Male Fischer Rats Research Articles

Regular nicotine intake increased tooth movement velocity, osteoclastogenesis and orthodontically induced dental root resorptions in a rat model

Orthodontic forces have been reported to significantly increase nicotine-induced periodontal bone loss. At present, however, it is unknown, which further (side) effects can be expected during orthodontic treatment at a nicotine exposure corresponding to that of an average European smoker. 63 male Fischer344 rats were randomized in three consecutive experiments of 21 animals each (A/B/C) to 3 experimental groups (7 rats, 1/2/3): (A) cone-beam-computed tomography (CBCT); (B) histology/serology; (C) reverse-transcription quantitative real-time polymerase chain reaction (RT-qPCR)/cotinine serology—(1) control; (2) orthodontic tooth movement (OTM) of the first and second upper left molar (NiTi closed coil spring, 0.25 N); (3) OTM with 1.89 mg·kg−1 per day s.c. of L(−)-nicotine. After 14 days of OTM, serum cotinine and IL-6 concentration as well as orthodontically induced inflammatory root resorption (OIIRR), osteoclast activity (histology), orthodontic tooth movement velocity (CBCT, within 14 and 28 days of OTM) and relative gene expression of known inflammatory and osteoclast markers were quantified in the dental-periodontal tissue (RT–qPCR). Animals exposed to nicotine showed significantly heightened serum cotinine and IL-6 levels corresponding to those of regular European smokers. Both the extent of root resorption, osteoclast activity, orthodontic tooth movement and gene expression of inflammatory and osteoclast markers were significantly increased compared to controls with and without OTM under the influence of nicotine. We conclude that apart from increased periodontal bone loss, a progression of dental root resorption and accelerated orthodontic tooth movement are to be anticipated during orthodontic therapy, if nicotine consumption is present. Thus patients should be informed about these risks and the necessity of nicotine abstinence during treatment.

Oxidative stress causes hypertension and activation of nuclear factor-\u03baB after high-fructose and salt treatments

There is evidence that diets rich in salt or simple sugars as fructose are associated with abnormalities in blood pressure regulation. However, the mechanisms underlying pathogenesis of salt- and fructose-induced kidney damage and/or consequent hypertension yet remain largely unexplored. Here, we tested the role of oxidative state as an essential factor along with high salt and fructose treatment in causing hypertension. Fischer male rats were supplemented with a high-fructose diet (20% in water) for 20 weeks and maintained on high-salt diet (8%) associate in the last 10 weeks. Fructose-fed rats exhibited a salt-dependent hypertension accompanied by decrease in renal superoxide dismutase activity, which is the first footprint of antioxidant inactivation by reactive oxygen species (ROS). Metabolic changes and the hypertensive effect of the combined fructose-salt diet (20 weeks) were markedly reversed by a superoxide scavenger, Tempol (10 mg/kg, gavage); moreover, Tempol (50 mM) potentially reduced ROS production and abolished nuclear factor-kappa B (NF-κB) activation in human embryonic kidney HEK293 cells incubated with L-fructose (30 mM) and NaCl (500 mosmol/kg added). Taken together, our data suggested a possible role of oxygen radicals and ROS-induced activation of NF-κB in the fructose- and salt-induced hypertension associated with the progression of the renal disease.

The exposure to formaldehyde causes renal dysfunction, inflammation and redox imbalance in rats

Twenty-eight Fischer male rats were divided into four groups: control group (CG), exposed to the ambient air, and groups exposed to formaldehyde (FA) at concentrations of 1% (FA1%), 5% (FA5%) and 10% (FA10%). Kidney function was assessed by dosage of uric acid, creatinine and urea. Morphometry was performed on the thickness of the lumen of Bowman's capsule and diameter of the lumen of the renal tubules. We evaluated the redox imbalance through the catalase and superoxide dismutase activity as well as oxidative damage by lipid peroxidation. Inflammatory chemokines CCL2, CCL3 and CCL5 were analyzed by enzyme immunoassays. There was an increase in the concentration of urea in FA10% compared with CG and FA1%. The levels of creatinine, renal lumen and lipid peroxidation increased in all FA-treated groups compared with CG. The concentration of uric acid in FA10% was lower compared with all other groups. There was an increase in the space of Bowman's capsule in FA5% and FA10% compared with CG and FA1%. However, the superoxide dismutase activity was higher in FA5% compared with other groups while CCL5 was higher in FA1% compared with CG. The exposure to formaldehyde in a short period of time leads to changes in the kidney function, inflammation and morphology, as well as promoted the increase of superoxide dismutase activity and oxidative damage.

