Saccharomyces boulardii modulates oxidative stress and renin angiotensin system attenuating diabetes-induced liver injury in mice

Type 1 diabetes (T1DM) is a chronic disease characterized by hyperglycemia due to a deficiency in endogenous insulin production, resulting from pancreatic beta cell death. Persistent hyperglycemia leads to enhanced oxidative stress and liver injury. Several studies have evaluated the anti-diabetic and protective effects of probiotic strains in animal models. In the present study, we investigated, through histopathological and biochemical analyses, the effects of eight weeks of administration of Saccharomyces boulardii (S. boulardii) yeast on the liver of streptozotocin (STZ) induced diabetic C57BL/6 mice. Our results demonstrated that S. boulardii attenuates hepatocytes hydropic degeneration and hepatic vessels congestion in STZ-induced diabetic mice. The treatment attenuated the oxidative stress in diabetic mice leading to a reduction of carbonylated protein concentration and increased activity of antioxidant enzymes superoxide dismutase and glutathione peroxidase, compared to untreated diabetic animals. The results also show the beneficial influence of S. boulardii in regulating the hepatic concentration of renin angiotensin system (RAS) peptides. Therefore, our results demonstrated that S. boulardii administration to STZ-induced diabetic mice reduces oxidative stress and normalizes the concentration of RAS peptides, supporting the hypothesis that this yeast may have a role as a potential adjunctive therapy to attenuate diabetes-induced liver injury.

Saccharomyces boulardii Tht 500101 changes gut microbiota and ameliorates hyperglycaemia, dyslipidaemia, and liver inflammation in streptozotocin-diabetic mice

Type 1 diabetes mellitus (T1DM) is a disorder resulting from chronic autoimmune destruction of insulin-producing pancreatic β-cells, lack of insulin production and hyperglycaemia. The aim of this study was to evaluate the hypothesis that streptozotocin-diabetic mice treated with Saccharomyces boulardii THT 500101 strain present improvement of glucose and triglycerides metabolism, reduction of liver inflammation concomitant with a beneficial impact in the gut microbiota profile. C57BL/6 male mice were randomly assigned into three groups: Control, Diabetes, Diabetes+Probiotic, and were euthanised 8 weeks after probiotic chronic administration. Mice submitted to treatment presented reduced glycemia in comparison with the diabetic group, which was correlated with an increase in C-peptide level and in hepatic glycogen content. Fat metabolism was significantly altered in streptozotocin-induced diabetic group, and S. boulardii treatment regulated it, leading to a decrease in serum triglycerides secretion, increase in hepatic triglycerides storage and modulation of inflammatory profile. The phenotypic changes seen from chronic S. boulardii treatment were found to be broadly associated with the changes in microbioma of diabetic animals, with increased proportion in Bacteroidetes, Firmicutes and Deferribacteres, and a decreased proportion of Proteobacteria and Verrucomicrobia phylum. Thus, the data presented here show up a novel potential therapeutic role of S. boulardii for the treatment and attenuation of diabetes-induced complications.

Intense resistance training induces pronounced metabolic stress and impairs hypertrophic response in hind-limb muscles of rats

Skeletal muscle hypertrophy is an exercise-induced adaptation, particularly in resistance training (RT) programs that use large volumes and low loads. However, evidence regarding the role of rest intervals on metabolic stress and muscular adaptations is inconclusive. Thus, we aimed to investigate the effects of a strenuous RT model (jump-training) on skeletal muscle adaptations and metabolic stress, considering the scarce information about RT models for rats. We hypothesized that jump-training induces metabolic stress and influences negatively the growth of soleus (SOL) and extensor digitorum longus (EDL) muscles of rats. Male Wistar rats (aged 60 days) were randomly assigned to non-trained or trained groups (n = 8/group). Trained rats performed jump-training during 5 days a week for 1, 3, or 5 weeks with 30 s of inter-set rest intervals. Forty-eight hours after the experimental period, rats were euthanized and blood samples immediately drawn to measure creatine kinase activity, lactate and corticosterone concentrations. Muscle weight-to-body weight ratio (MW/BW), cross-sectional area (CSA) and myosin heavy chain (MHC) isoform expression were determined. Higher lactate levels occurred after 20 min of training in weeks 1 and 3. Corticosterone levels were higher after 5 weeks of training. Jump-training had negative effects on hypertrophy of types-I and II muscle fibers after 5 weeks of training, as evidenced by decreased CSA and reduced muscle weight. Our results demonstrated that pronounced metabolic stress and impairment of muscle growth might take place when variables of exercise training are not appropriately manipulated. Lay summary Resistance training (RT) has been used to increase muscle mass. In this regard, training variables (intensity, volume, and frequency) must be strictly controlled in order to evoke substantial muscular fitness. This study shows that rats submitted to 5 weeks of intensive resistance jump-training - high intensity, large volume, and short rest intervals - present high levels of blood corticosterone associated with negative effects on hypertrophy of types-I and II muscle fibers.

