Inbred Rats Research Articles

Abstract B153: sVEGFR-1 functionalized nanoparticles for diagnosis of cancer using magnetic resonance imaging.

Abstract Cancer is considered to be an important public health problem throughout the world. Early diagnosis of cancer and recurrent tumors are extremely important for reducing mortality rates and also for following up the response to treatment. The increased need of oxygen leads to new vascular structures in and around the tumor. The most important components of this angiogenic process are vascular endothelial growth factor (VEGF) and its receptors which are overexpressed in tumor cells. The aim of this study is to develop soluble VEGF receptor-1 (sVEGFR-1) functionalized iron oxide nanoparticles for diagnosis of early stages of tumors or metastases by MRI. A single dose of N-nitroso-N-methylurea (NMU) at a concentration of 50 mg/kg was injected to inbred rats intraperitoneally on the 21st day of their birth to create breast cancer. In this study, in vivo characteristics of functionalized nanoparticles were studied by comparing rats with tumors and the healthy controls. Approximately 70 days later, tumor formed rats were administered with nanoparticles functionalized with sVEGFR-1, intravenously and scanned with MRI. MR images were taken before the treatment with nanoparticles (0 minute), and at 30th and 60th minutes after treatment. The evaluation of MRI data revealed that the images of metastases were hypointense at 30th minute with respect to the 0 minute and 60th minute images (p<0.05). Nanoparticles were observed to localize at the tumoral regions and there were significant contrast intensity differences in rats with tumor. These results showed that our sVEGFR-1 functionalized nanoparticles were localized at tumoral regions including metastasis. This method can be useful in diagnosis of early tumors, metastasis, and recurrencies. Further molecular and histological studies are necessary to explain the efficacy of these nanoparticles for tumor diagnosis. Citation Information: Mol Cancer Ther 2013;12(11 Suppl):B153. Citation Format: Taner Ozgurtas, Fatih Yesildal, Fevzi Nuri Aydin, Melis Sardan, Gozde Uzunalli, Murat Kocaoglu, Ayse Begum Tekinay, Mustafa Ozgur Guler, Rukan Genc, Salih Deveci. sVEGFR-1 functionalized nanoparticles for diagnosis of cancer using magnetic resonance imaging. [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2013 Oct 19-23; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2013;12(11 Suppl):Abstract nr B153.

Obese Locus in WNIN/Obese Rat Maps on Chromosome 5 Upstream of Leptin Receptor

WNIN/Obese (WNIN/Ob) rat a new mutant model of metabolic syndrome was identified in 1996 from an inbred Wistar rat strain, WNIN. So far several papers are published on this model highlighting its physical, biochemical and metabolic traits. WNIN/Ob is leptin resistant with unaltered leptin or its receptor coding sequences - the two well-known candidate genes for obesity. Genotyping analysis of F2 progeny (raised from WNIN/Ob × Fisher - 344) in the present study localized the mutation to a recombinant region of 14.15cM on chromosome 5. This was further corroborated by QTL analysis for body weight, which narrowed this region to 4.43 cM with flanking markers D5Rat256 & D5Wox37. Interval mapping of body weight QTL shows that the LOD score peak maps upstream of leptin receptor and shows an additive effect suggesting this as a novel mutation and signifying the model as a valuable resource for studies on obesity and metabolic syndrome.

Anti-anxiety self-medication induced by incentive loss in rats

Ethanol can be used to ameliorate negative emotion in anxiety-inducing situations. Two experiments tested whether rats would increase preference for ethanol immediately after anxiogenic sessions of appetitive extinction. It was predicted that preference for ethanol would be greater in inbred Roman low-avoidance rats (RLA-I) than in inbred Roman high-avoidance rats (RHA-I), given previous research demonstrating that the former strain exhibits greater sensitivity to incentive loss. Experiment 1 used a consummatory extinction task (22-to-0% sucrose downshift), whereas Experiment 2 used an instrumental extinction task (12-to-0 pellet downshift). In both experiments, postsession ethanol consumption was higher in RLA-I rats than in RHA-I rats. No strain differences in ethanol preference were found after acquisition sessions or in groups given postsession access to water. Because ethanol is an anti-anxiety drug, the present results suggest that rats are capable of changing their consummatory behavior to correct for an aversive emotional state induced by incentive loss.

