Totum-854 reduction of blood pressure is associated with tissue remodeling in aorta and heart of SHR rat

Introduction and purpose

Arterial Hypertension (AHT) is a major cause of premature death worldwide. We have developed Totum-854 (T-854), a polyphenol-rich botanical composition to reduce the risk of developing AHT. We assessed the acute and chronic effects on blood pressure in spontaneous hypertensive rats (SHR).

Method

Acute protocol: 12-week-old SHR rats received randomly in a cross-over design, a dose of vehicle (VEH, 1% Tween 20), Captopril (50mg/kg) and T-854 (1250mg/kg) per os with at least 48h-wash-out interval between two gavages. Arterial pressure was recorded during 24h post-gavage, thanks to a radio-telemetry device (HD-S10, DSI) directly into the abdominal aorta. Baseline arterial pressure was measured before oral gavage during 90 min.

Chronic study

18-week-old SHR rats received vehicle (VEH, 1% Tween 20) or T-854 (1000mg/kg) per os once a day for 8 weeks. Arterial pressure was recorded before the oral gavage for 90 min once a week with a radio-telemetry device (HD-S10, DSI). Delta (Δ) SBP and ΔDBP were calculated by subtracting baseline blood pressure (before the start of oral gavage) to measured blood pressure every week. At the end of supplementation, rats were euthanized, and aorta and heart were sampled. Aorta was embedded in paraffin and Masson's trichrome staining was performed in slides obtained by a microtome. Media thickness was measured with ImageJ. For the heart, mRNA was extracted using Trizol and cardiac hypertrophy/fibrosis gene expression was evaluated by RT-qPCR.

Results

Acute supplementation with T-854 exhibited an intermediate profile between VEH and Captopril response for change in SBP and DBP curves. SBP and DBP were reduced in comparison to VEH with 24h-AUC decreased by 93.6±67.8 mmHg h and 70.8±54.6 mmHg h for captopril and T-854, respectively.

When T-854 was administered chronically during 8 weeks, ΔSBP and ΔDBP evolution were significantly different in comparison to VEH group (p<0.05). These curves were maintained under vehicle curves from the 2nd week of supplementation and until the end of the study. After 8 weeks of T-854 supplementation, tissue analysis showed a decrease of 10% on the aorta media thickness in T-854 supplemented rats (p<0.05). Cardiac MMP-2 gene expression was also lower in T-854 group compared to VEH (p=0.059).

Conclusion

T-854 24h-post-gavage acute effect on blood pressure in hypertensive SHR rats suggests a rapid effect, with a decrease in blood pressure few hours after oral administration. Moreover, chronic T-854 supplementation prevents AHT development in SHR. In conclusion, T-854 appears as an efficient strategy to prevent HTA suggesting also a protective role of T-854 on vascular and heart structure and function.

Funding Acknowledgement

Type of funding sources: None.

Totum-070 prevents diet-induced hypercholesterolemia in western diet fed mice and inhibits cholesterol uptake in human enterocyte caco2 cell line

Introduction

It is well known that hypercholesterolemia is an important modifiable risk factor in the development of cardiovascular diseases. Lowering blood cholesterol level reduces the incidence of atherosclerotic disease. Totum-070 (T070) is a clinical stage polyphenol-rich active substance composed by the association of 5 plant extracts.

Purpose

We assessed the hypothesis that administration of T070 prevents hypercholesterolemia in western diet fed mice and explored the potential mechanisms involved in vitro in human enterocytes.

Methods

C57BL/6 mice were fed either a normal diet (ND) or western diet (WD) for 6 weeks and received either vehicle or T070 (1mg/kg or 3mg/kg) daily by gavage (n=14 mice per group). Food intake, body weight and plasma lipid were monitored along study duration. Liver and feces lipid content were quantified at the end of the study. For in vitro studies, human Caco2 cells were differentiated in transwells for 21 days. To perform cholesterol uptake assay, [1,2-3H(N)]-cholesterol was incubated in apical medium for 1 hour in presence or not of T070 prior to quantification of radioactivity in the cells.

