of spiral movements at the plantar surface of skin for 5 min on each rear extremity. The gene expression of proangiogenic factors, including VEGF-A, FGF-2, CD34 at the mRNA level was determined using real-time PCR. Immunohistochemistry was performed on paraffin sections of rat skin to determine VEGF-A, FGF-2 CD34 and Ki-67expression. An increase in mRNA expression in the skin of the rat's rear extremity for VEGF-A and FGF-2 in the first week of the experiment was shown in the M group compared with the control rats. The upregulation of CD34 mRNA expression was also observed in the M group. We observed positive correlations between VEGF-A mRNA expression and the expression of mRNA for FGF-2 and CD34, as well as correlation between the expression of mRNA for FGF-2 and CD34. The immunohistochemical expression of VEGF-A, FGF-2 and CD34 was at a much lower level in the skin of control rats relative to the skin of massaged animals. Moreover, significantly higher immunoreactivity was shown for nuclear protein Ki-67 in epidermal cells in the M group compared with the C group. Rat skin massage increased the expression of the main angiogenesis-stimulating factors and the proliferative activity of epidermal cells, which can stimulate skin regeneration and tissue repairing processes.

The protective action of tocopherol and acetylsalicylic acid on the behavior of rats treated with dioxins.

Dioxins contribute to neurological disorders in humans and animals, causing also neurological disorders in offspring during prenatal and postnatal periods. These compounds significantly affect the development of the central nervous system (CNS) structures, which results in behavioral changes. Tocopherol (TCP) and acetylsalicylic acid (ASA) may provide protective measures to reduce the inflammatory effects in the CNS associated with free radicals generated by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), thus contributing to the reduction of the negative effects of dioxin. The main objective of this study was to determine the influence of dioxin on rats and their behavioral functions, and to ascertain whether a combined administration of TCP and ASA to rats treated with TCDD shows the possibility of potential protective effect on the functioning of the CNS. Experiments were performed on 75 female and 12 male Buffalo strain rats, which are offspring of females from particular study groups. TCDD was used in the experiments, TCP and ASA were administered orally every day for 3 weeks. Animals were subjected to behavioral testing: the tail and swimming tests. During the observation of the offspring of both sexes born to females exposed to TCDD, males did not demonstrate any attempt to swim, whereas in females, the immobility time was significantly extended. Assessing the response times from the tail test in the animals treated with dioxins in relation to the control group, it was demonstrated that the response time was extended in the 3rd measurement in both females and males. Dioxin is characterized by neurotoxic effect causing behavioral disorders associated with prolonged response times. The use of TCP after the administration of dioxins causes a significant reduction and improvement of reflex response times. In contrast, ASA reduces the reflex response times also in the offspring of females exposed to TCDD and ASA.

P-629 - Deficiency of T-kininogen in the plasma of Buffalo strain rat.

P-629 - Deficiency of T-kininogen in the plasma of Buffalo strain rat.

The synthetic 87–99 peptide of myelin basic protein is encephalitogenic in Buffalo rats

A synthetic peptide corresponding to residues 87–99 (S87–99) of myelin basic protein (BP) induced the proliferation of an encephalitogenic, BP-specific T cell line selected in vitro from inbred Buffalo-strain rats (RT1 b). Active immunization with guinea pig (GP)-BP or S87–99 in complete Freund's adjuvant (CFA) and intraverous pertussigen induced acute experimental autoimmune encephalomyelitis (EAE) 10–12 days after immunization. Fifty percent of recovered rats developed a single relapse 17–21 days after immunization. T lymphocytes selected in vitro with S87–99 transferred acute, non-relapsing EAE into naive recipients. Histological examination during acute EAE revealed foci of inflammatory cells associated with demyelination in the spinal cords and peripheral nerve roots. Thus, as in several other rodent strains, the 87–99 region of BP is antigenic and encephalitogenic in the inbred Buffalo-strain rat. Additionally, the 87–99 sequence of GP-BP was predicted to be antigenic by two different methods. These suggest that the 87–99 region of BP, which is highly conserved among mammalian species, may be widely encephalitogenic due to antigenic-intrinsic properties.

Myelin basic protein-specific T cells induce demyelinating experimental autoimmune encephalomyelitis in buffalo rats

This is the first description of acute demyelinating experimental autoimmune encephalomyelitis (EAE) induced in rats by myelin basic protein (BP)-specific T lymphocytes without the administration of demyelinating antibodies. BP-specific T cell lines were selected from inbred Buffalo-strain rats (Rt-1b) following techniques used to develop similar lines from Lewis rats (Rt-1l). Unlike those of Lewis rats, the spinal cords of Buffalo rats with T cell line-mediated EAE had prominent perivascular demyelination associated with mononuclear inflammation. Like Lewis rat lines. Buffalo rat BP-specific T cell lines transferred acute, non-relapsing EAE into syngeneic recipients, demonstrating that demyelination in passive acute EAE can occur without subsequent clinical relapses.