90-kDa N-domain angiotensin I-converting enzyme (ACE): possible marker for hypertension in a renal transplant model

INTRODUCTION

Hypertension is nearly universal in kidney transplant and several factors are associated with post transplant hypertension, including immunosuppressive medications and genetic predisposition.

OBJECTIVE

The aims were to evaluate the effects of spontaneously hypertensive rats (SHR) kidney transplantation in Wistar rats and the possible transference of 80/90-kDa N-domain ACE.

METHODS

To do so, the data from Wistar recipients of kidney from SHR were compared to data from transplanted Wistar submitted to CsA treatment and, to Wistar Sham.

RESULTS AND DISCUSSION

Despite the unaltered blood pressure observed at early stages, 80/90-kDa ACE was found expressed in the urine of rats 7 and 15 days after transplantation, which was intense when rats became hypertensive 30 days post-surgery.

CONCLUSION

Our data show that this enzyme is associated with the development of hypertension, and this marker appears in the urine before any substantial blood pressure alteration.

Abstract P633: Resistance Training Counteracts The Systemic Catecholaminergic Hyperactivation Associated With Experimental Diabetes, But Not Normalize Cardiac Sympathetic Outflow

Previous studies from our laboratory have demonstrated that chronic diabetes in rats results in cardiomyopathy, associated with sympathetic nervous system (SNS) hyperactivity. On the other hand, it is well known that the beneficial cardiovascular effects of exercise training in diabetes are due in part to normalization of the sympathetic outflow and improvement in the responsiveness of the myocardium to autonomic stimulation. Recently, resistance training (RT) has been recognized as a useful therapeutic tool for the treatment of chronic diseases and similar to aerobic exercise, has been reported to improve metabolic profile and body composition. Therefore, the aim of this study was to evaluate the effect of moderate-intensity RT on circulating and cardiac catecholamines concentration, to understand whether this type of exercise is also associated with cardiovascular protection. Wistar rats (3 months old) were randomized into: control (C), diabetic (D), diabetic + RPT (DR) and diabetic + APT (DA). Animals were made diabetic with a single tail injection of streptozotocin (STZ, 50 mg/Kg). Resistance exercise training was performed on a vertical ladder (5 days/week, 8 weeks) at 40-60% maximal load, and moderate aerobic training was performed on a treadmill (5 days/week, 8 weeks). Diabetes significantly increased plasma concentration of adrenaline (D: 5.3 ± 1.0 vs. C: 4.1 ± 0.6 ng/mL) and noradrenaline (D: 14.5 ± 0.2 vs. C: 3.1± 0.8 ng/mL), and both exercise modalities induced a significant reduction of them: adrenaline (DR: 1.1 ± 0.3; DA: 0.7 ± 0.16 vs. D: 5.3 ± 1.0 ng/mL) and noradrenaline (DR: 1.0 ± 0.2; DA: 0.7 ± 0.1 vs. D: 14.5 ± 0.2 ng/mL). Cardiac concentration of noradrenaline was also increased in diabetic group (D: 62 ± 7 vs. CS: 34 ± 6 pg/g) and only aerobic exercise was capable to reduce its concentration in heart tissue (DA: 30 ± 6 vs. D: 62 ± 7; DR: 55 ± 7 pg/g). The results from the present study show for the first time additional beneficial effects of RT on modulating SNS activity in diabetes. Moreover, considering that RT does not modulate cardiac catecholaminergic secretion, it also highlights the importance of aerobic training in diabetes treatment. Financial Support: FAPESP, CAPES, CNPq

Abstract P634: Aerobic Training Prevents The Development Of Metabolic Abnormalities Induced By Chronic Stress, But Not Abnormal Circulating Levels Of Noradrenaline And Serotonin