Results

In mice, supplementation with T070 had no effect on food intake during the study. At the end of the in vivo study, body weight in WD-fed mice was increased to 28.3±0.8 g compared to the ND group (24.5±0.4 g, p<0.001). Interestingly, a significant (p<0.01) 29% reduction in body weight gain was observed in the T070 3mg/kg group compared to the WD group at the end of the study. Compared to WD group, total-cholesterol in mice supplemented by T070 was reduced in a dose dependent manner (298±8 mg/dl WD vs 276±9 mg/dl T070 1mg/kg, p=0.19, and 265±8 mg/dl T070 3mg/kg, p<0.05). Furthermore, hepatic steatosis induced by the WD was reduced by 73% (p<0.001) in the T070 3mg/kg group. Hepatic and intestinal gene expression were drastically altered by WD feeding compared to ND, while supplementation with T070 tended to restore normal expression levels for many genes implicated in lipid and lipoprotein metabolism. A significant increase in fecal cholesterol excretion was observed in mice supplemented with T070 3 mg/g compared to the mice fed with WD alone (442.3±151.7 nmol/day WD + T070 3mg/g vs 75.4±5.9 nmol/day WD, p<0.05). Studies in human enterocytes demonstrated that 1 g/l T070 reduced cholesterol uptake by 35% (p<0.001), suggesting that T070 inhibits intestinal cholesterol absorption.

Conclusion

Our results show the beneficial effect of supplementation with Totum-070 to prevent induction of hypercholesterolemia in a nutritional mouse model. Investigation of mechanisms of action in enterocytes demonstrate the role of Totum-070 to inhibit intestinal cholesterol absorption. These results highlight the interest of using Totum-070 for the management of hypercholesterolemia.

Funding Acknowledgement

Type of funding sources: None.

Soluble Milk Proteins Improve Muscle Mass Recovery after Immobilization-Induced Muscle Atrophy in Old Rats but Do not Improve Muscle Functional Property Restoration

OBJECTIVES

Effect of 3 different dairy protein sources on the recovery of muscle function after limb immobilization in old rats.

DESIGN

Longitudinal animal study.

SETTING

Institut National de la Recherche Agronomique (INRA). The study took part in a laboratory setting.

INTERVENTION

Old rats were subjected to unilateral hindlimb immobilization for 8 days and then allowed to recover with 3 different dietary proteins: casein, soluble milk proteins or whey proteins for 49 days.

MEASUREMENTS

Body weight, muscle mass, muscle fibre size, isometric, isokinetic torque, muscle fatigability and muscle oxidative status were measured before and at the end of the immobilization period and during the recovery period i.e 7, 21, 35 and 49 days post immobilization.

RESULTS

In contrast to the casein diet, soluble milk proteins and whey proteins were efficient to favor muscle mass recovery after cast immobilization during aging. By contrast, none of the 3 diary proteins was able to improve muscle strength, power and fatigability showing a discrepancy between the recovery of muscle mass and function. However, the soluble milk proteins allowed a better oxidative capacity in skeletal muscle during the rehabilitation period.

CONCLUSION

Whey proteins and soluble milk proteins improve muscle mass recovery after immobilization-induced muscle atrophy in old rats but do not allow muscle functional property restoration.

Chronic clenbuterol treatment compromises force production without directly altering skeletal muscle contractile machinery