Psychological stress-induced colonic barrier dysfunction: Role of immune-mediated mechanisms.

Evidence suggests that patients with irritable bowel syndrome (IBS) exhibit increases in gut permeability and alterations in tight junction (TJ) protein expression. Although psychological stress worsens IBS symptoms, the mechanisms by which stress enhances gut permeability and affects TJ protein expression remain to be determined. Here, we test the hypothesis that chronic intermittent psychological stress activates the release of proinflammatory cytokines to alter TJ proteins and promotes increased gut permeability. Male Fischer-344 rats were subjected to 1 hour of water avoidance stress (WAS) or SHAM stress per day for 7 days. Following the stress protocol, colonic permeability was measured via transepithelial electrical resistance (TEER) and macromolecular flux of horseradish peroxidase (HRP). In tissue isolated from rats exposed to the WAS or SHAM stress, TJ proteins claudin-2, junctional adhesion molecule-A (JAM-A) and zonula occluden-1 (ZO-1) were measured via Western blotting, histological appearance of the colonic segments was assessed via hematoxylin and eosin staining, and an inflammatory cytokine panel was quantified via quantitative reverse transcription-polymerase chain reaction. Repetitive daily exposure to WAS decreased the TEER, increased the macromolecular flux of HRP, and altered the expression of claudin-2, JAM-A and ZO-1 proteins within colonic tissue compared to SHAM controls. In the absence of a histologically defined inflammation, the cytokine profiles of WAS-treated animals revealed an increase in interleukin-1β and tumor necrosis factor (TNF)-α. Subsequent analysis revealed a significant positive correlation between TNF-α and expression of TJ protein claudin-2. Our findings suggest that chronic stress increases colonic permeability via sub-inflammatory cytokine-mediated remodeling of TJ protein expression.

Quantitative evaluation of oxygen metabolism in the intratumoral hypoxia: 18F-fluoromisonidazole and 15O-labelled gases inhalation PET

BackgroundIntratumoral hypoxia is one of the resistant factors in radiotherapy and chemotherapy for cancer. Although it is detected by 18F-fluoromisonidazole (FMISO) PET, the relationship between intratumoral hypoxia and oxygen metabolism has not been studied. The purpose of this study was to evaluate the intratumoral perfusion and oxygen metabolism in hypoxic regions using the rat xenograft model. Ten male Fischer rats with C6 glioma (body weight = 220 ± 15 g) were investigated with 18F-FMISO PET and steady-state inhalation method of 15O-labelled gases PET. The tumoral blood flow (TBF), tumoral metabolic rate of oxygen (TMRO2), oxygen extraction fraction (OEF), and tumoral blood volume (TBV) were measured under artificial ventilation with 15O–CO2, 15O–O2, and 15O–CO gases. Multiple volumes of interest (1-mm diameter sphere) were placed on the co-registered 18F-FMISO (3 h post injection) and functional 15O-labelled gases PET images. The TBF, TMRO2, OEF, and TBV values were compared among the three groups classified by the 18F-FMISO uptake as follows: group Low (L), less than 1.0; group Medium (M), between 1.0 and 2.0; and group High (H), more than 2.0 in the 18F-FMISO standardized uptake value (SUV).ResultsThere were moderate negative correlations between 18F-FMISO SUV and TBF (r = −0.56 and p < 0.01), and weak negative correlations between 18F-FMISO SUV and TMRO2 (r = −0.38 and p < 0.01) and 18F-FMISO SUV and TBV (r = −0.38 and p < 0.01). Quantitative values were as follows: TBF, (L) 55 ± 30, (M) 32 ± 17, and (H) 30 ± 15 mL/100 mL/min; OEF, (L) 33 ± 14, (M) 36 ± 17, and (H) 41 ± 16%; TMRO2, (L) 2.8 ± 1.3, (M) 1.9 ± 1.0, and (H) 2.1 ± 1.1 mL/100 mL/min; and TBV, (L) 5.7 ± 2.1, (M) 4.3 ± 1.9, and (H) 3.9 ± 1.2 mL/100 mL, respectively. Intratumoral hypoxic regions (M and H) showed significantly lower TBF, TMRO2, and TBV values than non-hypoxic regions (L). OEF showed significant increase in the severe hypoxic region compared to non-hypoxic and mild hypoxic regions.ConclusionsThis study demonstrated that intratumoral hypoxic regions showed decreased blood flow with increased oxygen extraction, suggesting the need for a treatment strategy to normalize the blood flow for oxygen-avid active tumor cells in hypoxic regions.

