Stiffness In Rats Research Articles

Botulinum toxin combined with static progressive stretching improves fibrous stiffness of knee joint in rats through TGF-β1/Smad pathway.

Joint stiffness and fibrosis are common complications that affect mobility and quality of life, necessitating effective therapeutic strategies to alleviate these issues. The study aimed to observe the therapeutic effect of static progressive stretching (SPS) combined with botulinum toxin type A (BTX-A) on knee joint stiffness in rats and its effect on the transforming growth factor beta 1 (TGF-β1)/small mother against decapentaplegic (Smad) pathway in the development of joint capsule fibrosis. Forty Sprague Dawley rats were randomly divided into the blank control group, model control group, SPS intervention group, BTX-A intervention group, and SPS combined with BTX-A intervention group. Except for the blank control group, the right knee joints of the other rats were surgically fixed with Kirschner wire internal immobilization in full flexion for four weeks to form joint flexion contracture and cause fibrotic stiffness of the joint. The therapeutic effect of each intervention was assessed by the range of motion (ROM) of the knee joint, joint stiffness, the number of total cells, and collagen deposition in the posterior joint capsule, as well as the protein level expressions of TGF-β1, Smad2, Smad3, Smad4, p-Smad2/3, collagen I and III, and alpha smooth muscle actin (α-SMA) in the posterior joint capsule in the TGF-β1/Smad pathway. SPS combined with BTX-A was more effective in relieving joint fibrosis stiffness, improving the histopathological changes in the posterior joint capsule, and suppressing the high expression of target proteins and the overactivated TGF-β1/Smad pathway. The overactivated TGF-β1/Smad pathway was involved in the formation of knee joint fibrosis stiffness in rats. SPS combined with BTX-A was effective in relieving joint flexion contracture and fibrosis of the joint capsule. Moreover, the inhibition of the overactivated TGF-β1/Smad pathway may be the potential molecular mechanism for its therapeutic effect.

Trans-Chalcone (1-3-diphenyl-2-propen-1-one) as a Therapeutic Candidate in Joint Inflammation via Reduction of TNF-α, IL-1β, IL-6, and IL-17 in Rodents: An In Vivo Study by RT-PCR and ELISA analysis.

Autoimmune disorders include vast and distinct illnesses and are characterized by an immune system-mediated attack on the body's own tissues. Because of their ability to impact any portion of the body, their clinical symptoms are incredibly varied. The variations in symptoms are normally linked with the release and activation of vasoactive, chemotactic substances and cytokines. Cytokines perform a multitude of vital biological tasks, such as immune response control, inflammation, proliferation, and tissue repair. The reversal of inflammatory cytokines and leukocyte infiltration into the inflamed tissue by natural compounds provides an effective remedy for autoimmune diseases. Here, the oral administration of trans-chalcone (TC) for 28 days was tested with gradually increasing doses (30, 60, and 120 mg/kg) in complete Freund's adjuvant (CFA)-provoked joint tissue stiffness in rats. Paw edema, arthritic index, joint stiffness, thermal and flexion pain, C-reactive protein, and rheumatoid factor (RF) levels were determined to check the tested drug effectiveness in a chronic inflammatory model. Molecular docking studies revealed strong binding affinity with inflammatory cytokines and mediators such as TNF-α, IL-17, COX-2, and iNOS; further, they were quantified at the mRNA level by RT-PCR and ELISA analysis. Oral administration of TC significantly ameliorated paw edema, thymus and spleen indices, joint stiffness, thermal and flexion pain, C-reactive protein, RF, mobility, and stance of the treated animals. This therapeutic effectiveness was linked with a reduction in the mRNA expression of proinflammatory cytokines such as IL-1β, IL-6, and IL-17. The findings of the reported research confirmed the effectiveness of TC in ameliorating joint stiffness and flexion pain by prominently lowering the inflammatory cytokines.

Long-term simulated microgravity fosters carotid aging-like changes via Piezo1.