Retraction of “Derivation and Genetic Modification of Embryonic Stem Cells from Disease-Model Inbred Rat Strains”

<i>Retraction of</i> “Derivation and Genetic Modification of Embryonic Stem Cells from Disease-Model Inbred Rat Strains”

Human placental alkaline phosphatase as a tracking marker for bone marrow mesenchymal stem cells.

Currently, adult mesenchymal stem cells (MSCs) are being evaluated for a wide variety of therapeutic approaches. It has been suggested that MSCs possess regenerative properties when implanted or injected into damaged tissue. However, the efficacy of MSCs in several of the proposed treatments is still controversial. To further explore the therapeutic potential of these cells, it is necessary to trace the fate of individual donor or manipulated cells in the host organism. Recent studies from our lab showed that human placental alkaline phosphatase (hPLAP) is a marker with great potential for cell tracking. However, a potential concern related to this marker is its enzymatic activity, which might alter cell behavior and differentiation by hydrolyzing substrates in the extracellular space and thereby changing the cellular microenvironment. Therefore, the aim of this study was to characterize bone marrow MSCs (BMSCs) derived from hPLAP-transgenic inbred F344 rats (hPLAP-tg) in comparison to wild type (wt) BMSCs. Here, we show that BMSCs from wt and hPLAP-tg donors are indistinguishable in terms of cell morphology, viability, adhesion, immune phenotype, and proliferation as well as in their differentiation capacity over six passages. The expression of the hPLAP marker enzyme was not impaired by extensive in vitro cultivation, osteogenic, adipogenic, or chondrogenic differentiation, or seeding onto two- or three-dimensional biomaterials. Thus, our study underscores the utility of genetically labeled BMSCs isolated from hPLAP-tg donors for long-term tracking of the fate of transplanted MSCs in regenerative therapies.

English

AIM: Pathological lesions have been widely used as biomarkers for health evaluation of organism exposed to pollutants and can be used as warning symptoms for organism health. There are few reports regarding morphological changes in kidney following pesticide Chlorpyrifos exposure which has prompted us to undertake this study. MATERIALS AND METHODOLOGY: The present study was conducted on 45 inbred adult Wistar albino rats of either sex, weighting 145 - 165 gms. These animals were randomly divided into 3 groups A, B, C. Oral Chlorpyrifos was given to the experimental groups B and C in dose of 5 mg/kg body weight and 10 mg/kg body weight respectively. Group A served as control and was left as such. The animals were observed for clinical signs of toxicity and behavioral changes throughout the experimental period. Body weight was recorded at zero day and then at 2 weekly interval for 8 weeks. 3 animals from each group were sacrificed after 1 week, 2nd week, 4th week, 6th week and 8th week of initiation of experiment to see the morphological changes in the kidney architecture. RESULTS: Gross The animals in group A were active, quick to respond and food intake was normal throughout the experimental period where as the animals of groups B & C showed decreased physical activity, dullness, depression, Piloerection, shivering salivation and lacrimation with more severity in Group C. Body Weight Decrease in weight gain was observed in both experimental groups (B & C) as compared to control group A. A statistically significant decrease in weight gain was observed in Group C after 6th and 8th week of Chlorpyrifos treatment. Macroscopic Changes Grossly the kidneys of rats in control group showed no significant changes. The kidneys of rats in Group B showed no change in colour and consistency after 1 st , 2 nd, and 4 th weeks of treatment with Chlorpyrifos. However after 6 th week there was congestion, thickening and adherence of capsule at some places. With increasing dose and duration of treatment with Chlorpyrifos i. e after 8 th week the kidneys were small in size, shrunken and had irregular contour. In Group C upto 1st week of treatment with Chlorpyrifos the kidneys were normal in gross appearance but after 2nd, 4th and 6th weeks the kidneys were grossly congested and friable to touch and the capsule was thickened. After 8 weeks of exposure the kidneys were small in size, shrunken and had irregular contour with thickened outer capsule. Naked eye observations of coronal section of kidney Group A showed clear demarcation of outer cortex and inner medulla. Group B showed no visible change after 1 st and 2 nd weeks of treatment. After 4 th and 6 th week there was visible haemorrhage at corticomedullary junction ranging from focal to completely obscuring of corticomedullary junction. After 8th week there was no demarcation between cortex and medulla and whole of medulla was congested. Group C (10 mg/kg b wt) upto 1st week there was no significant visible change in coronal section of kidneys. After 2 nd and 4 th weeks there was visible haemorrhage at corticomedullary junction. After 6 weeks of treatment whole of the medulla was congested and after 8weeks there was no demarcation between cortex and medulla, whole of the coronal section of the kidneys showed dark reddish brown colour due to haemorrhage.