Effects of aging and exercise training on the dynamics of vasoconstriction in skeletal muscle resistance vessels

We hypothesized that old age will slow, and exercise training will speed, the dynamics of skeletal muscle arteriolar vasoconstriction in resistance vessels of aged rats. Young (6month old) and aged (24month old) male Fischer-344 rats were assigned to sedentary (Sed: n = 6/age group) or exercise-trained (ET: n = 5 aged and 6 young; via treadmill running for 10-12weeks) groups. After completion of training, arterioles from the red portion of the gastrocnemius muscle were removed, cannulated, and exposed to 10-4M norepinephrine (NE) or 20mM caffeine. Changes in luminal diameter were recorded for analysis of constrictor dynamics. Old age blunted all kinetic parameters (i.e., time delay, time constant) resulting in vasoconstriction taking ~3 times as long to reach a steady state (SS) versus younger counterparts for NE (aged-sed: 15.6 ± 6.0 versus young-sed: 4.6 ± 0.5s; P < 0.05) with a similar time course to caffeine. Exercise training resulted in a similar time to SS between age groups for NE (aged-ET: 6.8 ± 1.6 versus young-ET: 7.0 ± 0.6s) and caffeine (aged-ET: 7.8 ± 0.6 versus young-ET: 8.6 ± 1.0s). The results of this study demonstrate that aging blunts the rate of vasoconstriction in skeletal muscle resistance vessels to the sympathetic neurotransmitter NE due, in part, to an attenuated rate of contraction from intracellular calcium release. Further, exercise training speeds the dynamics of constriction to both NE and caffeine with old age.

Effect of Low Level Subchronic Microwave Radiation on Rat Brain

ObjectiveThe present study was designed to investigate the effects of subchronic low level microwave radiation (MWR) on cognitive function, heat shock protein 70 (HSP70) level and DNA damage in brain of Fischer rats. MethodsExperiments were performed on male Fischer rats exposed to microwave radiation for 90 days at three different frequencies: 900, 1800, and 2450 MHz. Animals were divided into 4 groups: Group I: Sham exposed, Group II: animals exposed to microwave radiation at 900 MHz and specific absorption rate (SAR) 5.953 × 10−4 W/kg, Group III: animals exposed to 1800 MHz at SAR 5.835 × 10−4 W/kg and Group IV: animals exposed to 2450 MHz at SAR 6.672 × 10−4 W/kg. All the animals were tested for cognitive function using elevated plus maze and Morris water maze at the end of the exposure period and subsequently sacrificed to collect brain tissues. HSP70 levels were estimated by ELISA and DNA damage was assessed using alkaline comet assay. ResultsMicrowave exposure at 900–900–2450 MHz with SAR values as mentioned above lead to decline in cognitive function, increase in HSP70 level and DNA damage in brain. ConclusionThe results of the present study suggest that low level microwave exposure at frequencies 900, 1800, and 2450 MHz may lead to hazardous effects on brain.

Meloxicam medication reduces orthodontically induced dental root resorption and tooth movement velocity: a combined in vivo and in vitro study of dental-periodontal cells and tissue.

Non-steroidal anti-inflammatory drugs (NSAID) are used to alleviate pain sensations during orthodontic therapy but are also assumed to interfere with associated pseudo-inflammatory reactions. In particular, the effects of partially selective COX-2 inhibition over the constitutively expressed COX-1 (11:1) on periodontal cells and tissue, as induced by the NSAID meloxicam, remain unclear. We investigate possible adverse side-effects and potentially useful beneficial effects during orthodontic therapy and examine underlying cellular and tissue reactions. We randomly assigned 63 male Fischer344 rats to three consecutive experiments of 21 animals each (cone-beam computed tomography; histology/serology; reverse-transcription quantitative real-time polymerase chain reaction) in three experimental groups (n = 7; control; orthodontic tooth movement [OTM] of the first/second upper left molars [NiTi coil spring, 0.25N]; OTM with a daily oral meloxicam dose of 3mg/kg). In vitro, we stimulated human periodontal ligament fibroblasts (hPDL) with orthodontic pressure (2g/cm2) with/without meloxicam (10μM). In vivo, meloxicam significantly reduced serum C-reactive protein concentration, tooth movement velocity, orthodontically induced dentine root resorption (OIRR), osteoclast activity and the relative expression of inflammatory/osteoclast marker genes within the dental-periodontal tissue, while presenting good gastric tolerance. In vitro, we observed a corresponding significant decrease of prostaglandin E2/interleukin-6/RANKL(-OPG) expression and of hPDL-mediated osteoclastogenesis. By inhibiting prostaglandin synthesis, meloxicam seems to downregulate hPDL-mediated inflammation, RANKL-induced osteoclastogenesis and, consequently, tooth movement velocity by about 50%, thus limiting its suitability for analgesia during orthodontic therapy. However, its protective effects regarding OIRR and good tolerance profile suggest future prophylactic application, which merits its further investigation.