Elucidating the impacts of long-term spaceflight on cardiovascular health is urgently needed in face of the rapid development of human space exploration. Recent reports including the NASA Twins Study on vascular deconditioning and aging of astronauts in spaceflight are controversial. The aims of this study were to elucidate whether long-term microgravity promotes vascular aging and the underlying mechanisms. Hindlimb unloading (HU) by tail suspension was used to simulate microgravity in rats and mice. The dynamic changes of carotid stiffness in rats during 8 weeks of HU were determined. Simulated microgravity led to carotid artery aging-like changes as evidenced by increased stiffness, thickness, fibrosis, and elevated senescence biomarkers in the HU rats. Specific deletion of the mechanotransducer Piezo1 in vascular smooth muscles significantly blunted these aging-like changes in mice. Mechanistically, mechanical stretch-induced activation of Piezo1 elevated microRNA-582-5p in vascular smooth muscle cells, with resultant enhanced synthetic cell phenotype and increased collagen deposition via PTEN/PI3K/Akt signalling. Importantly, inhibition of miRNA-582-5p alleviated carotid fibrosis and stiffness not only in HU rats but also in aged rats. Long-term simulated microgravity induces carotid aging-like changes via the mechanotransducer Piezo1-initiated and miRNA-mediated mechanism.

Magnetic resonance elastography captures a transient benefit of exercise intervention on forebrain stiffness in a rat model of fetal alcohol spectrum disorders.

Fetal alcohol spectrum disorders (FASD), a group of prevalent conditions resulting from prenatal alcohol exposure, affect the maturation of cerebral white matter as first identified with neuroimaging. However, traditional methods are unable to track subtle microstructural alterations to white matter. This preliminary study uses a highly sensitive and clinically translatable magnetic resonance elastography (MRE) protocol to assess brain tissue microstructure through its mechanical properties following an exercise intervention in a rat model of FASD. Female rat pups were either alcohol-exposed (AE) via intragastric intubation of alcohol in milk substitute (5.25 g/kg/day) or sham-intubated (SI) on postnatal days (PD) four through nine to model alcohol exposure during the brain growth spurt. On PD 30, half of AE and SI rats were randomly assigned to either a wheel-running or standard cage for 12 days. Magnetic resonance elastography was used to measure whole brain and callosal mechanical properties at the end of the intervention (around PD 42) and at 1 month post-intervention, and findings were validated with histological quantification of oligoglia. Alcohol exposure reduced forebrain stiffness (p = 0.02) in standard-housed rats. The adolescent exercise intervention mitigated this effect, confirming that increased aerobic activity supports proper neurodevelopmental trajectories. Forebrain damping ratio was lowest in standard-housed AE rats (p < 0.01), but this effect was not mitigated by intervention exposure. At 1 month post-intervention, all rats exhibited comparable forebrain stiffness and damping ratio (p > 0.05). Callosal stiffness and damping ratio increased with age. With cessation of exercise, there was a negative rebound effect on the quantity of callosal oligodendrocytes, irrespective of treatment group, which diverged fromour MRE results. This is the first application of MRE to measure the brain's mechanical properties in a rodent model of FASD. MRE successfully captured alcohol-related changes in forebrain stiffness and damping ratio. Additionally, MRE identified an exercise-related increase to forebrain stiffness in AE rats.

Fructose-induced salt-sensitive blood pressure differentially affects sympathetically mediated aortic stiffness in male and female Sprague-Dawley rats.

Hypertension is the leading risk factor for major adverse cardiovascular events (MACE). Aortic stiffness and sympathoexcitation are robust predictors of MACE. Combined high fructose and sodium intake increases arterial pressure, aortic stiffness, renin, and sympathetic nerve activity in male rats. We hypothesized that activation of the renin angiotensin system (RAS) and/or the sympathetic system mediates aortic stiffness in rats with fructose-induced salt-sensitive blood pressure. Male and female Sprague-Dawley rats ingested 20% fructose or 20% glucose in drinking water with 0.4% NaCl chow for 1 week. Then, fructose-fed rats were switched to 4% NaCl chow (Fru + HS); glucose-fed rats remained on 0.4% NaCl chow (Glu + NS, controls for caloric intake). After 2 weeks, mean arterial pressure (MAP) and aortic pulsed wave velocity (PWV) were evaluated at baseline or after acute intravenous vehicle, clonidine, enalapril, losartan, or hydrochlorothiazide. Baseline global longitudinal strain (GLS) was also assessed. MAP and PWV were greater in male Fru + HS versus Glu + NS male rats (p < 0.05 and p < 0.001, respectively). PWV was similar between the female groups. Despite similarly reduced MAP after clonidine, PWV decreased in Fru + HS versus Glu + NS male rats (p < 0.01). Clonidine induced similar decreases in MAP and PWV in females on either diet. GLS was lower in Fru + HS versus Glu + NS male rats and either of the female groups. Thus, acute sympathoinhibition improved aortic compliance in male rats with fructose salt-sensitive blood pressure. Female rats retained aortic compliance regardless of diet. Acute RAS inhibition exerted no significant effects. Male rats on fructose high salt diet displayed an early deficit in myocardial function. Taken together, these findings suggest that adult female rats are protected from the impact of fructose and high salt diet on blood pressure, aortic stiffness, and early left ventricular dysfunction compared with male rats.

