F344 Rats Research Articles

Acute Stress Exposure Alters Food-Related Brain Monoaminergic Profiles in a Rat Model of Anorexia

BackgroundAdverse life experiences are a major risk factor for anorexia nervosa (AN). Eating-provoked anxiousness associated with AN is postulated to be due to food-related exaggerated serotonin activity in the brain and imbalances of monoamine neurotransmitters. ObjectivesUsing a rodent model of stress-induced hypophagia, we investigated if stress exposure augments food-related serotonin turnover and imbalances in measures of brain serotonin and dopamine activity in manners consistent with anxiousness toward food and restricted eating. MethodsAdult male F344 rats were conditioned to associate an audio cue with daily food over 2 weeks, after which half of the rats were exposed to a single episode of tail shocks (stress) or left undisturbed (nonstressed). All rats were killed 48 h later, during a control period, the food-associated cue, or a period of food access. Serotonin, dopamine, and norepinephrine, as well as metabolite concentrations, were assessed across brain regions comprising reward, emotion, and feeding circuits relevant to AN in acutely stressed and nonstressed rats using HPLC. Statistical significance level was 5%. ResultsStress-induced rat hypophagia paralleled an augmented serotonin turnover in response to the food-associated cue in the hypothalamus and hippocampus, as well as food access in the hypothalamus and cortical areas (all P < 0.05). Stress exposure increased the ratio of serotonin to dopamine metabolites across several brain areas, but the magnitude of this imbalance was further augmented during the food-associated cue and food access in the brainstem, hippocampus, and cortical areas (all P < 0.05). Finally, stress lowered norepinephrine concentrations by 18% in the hypothalamus (P < 0.05). ConclusionsThe observed stress-induced changes to monoamine profiles in rats could have key implications for physiological states that contribute to restricted eating and may hold relevance for the development of AN precipitated by adverse life experiences.

Interleukin-5 (IL-5) Therapy Prevents Allograft Rejection by Promoting CD4+CD25+ Ts2 Regulatory Cells That Are Antigen-Specific and Express IL-5 Receptor

CD4+CD25+Foxp3+T cell population is heterogenous and contains three major sub-groups. First, thymus derived T regulatory cells (tTreg) that are naïve/resting. Second, activated/memory Treg that are produced by activation of tTreg by antigen and cytokines. Third, effector lineage CD4+CD25+T cells generated from CD4+CD25- T cells’ activation by antigen to transiently express CD25 and Foxp3. We have shown that freshly isolated CD4+CD25+T cells are activated by specific alloantigen and IL-4, not IL-2, to Ts2 cells that express the IL-5 receptor alpha. Ts2 cells are more potent than naïve/resting tTreg in suppressing specific alloimmunity. Here, we showed rIL-5 promoted further activation of Ts2 cells to Th2-like Treg, that expressed foxp3, irf4, gata3 and il5. In vivo, we studied the effects of rIL-5 treatment on Lewis heart allograft survival in F344 rats. Host CD4+CD25+T cells were assessed by FACS, in mixed lymphocyte culture and by RT-PCR to examine mRNA of Ts2 or Th2-like Treg markers. rIL-5 treatment given 7 days after transplantation reduced the severity of rejection and all grafts survived ≥60d whereas sham treated rats fully rejected by day 31 (p<0.01). Treatment with anti-CD25 or anti-IL-4 monoclonal antibody abolished the benefits of treatment with rIL-5 and accelerated rejection. After 10d treatment with rIL-5, hosts’ CD4+CD25+ cells expressed more Il5ra and responded to specific donor Lewis but not self. Enriched CD4+CD25+ cells from rIL-5 treated rats with allografts surviving >60 days proliferated to specific donor only when rIL-5 was present and did not proliferate to self or third party. These cells had more mRNA for molecules expressed by Th2-like Treg including Irf4, gata3 and Il5. These findings were consistent with IL-5 treatment preventing rejection by activation of Ts2 cells and Th2-like Treg.

Effects of Magnesium Orotate, Benfotiamine and a Combination of Vitamins on Mitochondrial and Cholinergic Function in the TgF344-AD Rat Model of Alzheimer's Disease.