Changes in cardiovascular responses to chemoreflex activation of rats recovered from protein restriction are not related to AT1 receptors.

What is the central question of this study? In this study, we sought to investigate whether cardiovascular responses to peripheral chemoreflex activation of rats recovered from protein restriction are related to activation of AT1 receptors. What is the main finding and its importance? This study highlights the fact that angiotensinergic mechanisms activated by AT1 receptors do not support increased responses to peripheral chemoreflex activation by KCN in rats recovered from protein restriction. Also, we found that protein restriction led to increased resting ventilation in adult rats, even after recovery. The effects of a low-protein diet followed by recovery on cardiorespiratory responses to peripheral chemoreflex activation were tested before and after systemic angiotensinII type1 (AT1 ) receptor antagonism. Male Fischer rats were divided into control and recovered (R-PR) groups after weaning. The R-PR rats were fed a low-protein (8%) diet for 35 days and recovered with a normal protein (20%) diet for 70 days. Control rats received a normal protein diet for 105 days (CG105 ). After cannulation surgery, mean arterial pressure, heart rate, respiratory frequency, tidal volume and minute ventilation were acquired using a digital recording system in freely moving rats. The role of angintensin II was evaluated by systemic antagonism of AT1 receptors with losartan (20mgkg-1 i.v.). The peripheral chemoreflex was elicited by increasing doses of KCN (20-160μgkgmin-1 , i.v.). At baseline, R-PR rats presented increased heart rate and minute ventilation (372±34beatsmin-1 and 1.274±377mlkg-1 min-1 ) compared with CG105 animals (332±22beatsmin-1 and 856±112mlkg-1 min-1 ). Mean arterial pressure was not different between the groups. Pressor and bradycardic responses evoked by KCN (60μgkg-1 ) were increased in R-PR (+45±13mmHg and -77±47beatsmin-1 ) compared with CG105 rats (+25±17mmHg and -27±28beatsmin-1 ), but no difference was found in the tachypnoeic response. These differences were preserved after losartan. The data suggest that angiotensinII acting on AT1 receptors may not be associated with the increased heart rate, increased minute ventilation and acute cardiovascular responses to peripheral chemoreflex activation in rats that underwent postweaning protein restriction followed by recovery.

Interactive effects of periodontitis and orthodontic tooth movement on dental root resorption, tooth movement velocity and alveolar bone loss in a rat model

BackgroundMany adult orthodontic patients suffer from chronic periodontitis with recurrent episodes of active periodontal inflammation. As their number is steadily increasing, orthodontists are more and more frequently challenged by respective treatment considerations. However, little is currently known regarding interactive effects on undesired dental root resorption (DRR), tooth movement velocity, periodontal bone loss and the underlying cellular and tissue reactions. Material and methodsA total of 63 male Fischer344 rats were used in three consecutive experiments employing 21 animals each (A/B/C), randomly assigned to 3 experimental groups (n=7, 1/2/3), respectively: (A) CBCT; (B) histology/serology; (C) RT-qPCR—(1) control; (2) orthodontic tooth movement (OTM) of the first/second upper left molars (NiTi coil spring, 0.25N); (3) OTM with experimentally induced periodontitis (cervical silk ligature). After 14days of OTM, we quantified blood leukocyte level, DRR, osteoclast activity and relative gene expression of inflammatory and osteoclast marker genes within the dental-periodontal tissue as well as tooth movement velocity and periodontal bone loss after 14 and 28 days. ResultsThe experimentally induced periodontal bone loss was significantly increased by concurrent orthodontic force application. Periodontal inflammation during OTM on the other hand significantly augmented the extent of DRR, relative expression of inflammatory/osteoclast marker genes, blood leukocyte level and periodontal osteoclast activity. In addition, contrary to previous studies, we observed a significant increase in tooth movement velocity. ConclusionsAlthough accelerated tooth movement would be favourable for orthodontic treatment, our results suggest that orthodontic interventions should only be performed after successful systematic periodontal therapy and paused in case of recurrent active inflammation.