Effects of Exercise on Aortic Stiffness Associated with 5‐Flurouracil in Rats

Background5‐fluorouracil (5‐FU) is a chemotherapy drug that is often prescribed in treatment regimens for malignancies of the gastrointestinal tract, breast, and head/neck. However, despite its clear efficacy in cancer treatment, it is also the second most common chemotherapeutic implicated in the development of short and/or long‐term cardiotoxicity that can lead to a less efficacious cancer treatment regimen. Specifically, 5‐FU is associated with increases in arterial stiffness, leading to increased risks for developing heart failure and cardiovascular disease. Exercise, both acutely and following long‐term training, has exhibited cardiovascular health benefits and protection in healthy and disease populations, including reductions in e.g., pulse wave velocity (PWV), a clinical measure of arterial stiffness. Therefore, the purpose of this study was to investigate 5‐FU induced arterial stiffness (via PWV) and evaluate the efficacy of multiple acute bouts of exercise to mitigate arterial stiffness associated with 5‐FU. Further, we utilized reverse phase protein analysis (RPPA) to investigate mechanisms associated with 5‐FU induced arterial stiffness.MethodsMale Sprague Dawley rats aged 6‐8 months (n=26) were used in this series of experiments. All animals were first acclimated to treadmill exercise, and randomized into four groups: Control (CON, n=8), 5‐FU only (5‐FU=7), exercise (EX, n=4), and 5‐FU with exercise (5‐FUEX, n=7). All animals were surgically instrumented with catheters in the external jugular vein and tail artery. Animals received a clinically relevant dose of 5‐FU with the combination of a bolus (50mg/kg), followed immediately by a 2h continuous infusion of 5‐FU (265mg/kg) through the jugular catheter. This was done to better imitate clinical drug delivery rather than i.p injections typically used in pre‐clinical models. Baseline and 2h measurements of PWV were made from the descending to lower abdominal aorta. Both exercise groups underwent four, 20–30‐minute acute bouts of moderate intensity exercise (20m/min, 5% incline) on consecutive days, 24h apart, with the last being ~10 minutes before surgical instrumentation. RPPA analysis was performed on abdominal aorta from each animal for analysis of changes in protein expression.ResultsThere were no differences in PWV between groups at either time point (p&gt;0.05). However, a significant increase in PWV from baseline to the 2h time point was evident in the 5‐FU group alone (CON ‐1.1±4.9, 5‐FU 14.8±4.4, EX 4.6±5.7, 5‐FUEX 5.4.9±2.2%, p&lt;0.05). Preliminary RPPA analysis indicated 1.5log2fold changes in 5‐FU animals in multiple factors, several of which have been associated with increased vascular stiffness including Steroid Receptor Co‐activator (SRC‐1) and mitogen‐activated protein kinase (MAPK1/MAPK3) that will require further investigation.ConclusionThis study suggests that 5‐FU induces aortic stiffness in rats that can be attenuated with prior acute bouts of exercise. These findings provide further efficacy of exercise therapy in cancer standards of care besides its established benefits for reducing fatigue and improving quality of life in cancer patients. Lastly, the potential to mitigate cardiovascular complications of 5‐FU therapy is clinically important as it can possibly prevent early cessation or reductions of this efficacious therapy.

Detection of liver and spleen stiffness in rats with portal hypertension by two-dimensional shear wave elastography