Clenbuterol is a β2 -adrenergic receptor agonist known to induce skeletal muscle hypertrophy and a slow-to-fast phenotypic shift. The aim of the present study was to test the effects of chronic clenbuterol treatment on contractile efficiency and explore the underlying mechanisms, i.e. the muscle contractile machinery and calcium-handling ability. Forty-three 6-week-old male Wistar rats were randomly allocated to one of six groups that were treated with either subcutaneous equimolar doses of clenbuterol (4 mg kg(-1) day(-1) ) or saline solution for 9, 14 or 21 days. In addition to the muscle hypertrophy, although an 89% increase in absolute maximal tetanic force (Po ) was noted, specific maximal tetanic force (sPo) was unchanged or even depressed in the slow twitch muscle of the clenbuterol-treated rats (P < 0.05). The fit of muscle contraction and relaxation force kinetics indicated that clenbuterol treatment significantly reduced the rate constant of force development and the slow and fast rate constants of relaxation in extensor digitorum longus muscle (P < 0.05), and only the fast rate constant of relaxation in soleus muscle (P < 0.05). Myofibrillar ATPase activity increased in both relaxed and activated conditions in soleus (P < 0.001), suggesting that the depressed specific tension was not due to the myosin head alteration itself. Moreover, action potential-elicited Ca(2+) transients in flexor digitorum brevis fibres (fast twitch fibres) from clenbuterol-treated animals demonstrated decreased amplitude after 14 days (-19%, P < 0.01) and 21 days (-25%, P < 0.01). In conclusion, we showed that chronic clenbuterol treatment reduces contractile efficiency, with altered contraction and relaxation kinetics, but without directly altering the contractile machinery. Lower Ca(2+) release during contraction could partially explain these deleterious effects.

Muscle mitochondrial metabolism and calcium signaling impairment in patients treated with statins

The most common and problematic side effect of statins is myopathy. To date, the patho-physiological mechanisms of statin myotoxicity are still not clearly understood. In previous studies, we showed that acute application in vitro of simvastatin caused impairment of mitochondrial function and dysfunction of calcium homeostasis in human and rat healthy muscle samples. We thus evaluated in the present study, mitochondrial function and calcium signaling in muscles of patients treated with statins, who present or not muscle symptoms, by oxygraphy and recording of calcium sparks, respectively. Patients treated with statins showed impairment of mitochondrial respiration that involved mainly the complex I of the respiratory chain and altered frequency and amplitude of calcium sparks. The muscle problems observed in statin-treated patients appear thus to be related to impairment of mitochondrial function and muscle calcium homeostasis, confirming the results we previously reported in vitro.

Relationships between maximal muscle oxidative capacity and blood lactate removal after supramaximal exercise and fatigue indexes in humans

The present study investigated whether blood lactate removal after supramaximal exercise and fatigue indexes measured during continuous and intermittent supramaximal exercises are related to the maximal muscle oxidative capacity in humans with different training status. Lactate recovery curves were obtained after a 1-min all-out exercise. A biexponential time function was then used to determine the velocity constant of the slow phase (γ2), which denoted the blood lactate removal ability. Fatigue indexes were calculated during all-out (FIAO) and repeated 10-s cycling sprints (FISprint). Biopsies were taken from the vastus lateralis muscle, and maximal ADP-stimulated mitochondrial respiration ( Vmax) was evaluated in an oxygraph cell on saponin-permeabilized muscle fibers with pyruvate + malate and glutamate + malate as substrates. Significant relationships were found between γ2 and pyruvate + malate Vmax ( r = 0.60, P < 0.05), γ2 and glutamate + malate Vmax ( r = 0.66, P < 0.01), and γ2 and citrate synthase activity ( r = 0.76, P < 0.01). In addition, γ2, glutamate + malate Vmax, and pyruvate + malate Vmax were related to FIAO (γ2 − FIAO: r = 0.85; P < 0.01; glutamate + malate Vmax − FIAO: r = 0.70, P < 0.01; and pyruvate + malate Vmax − FIAO: r = 0.63, P < 0.01) and FISprint (γ2 − FISprint: r = 0.74, P < 0.01; glutamate + malate Vmax − FISprint: r = 0.64, P < 0.01; and pyruvate + malate Vmax − FISprint: r = 0.46, P < 0.01). In conclusion, these results suggested that the maximal muscle oxidative capacity was related to blood lactate removal ability after a 1-min all-out test. Moreover, maximal muscle oxidative capacity and blood lactate removal ability were associated with the delay in the fatigue observed during continuous and intermittent supramaximal exercises in well-trained subjects.