Glucose hypometabolism, mitochondrial dysfunction, and cholinergic deficits have been reported in early stages of Alzheimer’s disease (AD). Here, we examine these parameters in TgF344-AD rats, an Alzheimer model that carries amyloid precursor protein and presenilin-1 mutations, and of wild type F344 rats. In mitochondria isolated from rat hippocampi, we found reductions of complex I and oxidative phosphorylation in transgenic rats. Further impairments, also of complex II, were observed in aged (wild-type and transgenic) rats. Treatment with a “cocktail” containing magnesium orotate, benfotiamine, folic acid, cyanocobalamin, and cholecalciferol did not affect mitochondrial activities in wild-type rats but restored diminished activities in transgenic rats to wild-type levels. Glucose, lactate, and pyruvate levels were unchanged by age, genetic background, or treatment. Using microdialysis, we also investigated extracellular concentrations of acetylcholine that were strongly reduced in transgenic animals. Again, ACh levels in wild-type rats did not change upon treatment with nutrients, whereas the cocktail increased hippocampal acetylcholine levels under physiological stimulation. We conclude that TgF344-AD rats display a distinct mitochondrial and cholinergic dysfunction not unlike the findings in patients suffering from AD. This dysfunction can be partially corrected by the application of the “cocktail” which is particularly active in aged rats. We suggest that the TgF344-AD rat is a promising model to further investigate mitochondrial and cholinergic dysfunction and potential treatment approaches for AD.

Deficient Play-Derived Experiences in Juvenile Long Evans Rats Reared with a Fischer 344 Partner: A Deficiency Shared by Both Sexes

Play fighting during the juvenile period has been shown to be an important experience for the development of sociocognitive skills and the underlying neural mechanisms that support them. Various paradigms have been used to deprive rats of play while still providing social contact. We used the paradigm of rearing a playful rat with a low-playing Fischer 344 (F344) partner to limit the play experienced by Long Evans (LE) rats during the juvenile period. This rearing paradigm has previously been shown to cause sociocognitive impairments in adulthood. In the present paper, we examined the play of same sex LE rats with LE or F344 partners at the peak juvenile period (around 35 days of age). F344 rats launched fewer playful attacks and when attacked, defended atypically compared to how LE do in LE-LE pairs. Playing with an F344 partner afforded LE rats fewer opportunities to engage in prolonged wrestling and fewer opportunities to ward off counterattacks (in which the defending rat becomes the attacker). In addition, there are fewer vocalizations emitted during the encounters in LE-F344 pairs and the types of calls most often emitted differed to those between LE-LE pairs. The altered play and communication experiences were equally present in male and female pairs. These findings are consistent with the hypothesis that, in such rearing paradigms, it is impoverished play experiences in the juvenile period that lead to impaired sociocognitive skills in adulthood.

Successful use of bio plugs for delayed bronchial closure after pneumonectomy in experimental settings

OBJECTIVESCell therapies, such as stem cell suspension injection, are used to treat bronchopleural fistula. Although it is safe and effective, injected cells cannot remain within the bronchioles of the fistula due to cell leakage into the thoracic cavity. Here, we inserted a ‘bio plug’ into the fistula, produced using cells and a bio-3D printer, to examine the effectiveness of bio plugs for the closure of bronchopleural fistulas, the optimal cell source and the closure mechanism.METHODSBio plugs were made with mesenchymal stem (stromal) cells derived from bone marrow (MSCBM), fibroblasts and rat lung micro-vessel endothelial cells using a bio-3D printer with different cell mixing ratios. Six groups, according to the presence or absence and the type of bio plugs, were compared. The plugs were inserted into the bronchi of F344 rats. The obstruction ratio and histological and immunohistochemical findings were evaluated.RESULTSMSCBM+ rat lung micro-vessel endothelial cell group exhibited a higher obstruction ratio among all groups excluding the MSCBM group (P = 0.039). This group had fibrosis and CD31-positive cells and fewer CD68-positive cells than MSCBM and MSCBM+ fibroblast groups.CONCLUSIONSBio plugs with mixed cells, including stem cells, contribute to bronchial closure in the current experimental setting. Endothelial cells effectively maintain the structure in this model. Although bronchial closure for bronchopleural fistula could not be described as clinical conditions were not reproduced, we collected essential data on bronchial closure; however, further experiments are warranted.