Insulin Prevents Hyperfiltration and Proteinuria but Not Glomerular Hypertrophy and Increases Mesangial Matrix Expansion in Diabetic Rats

Objective: The aim of this work was to study the effect of 7 days of strict glycemic control with insulin on glomerular function and structure in streptozotocin (STZ)-diabetic rats. Materials and Methods: Three groups of adult male Fischer rats were studied: controls (n = 15), diabetics (n = 15), and insulin-treated diabetics (n = 15). Diabetes was induced by treating the rats with STZ (55 mg/kg i.p.). One week after the induction of diabetes, blood glucose, protein excretion rate (PER), glomerular filtration rate (GFR), and renal plasma flow (RPF) were estimated in each group. Furthermore, morphometric analysis was performed to estimate the tuft volume and changes in mesangial matrix area. The results are expressed as the mean ± SEM. Results: STZ diabetes caused significant increases in GFR (0.89 ± 0.1 to 1.21 ± 0.1 mL/min/100 g; p < 0.01) and RPF (1.78 ± 0.37 to 3.32 ± 0.6 mL/min/100 g; p < 0.05). Furthermore, the diabetic rats had higher glomerular volumes but mesangial matrix areas similar to controls. Insulin treatment prevented the increases in blood glucose (4.5 ± 0.2 m<smlcap>M</smlcap>), PER (66.1 ± 7.8 mg/day), GFR (0.6 ± 0.07 mL/min/100 g), and RPF (1.72 ± 0.36 mL/min/100 g), but did not prevent glomerular hypertrophy (21.7% increase), but induced mesangial matrix expansion (25% increase). Conclusions: Insulin prevented the diabetes-induced hyperfiltration and proteinuria, but did not prevent glomerular growth, and induced mesangial expansion. Hyperglycemic episodes could be partly responsible for persistent glomerular growth and accelerated mesangial growth.

Dietary exposure to honeybush (Cyclopia) polyphenol-enriched extracts altered redox status and expression of oxidative stress and antioxidant defense-related genes in rat liver

Interest in Cyclopia spp. (honeybush) as a source material for production of polyphenol-enriched extracts (PEEs) for the food ingredient and nutraceutical markets requires investigation of their safety. PEEs of Cyclopia subternata (PECsub) and Cyclopia genistoides (PECgen) were fed (2.5g/kg feed) to male Fischer rats for 28days, while PECsub, having the highest total polyphenol content and antioxidant activity, was also fed for 90days. Their dietary intake did not significantly (P≥0.05) affect body weight gain or relative liver and kidney weight. PECsub resulted in a significant (P<0.05) increase in the total serum bilirubin after 28days, while serum alkaline phosphatase levels were only significantly (P<0.05) increased after 90days, suggesting alterations in the biliary system. No effect on serum iron levels was noticed after 28days, but PECsub significantly (P<0.05) reduced serum iron after 90days. Both PECsub and PECgen increased glutathione reductase activity in the liver significantly (P<0.05) after 28days. Reduced glutathione (GSH) content was significantly (P<0.05) decreased after 90days by PECsub resulting in a marked, but not significant (P≥0.05) decrease in the GSH/GSSG ratio. Considering the expression of oxidative stress and antioxidant defense-related genes after 28days, the expression of eleven genes was altered by PECsub and PECgen. Seven genes, mutually affected by PECsub and PECgen, included (i) antioxidant-related genes, prostaglandin-endoperoxide synthase 1 (Ptgs1), kinesin family member 9 (Kif9) and serine (or cysteine) peptidase inhibitor clade B member 1b (Serpinb1b); (ii) genes involved in reactive oxygen species (ROS) metabolism, xeroderma pigmentosum complementation group A (Xpa) and thioredoxin interacting protein (Txnip) as well as (iii) oxygen transporter-related genes, Fanconi anemia complementation group C (Fancc) and vimentin (Vim). The expression of NADPH oxidase organiser 1 (Noxo1) increased 19.97-fold by PECsub and the thyroid peroxidase (Tpo) 372-fold by PECgen. Changes in the expression of the oxidative stress and antioxidant defense-related genes could be indicative of an underlying stress effected by the honeybush PEEs in the liver. Differential gene expression could likely be attributed to the differences in phenolic composition of the extracts. The daily dietary intake of total polyphenol and individual phenolic constituents, recalculated to a human equivalent dose, was much higher, especially for C. subternata, than normally consumed when habitually drinking “fermented” honeybush herbal tea. Subsequent studies verifying the protein-associated changes governing the oxidative status in the liver is required.

