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Query: UMLS:C0155339 (Brown)
 12,436 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have investigated the potential of the inbred Brown Norway (BN) rat as a model for food allergy using two different antigens, ovalbumin (OA) and semi-skimmed milk (SSM). The use of milk-free diet prior to and during exposure to SSM was a key factor in the induction of sensitisation to milk proteins. Investigation of dose received and timing of administration identified a sensitisation regimen using 500 micrograms SSM injected i.p. together with 1 mg CGN (adjuvant) on days 0 and 7 as the optimum conditions for induction of reaginic antibody production. In this model milk proteins were less allergenic than OA as the amount of SSM required to induce sensitivity was 20-fold greater. Examination of antigen-specificity of the IgG and reaginic antibody responses to a range of proteins, present in SSM, showed that the BN rats were capable of recognising a similar profile of allergens as those recognised by milk sensitive humans. Lactoferrin which is present in low concentrations in milk proved as allergenic as the major proteins in milk, the caseins and beta-lactoglobulin. These studies have identified conditions for induction of sensitisation to milk proteins, and have shown the antibody specificity of the response to be similar to that in man. This suggests that the BN rat could provide the basis of a model for the investigation of allergic reactions to food.
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PMID:Assessment [correction of Asessment] of the brown Norway rat as a suitable model for the investigation of food allergy. 807 65

The Brown Norway (BN) rat was examined as a model for investigating factors that influence the development of food allergy. An antigen dose-response curve for the production of antigen-specific reaginic antibody (IgE) induced through the oral route was determined. Animals were dosed orally with 1.0, 2.5, 5.0, 7.5, 10.0 and 12.0 mg ovalbumin/ml (0.5 ml/100 g twice a week for 6 wk). To promote IgE production the adjuvant carrageenan was administered once a week by the i.p. route. The effect on oral sensitization of 1.5 mg Gypsophila sp. saponin/ml administered together with the antigen on oral sensitization was examined in animals treated with 2.5, 6.0 or 10.0 mg ovalbumin/ml. The number of animals producing antigen specific reaginic antibody in response to 2.5 mg ovalbumin/ml was significantly increased (P < 0.01) in the group that received saponin with 2.5 mg ovalbumin/ml. These studies indicate that the BN rat is a sensitive model for the investigation of allergic reactions to food and has the potential to determine the impact of other dietary factors on the development of oral sensitization.
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PMID:Brown Norway rat model of food allergy: effect of plant components on the development of oral sensitization. 860 94

The ability of saponins and glycoalkaloids to permeabilise the mammalian intestinal barrier has been previously demonstrated in vitro, leading to the hypothesis that membranolytic saponins may facilitate transfer to the tissues of otherwise excluded macromolecules. An enhanced uptake of, for instance, potentially allergenic species from the lumen is one of the factors that may affect the induction of food allergy, and its presentation in already sensitised individuals. In the experiments described here, an increase in the transmucosal uptake of the milk allergen beta-lactoglobulin (beta LG) was assessed in non-sensitised and sensitised Brown Norway rats in the presence of Gypsophila saponin. Isolated jejunal loops were exposed in vivo to either beta LG followed by saponin, saponin followed by beta LG or the two compounds simultaneously. Portal vein blood samples were collected and assayed for beta LG and rat mucosal mast cell protease (RCMP II) activity. Mucosal tissue was also examined histologically and assayed for histamine content. Sham-operated animals, exposed to physiological buffer alone, were included as controls and beta LG measurements corrected for this component which was negligible. No transfer of beta LG occurred in the absence of saponin in non-sensitised rats, whereas a significant enhancement was observed in the presence of saponin. beta LG was detected in the portal circulation of sensitised rats exposed to beta LG alone; however addition of saponin to the intestinal lumen further enhanced this uptake, possibly by an independent mechanism. Histological examination of the mucosal epithelium exposed to saponin revealed damage, especially at the villus tips. Mucosal histamine and serum RCMP II concentrations were consistent with the differences observed between sensitised and non-sensitised animals. It is concluded that exposure to food constituents capable of permeabilising the mucosal epithelium may increase the risk of sensitisation to dietary antigens.
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PMID:Effect of saponin on the transmucosal passage of beta-lactoglobulin across the proximal small intestine of normal and beta-lactoglobulin-sensitised rats. 905 1