A 90-day subchronic toxicity study of Myrrh in F344 rats

Myrrh is a flavoring agent and food additive. Here, we performed a subchronic toxicity study of Myrrh in male and female F344 rats by feeding at 5,000, 15,000 and 50,000 ppm for 90 days. No deaths or clinical signs were observed. Suppression of body weight gain was observed from the early phase of administration in both males and females in the 50,000 ppm group. Because there were no obvious changes in food intake in any of the Myrrh groups compared with the control group, suppression of body weight gain was considered an adverse effect of Myrrh. Hematology and serum biochemistry parameters with significant changes observed in the Myrrh groups were considered to have no toxicological significance. We observed a significant increase in relative kidney weight in male rats treated with 50,000 ppm Myrrh; this effect was considered to be related to the appearance of hyaline droplets in the epithelium of the proximal tubules histopathologically observed in this group. Immunohistochemical staining with anti-α2u-globulin antibodies suggested that these hyaline droplets were caused by factors other than α2u-globulin deposition. Thus, the no-observed-adverse-effect level of Myrrh was determined to be 15,000 ppm (males: 0.85 g/kg/day, females: 0.95 g/kg/day).

Spontaneous Primary Pleural Mesothelioma in Fischer 344 (F344) and Other Rat Strains: A Retrospective Review.

Spontaneous primary pleural mesotheliomas in Fischer 344 (F344) or other rat strains have rarely been reported. The objectives of this retrospective study were to develop historical incidence data and better characterize the light-microscopic morphology of these naturally occurring neoplasms in a large cohort of rats of several strains. A retrospective review was performed of National Toxicology Program (NTP) studies in rats conducted between 1980 and 2019 and comprising a total of 104,029 rats (51,326 males, 52,703 females), predominantly (90%) of the F344 strain. Of the 94,062 F344 rats surveyed, there were 30 cases of primary pleural mesotheliomas (22 males, 8 females). Of the 2998 Wistar Han rats surveyed, primary pleural mesotheliomas were present in 2 male rats. No primary pleural mesotheliomas were noted in male and female rats of other strains (6669 Sprague Dawley; 300 Osborne-Mendel). All primary pleural mesotheliomas in control and treated F344 and Wistar Han rats were considered spontaneous and unrelated to treatment. Based on light-microscopic evaluation of paraffin-embedded hematoxylin and eosin stained sections, only epithelioid and biphasic histologic subtypes were observed: 18 and 12 in F344 rats, respectively, and one each in Wistar Han rats. No sarcomatoid subtype cases were noted in any strain of rat.

Impact of Large Granular Lymphocyte Leukemia on Blood DNA Methylation and Epigenetic Clock Modeling in Fischer 344 Rats.

Age-dependent differences in methylation at specific cytosine-guanine (CpG) sites have been used in "epigenetic clock" formulas to predict age. Deviations of epigenetic age from chronological age are informative of health status and are associated with adverse health outcomes, including mortality. In most cases, epigenetic clocks are performed on methylation from DNA extracted from circulating blood cells. However, the effect of neoplastic cells in the circulation on estimation and interpretation of epigenetic clocks is not well understood. Here, we explored this using Fischer 344 (F344) rats, a strain that often develops large granular lymphocyte leukemia (LGLL). We found clear histological markers of LGLL pathology in the spleens and livers of 27 out of 61 rats aged 17-27 months. We assessed DNA methylation by reduced representation bisulfite sequencing with coverage of 3 million cytosine residues. Although LGLL broadly increased DNA methylation variability, it did not change epigenetic aging. Despite this, the inclusion of rats with LGLL in clock training sets significantly altered predictor selection probability at 83 of 121 commonly utilized CpG sites. Furthermore, models trained on rat samples that included individuals with LGLL had greater absolute age error than those trained exclusively rats free of LGLL (39% increase; p < .0001). We conclude that the epigenetic signals for aging and LGLL are distinct, such that LGLL assessment is not necessary for valid measures of epigenetic age in F344 rats. The precision and architecture of constructed epigenetic clock formulas, however, can be influenced by the presence of neoplastic hematopoietic cells in training set populations.