Methionine metabolism in the Buffalo rat following ethanol feeding.

Earlier studies have demonstrated that the Buffalo strain rat may have a defect in the process of methylneogenesis or lack the methyl-transfer enzyme system in the liver involved in methionine biosynthesis. The results of this study demonstrate that the enzyme systems responsible for methionine formation are present in the Buffalo rat and that these systems respond to ethanol feeding in a manner similar to that already shown in the Sprague-Dawley animal. These findings suggest that the previously described defect in methionine metabolism of the Buffalo rat may lie within the mechanism of methylneogenesis.

The effect of T cell subset depletion on autoimmune thyroiditis in the Buffalo strain rat

The aim of these experiments was to analyse the functional roles of phenotypically defined T cells from Buffalo strain rats with immunisation or neonatal thymectomy-induced autoimmune thyroiditis. Rats were depleted either of CD8-positive T cells by administration of the Ox8 monoclonal antibody or of activated T cells by administration of low-dose cyclosporin A (Cs A) with an anti-IL-2 receptor monoclonal antibody (ART-18), and the effects on subsequent disease assessed. Even though animals were not completely depleted of Ox8 cells, immunisation-induced thyroiditis was enhanced by Ox8 treatment, whereas thyroglobulin antibodies were reduced compared with controls. Subtherapeutic doses of either Cs A or ART-18 alone had little effect on thymectomy-induced thyroiditis, in contrast to Cs A and ART-18 in conjunction, which prevented disease developing. These results suggest important roles for CD8-positive and IL-2 receptor-bearing T cells in experimental autoimmune thyroiditis.

Minimal dose and time protection by lindane (γ‐isomer of 1,2,3,4,5,6 hexachlorocyclohexane) against liver tumors induced by aflatoxin b1

This study was carried out in order to investigate the minimal exposure to lindane (LD, 99.72% gamma isomer of 1,2,3,4,5,6 hexachlorocyclohexane), a chlorinated hydrocarbon insecticide, required to protect against liver tumor induced by aflatoxin B1 (AFB1). Materials fed to Buffalo strain rats were as follows: LD 100 ppm; AFB1 1 ppm, LD 100 ppm plus AFB1 1 ppm; and control basal diet. The experimental animals were clinically observed and then serially killed at 1, 3, 5, 10, 15 and 82 weeks. Concurrent administration of LD with AFB1 to rats for more than 3 weeks totally inhibited the incidence of AFB1-induced hepatocellular carcinomas by week 82. Only 1 of 20 rats (5%) fed the same regimen for 1 week developed liver tumors. Animals given 1 ppm AFB1 singly for 15 weeks had a high liver tumor incidence (31.5%). No animals developed liver tumors in LD-treated and control groups. LD may inhibit AFB1-induced liver tumors by stimulating hepatic metabolism and excretion of AFB1 so that less carcinogen is available to liver tissue.

Mechanisms of differential strain sensitivity in gastric carcinogenesis.

The genetically‐controlled, distinct sensitivity of different rat strains to N‐methyl‐N′‐nitro‐N‐nitrosoguanidine (MNNG)‐induced cancer of the glandular stomach and duodenum was investigated. MNNG is activated through thiols, and the thiol content of the glandular stomach, duodenum, and liver of the BN rat tended to be slightly, but not significantly higher than that of the Wistar, Sprague‐Dawley, Lewis, and Buffalo rats. The levels of the DNA repair system, O6‐alkylguanine transferase (AGT), in sensitive Wistar strain rats had values similar to those in resistant Buffalo strain rats. Administration of 80 mg/liter of MNNG in the drinking water for six weeks up to the time of tissue collection yielded the same AGT levels. Of all the parameters examined to account for genetically‐mediated sensitivity to gastrointestinal cancer induction, namely, N‐denitrosation, thiol activation, AGT‐related DNA repair, and cell duplication rates, the latter yielded the best association, although these factors acting together may be involved.

The effect of iodide depletion and supplementation in the Buffalo strain rat.