Although several in vivo antigenicity assays using parenteral immunization are operational, no full validated enteral models are available to study food allergy and allergenicity of food proteins. To further validate a developed enteral Brown Norway (BN) rat food allergy model, systemic and local immune-mediated reactions were studied upon oral challenges. The animals were exposed to ovalbumin (OVA) by daily gavage dosing (1 mg OVA/rat/day) for 6 weeks, without the use of an adjuvant, or by intraperitoneal injections with OVA together with AL(OH)3. Subsequently, effects on breathing frequency, blood pressure, and gastrointestinal permeability were investigated upon an oral challenge with 10 to 100 mg OVA in vivo. In both parenterally and orally sensitized rats, an increase in gut permeability (increased passage of beta-lactoglobulin as bystander protein) was determined between 0.5 and 1 h after an oral OVA challenge was given. An oral challenge with OVA did not induce a clear effect on the respiratory system or blood pressure in the majority of the animals. However, some animals demonstrated a temporary decrease in breathing frequency or systolic blood pressure. Upon oral challenge with OVA of orally and parenterally sensitized animals, local effects were observed in all animals whereas systemic effects were observed at a low frequency, which reflects the situation in food allergic patients after an oral challenge. These studies show that the BN rat provides a suitable animal model to study oral sensitization to food proteins as well as immune-mediated effects after oral challenge with food proteins.
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PMID:Immune-mediated effects upon oral challenge of ovalbumin-sensitized Brown Norway rats: further characterization of a rat food allergy model. 1022 8

No adequate enteral sensitization models are available to study food allergy and allergenicity of food proteins. Using a previously described oral sensitization protocol to sensitize Brown Norway rats (BN) to food proteins, the influence of genetically-based strain-specific characteristics of the immune system on the outcome of oral sensitization studies was investigated. BN, Hooded Lister (HL), Piebald Virol Glaxo (PVG) and Wistar rats were daily administered 1 mg of ovalbumin (OVA) by gavage dosing for 42 days without the use of an adjuvants. The highest OVA-specific IgG responses were detected in the BN rats followed by Wistar, HL and PVG rats. OVA-specific IgE responses were only detectable in the BN rats. The cellular immune response was examined by determination of delayed-type hypersensitivity (DTH) reactions in the animals. The response was most pronounced in the HL and Wistar rats. PVG and BN rats showed comparable DTH responses but the responses were significantly weaker than those observed in HL and Wistar rats. It was concluded that the genetic make-up of different rat strains influences the outcome of oral sensitization studies. In addition, using the described oral sensitization protocol, the BN rat seems to be the most suitable strain for inducing oral sensitization.
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PMID:Humoral and cellular immune responses in different rat strains on oral exposure to ovalbumin. 1050 12

We developed an oral sensitization protocol for food proteins for the rat. Young Brown Norway (BN) rats were exposed to 1 mg ovalbumin (OVA) by daily gavage dosing for 42 days without the use of an adjuvant. OVA-specific IgE and IgG responses were determined by ELISA. On an oral challenge with OVA some clinical symptoms of food allergy-like effects on the respiratory system, blood pressure, and permeability of the gastrointestinal barrier were studied. In addition, BN rats were orally exposed to a total hen egg white protein (HEW) extract and cow's milk (CM) and the specificities of induced antibody responses were compared with the specificities of antibodies in sera from egg- and milk-allergic patients using immunoblotting. Animals orally exposed to the allergens developed specific IgE and IgG antibodies which recognized the same proteins compared with antibodies from egg- or CM-allergic patients. Among the various clinical symptoms of food allergy, gut permeability was increased after an oral challenge. In addition, some animals demonstrated a temporary decrease in breathing frequency or systolic blood pressure. The results obtained show that the Brown Norway rat is a suitable animal model for inducing specific IgG and IgE responses on daily intragastric dosing of OVA without the use of an adjuvant. Moreover, local immune-mediated effects on oral challenge are observed. The observation that enterally exposed BN rats and food-allergic patients demonstrate antibody responses to a comparable selection of proteins on exposure to different protein mixtures (HEW and CM) further supports the suitability of the BN rat as an animal model for food allergy research and for the study of the allergenicity of (novel) food proteins.
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PMID:An oral sensitization model in Brown Norway rats to screen for potential allergenicity of food proteins. 1052 41