BackgroundThe measurement of liver stiffness (LS) and spleen stiffness (SS) based on ultrasound elastography can be used for non-invasive assessment of portal hypertension (PH). However, there are few studies on the corresponding mechanism of increased spleen stiffness. Our aim was to use two-dimensional shear wave elastrography (2D-SWE) to evaluate the relationship between LS and SS and the severity of PH in rats. And explore the mechanism of the increase of LS and SS in PH.MethodsSixty male Sprague–Dawley rats were randomly divided into portal hypertension (PH group, n = 45) and normal control (NC group, n = 15). At 12 weeks, LS and SS was detected by 2D-SWE in vivo. Related hemodynamic parameters and portal vein pressure (PVP) was measured. Spleen and liver 2D-SWE detection was performed again after sacrifice. Pathological changes were observed.ResultsThe SS and LS were increased in PH group (P < 0.05). The SS decreased after sacrifice, and what's more the magnitude of SS decline significantly higher in PH group than in NC group (P < 0.05). The correlation between SS and PVP is stronger than LS (r = 0.624, P < 0.001). SS has positive correlation with indexes of hyperdynamic circulation, but LS was weakly. The correlation between SS and the pathological grade (r = 0.633, P < 0.001) was lower than that in LS (r = 0.905, P < 0.001). Multiple linear regression analysis revealed that SS, portal vein inner diameter (PVD) and splenic vein blood flow velocity (SVV) were significantly associated with PH.ConclusionsSpleen and liver measurement by 2D-SWE may be helpful in evaluating PVP. The correlation between SS and PVP is stronger than LS in rats measured by 2D-SWE. Hemodynamic circulation are important in the elevation of SS with portal hypertension. Pathological changes also have a degree of influence, but have more significance for the elevation of LS. SS may be a more effective noninvasive predictor of PH than LS.

Remote Ischemic Perconditioning Ameliorates Myocardial Ischemia and Reperfusion-Induced Coronary Endothelial Dysfunction and Aortic Stiffness in Rats.

Background:Vascular stiffness and endothelial dysfunction are accelerated by acute myocardial infarction (AMI) and subsequently increase the risk for recurrent coronary events.Aim:To explore whether remote ischemic perconditioning (RIPerc) protects against coronary and aorta endothelial dysfunction as well as aortic stiffness following AMI.Methods:Male OFA-1 rats were subjected to 30 min of occlusion of the left anterior descending artery (LAD) followed by reperfusion either 3 or 28 days with or without RIPerc. Three groups: (1) sham operated (Sham, without LAD occlusion); (2) myocardial ischemia and reperfusion (MIR) and (3) MIR + RIPerc group with 3 cycles of 5 minutes of IR on hindlimb performed during myocardial ischemia were used. Assessment of vascular reactivity in isolated septal coronary arteries (non-occluded) and aortic rings as well as aortic stiffness was assessed by wire myography either 3 or 28 days after AMI, respectively. Markers of pro-inflammatory cytokines, adhesion molecules were assessed by RT-qPCR and ELISA.Results:MIR promotes impaired endothelial-dependent relaxation in septal coronary artery segments, increased aortic stiffness and adverse left ventricular remodeling. These changes were markedly attenuated in rats treated with RIPerc and associated with a significant decline in P-selectin, IL-6 and TNF-α expression either in infarcted or non-infarcted myocardial tissue samples.Conclusions:Our study for the first time demonstrated that RIPerc alleviates MIR-induced coronary artery endothelial dysfunction in non-occluded artery segments and attenuates aortic stiffness in rats. The vascular protective effects of RIPerc are associated with ameliorated inflammation and might therefore be caused by reduced inflammatory signaling.

Maternal separation-induced increases in vascular stiffness are independent of circulating angiotensinogen levels.

The renin-angiotensin system (RAS) precursor angiotensinogen (AGT) has been implicated in the functional and mechanical alterations of the vascular wall in response to high-fat diet (HFD). Previously, we showed that HFD exacerbates angiotensin II-induced constriction in isolated aortic rings from male rats exposed to maternal separation (MatSep), a model of early-life stress. Thus, the aim of this study was to investigate whether MatSep increases AGT secretion promoting vascular stiffness in rats fed a HFD. Male Wistar-Kyoto MatSep offspring were separated (3 h/day, postnatal days 2-14), and undisturbed littermates were used as controls. At weaning, rats were fed for 17 wk a normal diet (ND) or a HFD, 18% or 60% kcal from fat, respectively. In plasma, there was a main effect of MatSep reducing AGT concentration (P < 0.05) but no effect due to diet. In urine, ND-fed MatSep rats displayed higher AGT concentrations that were further increased by HFD (P < 0.05 vs. control). AGT mRNA abundance and protein expression were increased in adipose tissue from HFD-fed MatSep rats compared with control rats (P < 0.05). No significant differences in liver and kidney AGT levels were found between groups. In addition, MatSep augmented vascular stiffness assessed on freshly isolated aortic rings from ND-fed rats (P < 0.05), yet HFD did not worsen vascular stiffness in either MatSep or control rats. There was no correlation between plasma AGT and vascular stiffness in ND-fed rats; however, this relationship was negative in HFD-fed MatSep rats only (P < 0.05). Therefore, this study shows that MatSep-induced increases in vascular stiffness are independent of diet or plasma AGT.NEW & NOTEWORTHY This study demonstrates that there was no correlation between circulating levels of angiotensinogen (AGT) and the development of vascular stiffness in rats exposed to early-life stress and fed a normal diet. This study also shows that early-life stress-induced hypersensitive vascular contractility to angiotensin II in rats fed a high-fat diet is independent of circulating levels of AGT and occurs without further progression of vascular stiffness. Our data show that early-life stress primes the adipose tissue to secrete AGT in a sex- and species-independent fashion.