Whey protein increases muscle weight gain through inhibition of oxidative effects induced by resistance exercise in rats

Whey protein (WP) is known for its nutritional value and antioxidant properties. The aim of this study was to evaluate whether the antioxidant properties of WP could contribute to muscle weight gain in response to resistance exercise (RE). We hypothesized that WP ingestion could increase muscle weight gain in rats subjected to an RE program, through inhibition of oxidative effects induced by high-intensity RE. Thirty-two male Fischer rats were randomly assigned to control sedentary, control exercised, WP sedentary, and WP exercised groups (n=8/group). The RE consisted of inducing the rats to perform sets of jumps for 8 weeks. Body and muscle weight gains, muscle glutathione content, histopathology, muscle antioxidant enzyme activities, and gene expression were evaluated. Body and muscle weight gains of exercised rats fed WP were higher than those of control exercised rats. Concomitantly, RE induced an increase in phagocyte infiltration, protein oxidation, and down-regulation of glutathione peroxidase and gamma-glutamylcysteine synthetase messenger RNA expression in gastrocnemius muscle (P<.05), effects that were inhibited by WP ingestion. Cytosolic superoxide dismutase and catalase messenger RNA expression were reduced only by RE (P<.05), and muscle glutathione content was increased only by WP (P<.05) with no significant interaction observed (P>.05). These findings suggest that differences in body and muscle weight gain in exercised rats fed control or WP diets were mediated, in part, by the antioxidant properties of WP, and indicate that when associated with RE, WP represents a nutritional aid to support muscle growth.

Greater Amino Acid Intake Is Required to Maximize Whole-Body Protein Synthesis Immediately after Endurance Exercise Than at Rest in Endurance-Trained Rats, as Determined by an Indicator Amino Acid Oxidation Method

Background: The indicator amino acid oxidation (IAAO) method has contributed to establishing protein and amino acid (AA) requirements by determining the optimal protein and AA intake that maximizes whole-body protein synthesis. However, it has not been used with endurance-trained subjects.Objective: This study aimed to determine the optimal AA intake immediately after endurance exercise and at rest in endurance-trained rats by using the IAAO method.Methods: Four-week-old male Fischer rats were divided into a sedentary (SED) group and a trained (TR) group, which underwent treadmill training 5 d/wk for 6 wk at 26 m/min for 60 min/d. On the metabolic trial day, half of the TR group was provided with test diets after daily treadmill running (TR-PostEx). The other half of the TR group (TR-Rest) and all of the SED group were provided with test diets while at rest. The test diets contained different amounts of AAs (3.3–37.3 g ⋅ kg−1 ⋅ d−1). Phenylalanine in the test diet was replaced with L-[1-13C phenylalanine. The phenylalanine oxidation rate (PheOx) was determined with 13CO2 enrichment in breath, CO2 excretion rate, and enrichment of phenylalanine in blood during the feeding period. The optimal AA intake was determined with biphasic mixed linear regression crossover analysis for PheOx, which identified a breakpoint at the minimal PheOx in response to graded amounts of AA intake.Results: The optimal AA intake in the TR-PostEx group (26.8 g ⋅ kg−1 ⋅ d−1; 95% CI: 21.5, 32.1 g ⋅ kg−1 ⋅ d−1) was significantly higher than in the SED (15.1 g ⋅ kg−1 ⋅ d−1; 95% CI: 11.1, 19.1 g ⋅ kg−1 ⋅ d−1) and TR-Rest (13.3 g ⋅ kg−1 ⋅ d−1; 95% CI: 10.9, 15.7 g ⋅ kg−1 ⋅ d−1) groups, which did not differ.Conclusions: Greater AA intake is required to maximize whole-body protein synthesis immediately after endurance exercise than at rest, but not at rest in endurance-trained rats.

Effect of cerebrolysin on dopaminergic neurodegeneration of rat with oxidative stress induced by 3-nitropropionic acid.

The study tested the hypothesis that cerebrolysin protects the brain from free radicals in rats treated with 3-nitropropionic acid (3-NPA). To address this hypothesis, the levels of dopamine (DA) and some oxidative stress biomarkers were measured after administration of 3-NPA. Young male Fischer rats were treated for three days with cerebrolysin, 3-NPA or both substances. Their brains were extracted, and DA, lipid peroxidation (LP), glutathione (GSH), calcium, and H2O2 were measured using validated methods. In the cortex, hemispheres and cerebellum/medulla oblongata of the group treated with cerebrolysin and 3-NPA, the levels of DA and LP decreased. In addition, calcium and H2O2 levels decreased in the hemispheres of the same group, while GSH increased in cortex. The increased dopamine metabolism due to the administration of cerebrolysin led to increased formation of radical species and oxidative stress, especially when free radicals were generated by 3-NPA.