Incorporation of hydroxyapatite into collagen scaffolds enhances the therapeutic efficacy of rhBMP-2 in a weight-bearing femoral defect model

Traditional methods to promote bone healing, such as autologous bone grafting, and therapeutic strategies involving recombinant bone morphogenetic proteins (BMPs), such as BMP-2 and BMP-7, have been associated with performance limitations and dose-related safety concerns, respectively. Thus, there is an unmet need for osteoinductive bone graft substitutes that can enhance the therapeutic efficacy of rhBMP-2 and facilitate dose-reduction approaches. This study aimed to determine the therapeutic efficacy of rhBMP-2 delivered using a collagen-only scaffold (CO) (representative of clinical standards), a collagen-hydroxyapatite scaffold (CHA), and a thermoresponsive hyaluronic acid hydrogel doped with gelatin and laminin (HyA-GL). Efficacy over 14 weeks was evaluated using 2 mm segmental femoral defects in skeletally mature female F344 rats, internally fixated using a 1.25 mm-thick polyetheretherketone plate. Empty defects failed to bridge but administration of rhBMP-2 using either CO or CHA scaffolds led to successful bridging, while using HyA-GL resulted in non-union. CHA scaffolds induced enhanced and stiffer new bone formation compared to both CO and HyA-GL scaffolds. Limited luminal remodeling occurred in both CO and CHA groups. Taken together, this study has determined that a collagen-hydroxyapatite scaffold can enhance the therapeutic efficacy of rhBMP-2 compared to collagen-only scaffolds routinely used in standard clinical practice.

Changes of stem cell niche during experimental pituitary tumor development

To investigate the putative stem cell/tumor stem cell (SC/TSC) niche contribution to hyperplasic/adenomatous pituitary lesions, we analyzed variation in the pituitary stem cell population during the development of experimental pituitary tumors. Pituitary tumors were induced in female F344 rats with estradiol benzoate for 5, 10, 20 and 30days. Cells positive for GFRa2, Sox2, Sox9, Nestin, CD133 and CD44 were identified in the marginal zone and in the adenoparenchyma in both control and 30D groups, with predominant adenoparenchyma localization of GRFa2 and SOX9 found in tumoral pituitaries. GFRa2, Nestin, CD133 and CD44 were upregulated at the initial stages of tumor growth, whereas Sox9 significantly decreased at 5D, with Sox2 remaining invariable during the hyperplasic/adenomatous development. In addition, isolated pituispheres from normal and tumoral pituitary glands enriched in SC/TSC were characterized. Pituispheres from the 30D glands were positive for the above-mentioned markers and showed a significant increase in the proliferation. In conclusion, our data revealed pituitary SC pool fluctuations during hyperplastic/adenomatous development, with differential localization of the SC/TSC niche in this process. These findings may help to provide a better understanding of these cell populations, which is crucial for achieving advancements in the field of pituitary tumor biology.

Longitudinal characterization of neuroanatomical changes in the Fischer 344 rat brain during normal aging and between sexes

Animal models are widely used to study the pathophysiology of disease and to evaluate the efficacy of novel interventions, crucial steps towards improving disease outcomes in humans. The Fischer 344 (F344) wildtype rat is a common experimental background strain for transgenic models of disease and is one of the most frequently used models in aging research. Despite frequency of use, characterization of agerelated neuroanatomical change has not been performed in the F344 rat. To this end, we present a comprehensive longitudinal examination of morphometric change in 73 brain regions and at a voxel-wise level during normative aging in vivo in a mixed-sexcohort of F344 rats. We identified the greatest vulnerability to aging within the cortex, caudoputamen, hindbrain, and internal capsule, while the influence of sex was strongest in the caudoputamen, hippocampus, nucleus accumbens, and thalamus, many of which are implicated in memory and motor control circuits frequently affected by aging and neurodegenerative disease. These findings provide a baseline for neuroanatomical changes associated with aging in male and female F344 rats, to which data from transgenic models or other background strains can be compared.

Prodromal dysfunction of α5GABA-A receptor modulated hippocampal ripples occurs prior to neurodegeneration in the TgF344-AD rat model of Alzheimer's disease

Decades of research attempting to slow the onset of Alzheimer's disease (AD) indicates that a better understanding of memory will be key to the discovery of effective therapeutic approaches. Here, we ask whether prodromal neural network dysfunction might occur in the hippocampal trisynaptic circuit by using α5IA (an established memory enhancer and selective negative allosteric modulator of extrasynaptic tonically active α5GABA-A receptors) as a probe drug in TgF344-AD transgenic rats, a model for β-amyloid induced early onset AD. The results demonstrate that orally bioavailable α5IA increases CA1 pyramidal cell mean firing rates during foraging and peak ripple amplitude during wakeful immobility in wild type F344 rats in a familiar environment. We further demonstrate that CA1 ripples in TgF344-AD rats are nonresponsive to α5IA by 9 months of age, prior to the onset of AD-like pathology and memory dysfunction. TgF344-AD rats express human β-amyloid precursor protein (with the Swedish mutation) and human presenilin-1 (with a Δ exon 9 mutation) and we found high serum Aβ42 and Aβ40 levels by 3 months of age. When taken together, this demonstrates, to the best of our knowledge, the first evidence for prodromal α5GABA-A receptor dysfunction in the ripple-generating hippocampal trisynaptic circuit of AD-like transgenic rats. As α5GABA-A receptors are found at extrasynaptic and synaptic contacts, we posit that negative modulation of α5GABA-A receptor mediated tonic as well as phasic inhibition augments CA1 ripples and memory consolidation but that this modulatory mechanism is lost at an early stage of AD onset.