Standardization of a new non-invasive device for assessment of arterial stiffness in rats: Correlation with age-related arteries’ structure

Pulse wave velocity (PWV) has become a gold standard index to quantify the stiffness of the aorta and is a predictor of cardiovascular events. A recent paper compared the pOpmètreⓇ, a device for measuring the finger-toe PWV, with other techniques and demonstrated its accuracy and validity. However, human devices do not allow the advancement of our knowledge on conditioning mechanisms. Based on its human validation, a new device, pOpetⓇ 1.0 system was designed for estimation of PWV in small animals and this present study aimed to standardize the pOpetⓇ 1.0 for estimation of arterial stiffness in rats, and to confirm its liability and stability as well as the reproducibility of assessments. Therefore several precautions were taken into consideration like as the correct position of the animal and photodiodes according to manufacturers’ suggestions. Results indicated that estimation of PWV through the new pOpetⓇ 1.0 device exhibits good internal consistency, stability and objectivity in all tests performed between days and evaluators. Importantly, data suggest for the first time that this new device is able to detect changes in arterial stiffness that are conditioned by age and pressure-related arterial remodeling.• This new pOpetⓇ device is able to detect changes in vessel structure.• This new pOpetⓇ device exhibits good internal consistency, stability and objectivity in all tests performed• Correct position of the animal and photodiodes are crucial to obtain a very stable signal.

Hypertension accelerates age-related intrarenal small artery (IRSA) remodelling and stiffness in rats with possible involvement of AGEs and RAGE.

To study changes in morphology, advanced glycation end products (AGEs) and the AGEs receptor, RAGE, that occur with ageing in intrarenal small arteries (IRSAs) of spontaneously hypertensive rats (SHRs) and to investigate the possible roles of hypertension, AGEs and RAGE in the progression of IRSA remodelling and stiffness with ageing in rats. Ageing SHRs and ageing normotensive Wistar Kyoto (WKY) rats were studied. The minimal renal vascular resistance (minRVR) was measured. Renal arcuate arteries (RAAs) and interlobular arteries (RILAs), the expression of α-smooth muscle actin, proliferating cell nuclear antigen, AGEs, RAGE and the plasma concentrations of AGEs were also examined. The IRSA minRVR, wall thickening, cell proliferation and collagen deposition in RILAs and RAAs gradually increased with age in SHRs and were much higher in 24-week-old SHRs than in age-matched WKY rats (p<0.05); these indexes in WKY rats were only elevated in the 72-week group (p<0.05). The expression of RAGE in the RAA and RILA tunica media in SHRs was upregulated by 24 weeks and 12 weeks (p<0.05), respectively, while AGEs levels in the plasma and in the IRSA tunica media were increased by 48 weeks (p<0.05) and increased gradually with age. The levels of both RAGE and AGEs in WKY rats were increased only at 72 weeks (p<0.05). Hypertension accelerates the development of age-related IRSA remodelling and stiffness in rats, which may be related to upregulation of RAGE in the IRSA tunica media and increased expression of AGEs at the late stage.

Evaluation of rat liver with ARFI elastography: In vivo and ex vivo study.

ObjectiveThe aim of this study was to compare in vivo vs ex vivo liver stiffness in rats with acoustic radiation force impulse (ARFI) elastography using the histological findings as the gold standard.MethodsEighteen male Wistar rats aged 16–18 months were divided into a control group (n = 6) and obese group (n = 12). Liver stiffness was measured with shear wave velocity (SWV) using the ARFI technique both in vivo and ex vivo. The degree of fibrosis, steatosis and liver inflammation was evaluated in the histological findings. Pearson’s correlation coefficient was applied to relate the SWV values to the histological parameters.ResultsThe SWV values acquired in the ex vivo study were significantly lower than those obtained in vivo (P < 0.004). A significantly higher correlation value between the degree of liver fibrosis and the ARFI elastography assessment was observed in the ex vivo study (r = 0.706, P < 0.002), than the in vivo study (r = 0.623, P < 0.05).ConclusionAssessment of liver stiffness using ARFI elastography yielded a significant correlation between SWV and liver fibrosis in both the in vivo and ex vivo experiments. We consider that by minimising the influence of possible sources of artefact we could improve the accuracy of the measurements acquired with ARFI.