Strain differences in the humoral immune response to commensal bacterial antigens in rats

We have investigated the immune response to commensal bacterial species in the two inbred rat strains: Dark Agouti (DA) and Albino Oxford (AO). The predominant Gram-negative aerobe in our rats' intestinal bacterial flora was Escherichia coli, while Proteus mirabilis was isolated only from DA rat strain. We report that sera from both DA and AO rat strains contain specific IgG against predominant intestinal flora. Intramuscular administration of commensal bacterial antigens provoked only Th1-type antibody response in AO rats while DA rats developed mixed Th1- and Th2-type antibody response to E. coli and Th1-type response to P. mirabilis antigens. Weaker antibody production to own E. coli and higher serum levels of natural IgG and IgA P. mirabilis-specific antibodies combined with higher CD3+ cells proliferation was found in AO rats. Strain difference in the pattern of antibody production and differential regulation of immune response to commensal bacteria may contribute to the marked differences in the immune reactivity of AO and DA rats.

Autoimmune Saccitis and Cochlear Change

Objectives: Injury to the endolymphatic sac may play an important role in the pathogenesis of Ménière’s disease. The purpose of this study was to) investigate the effect of an autoimmune stimulation of the endolymphatic sac in rats. Methods: Nineteen inbred male Lewis rats in an animal laboratory at the University of Copenhagen were studied. Outcome measurements: Distortion product oto-acoustic emissions (DPOAE) and transmission electron microscopy (TEM). Independent variables: autoimmunization. Preliminary analyses: Endolymphatic hydrops. Results: At day 21 the immunized group showed no significant differences in hearing assessment, on full range of frequencies, compared to the controls ( P &gt;0.05; Welsh t-test). At day 183, the hearing assessment showed a 1.5 dB (6,35%) drop in CDP in the immunized group compared to the controls from 2-16kHz ( P &lt; 0.05; Welsh t-test) and a 2.5 dB (11.1%) decrease in the low frequency area, from 2-5kHz ( P &lt; 0.01; Welsh t-test). TEM investigation indicated stimulation of the endolymphatic sacs in all immunized rats: The ribosome-rich cells appeared hyperactive, and a focal inflammation of immunologically active cells and phagocytosis of ribosome-rich cells were observed. Conclusions: An autoantigen, capable of inducing an endolymphatic saccitis with concomitant cochlear change, exists in the rat. A possible relationship between these observations and Ménière’s disease is proposed.