The chronic mild and unpredictable stress (CMS) protocol induces insulin resistance, dyslipidemia, oxidative stress and endothelial dysfunction in rats. Regular physical exercise is an effective non-pharmacological tool for the treatment of disorders induced by stress. The aim was to evaluate the role of physical training on hormonal and metabolic changes triggered by CMS. Forty male Sprague-Dawley rats were randomized into: Control, Stress, Exercise, Exercise + Stress, submitted to CMS protocol or to 8-week treadmill training (50-70% of the maximal exercise test). In the 4 th , 5 th and 6 th wk, the animals were submitted to CMS protocol over seven days, repeating the procedures for 3 consecutive weeks. Two weeks after last stressor stimulus, blood and left ventricle were collected. Physical performance of animals submitted to the CMS was lower when compared to control animals, and physical training has not been able to alleviate this loss (p<0.05). The exercise prevented the development of metabolic changes induced by CMS, reducing hyperinsulinemia (Stress: 1.7±0.1 vs. Exercise: 1.4±0.1; Exercise + Stress: 1.3±0.1; Control: 1.4±0.0 ng/mL), insulin resistance index (Stress: 9.2±0.3 vs. Exercise: 7.1±0.2; Exercise + Stress: 5.8±0.2; Control: 8.1±0.2) and serum free fatty acids (Stress: 311.9±10.0 vs. Exercise: 193.0±16.7; Exercise + Stress: 251.6±14.16; Control: 190.1±17.3 mg/dL, p<0.05). In addition, it was also capable of reducing the cardiac concentration of serotonin (Stress: 3.1±0.1 vs. Exercise: 0.6±0.1; Exercise + Stress: 0.5±0.0; Control: 1.3±0.1 pg/g, p<0.05) of stressed animals (CMS). Physical training did not reduce the circulating concentration of noradrenaline (Stress: 603.7±52.2; Exercise: 83.8±10.8; Exercise + Stress: 748.9±46.1 vs. Control: 165.1±27.1 pg/mL) and serotonin (Stress: 1296.0±47.0; Exercise: 1196.0±68.1; Exercise + Stress: 1736.0±60.12 vs. Control: 619.8±79.6), which remained high in the groups submitted to the CMS (p>0.05). The results show that exercise improves metabolic losses triggered by CMS, but not the but not abnormal circulating levels of noradrenaline and serotonin, and suggest that physical training must be prescribed with caution to stressed individuals.

Abstract 233: Resistance Training Attenuates Renal Dysfunction in Animal Diabetic Nephropathy but Does Not Restore Kidney ACE/ACE2 Balance

Overactivity of the intrarenal renin-angiotensin system (RAS) has been implicated in the pathogenesis of diabetic nephropathy. Our group has already demonstrated that aerobic exercise reduces kidney angiotensin II levels and attenuates renal dysfunction under concurrence of diabetes and hypertension. Resistance training (RT) has recently been recognized as a useful therapeutic tool for the treatment chronic diseases and similar to aerobic exercise, has been reported to improve glycemic control. Therefore, the aim of this study was to evaluate the effect of RT on renal function and RAS in diabetic animals, to understand whether this type of exercise is also associated with renoprotection. Wistar rats (3 months old) were randomized into: sedentary control (SC); trained control (TC); sedentary diabetic (SD) and trained diabetic (TD). Animals were made diabetic with a single tail injection of streptozotocin (STZ, 50 mg/Kg). RT was performed on an 110-cm ladder (8 ladder climbs, once/day, 5 days/week, 8 weeks), carrying a load of 50-80% body weight (BW) appended to the tail. At week 8, 24 hr urine volume and albuminuria were evaluated. Kidney was excised and ACE and ACE2 activities were determined (ZPhe-HL and 7-Mca-APK(Dnp), respectively) (Two way ANOVA + Tukey test; P<0.05). RT significantly reduced blood glucose (TD = 449 ± 17 vs. SD = 572 ± 18 mg/dL) and attenuated BW loss of diabetic animals. DM reduced renal ACE activity in sedentary and trained groups (SD = 3.72 ± 0.48, TD = 3.85 ± 0.40 vs. SC = 9.2 ± 0.59 nmol/min/mg), while RT reduced enzyme activity only in control group (TC = 5.14 ± 0.26 vs. SC = 9.2 ± 0.59 nmol/min/mg). RT reduced renal ACE2 in the control group compared to the others (TC = 0.05 ± 0.0001 vs. SC = 0.09 ± 0.004, SD = 0.09 ± 0.003, TD = 0.10 ± 0.002 μM/min/mg), with no effect of diabetes on enzyme activity. RT improved renal function, decreasing urinary volume and albuminuria (DT = 4.13 ± 0.84 vs. SD = 11 ± 2.11 mg/24h) in DT group. The results from the present study show that RT is strongly associated with renoprotection in an experimental model of diabetic nephropathy. Moreover, results show that this improvement on renal function is modulated by other pathways apart from ACE and ACE2 converting enzymes. Financial Support: FAPESP, CAPES, CNPq.