Chronic effects of vaping with and without nicotine on arterial stiffness in rats

The use of electronic cigarette (E‐cig) devices has increased over the last decade. However, little is known about the cardiovascular effects of vaping over prolonged periods of time.Preliminary data from female Sprague Dawley rats exposed to either air (n=1), nicotine‐free E‐cig vapor without nicotine (E‐cig0, n=3) or E‐cig vapor with 18 mg/ml free‐base nicotine (E‐cig18, n=1) were obtained using 75/25 VG/PG base solution with a 3rd generation tank‐style E‐cig device. Whole body exposure was performed via a dual chamber exposure system (Scireq InExpose) consisting of 20 puffs over 1‐hour each day (1 puff every 3 minutes), 5 days/week, using 5‐sec (55 ml) puffs @17.5 watts. This resulted in an average daily total particulate matter (TPM) concentration of ~120 mg/m3. Total number of particles measured in E‐cig0 and E‐cig18 chambers was 1.09 × 1010 and 2.14 × 1010, with an average daily particle exposure of 6.4 × 105 and 1.18 ×106 particles, respectively. In‐vivo aortic stiffness was assessed under anesthesia using Vevo2100 ultra‐high frequency ultrasound imaging system (VisualSonics) by measuring pulse wave velocity (PWV) in B‐mode and Doppler ultrasound of blood flow signals of the common carotid artery (between the aortic arch and the carotid bifurcation from a single, EKG‐gated, image).Exposure began at 18 weeks (4.2 months) and ended at 40 weeks (9.3 months) of age, resulting in a total exposure period of 22 weeks (5.1 months). Based on the average life expectancy of a rat (24 months) to humans (78 years), 5.1 months of exposure in rat equates ~16.5 years of vaping in humans. Following this exposure in rats, we observed that PWV was 2.94 m/s in the air (control) group, 4.87 m/s in the E‐cig0 group, and 4.45 m/s in the E‐cig18 group. The difference in PWV between air and E‐cig groups was +1.66 m/s (E‐cig0) and +1.51 m/s (E‐cig18). These preliminary data are consistent with previous findings from chronic exposure (up to 8‐months) in mice showing significant increases in PWV with E‐cig18 (+1.14 m/s) and traditional cigarette (+1.28 m/s) exposure (p&lt;0.05).These findings suggest that chronic vaping with or without nicotine will likely illicit similar harmful effects toward arterial stiffness in rats and mice. Given that a +1.0 m/s increase in central PWV is associated with a ~15% greater risk of cardiovascular and all‐cause mortality risk in humans, the clinical implications are that chronic vaping with or without nicotine will increase arterial stiffness and associated mortality. Clinical monitoring of vascular health should be strongly encouraged in all E‐cig users.Support or Funding Information Support: WVU Cancer Institute Philip R Dino Innovative Research Grant (IMO); Transition Grant Support; Office of Research and Graduate Education (IMO), APS STRIDE Fellowship (JO); NIHGMS 5U54GM104942‐03 (PDC)This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Role of Virtual Touch Tissue Imaging Quantification in the Assessment of Hepatic Sinusoidal Obstruction Syndrome in a Rat Model.

To investigate the value of liver stiffness in rats with various degrees of hepatic sinusoidal obstruction syndrome (HSOS) induced by monocrotaline by comparing liver histopathologic findings. Seventy rats were randomly divided into a control group (n = 10), a low-dose monocrotaline group (n = 30), and a high-dose monocrotaline group (n = 30). After successful modeling, the liver shear wave velocity (SWV) by Virtual Touch tissue imaging quantification (Siemens Medical Solutions, Mountain View, CA) and the alanine aminotransferase (ALT), aspartate aminotransferase (AST), and total bilirubin levels of the groups were obtained on days 3 and 5, and the intergroup differences were compared. Liver histopathologic characteristics were analyzed to evaluate the degrees of HSOS, and the scores were recorded. On days 3 and 5, the total bilirubin, AST, and ALT, levels and liver SWV in the low- and high-dose groups were elevated; the portal vein velocity (PVV) of these groups was decreased compared with the control group; and the high-dose rats showed higher serum AST and ALT levels than the low-dose rats. The high-dose rats had a lower PVV than the low-dose rats at day 3. The liver SWV values had significant correlations with the histologic score and PVV. In a multivariate analysis, the liver SWV (β = 0.813; P < .001) was independently associated with the histopathologic score. Liver stiffness as measured by Virtual Touch tissue imaging quantification increases with the severity of HSOS and can be recommended as a marker for diagnosis and assessment of HSOS.