Cholesterol diet counteracts repeated anesthesia/infusion-induced cognitive deficits in male Brown Norway rats

A variety of cardiovascular and cerebrovascular diseases are associated with alterations in cholesterol levels and metabolism. Moreover, convincing evidence shows that high cholesterol diet can lead to learning and memory impairments. On the other hand, a significant body of research has also demonstrated that learning is improved by elevated dietary cholesterol. Despite these conflicting findings, it is clear that cholesterol plays an important role in these cognitive properties. However, it remains unclear how this blood-brain barrier (BBB)-impenetrable molecule affects the brain and under what circumstances it provides either detrimental or beneficial effects to learning and memory. The aim of this study was to characterize the effects of 5% cholesterol diet on six-month-old inbred Brown Norway rats. More important, we sought to examine the role that cholesterol can play when repeated anesthesia and intravenous infusion disrupts cognitive function. This present study supports previous work showing that enriched cholesterol diet leads to significant alterations in neuroinflammation and BBB disruption. Following repeated anesthesia and intravenous infusion of saline we observe that animals under normal diet conditions exhibit significant deficiencies in spatial learning and cholinergic neuron populations compared to animals under enriched cholesterol diet, which do not show such deficiencies. These findings indicate that cholesterol diet can protect against or counteract anesthesia/infusion-induced cognitive deficits. Ultimately, these results suggest that cholesterol homeostasis serves an important functional role in the brain and that altering this homeostasis can either exert positive or negative effects on cognitive properties.

Comparison of Myosin Heavy Chain mRNAs, Protein Isoforms and Fiber Type Proportions in the Rat Slow and Fast Muscles

We studied the expression of myosin heavy chain isoforms at mRNA and protein levels as well as fiber type composition in the fast extensor digitorum longus (EDL) and slow soleus (SOL) twitch muscles of adult inbred Lewis strain rats. Comparison of the results from Real Time RT-PCR, SDS-PAGE and fiber type analysis showed corresponding proportions of MyHC transcripts (MyHC-1, -2a, -2x/d, -2b), protein isoforms (MyHC-1, -2a, -2x/d, -2b) and fiber types (type 1, 2A, 2X/D, 2B) in both muscles. Furthermore, we found that slow MyHC-1 mRNA expression in the SOL was up to three orders higher than that of fast MyHC transcripts. This finding can explain the predominance of MyHC-1 isoform and fiber type 1 and the absence of pure 2X/D and 2B fibers in the SOL muscle. Based on our data presenting quantitative evidence of corresponding proportions between mRNA level, protein content and fiber type composition, we suggest that the Real Time RT-PCR technique can be used as a routine method for analysis of muscle composition changes and could be advantageous for the analysis of scant biological samples such as muscle biopsies in humans.

Efficient collection and cryopreservation of embryos in F344 strain inbred rats

In rats, it is now possible to produce genetically engineered strains, not only as transgenic animals but also using gene knockout techniques. Reproductive technologies have been used as indispensable tools to produce and maintain these novel valuable strains. Although studies for collecting and cryopreserving embryos have been reported using outbred rats, efficient methods have not been established in inbred strains. The F344 inbred strain is important in rat breeding and has been used for the production of transgenic/knockout strains and for genome sequencing. Here we studied the optimal conditions for oocyte collection by induction of superovulation, and the development of embryos after cryopreservation in F344 rats. The response to pregnant mare serum gonadotropin (PMSG) and human chorionic gonadotropin (hCG) was examined by injection of 150IU/kg PMSG+75IU/kg hCG or 300IU/kg PMSG+300IU/kg hCG. Superovulation was achieved at high efficiency by an injection of 150IU/kg PMSG+75IU/kg hCG. Furthermore, superovulation in this strain showed similar high response as Wistar rats. Of 2-cell embryos cryopreserved by vitrification in a solution containing 10% propylene glycol, 30% ethylene glycol, 20% Percoll and 0.3M sucrose, more than 90% survived after warming and 32% developed to offspring. However, the freezability of pronuclear stage embryos was extremely low. This study demonstrated that sufficient unfertilized oocytes and embryos can be collected from F344 rats by the induction of superovulation with 150IU/kg PMSG+75IU/kg hCG. Furthermore, cryopreservation of 2-cell embryos using this vitrification protocol can now be applied to maintaining valuable rat strains derived from the F344 inbred strain as genetic resources.