PD37-08 PHOSPHATIDYLDIGLYCEROL-BASED THERMOSENSITIVE LIPOSOMES SHOW SUPERIOR THERAPEUTIC EFFICACY AGAINST MUSCLE-INVASIVE BLADDER CANCER IN VIVO

You have accessJournal of UrologyBladder Cancer: Basic Research & Pathophysiology I (PD37)1 Sep 2021PD37-08 PHOSPHATIDYLDIGLYCEROL-BASED THERMOSENSITIVE LIPOSOMES SHOW SUPERIOR THERAPEUTIC EFFICACY AGAINST MUSCLE-INVASIVE BLADDER CANCER IN VIVO Iris Brummelhuis, Michiel Simons, Lars Lindner, Simone Kort, Sytse de Jong, Martin Hossann, Alfred Witjes, and Egbert Oosterwijk Iris BrummelhuisIris Brummelhuis More articles by this author , Michiel SimonsMichiel Simons More articles by this author , Lars LindnerLars Lindner More articles by this author , Simone KortSimone Kort More articles by this author , Sytse de JongSytse de Jong More articles by this author , Martin HossannMartin Hossann More articles by this author , Alfred WitjesAlfred Witjes More articles by this author , and Egbert OosterwijkEgbert Oosterwijk More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002047.08AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Recommended treatments for muscle-invasive bladder cancer (MIBC) are associated with substantial morbidity. Hyperthermia (HT) triggered drug release from phosphatidyldiglycerol-based thermosensitive liposomes (DPPG2-TSL) might prevent surgical bladder removal and toxicity from systemic chemotherapy. We aimed to assess the efficacy of DPPG2-TSL encapsulated doxorubicin (DOX; DPPG2-TSL-DOX) combined with bladder HT, compared to free systemic and intravesical DOX, in a syngeneic orthotopic rat urothelial carcinoma model. METHODS: A total of 191 female Fischer F344 rats were used. Bladder tumors were initiated by inoculation of AY-27 cells and tumor bearing rats were selected with cystoscopy and semi-randomized over treatment groups. At day 5 and 8, animals were treated with 2 mg/kg DOX in different treatment modalities: intravenous (iv) DPPG2-TSL-DOX with HT, iv free DOX without HT, intravesical DOX without HT, intravesical DOX with HT or no treatment (control group), respectively. Animals were euthanized at day 14 and complete tumor response was assessed by histopathological evaluation. RESULTS: Treatment with iv DPPG2-TSL-DOX with HT resulted in the highest rate of animals with complete tumor response of 70%, which was significantly better than iv free DOX (18%, p=0.02) and no treatment (0%, p=0.001), and non-significantly better than intravesical DOX with (43%, p=0.35) or without HT (50%, p=0.41; Figure 1). All rats receiving intravesical DOX with HT (7/7) and 24% (5/21) of rats treated with DPPG2-TSL-DOX containing the same DOX dose with HT had to be euthanized before day 14 because of >15% body weight loss, while some rats showed dilated ureters (3/7 and 4/21) and urine retention (2/7 and 1/21, respectively).Figure 1. Tumor stage as determined by histopathological evaluation per group. Green colored parts of bars represent T1 tumors, and purple T2. CONCLUSIONS: Treatment with DPPG2-TSL-DOX combined with intravesical HT outperformed systemic and intravesical DOX in a syngeneic orthotopic rat UC model. There might be a role for DPPG2-TSL encapsulating chemotherapeutics in treatment of MIBC in the future. Source of Funding: This study was partially sponsored by Thermosome © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e658-e658 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Iris Brummelhuis More articles by this author Michiel Simons More articles by this author Lars Lindner More articles by this author Simone Kort More articles by this author Sytse de Jong More articles by this author Martin Hossann More articles by this author Alfred Witjes More articles by this author Egbert Oosterwijk More articles by this author Expand All Advertisement Loading ...