Effects of Different Exercise Modes on Arterial Stiffness and Nitric Oxide Synthesis.

Aerobic training (AT) and high-intensity intermittent training (HIIT) reduce arterial stiffness, whereas resistance training (RT) induces deterioration of or no change in arterial stiffness. However, the molecular mechanism of these effects of different exercise modes remains unclear. This study aimed to clarify the difference of different exercise effects on endothelial nitric oxide synthase (eNOS) signaling pathway and arterial stiffness in rats and humans. In the animal study, forty 10-wk-old male Sprague-Dawley rats were randomly divided into four groups: sedentary control (CON), AT (treadmill running, 60 min at 30 m·min, 5 d·wk for 8 wk), RT (ladder climbing, 8-10 sets per day, 3 d·wk for 8 wk), and HIIT (14 repeats of 20-s swimming session with 10-s pause between sessions, 4 d·wk for 6 wk from 12-wk-old) groups (n = 10 in each group). In the human study, we confirmed the effects of 6-wk HIIT and 8-wk AT interventions on central arterial stiffness and plasma nitrite/nitrate level in untrained healthy young men in randomized controlled trial (HIIT, AT, and CON; n = 7 in each group). In the animal study, the effect on aortic pulse wave velocity (PWV), as an index of central arterial stiffness, after HIIT was the same as the decrease in aortic PWV and increase in arterial eNOS/Akt phosphorylation after AT, which was not changed by RT. A negative correlation between aortic PWV and eNOS phosphorylation was observed (r = -0.38, P < 0.05). In the human study, HIIT- and AT-induced changes in carotid-femoral PWV (HIIT -115.3 ± 63.4 and AT -157.7 ± 45.7 vs CON 71.3 ± 61.1 m·s, each P < 0.05) decreased, and plasma nitrite/nitrate level increased compared with those in CON. HIIT may reduce central arterial stiffness via the increase in aortic nitric oxide bioavailability despite it being done in a short time and short term and has the same effects as AT.

Internal jugular vein blood flow in the upright position during external compression and increased central venous pressure: an ultrasound study in healthy volunteers.

External compression of the jugular veins is an effective method to increase intracranial blood volume and brain stiffness in rats and healthy volunteers. It has been reported that, on assuming an upright posture, cerebral venous drainage is distributed away from the internal jugular veins (IJVs) to the cervical venous plexus, causing complete collapse of the IJV. If so, it is not clear why external IJV compression would increase intracranial blood volume, but the latter is frequently observed in neurosurgery in the sitting position. The aim of this study was to observe the effect of external IJV compression and the Valsalva maneuver on the change in IJV cross-sectional area and IJV flow in volunteers in the upright posture. After Research Ethics Board approval, we used ultrasound to evaluate both IJV cross-sectional areas and peak velocities in ten healthy volunteers in the sitting position. With the volunteers breathing normally at rest, we applied the Valsalva maneuver along with circumferential supraclavicular compression of 15 mmHg. Imaging was performed at the level of the cricoid cartilage and at the most superior level under the mandible. The IJV flow was calculated using the product of Doppler velocity and IJV cross-sectional area. Flow was detected in both IJVs of all subjects. The median [interquartile range] cross-sectional area for the right IJV at the level of the cricoid was 0.04 [0.03-0.08] cm2 (baseline), with collar 0.4 [0.2-0.6] cm2 (P=0.003 compared with baseline). There were no significant changes in the median blood flow. Compression of the internal jugular veins or an increase in intrathoracic pressure does not reduce venous drainage but actually may increase intracranial venous volume.

Relationship between liver tissue stiffness and histopathological findings analyzed by shear wave elastography and compression testing in rats with non-alcoholic steatohepatitis.