For the safety evaluation of genetically engineered crops the potential allergenicity of the newly introduced protein(s) has become an important issue. There is, however, no universal and reliable test system for the evaluation of the allergenic potency of food products. The best known allergy assessment proposal is the careful stepwise process using the IFBC/ILSI decision tree. Unfortunately, the described tests are not always conclusive, especially if the gene source coding for the protein has no history of dietary use and/or an unknown history in terms of allergenicity. The further testing warranted should in particular be focused on the prediction of the sensitizing potential of the novel protein, for which animal models are considered to be needed. In this paper the results are summarized of a promising food allergy model developed in Brown Norway (BN) rats. The results demonstrate that BN rats can be sensitized orally to the various allergenic food proteins tested, resulting in significant antigen-specific IgE responses, without the use of adjuvants. Upon oral challenge of previously sensitized animals, local and systemic immune-mediated effects, such as increased gastrointestinal permeability and decreased breathing frequency and blood pressure, could also be observed.
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PMID:Determination of protein allergenicity: studies in rats. 1132 75

The risks associated with IgE-mediated food allergy highlight the need for methods to screen for potential food allergens. Clinical and immunological tests are available for the diagnosis of food allergy to known food allergens, but this does not extend to the evaluation, or prediction of allergenicity in novel foods. This category, includes foods produced using novel processes genetically modified (GM) foods, and foods that might be used as alternatives to traditional foods. Through the collation and analysis of the protein sequences of known allergens and their epitopes, it is possible to identify related groups which correlate with observed clinical cross-reactivities. 3-D modelling extends the use of sequence data and can be used to display eptiopes on the surface of a molecule. Experimental models support sequence analysis and 3-D modelling. Observed cross-reactivities can be examined by Western blots prepared from native 2-D gels of a whole food preparation (e.g. hazelnut, peanut), and common proteins identified. IgEs to novel proteins can be raised in Brown Norway rat (a high IgE responder strain) and the proteins tested in simulated digest to determine epitope stability. Using the CSL serum bank, epitope binding can be examined through the ability of an allergen to cross-link the high affinity IgE receptor and thereby release mediators using in vitro cell-based models. This range of methods, in combination with data mining, provides a variety of screening options for testing the potential of a novel food to be allergenic, which does not involve prior exposure to the consumer.
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PMID:Food allergy--towards predictive testing for novel foods. 1176 Nov 21

For the safety evaluation of genetically engineered crops, the potential allergenicity of the newly introduced protein(s) has become an important issue. There is, however, no universal and reliable test system for the evaluation of the allergic sensitizing ability of food proteins. Therefore, there is a growing interest in the development of animal models. This paper summarizes the results of a promising food allergy model developed in Brown Norway (BN) rats. The results demonstrate that BN rats can be sensitized via the relevant oral route of exposure. Daily gavage dosing of the animals with several food proteins, without the use of adjuvants, resulted in significant antigen-specific IgE responses. In addition, the profile of allergens recognized by the immune system of the BN rat, appeared comparable to the profile of allergens recognized by allergic humans. Besides oral sensitization, local and systemic immune-mediated effects, such as increased gastrointestinal permeability, decreased breathing frequency, and decreased blood pressure, could also be observed in the sensitized animals after an oral challenge. All together, these observations suggest that this BN rat model might provide a suitable animal model to study the allergenicity of food proteins in humans.
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PMID:Assessment of protein allergenicity: studies in brown norway rats. 1202 2

The need for widely accepted and validated animal models to test the potential allergenicity and potency of novel (biotechnology-derived) proteins has become an important issue for their safety evaluation. In this article, we summarize the results of the development of an oral sensitization protocol for food proteins in the rat. Young Brown Norway rats were exposed to either various purified allergenic proteins (e.g., ovalbumin, partly purified), a whole food (cow's milk), or total protein extracts (hen's egg white, peanut) by daily gavage dosing during 42 days without the use of an adjuvant. The results showed that Brown Norway rats can be sensitized orally to the various allergenic food proteins tested, resulting in antigen-specific immunoglobulin (Ig) G and IgE responses, without the use of adjuvants. Animals orally exposed to cow's milk or total protein extracts of egg white also developed specific IgE and IgG antibodies that recognized the same proteins compared with antibodies from patients allergic to egg white or cow's milk. We also studied local and systemic immune-mediated effects. In ovalbumin-sensitized rats, some clinical symptoms of food allergy were studied upon an oral challenge with ovalbumin. The results demonstrated that gut permeability was increased and that in some animals breathing frequency and systolic blood pressure were temporarily decreased. The results obtained show that the Brown Norway rat provides a suitable animal model for food allergy research and for the study of relative allergenicity of existing and novel food proteins.
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PMID:Assessment of the allergic potential of food protein extracts and proteins on oral application using the brown Norway rat model. 1257 12


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