Aflatoxin B1 Induces Gut-Inflammation-Associated Fecal Lipidome Changes in F344 Rats

Abstract Aflatoxin B1 (AFB1) induced intestinal epithelial damage in rodent models, which indicates that long-term exposure to AFB1 may cause chronic gut disorders. In this study, we tested the hypothesis that AFB1-induced adverse effects on gut is mediated by gut-microbiota, which is partially reflected by the changes of fecal microbiome and metabolome. F344 rats were orally exposed to AFB1 of 0, 5, 25, and 75 µg kg−1 body weight for 4 weeks and fecal samples were collected. An ion-fragmentation-spectrum-based metabolomics approach was developed to investigate the fecal microbiota-associated metabolic changes in fecal samples. We found that AFB1 inhibited the hepatic and intestinal metabolism of bile constituents. As compared with the controls, bile acid synthesis-associated cholesterols in rats treated with 25 µg kg−1 (the middle-dose group) were significantly decreased in the fecal samples, for example, lathosterol (45% reduction), cholesterol ester (21% reduction), chenodeoxycholic acid (20% reduction), dihydroxycholesterol (55% reduction), hydroxycholesterol (20% reduction), and 5-cholestene (29% reduction). Although disease-associated lipids were not detectable in the feces of the control group, they were found in AFB1-treated groups, including diglyceride, monoacylglyceride, 19,20-dihydroxy-docosapentaenoic acid, and phosphatidylethanolamine. Metabolisms of carbohydrates and production of short-chain fatty acids were remarkedly decreased in all treated groups. Moreover, an inflammatory-bowel-disease (IBD)-associated taxonomic structure of fecal microbiota was observed as ∼25% Lachnospiraceae, ∼25% Ruminococcaceae, and &amp;lt;1% Lactobacillales, which was similar to the composition pattern found in IBD patients. These results suggest that AFB1-induced disruption on gut-microbiota, partially reflected by fecal microbiome and metabolome, may play important roles in the pathogenesis of chronic gut disorders.

Humidifier disinfectant, sodium dichloroisocyanurate (NaDCC): assessment of respiratory effects to protect workers’ health

In South Korea, it has been found that biocides used to control and eliminate harmful organisms are used as humidifier disinfectants and cause lung disease in users. Hence, efforts have been focused on studying the toxicity of biocides in workers who handle them. The purpose of this study was to evaluate the effects of inhalation exposure to sodium dichloroisocyanurate (NaDCC) to protect the health of workers handling NaDCC. F344 rats were exposed to 0.8-, 4-, and 20-mg/m3 of NaDCC for 6 h per day, 5 days per week for 14 days, and the recovery period after exposure was 14 days. In the 20-mg/m3-exposure group, we observed a decrease in food intake in females, a weight loss in males, and a decrease in partially active thromboplastin time in males and females 2 weeks after exposure. We noted a decrease in white blood cells in males in the 4- and 20-mg/m3-exposed groups. Both males and females in the 20-mg/m3 group and males in the 4-mg/m3 group showed irritation in the larynx related to test substance exposure. However, these findings were not observed in the recovery group. The main target organs affected by repeated 2-week inhalation exposure to NaDCC were the nasal cavity and larynx in the upper respiratory tract. The No Observed Adverse Effect Level (NOAEL) was considered to be 0.8 mg/m3 because effects related to NaDCC exposure were observed even at of 4 mg/m3, and these effects were found to be reversible.

Proton Pump Inhibitor Omeprazole Suppresses Carcinogen-induced Colonic Adenoma Progression to Adenocarcinoma in F344 Rat.