The aim of the present study was to investigate two methods of determining liver stiffness in rats with various degrees of non-alcoholic steatohepatitis induced by a methionine- and choline-deficient (MCD) diet by comparing each finding with reference to histopathological liver findings. Twenty male Wister rats were fed an MCD diet for up to 32weeks, and four were fed a normal diet. Ultrasound-based shear wave elastography (SWE) and mechanical compression testing using an Instron Universal Testing machine were performed on each rat at designated time points. After each examination, liver histopathology was analyzed to evaluate the degrees of steatosis, inflammation, and fibrosis based on non-alcoholic fatty liver disease (NAFLD) activity score, and each finding was compared with reference to liver histopathologic findings. Median liver stiffness values measured using SWE showed a stepwise increase with increasing histological inflammation score (P=0.002), hepatic fibrosis stage (P=0.029), ballooning score (P=0.012), and steatosis grade (P=0.030). Median liver stiffness measured using an Instron machine showed a stepwise increase only with increasing histological fibrosis stage (P=0.033). Degree of liver stiffness measured by SWE and the Instron machine differed. SWE reflected mainly inflammation, whereas Instron machine-derived values primarily reflected fibrosis. This is the main source of discrepancies between measurements made with these two modalities.

SAT-443 - Pharmacological Vasodilatation Efficiently Decreases Liver Stiffness in Rats with TAA-Induced Liver Cirrhosis

SAT-443 - Pharmacological Vasodilatation Efficiently Decreases Liver Stiffness in Rats with TAA-Induced Liver Cirrhosis

Acute Doxorubicin-Induced Cardiotoxicity is Associated with Matrix Metalloproteinase-2 Alterations in Rats

Background: Doxorubicin can cause cardiotoxicity. Matrix metalloproteinases (MMP) are responsible for degrading extracellular matrix components which play a role in ventricular dilation. Increased MMP activity occurs after chronic doxorubicin treatment. In this study we evaluated in vivo and in vitro cardiac function in rats with acute doxorubicin treatment, and examined myocardial MMP and inflammatory activation, and gene expression of proteins involved in myocyte calcium transients. Methods: Wistar rats were injected with doxorubicin (Doxo, 20 mg/kg) or saline (Control). Echocardiogram was performed 48 h after treatment. Myocardial function was assessed in vitro in Langendorff preparation. Results: In left ventricle, doxorubicin impaired fractional shortening (Control 0.59±0.07; Doxo 0.51±0.05; p<0.001), and increased isovolumetric relaxation time (Control 20.3±4.3; Doxo 24.7±4.2 ms; p=0.007) and myocardial passive stiffness. MMP-2 activity, evaluated by zymography, was increased in Doxo (Control 141338 ± 8924; Doxo 188874 ± 7652 arbitrary units; p<0.001). There were no changes in TNF-α, INF-γ, IL-10, and ICAM-1 myocardial levels. Expression of phospholamban, Serca-2a, and ryanodine receptor did not differ between groups. Conclusion: Acute doxorubicin administration induces in vivo left ventricular dysfunction and in vitro increased myocardial passive stiffness in rats. Cardiac dysfunction is related to myocardial MMP-2 activation. Increased inflammatory stimulation or changed expression of the proteins involved in intracellular calcium transients is not involved in acute cardiac dysfunction.

Correlation between Echo-Tracking Parameters and In Vitro Measurements of Arterial Contraction and Relaxation in Rats Fed a High-Cholesterol Diet.

BackgroundEcho-tracking (ET) is a new technique that allows the assessment of arterial function and stiffness. This study aimed to ascertain the utility of the echo-tracking (ET) technique to assess vascular stiffness in rats with hypercholesterolemia and atherosclerosis.Material/MethodsET was used to measure the arterial stiffness of the aorta in cholesterol-fed Sprague-Dawley rats (group T1, n=10, for 4 weeks; group T2, n=10, for 12 weeks) and normal control rats (group C1, n=10; group C2, n=10). In vitro isometric tension experiments were used to measure the maximum contractile tension (MCT) and maximum relaxation percentage (MRR%) of aortic rings. Indicators of arterial stiffness and aortic MCT and MRR% were compared between groups using linear regression analysis. Light microscopic evaluation was used to demonstrate atherosclerotic changes in the aorta.ResultsThe rat models were successfully induced; pathological examination of the aortas showed significant atherosclerosis in group T2, but not in groups C1, C2, or T1. The arterial stiffness parameters obtained using ET and aortic rings in vitro showed significant impairments in T1 and T2 rats compared with C1 and C2 controls (all P<0.05 vs. controls). In addition, these impairments were greater in the T2 group than in the T1 group (all P<0.05). Finally, MRR% correlated with the distensibility coefficient (r=0.396, P=0.012), arterial compliance (r=0.317, P=0.047), stiffness parameter β (r=−0.406, P=0.009) and one-point pulse wave β (r=−0.434, P=0.005).ConclusionsThese results suggest that ET could be used to evaluate the changes in arterial wall elasticity associated with atherosclerosis and hypercholesterolemia.