Whole-Genome Sequences of DA and F344 Rats with Different Susceptibilities to Arthritis, Autoimmunity, Inflammation and Cancer

DA (D-blood group of Palm and Agouti, also known as Dark Agouti) and F344 (Fischer) are two inbred rat strains with differences in several phenotypes, including susceptibility to autoimmune disease models and inflammatory responses. While these strains have been extensively studied, little information is available about the DA and F344 genomes, as only the Brown Norway (BN) and spontaneously hypertensive rat strains have been sequenced to date. Here we report the sequencing of the DA and F344 genomes using next-generation Illumina paired-end read technology and the first de novo assembly of a rat genome. DA and F344 were sequenced with an average depth of 32-fold, covered 98.9% of the BN reference genome, and included 97.97% of known rat ESTs. New sequences could be assigned to 59 million positions with previously unknown data in the BN reference genome. Differences between DA, F344, and BN included 19 million positions in novel scaffolds, 4.09 million single nucleotide polymorphisms (SNPs) (including 1.37 million new SNPs), 458,224 short insertions and deletions, and 58,174 structural variants. Genetic differences between DA, F344, and BN, including high-impact SNPs and short insertions and deletions affecting >2500 genes, are likely to account for most of the phenotypic variation between these strains. The new DA and F344 genome sequencing data should facilitate gene discovery efforts in rat models of human disease.

Of Rats and Men

The selective breeding of rats as physiological, behavioral, and disease models generated a wealth of variation relevant to the genetics of complex traits. In this issue, Atanur and colleagues sequence the genomes of 25 inbred rat strains to understand how artificial selection shaped their genomes.

Comparative antigen-induced gene expression profiles unveil novel aspects of susceptibility/resistance to adjuvant arthritis in rats

Lewis (LEW) and Wistar Kyoto (WKY) rats of the same major histocompatibility complex (MHC) haplotype (RT.1l) display differential susceptibility to adjuvant-induced arthritis (AIA). LEW are susceptible while WKY are resistant to AIA. To gain insights into the mechanistic basis of these disparate outcomes, we compared the gene expression profiles of the draining lymph node cells (LNC) of these two rat strains early (day 7) following a potentially arthritogenic challenge. LNC were tested both ex vivo and after restimulation with the disease-related antigen, mycobacterial heat-shock protein 65. Biotin-labeled fragment cRNA was generated from RNA of LNC and then hybridized with an oligonucleotide-based DNA microarray chip. The differentially expressed genes (DEG) were compared by limiting the false discovery rate to <5% and fold change ≥2.0, and their association with quantitative trait loci (QTL) was analyzed. This analysis revealed overall a more active immune response in WKY than LEW rats. Important differences were observed in the association of DEG with QTL in LEW vs. WKY rats. Both the number of upregulated DEG associated with rat arthritis-QTL and their level of expression were relatively higher in LEW when compared to WKY rat; however, the number of downregulated DEG-associated with rat arthritis-QTL as well as AIA-QTL were found to be higher in WKY than in LEW rats. In conclusion, distinct gene expression profiles define arthritis-susceptible versus resistant phenotype of MHC-compatible inbred rats. These results would advance our understanding of the pathogenesis of autoimmune arthritis and might also offer potential novel targets for therapeutic purposes.