Colorectal cancer causes over 53,000 deaths annually in the United States. Its rising incidences worldwide and particularly in young adults is a major concern. Here, we evaluated the efficacy of omeprazole that is clinically approved for treating acid reflux, to enable its repurposing for colorectal cancer prevention. In the azoxymethane-induced rat colorectal cancer model, dietary omeprazole (250 and 500 ppm) was administered at early adenoma stage (8 weeks after azoxymethane) to assess the progression of early lesions to adenocarcinoma. Administration of omeprazole at 250 or 500 ppm doses led to suppression of total colon adenocarcinoma incidence by 15.7% and 32% (P < 0.01), respectively. Importantly, invasive carcinoma incidence was reduced by 59% (P < 0.0005) and 90% (P < 0.0001) in omeprazole-administered rats in a dose-dependent manner. There was also a strong and dose-dependent inhibition in the adenocarcinoma multiplicity in rats exposed to omeprazole. Administration of 250 and 500 ppm omeprazole inhibited total colon adenocarcinoma multiplicity by approximately 49% and approximately 65% (P < 0.0001), respectively. While noninvasive adenocarcinomas multiplicity was suppressed by approximately 34% to approximately 48% (P < 0.02), the invasive carcinomas multiplicity was reduced by approximately 74% to approximately 94% (P < 0.0001) in omeprazole-exposed rats in comparison with the untreated rats. Biomarker analysis results showed a decrease in cell proliferation and anti-apoptotic/pro-survival proteins with an increase in apoptosis. Transcriptome analysis of treated tumors revealed a significant increase in adenocarcinoma inhibitory genes (Olmf4; Spink4) expression and downregulation of progression promoting genes (SerpinA1, MMP21, IL6). In summary, omeprazole showed significant protection against the progression of adenoma to adenocarcinoma. PREVENTION RELEVANCE: Preventing colon cancer is urgently needed because of its high incidence and mortality rates worldwide. Toward this end, preventive efficacy of omeprazole, a common medication, was evaluated in animal model of colorectal cancer and was found to suppress colonic adenoma progression to carcinoma. These findings warrant its further evaluation in humans.

Age-and Region-Dependent Disposition of Raloxifene in Rats.

Raloxifene undergoes extensive glucuronidation in the gastrointestinal (GI) tract and the liver. However, the impact of age on raloxifene disposition has never been studied. The purpose of this paper is to determine glucuronidation and Pharmacokinetics (PK) profiles of raloxifene in rats at different ages. Raloxifene glucuronidation was characterized using S9 fractions prepared from different intestinal segments and the liver of F344 rats at 4-, 11-, and 28-week. PK studies were conducted to determine raloxifene oral bioavailability at different ages. Raloxifene and its glucuronides were quantified using LC-MS/MS. Raloxifene-6-glucuronide and raloxifene-4'-glucuronide were detected as the major metabolites and the ratio of these two glucuronides were different ranging from 2.1 to 4.9 folds in the ileum, jejunum, liver, and duodenum, and from 14.5 to 50 folds in the colon. The clearances in the duodenum at 4-week for both two glucuronides were significantly lower than those at the other two ages. PK studies showed that the oral bioavailability of raloxifene is age dependent. The absolute oral bioavailability of raloxifene was 3.5-folds higher at 4-week compared to that at 11-weeks. When raloxifene was administered throughIV bolus, its half-life was 5.9 ± 1.16h and 3.7 ± 0.68h at 11-and 4-week, respectively. These findings suggested that raloxifene metabolism in the duodenum was significantly slower at young age in rats, which increased the oral bioavailability of raloxifene. At 11-week, enterohepatic recycling efficiency was higher than that of 4-week. Raloxifene's dose at different ages should be carefully considered.

2: Sensorimotor Myoelectric Control Using Surface Based Regenerative Peripheral Nerve Interface (RPNI)