Abstract 229: Increased Ace Gene Dosage Reduces Ace2 Activity in Diabetic Mice Kidney: Involvement of Ace/ace2 Balance on the Development of Diabetic Nephropathy

The mechanisms underlying the link between high constitutive levels of ACE and diabetic nephropathy has not been completely understood, but an imbalance between angiotensin I (ACE) and II (ACE2) converting enzymes homeostasis has been described in diabetic kidney disease. The aim of this study was to evaluate ACE/ACE2 homeostasis in kidney from diabetic mice presenting increased dosage of ACE gene. Male mice (3 months old) genetically engineered to harbor one or three copies of the ACE gene were made diabetic (streptozotocin - STZ, 50 mg/Kg) and randomly assigned into: 1-copy control (1CC), 1-copy diabetic (1CD), 3-copy control (3CC) and 3-copy diabetic. At the end of experimental period body weight was evaluated and kidney was excised. Kidney-to-body weight ratio and ACE and ACE 2 activities were determined using specific substrates (ZPhe-HL and 7-Mca-APK(Dnp), respectively) (Two way ANOVA + Tukey test; P<0.05). Diabetes increased blood glucose (1CD : 436 ± 25 vs. 1CC: 90 ± 2; 3CD: 556 ± 6 vs. 3CC: 112 ± 4 mg/dL) and kidney-to-body weight ratio (1CD: 7.5 ± 0.2 vs. 1CC: 5.8 ± 0.2; 3CD: 7.8 ± 0.1 vs. 3CC: 5.8 ± 0.1 mg/g) with no influence of ACE genotype. As expected, renal ACE activity was directly related to ACE gene copy number in control group (3CC: 9.4 ± 2.11 vs. 1CC:5.6 ± 0.9 mU/mg protein). Renal ACE activity was decreased in diabetic groups (1CD: 3.6 ± 0.2 vs. 1CC: 5.6 ± 0.9; 3CD: 2.3 ± 0.4 vs. 3CC: 9.4 ± 2.1 mU/mg protein) with no influence of ACE genotype. Under physiological condition, renal ACE2 activity remained unchanged regardless of the ACE genotype (1CC: 1.9 ± 0.2 = 3CC: 1.4 ± 0.1 μM/min/mg). However upon a pathological stimulus, renal ACE2 activity was efficiently increased only in 1CD group, but not in 3CD, as compared with the others (1CD: 5.1 ± 0.9 vs. 1CC: 1.9 ± 0.2 = 3CC: 1.4 ± 0.1 = 3CD: 2.2 ± 0.2 μM/min/mg). Taken together, our results show for the first time, that susceptibility for the development of diabetic nephropathy associated with increased ACE gene dosage may be, at least in part, caused by a decrease on renal ACE2 activity. This may result in increased local levels of angiotensin II and decreased angiotensin (1-7), leading to altered glomerular permeability and albuminuria, functional alterations presented by 3CD animals. Financial Support: FAPESP, CAPES, CNPq.

Abstract 508: Resistance Exercise Training Performed Prior Diabetes Mellitus Suppresses Renal and Skeletal Muscle Abnormalities

Prior study of our group shown that previous aerobic exercise training improved the damage caused by diabetes mellitus on renal and cardiovascular system. Resistance exercise training, also known as strength training, is traditionally performed to gain muscle mass; however, it is not clear whether this type of exercise modulates renal system. Additionally, it is also unknown whether previous resistance exercise training can potentially influence the kidney and skeletal muscle. Wistar rats were submitted to resistance exercise training in an apparatus developed especially to this type of exercise (8 - 12 climbs/day, 5 days/week, 12 weeks). Previous resistance exercise trained group (PTD) performed for 4 weeks before the establishment of the disease and after this period they were followed by 8 weeks of resistance exercise training. Additional trained groups such as trained diabetic (TD) and trained control (TC) groups were followed by 8 weeks of resistance exercise training. Control groups were also followed (control - C, diabetes - D). We have found that PTD suppressed abnormalities linked to renal system such as, water consumption and amount of urine PTD=71mL vs. DT=127mL vs. D=138mL (measured during metabolic cage period), as well as attenuated proteinuria and kidney weight. Regarding to skeletal muscle, PTD group had increased muscle weight (extensor digitorium longus - EDL; C=192mg, D=116mg, TD=106mg and PTD=126mg; Tibialis anterior, C=780mg, D=496mg, DT=450mg and PTD=535mg); we also found a great muscle force level in the PTD group (C=573g, CT=1037, D=414g, TD=737g and PTD=825g), suggesting a protective effect of previous exercise in this group. PTEN was suppressed in PTD group and Akt and 4EBP1 (upstream and downstream of mTOR) were activated in PTD group, measured by western blot. These data suggest that, resistance exercise performed prior the establishment of the diabetes mellitus can protect kidney from diabetic nephropathy and skeletal muscle from atrophy. The mechanisms by which kidney and skeletal muscle have been improved are linked to mTOR signaling pathway. Further studies will be performed to confirm the potential involvement of this signaling pathway.