Hindlimb Immobilization, But Not Castration, Induces Reduction of Undercarboxylated Osteocalcin Associated With Muscle Atrophy in Rats.

Undercarboxylated osteocalcin (ucOC) has been implicated in skeletal muscle insulin sensitivity and function. However, whether muscle mass and strength loss in atrophic conditions is related to a reduction in ucOC is not clear. We hypothesized that both immobilization and testosterone depletion would lead to reductions in ucOC, associated with not only the degree of muscle atrophy but also changes to atrophy signaling pathway(s) in male rats. We subjected 8-week-old male Fischer (F344) rats to 7 days of hindlimb immobilization 10 days after castration surgery. Hindlimb immobilization, but not castration, resulted in a significant reduction in ucOC (30%) and lower ucOC was correlated with the degree of muscle loss and muscle weakness. ucOC levels, the expression of ucOC-sensitive receptor G protein-coupled receptor, class C, group 6, member A (GPRC6A), as well as the activity of extracellular signal-regulated kinase (ERK) and 5' adenosine monophosphate-activated protein kinase (AMPK) were associated with the expression and activity of a number of proteins in the mammalian target of rapamycin complex 1 (mTORC1) and Forkhead Box O (FOXO) signaling pathways in a muscle type-specific manner. These data suggest that ucOC may have other effects on skeletal muscle in addition to its insulin sensitizing effect. © 2016 American Society for Bone and Mineral Research.

Cheese consumption prevents fat accumulation in the liver and improves serum lipid parameters in rats fed a high-fat diet

Cheese consumption has been reported to reduce the risk of metabolic syndrome; however, the mechanisms by which cheese prevents these disorders are not fully understood. The purpose of this study was to examine the effects of cheese consumption on lipid accumulation in the liver as well as to evaluate various serum lipid parameters. Two groups (n = 7) of male Fischer-344 rats were fed the following high-fat diets for 9 weeks: AIN76-modified 20% fat diet containing casein and butter oil (control diet) or the 20% fat diet containing a freeze-dried cheese powder (cheese diet). Blood samples, liver tissue, and fecal specimens were collected and analyzed. Cheese consumption for 9 weeks reduced the accumulation of triglyceride and cholesterol in the liver (P = 0.016 and P < 0.001, respectively), as well as the serum non-high-density lipoprotein (non-HDL) cholesterol concentration (P = 0.013). In contrast, cheese consumption increased the serum HDL concentration with statistical tendency (P = 0.086). We also observed an increase in the serum adiponectin concentration at week 9 in rats fed the cheese diet (P = 0.029). Furthermore, cheese consumption also increased fat excretion in the feces (P < 0.001). Taken together, our results suggest that cheese mediates various beneficial effects for preventing the development of metabolic syndrome by suppressing the accumulation of fat in the liver.

Ozone Inhalation Provokes Glucocorticoid-Dependent and -Independent Effects on Inflammatory and Metabolic Pathways.

Growing evidence implicates air pollutants in adverse health effects beyond respiratory and cardiovascular disease, including metabolic impacts (diabetes, metabolic syndrome, obesity) and neurological/neurobehavioral outcomes (neurodegenerative disease, cognitive decline, perceived stress, depression, suicide). We have shown that inhalation of particulate matter or ozone activates the hypothalamic-pituitary-adrenal axis in rats and increases plasma levels of the glucocorticoid corticosterone. To investigate the role of corticosterone in mediating inflammatory and metabolic effects of pollutant exposure, in this study male Fischer-344 rats were administered the 11β-hydroxylase inhibitor metyrapone (0, 50, 150 mg/kg body weight) and exposed by nose-only inhalation for 4 h to air or 0.8 ppm ozone. Ozone inhalation provoked a 2-fold increase in plasma corticosterone, an effect blocked by metyrapone, but did not alter epinephrine levels. Inhibition of corticosterone production was associated with increased inflammatory signaling in the lungs and plasma in response to ozone, consistent with a role for glucocorticoids in limiting local and systemic inflammatory responses. Effects of ozone on insulin and glucagon, but not ghrelin or plasminogen activator inhibitor-1, were modified by metyrapone, revealing glucocorticoid-dependent and -independent effects on circulating metabolic and hemostatic factors. Several immunosuppressive and metabolic impacts of ozone in the lungs, heart, liver, kidney, and spleen were blocked by metyrapone and reproduced through exogenous administration of corticosterone (10 mg/kg body weight), demonstrating glucocorticoid-dependent effects in target tissues. Our results support involvement of endogenous glucocorticoids in ozone-induced inflammatory and metabolic effects, providing insight into potential biological mechanisms underlying health impacts and susceptibility.