We have investigated the effect of excess iodide alone, following iodide depletion or in conjunction with a mild thyroid insult (trypan blue) in Buffalo strain rats, which are genetically susceptible to experimental autoimmune thyroiditis. In all three cases a high iodine diet led to enhanced thyroglobulin antibody production, usually accompanied by worsening of the severity of thyroiditis. Moreover, the administration of a normal iodine diet after iodide depletion resulted in thyroglobulin antibody formation. These results provide further support for a role for dietary iodine in modulating experimental autoimmune thyroiditis with implications for human thyroid autoimmunity.

Sequential analysis of experimental autoimmune thyroiditis induced by neonatal thymectomy in the Buffalo strain rat

We have studied the evolution of thyroiditis induced by neonatal thymectomy in Buffalo strain rats, with particular emphasis on the thyroid lymphocytic infiltrate. The earliest change was increased endothelial Ia expression, and infiltration of the thyroid at 5 weeks by ED1- and ED2-positive macrophages and B and T cells. The T cells comprised equal numbers of Ox 8 (T cytotoxic/suppressor)- and W3/25 (T helper)-positive cells. Ia-positive thyroid follicular cells were seen only in the presence of a T-cell infiltrate. Thyroglobulin antibody levels, thyroid weight, thyroid follicular cell Ia expression and lymphocytic infiltration of the thyroid were maximal between Weeks 12 and 24 and impairment of macrophage function by injection of silica at this time produced amelioration of disease. The thyroid weight returned to control levels by Week 34 and Ia expression by thyroid cells disappeared. Circulating Ox 8-positive T cells were reduced between Weeks 12 and 24 and by Week 34 had returned to control levels. Our results indicate that the mononuclear infiltrate precedes thyroid follicular cell Ia expression and macrophages play an important role in perpetuating thyroiditis. Recovery from disease is accompanied by a return to normal in circulating suppressor/cytotoxic T cells.

Multiple forms of growth inhibitors secreted from cultured rat liver cells: purification and characterization.

It was found that a non-tumorigenic epithelial cell line from the liver of a Buffalo-strain rat (BRL) secreted into the culture medium various inhibitors of the growth of BRL and RSV-BRL (tumorigenic BRL transformed by infection of Rous sarcoma virus). The secreted inhibitors were classified into two types: one inhibited the growth of BRL to a greater extent than that of RSV-BRL (non-tumorigenic BRL growth inhibitor, NGI), and the other, vice versa (tumorigenic BRL growth inhibitor, TGI). Two NGI (NGI-I and NGI-II) and two TGI (TGI-I and TGI-II) were highly purified from the serum-free conditioned medium. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis without 2-mercaptoethanol, NGI-I and II gave protein bands with molecular weights (Mr) of 56,000 and 21,000, respectively. TGI-I and II gave a band that migrated faster than bromophenol blue marker dye, but they did not pass through an ultrafiltration membrane with an Mr cutoff of 5,000. In the presence of a reducing reagent, only NGI-II showed a decrease of Mr, from 21,000 to 11,000. NGI and TGI showed 50% growth inhibition with BRL and RSV-BRL, respectively, at 5-15 ng/ml in the medium containing 10% fetal calf serum. NGI and TGI all were stable to 1 M acetic acid (pH 2.3) and 6 M urea, but labile to 5 mM dithiothreitol or trypsin. Of the eight cell lines tested, NGI-I was most effective on BRL, NGI-II on BRL and HSC-3 (human tongue squamous carcinoma), and both TGI-I and II on RSV-BRL.

Selective modulation of nucleotide levels in rat liver and hepatomas by high-orotate or arginine-deficient diets and by carbamoylating agents

Transplanted Morris hepatomas in Buffalo-strain rats were found to be resistant to the changes in ribonucleotide levels in rat liver caused by a high-orotate diet or an arginine-deficient diet. The increase in UTP levels and decrease in ATP levels seen in the livers of rats on a 1%-orotate diet were less marked in the livers of BUB- and DBA-strain mice on this diet. Although the changes were less than in rat liver, there was a 2–3-fold increase in UTP concentration in the livers of mice on the high-orotate diet. However, there was a similar response in nucleotide levels in the two species when the animals were maintained on an arginine-deficient diet, and there was a greater than 10-fold increase in the UTP level in the livers of both rats and mice. These diets had much less effect on the levels of deoxyribonucleotides than of ribonucleotides. In contrast to the insensitivity of hepatomas to dietary modulation of nucleotide levels, treatment of hepatoma-bearing rats with carbamoylating agents (sodium cyanate and 2-chloroethyl isocyanate) caused decreases in the levels of nucleotides in the tumors which were generally greater than in host livers. For example, 2-chloroethyl isocyanate depressed ATP levels in the Morris hepatomas 5123C and 20 under conditions in which there was no significant effect on host liver ATP. The data revealed selective modulation of nucleotide levels in normal and neoplastic liver which may be achieved by either dietary modification or drug treatment.