Genetic and phenotypic characterization of a Japanese wild-derived DOB/Oda rat strain

Wild-derived rat strains can provide novel genome resources that are not available in standard laboratory strains. Genetic backgrounds of wild-derived strains can facilitate effective genetic linkage analyses and often modulate the expression of mutant phenotypes. Here we describe the development and characterization of a new inbred rat strain, DOB/Oda, from wild rats (Rattus norvegicus) captured in Shitara, Aichi, Japan. Phenotype analysis of 109 parameters revealed that the DOB/Oda rats had small body weight, preference for darkness, and high locomotor activity compared with the rat strains in the National BioResource Project for the Rat (NBRP-Rat) database. Genome analysis with 357 SSLP markers identified DOB/Oda-specific alleles in 70 markers. The percentage of SSLP markers that showed polymorphism between the DOB/Oda strain and any of 132 laboratory strains from NBRP-Rat varied from 89 to 95%. The polymorphic rate (average of the values of the percentage) for the DOB/Oda strain was 91.6%, much higher than the rates for available wild-derived strains such as the Brown Norway rat. A phylogenic tree constructed with DOB/Oda and all the strains in NBRP-Rat showed that the DOB/Oda strain localized within the wild rat groups, apparently separate from the laboratory strains. Together, these findings indicated that the DOB/Oda rat has a unique genome that is not available in the laboratory strains. Therefore, the new DOB/Oda strain will provide an important genome resource that will be useful for designing genetic experiments and for the discovery of genes that modulate mutant phenotypes.

Genome Sequencing Reveals Loci under Artificial Selection that Underlie Disease Phenotypes in the Laboratory Rat

SummaryLarge numbers of inbred laboratory rat strains have been developed for a range of complex disease phenotypes. To gain insights into the evolutionary pressures underlying selection for these phenotypes, we sequenced the genomes of 27 rat strains, including 11 models of hypertension, diabetes, and insulin resistance, along with their respective control strains. Altogether, we identified more than 13 million single-nucleotide variants, indels, and structural variants across these rat strains. Analysis of strain-specific selective sweeps and gene clusters implicated genes and pathways involved in cation transport, angiotensin production, and regulators of oxidative stress in the development of cardiovascular disease phenotypes in rats. Many of the rat loci that we identified overlap with previously mapped loci for related traits in humans, indicating the presence of shared pathways underlying these phenotypes in rats and humans. These data represent a step change in resources available for evolutionary analysis of complex traits in disease models.PaperClip

Modularization and epistatic hierarchy determine homeostatic actions of multiple blood pressure quantitative trait loci

Hypertension, the most frequently diagnosed clinical condition world-wide, predisposes individuals to morbidity and mortality, yet its underlying pathological etiologies are poorly understood. So far, a large number of quantitative trait loci (QTLs) have been identified in both humans and animal models, but how they function together in determining overall blood pressure (BP) in physiological settings is unknown. Here, we systematically and comprehensively performed pair-wise comparisons of individual QTLs to create a global picture of their functionality in an inbred rat model. Rather than each of numerous QTLs contributing to infinitesimal BP increments, a modularized pattern arises: two epistatic 'blocks' constitute basic functional 'units' for nearly all QTLs, designated as epistatic module 1 (EM1) and EM2. This modularization dictates the magnitude and scope of BP effects. Any EM1 member can contribute to BP additively to that of EM2, but not to those of the same module. Members of each EM display epistatic hierarchy, which seems to reflect a related functional pathway. Rat homologues of 11 human BP QTLs belong to either EM1 or EM2. Unique insights emerge into the novel genetic mechanism and hierarchy determining BP in the Dahl salt-sensitive SS/Jr (DSS) rat model that implicate a portion of human QTLs. Elucidating the pathways underlying EM1 and EM2 may reveal the genetic regulation of BP.