Purpose:Although advanced prosthetic devices have the potential to allow fine-motor movements and extract somatosensory signals via sensitive pressure sensors, an ideal interface to integrate the human nervous system with the prosthetic doesn’t exist. Furthermore, the requirement for the implantation of indwelling electrodes and prohibitive costs limits the application of current technologies. The Regenerative Peripheral Nerve Interface (RPNI) was developed as a stable biologic interface on the notion of providing physiologic end-organ targets for regenerating axons by implantation of a residual nerve into an autogenous free muscle graft. Despite providing intuitive motor control, RPNI sensory feedback is limited and also relies on implantable electrodes for myoelectric signal transmission. To address these challenges, we investigated the placement of RPNIs underneath the defatted skin in rats to capture myoelectric signals using surface electrodes. This strategy simultaneously provides sensory feedback through the sensory reinnervation of the overlying skin.Methods:Utilizing six male F344 rats, the right tibial nerve was transected distally in the thigh before entering the leg’s posterior compartment. Subsequently, the left side extensor digitorum longus (EDL) muscle was harvested and co-apted with the proximal segment of the tibial nerve for RPNI fabrication. The RPNI was placed and secured in between the biceps femoris muscle near the skin while the side opposite to the nerve coaptation was facing the dermis. The overlying skin was defatted and fixed on top of the superficial RPNI (S-RPNI). At two months post-surgery, functional motor reinnervation was evaluated by electrical stimulation of the tibial nerve and compound muscle action potentials (CMAPs) were recorded using surface electrodes. Sensory feedback was assessed by electrical and mechanical stimulation of the skin to respectively record sensory nerve action potentials (SNAPs) and sensory afferent signals. The S-RPNI construct and its overlying skin were subsequently harvested and processed for immunohistochemistry and whole-mount immunostaining.Results:Recording muscle CMAPs from the skin was readily feasible in all animals, showing robust signals with minimal noise distortion (366 µV ± 86.3). Electrical stimulation of the skin on the lateral thigh, which is not innervated by the tibial nerve normally, resulted in classic tri-phasic SNAP generation in this nerve. Brushing the overlying skin using a cotton swab generated synchronized monomorphic afferent signals. Sensory reinnervation of the skin was shown using IHC. Whole-mount staining of the muscle component showed regenerated muscle with new neuromuscular junctions (NMJs) and spatial segregation of sensory fibers toward their end-target organ.Conclusion:Superficially placed RPNI is a viable and an alternate methodology that is simple to implicate and has the potential to transmit simultaneous, real-time, and independent sensory and motor signals between the residual nerve and the prostheses.

Attenuated NMDAR signaling on fast-spiking interneurons in prefrontal cortex contributes to age-related decline of cognitive flexibility

Ionotropic glutamate receptors of the NMDA and AMPA subtypes transduce excitatory signaling on neurons in the prefrontal cortex (PFC) in support of cognitive flexibility. Cognitive flexibility is reliably observed to decline at advanced ages, coinciding with changes in PFC glutamate receptor expression and neuronal physiology. However, the relationship between age-related impairment of cognitive flexibility and changes to excitatory signaling on distinct classes of PFC neurons is not known. In this study, one cohort of young adult (4 months) and aged (20 months) male F344 rats were characterized for cognitive flexibility on an operant set-shifting task. Expression of the essential NMDAR subunit, NR1, was correlated with individual differences in set-shifting abilities such that lower NR1 in the aged PFC was associated with worse set-shifting. In contrast, lower expression of two AMPAR subunits, GluR1 and GluR2, was not associated with set-shift abilities in aging. As NMDARs are expressed by both pyramidal cells and fast-spiking interneurons (FSI) in PFC, whole-cell patch clamp recordings were performed in a second cohort of age-matched rats to compare age-associated changes on these neuronal subtypes. Evoked excitatory postsynaptic currents were generated using a bipolar stimulator while AMPAR vs. NMDAR-mediated components were isolated using pharmacological tools. The results revealed a clear increase in AMPA/NMDA ratio in FSIs that was not present in pyramidal neurons. Together, these data indicate that loss of NMDARs on interneurons in PFC contributes to age-related impairment of cognitive flexibility.

Antitumor Effects of Astaxanthin on Esophageal Squamous Cell Carcinoma by up-Regulation of PPARγ

Esophageal squamous cell carcinoma is a malignant tumor that is difficult to find and has a poor prognosis. The aim of this study is to explore the chemoprevention effect of Astaxanthin (AST) and reveal the possible mechanism of AST on the development of esophageal cancer based on PPARγ. We found that a stable and strong binding between PPARγ molecules and AST molecules using Autodock 4.0 software. AST significantly inhibited the viability of EC109 cells in a dose and time dependent manners (all P < 0.05), and up-regulated the protein expression level of PPARγ from the concentration of 6.25 µM (P < 0.05). Animal experiment showed that AST significantly decreased the incidences of NMBzA-induced esophageal carcinogenesis at 50 mg/kg AST in F344 rats (P < 0.05). AST inhibited the oxidative stress by improving the levels of superoxide dismutase (SOD), total antioxidant capacity (TAOC) and suppressing malondialdehyde (MDA) in serum, and increasing the protein of PPARγ, Bax/Bcl-2, Caspase-3 in esophagus tissue, especially in the 50 mg/kg of AST intervention group (all P < 0.05). In conclusion, our data suggested that protective effect of AST on esophageal cancer by inhibiting oxidative stress, up-regulating PPARγ, and activating the apoptotic pathway, which could provide a basis for clinical application of AST.