Abnormal Prothrombin in the Plasma of Rats Carrying Hepatic Tumors

Vitamin K is required for the posttranslational formation of gamma-carboxyglutamyl residues in a number of plasma clotting factors. Interference with vitamin K action results in the appearance of abnormal (des-gamma-carboxy) forms of prothrombin in human plasma. Vitamin K-sufficient patients with primary hepatocellular carcinoma also secrete significant quantities of abnormal prothrombin; this response has now been studied in a rat model. Normal Buffalo strain rats had 9 micrograms/mL of circulating plasma abnormal prothrombin, whereas Buffalo strain rats carrying the transplantable Morris hepatoma tumor no. 7777 had 33 micrograms/mL at 3 weeks after transplant. Vitamin K-dependent carboxylase activity was normal in the liver of these rats, but very low in the tumor tissue. Rats carrying Morris hepatoma tumors no. 9618A and 5123D did not secrete significant amounts of abnormal prothrombin. Carboxylase activity in these tumors was 15 times that of the 7777 tumor. The data suggest that the secretion of abnormal prothrombin by hepatocellular tumors is the result of normal expression of the prothrombin gene by those tumors and a failure of the tumor to express the carboxylase gene.

Abnormal prothrombin in the plasma of rats carrying hepatic tumors

Vitamin K is required for the posttranslational formation of gamma- carboxyglutamyl residues in a number of plasma clotting factors. Interference with vitamin K action results in the appearance of abnormal (des-gamma-carboxy) forms of prothrombin in human plasma. Vitamin K-sufficient patients with primary hepatocellular carcinoma also secrete significant quantities of abnormal prothrombin; this response has now been studied in a rat model. Normal Buffalo strain rats had 9 micrograms/mL of circulating plasma abnormal prothrombin, whereas Buffalo strain rats carrying the transplantable Morris hepatoma tumor no. 7777 had 33 micrograms/mL at 3 weeks after transplant. Vitamin K-dependent carboxylase activity was normal in the liver of these rats, but very low in the tumor tissue. Rats carrying Morris hepatoma tumors no. 9618A and 5123D did not secrete significant amounts of abnormal prothrombin. Carboxylase activity in these tumors was 15 times that of the 7777 tumor. The data suggest that the secretion of abnormal prothrombin by hepatocellular tumors is the result of normal expression of the prothrombin gene by those tumors and a failure of the tumor to express the carboxylase gene.

Lymphoid abnormalities in rats with adjuvant-induced arthritis. I. Mitogen responsiveness and lymphokine synthesis.

Lewis rats injected in the hind paw with Mycobacterium butyricum develop a severe polyarthritis which shares certain features in common with rheumatoid arthritis in man. Spleen and peripheral blood mononuclear cells from rats with this form of arthritic disease proliferate poorly in vitro in response to concanavalin A (con A), phytohaemagglutinin (PHA), and pokeweed mitogen (PWM). The splenic hyporesponsiveness appears within four days of M. butyricum injection (three to five days prior to the development of detectable arthritis), reaches a peak 16-22 days following injection, and persists for at least 40 days. Buffalo strain rats injected with M. butyricum do not develop arthritis, and their spleen cells respond normally to con A, PHA, and PWM. In response to lipopolysaccharide (LPS) the synthesis of interleukin 1 (IL-1) by spleen or peritoneal macrophages from arthritic Lewis rats equalled or exceeded that of macrophages from normal rats. In contrast splenic T cells from arthritic rats produced reduced amounts of interleukin 2 (IL-2; T cell growth factor) in response to stimulation with PHA or con A. Moreover, con-A-activated spleen cells from arthritic rats failed to bind IL-2 and to respond to this growth factor with increased 3H-TdR uptake as did normal spleen cells. In-vitro treatment of 'arthritic' cells with 10(-5) M indomethacin did not restore to normal their reduced mitogen responsiveness, and spleen cells from normal and arthritic rats were equally sensitive to the inhibitory effects of prostaglandin E2 on con-A-induced proliferative responses. These results indicate that peripheral lymphoid function is compromised in rats with adjuvant-induced arthritis and that this functional deficit is mediated by aberrant synthesis of and response to IL-2 by T cells of arthritic animals.

Analysis of the stearoyl-CoA desaturase system in the Morris hepatoma 7288C and 7288CTC.