Strong genetic influences on measures of behavioral‐regulation among inbred rat strains

A fundamental challenge for any complex nervous system is to regulate behavior in response to environmental challenges. Three measures of behavioral-regulation were tested in a panel of eight inbred rat strains. These measures were: (1) sensation seeking as assessed by locomotor response to novelty and the sensory reinforcing effects of light onset, (2) attention and impulsivity, as measured by a choice reaction time task and (3) impulsivity as measured by a delay discounting task. Deficient behavioral-regulation has been linked to a number of psychopathologies, including ADHD, Schizophrenia, Autism, drug abuse and eating disorders. Eight inbred rat strains (August Copenhagen Irish, Brown Norway, Buffalo, Fischer 344, Wistar Kyoto, Spontaneous Hypertensive Rat, Lewis, Dahl Salt Sensitive) were tested. With n = 9 for each strain, we observed robust strain differences for all tasks; heritability was estimated between 0.43 and 0.66. Performance of the eight inbred rat strains on the choice reaction time task was compared to the performance of outbred Sprague Dawley (n = 28) and Heterogeneous strain rats (n = 48). The results indicate a strong genetic influence on complex tasks related to behavioral-regulation and indicate that some of the measures tap common genetically driven processes. Furthermore, our results establish the potential for future studies aimed at identifying specific alleles that influence variability for these traits. Identification of such alleles could contribute to our understanding of the molecular genetic basis of behavioral-regulation, which is of fundamental importance and likely contributes to multiple psychiatric disorders.

Lipoxin A4 Attenuates Acute Rejection Via Shifting Th1/Th2 Cytokine Balance in Rat Liver Transplantation

AimsTo study the role of lipoxin A4 (LXA4) in rat liver transplant rejection. MethodsAn acute rejection model of liver transplantation was established in inbred rats DA to LEW that were randomly divided into a control group and a LXA4 group. Liver morphologic changes were examined using hematoxylin/eosin staining. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were quantified to measure liver injury. Intragraft mRNA and protein expressions of interferon (IFN)-γ interleukin and (IL)-10 were detected by real-time polymerase chain reaction and Western blots, respectively. The serum levels of IFN-γ and IL-10 were assayed by enzyme-linked immunosorbent assay. ResultsLXA4 treatment improved hepatic tissue injury as indicated by morphologic analysis. Serum ALT and AST levels were significantly decreased at day 7 post-transplantation (P < .05). Concurrently, expression of IFN-γ was downregulated (P < .05) and secretion of IL-10 was enhanced (P < .05). ConclusionsLXA4 attenuated acute rejection with a parallel shift from Th1 to Th2 responses in rat liver transplantation.

Six-Month Feeding of Low-Dose Fish Oil Decreases Vascular Expression of High Mobility Group Box1 and Receptor for Advanced Glycation End-Products in Rat Chronic Allograft Vasculopathy

Chronic allograft vasculopathy (CAV) is a typical feature of chronic rejection of small bowel transplantations (SBTx). Our previous studies revealed that feeding fish oil, a natural source of n-3 polyunsaturated fatty acids (PUFAs), protected against CAV. The underlying mechanism remains to be clarified. The pathway mediated by the receptor for advanced glycation end products (RAGE) and its ligand, high mobility group box-1 (HMGB1), which may contribute to the pathogenesis of CAV, is potentially regulated by n-3 PUFAs. Using a chronic rejection model of rat SBTx, the present study investigated whether amelioration of CAV by fish oil feeding was associated with regulation of the RAGE signaling pathway. Moreover, our previous studies also showed that feeding low-dose fish oil for 3 months had no effect. Since an relatively short duration of treatment might fail to produce a visible response, we fed low-dose fish oil for 190 postoperative days. Male inbred Lewis rats and F344 rats were used to establish a chronic rejection model of SBTx. The recipient rats were administered phosphate-buffered saline or fish oil at a daily dose of 3 mL/kg. All rats survived over 190 postoperative days. The expression of HMGB1 and RAGE increased in CAV-bearing vessels. Feeding low-dose fish oil for 6 months attenuated CAV, and significantly reduced HMGB1 and RAGE expressions, indicating beneficial effects of low-dose fish oil on CAV may occur via down-regulation of the HMGB1-RAGE pathway.