Impact of Superoxide Dismutase Mimetic AEOL 10150 on the Endothelin System of Fischer 344 Rats.

Endothelin-1 is a potent vasoconstrictor and mitogenic peptide involved in the regulation of vasomotor tone and maintenance of blood pressure. Oxidative stress activates the endothelin system, and is implicated in pulmonary and cardiovascular diseases including hypertension, congestive heart failure, and atherosclerosis. Superoxide dismutase mimetics designed with the aim of treating diseases that involve reactive oxygen species in their pathophysiology may exert a hypotensive effect, but effects on the endothelin system are unknown. Our objective was to determine the effect of the superoxide dismutase mimetic AEOL 10150 on the basal endothelin system in vivo. Male Fischer-344 rats were injected subcutaneously with 0, 2 or 5 mg/kg body weight of AEOL 10150 in saline. Plasma oxidative stress markers and endothelins (bigET-1, ET-1, ET-2, ET-3) as well as lung and heart endothelin/nitric oxide system gene expressions were measured using HPLC-Coularray, HPLC-Fluorescence and RT-PCR respectively. AEOL 10150 reduced (p<0.05) the circulating levels of isoprostane (-25%) and 3-nitrotyrosine (-50%) measured in plasma 2h and 24h after treatment, confirming delivery of a physiologically-relevant dose and the potent antioxidant activity of the drug. The reduction in markers of oxidative stress coincided with sustained 24h decrease (p<0.05) of plasma levels of ET-1 (-50%) and ET-3 (-10%). Expression of preproET-1 and endothelin converting enzyme-1 mRNA were not altered significantly in the lungs. However preproET-1 (not significant) and ECE-1 mRNA (p<0.05) were increased (10–25%) in the heart. Changes in the lungs included decrease (p<0.05) of mRNA for the ET-1 clearance receptor ETB and the vasoconstriction-signaling ETA receptor (-30%), and an early surge of inducible nitric oxide synthase expression followed by sustained decrease (-40% after 24 hours). The results indicate that interception of the endogenous physiological flux of reactive nitrogen species and reactive oxygen species in rats impacts the endothelin/nitric oxide system, supporting a homeostatic relationship between those systems.

An Endochondral Ossification-Based Approach to Bone Repair: Chondrogenically Primed Mesenchymal Stem Cell-Laden Scaffolds Support Greater Repair of Critical-Sized Cranial Defects Than Osteogenically Stimulated Constructs In Vivo.

The lack of success associated with the use of bone grafts has motivated the development of tissue engineering approaches for bone defect repair. However, the traditional tissue engineering approach of direct osteogenesis, mimicking the process of intramembranous ossification (IMO), leads to poor vascularization. In this study, we speculate that mimicking an endochondral ossification (ECO) approach may offer a solution by harnessing the potential of hypertrophic chondrocytes to secrete angiogenic signals that support vasculogenesis and enhance bone repair. We hypothesized that stimulation of mesenchymal stem cell (MSC) chondrogenesis and subsequent hypertrophy within collagen-based scaffolds would lead to improved vascularization and bone formation when implanted within a critical-sized bone defect in vivo. To produce ECO-based constructs, two distinct scaffolds, collagen-hyaluronic acid (CHyA) and collagen-hydroxyapatite (CHA), with proven potential for cartilage and bone repair, respectively, were cultured with MSCs initially in the presence of chondrogenic factors and subsequently supplemented with hypertrophic factors. To produce IMO-based constructs, CHA scaffolds were cultured with MSCs in the presence of osteogenic factors. These constructs were subsequently implanted into 7 mm calvarial defects on Fischer male rats for up to 8 weeks in vivo. The results demonstrated that IMO- and ECO-based constructs were capable of supporting enhanced bone repair compared to empty defects. However, it was clear that the scaffolds, which were previously shown to support the greatest cartilage formation in vitro (CHyA), led to the highest new bone formation (p < 0.05) within critical-sized bone defects 8 weeks postimplantation. We speculate this to be associated with the secretion of angiogenic signals as demonstrated by the higher VEGF protein production in the ECO-based constructs before implantation leading to the greater blood vessel ingrowth. This study thus demonstrates the ability of recapitulating a developmental process of bone formation to develop tissue-engineered constructs that manifest appreciable promise for bone defect repair.