The microsomal stearoyl-CoA desaturase system was examined in both the Morris hepatoma 7288CTC, maintained in the host Buffalo strain rat, and the Morris hepatoma 7288C, maintained in tissue culture. In vitro examination shows the stearoyl-CoA desaturase system to be similar in the 2 tissues. Both show extremely low overall stearoyl-CoA desaturase activity, having 4% and 8% of normal liver values respectively. Examination of the electron transport system showed both tissues have decreased electron transport components cytochrome b5 and cytochrome b5 reductase. Particularly noticeable were the extremely low levels of cytochrome b5 (2% compared with normal liver). Microsomes from both tissues showed a decreased ability to reduce an artificial electron acceptor, cytochrome c. With the low levels of cytochrome b5 observed in these tissues, the low levels of overall desaturase activity may be caused by lack of terminal enzyme, lack of sufficient cytochrome b5, or both. Analysis of the stearoyl-CoA desaturase system in cultured hepatoma cells suggests that these cells are similar to the host-grown tumor in this respect and may be used as a model in further examinations of the stearoyl-CoA desaturase system.

Enhancing effects of dimethylnitrosamine on aflatoxin B hepatocarcinogenesis in rats.

In a study of possible enhancing effects of dimethylnitrosamine (DMN) on aflatoxin B1 (AFB1) hepatocarcinogenesis, male Buffalo strain rats were fed diets containing 1 ppm AFB1, 25 ppm DMN, and a combination of 1 ppm AFB1 and 25 ppm DMN (AFB1 + DMN). The diets were replaced by chow pellets after 6 months, and animals were killed 3, 6, 9 and 12 months after the onset of the experiment. In the untreated control group animals were free of hepatocellular carcinoma but the treated groups fed AFB1, DMN and AFB1 plus DMN developed hepatic lesions ranging from multiple cysts, altered cell foci and neoplastic nodules to hepatocellular carcinomas. Hepatocellular carcinomas developed in 79%, 45% and 5% of rats fed AFB1 plus DMN, AFB1 and DMN respectively at the end of the experiment. Multiple cysts were also found in all periods in animals fed AFB1 plus DMN, whereas rats fed AFB1 and DMN separately developed a few multiple cysts by the end of the experiment. These findings suggest that DMN potentiates the hepatocarcinogenesis induced by AFB1 in rats.

Interactions of tumor-associated fetal antigens with rat histocompatibility antigens

The physical interactions of fetal antigens (tumor-associated fetal antigens; TAFA-I, TAFA-II, and TAFA-III) with rat histocompatibility antigens were studied. TAFA-I and TAFA-III are present on syngeneic (NBR) and allogeneic (Fisher F344, Wistar Furth, and White Buffalo) rat embryo fibroblasts and on tumor cells. TAFA-II was found only on NBR (syngeneic) rat embryo fibroblasts and on NBR tumor cells. Antibody-blocking experiments were used to examine the fetal and histocompatibility antigen topography on cell membranes of tumor cells transformed by chemical and viral carcinogens. Precoating the tumor cells with alloantisera inhibited the subsequent adsorption of anti-NBR embryo, anti-TAFA-I, and anti-TAFA-III sera, but not anti-TAFA-II serum. Immunofluorescent cocapping experiments indicated that TAFA-I and TAFA-III, as well as other fetal antigens found on cells from 14-day gestation NBR embryos cocap with histocompatibility antigens when tested on syngeneic embryo fibroblasts and on sarcoma cells. TAFA-I cocapped with White Buffalo (Buf) strain rat histocompatibility antigens on herpes simplex Type II virus-transformed cells. The specificity of the TAFA-histocompatibility interactions was confirmed by demonstrating that the different anti-TAFA sera did not have contaminating antiviral antigen specificity; and also that these interactions did not occur on normal adult fibroblasts or spleen cells.

Morphologic and Biologic Correlation of Hyperplastic and Neoplastic Renal Lesions Occurring in Buffalo and Fischer Strain Rats Ingesting N-4-(4'-Fluorobiphenyl)Acetamide

Hyperplastic and neoplastic lesions of the kidney induced in inbred Buffalo and Fisher strain rats with 0.04% N-4-(4'-fluorobiphenyl) acetamide were transplanted s.c. to rats of the same strain. Hyperplastic renal lesions ("areas" or nodules) did not survive and grow. Carcinomas of the kidney grew and killed the animals. Growth was related to the size and the degree of differentiation of the carcinoma. It is concluded that the histologic pattern of hyperplastic and neoplastic lesions of the kidney can be correlated with the results obtained on transplantation.