Support: FAPESP, CAPES, CNPq.

Purification and characterization of angiotensin converting enzyme 2 (ACE2) from murine model of mesangial cell in culture

Angiotensin converting enzyme 2 (ACE2) is a component of the renin–angiotensin system (RAS) which converts Ang II, a potent vasoconstrictor peptide into Ang 1–7, a vasodilator peptide which may act as a negative feedback hormone to the actions of Ang II. The discovery of this enzyme added a new level of complexity to this system. The mesangial cells (MC) have multiple functions in glomerular physiology and pathophysiology and are able to express all components of the RAS. Despite of being localized in these cells, ACE2 has not yet been purified or characterized. In this study ACE2 from mice immortalized MC (IMC) was purified by ion-exchange chromatography. The purified enzyme was identified as a single band around 60–70 kDa on SDS-polyacrylamide gel and by Western blotting using a specific antibody. The optima pH and chloride concentrations were 7.5 and 200 mM, respectively. The N-terminal sequence was homologous with many species ACE2 N-terminal sequences as described in the literature. ACE2 purified from IMC was able to hydrolyze Ang II into Ang 1–7 and the K_m value for Ang II was determined to be 2.87 ± 0.76 μM. In conclusion, we purified and localized, for the first time, ACE2 in MC, which was able to generate Ang 1–7 from Ang II. Ang 1–7 production associated to Ang II degradation by ACE2 may exert a protective effect in the renal hemodynamic.

[Nandrolone administration does not promote hypertrophy of soleus muscle in rats]

Anabolic androgenic steroids (AAS) are compounds formed from testosterone or one of its derivatives, which are largely used by amateur e professional athletes to improve the athletic performance. However, the scientific information about the relation between the use of AAS and muscle hypertrophy is controversial. The aim of this study was to evaluate the effects of testosterone and physical training on muscle hypertrophy. Male Wistar rats received i.m. injections of Deca-Durabolin or vehicle during 6 weeks. Trained rats were submitted to a resistance physical training, by jumping up and down in water carrying an overload. Sedentary and trained animals were anesthetized and sacrificed. Soleus muscle was removed for the quantification of total protein and DNA concentration. In the end of the treatment, body weight of trained animals treated with vehicle or AAS was lower than the body weight of respective sedentary. Total protein concentration and the ratio muscle weight/body weight of all experimental groups were not altered. Trained group treated with AAS presented lower DNA concentration than trained group treated with vehicle. The administration of nandrolone decanoate did not promote hypertrophy on soleus muscle, not even when the use of AAS was associated to resistance physical training.

Relationship between renal and cardiovascular changes in a murine model of glucose intolerance

Nutrition is an important variable which may affect the risk for renal disease. We previously showed that a high fructose diet in mice produced hypertension and sympathetic activation [8]. The purpose of this study was to determine if a fructose diet altered renal function. A high fructose diet for 12 weeks impaired glucose tolerance, but caused no change in body weight, blood glucose or plasma insulin. Impairment in renal function was documented by the almost two fold increase in urinary protein excretion (

CONTROL

6.6+/-0.6 vs. Fructose: 15.0+/-0.7 mmol protein/mmol creatinine; p<0.05) which was also accompanied by increases in urinary volume. The diet produced little change in renal histology, kidney weight or kidney weight/body weight ratio. Urinary excretion of angiotensin II/creatinine (

CONTROL

78.9+/-16.6 vs. Fructose: 80.5+/-14.2 pg/mmol) and renal angiotensin converting enzyme activity (

CONTROL

9.2+/-1.6 vs. Fructose: 7.6+/-1.0 ACE units) were not different between groups. There was a positive correlation between mean arterial pressure (r=0.7, p=0.01), blood pressure variability (BPV) (r=0.7, p=0.02), low frequency BPV component (r=0.677, p=0.03) and urinary protein excretion. Results show that consumption of a high fructose diet in mice had deleterious effects on renal function, which were correlated with cardiovascular changes.

Nocturnal hypertension in mice consuming a high fructose diet

OBJECTIVE

To investigate the effect of fructose consumption on the light/dark pattern of blood pressure, heart rate and autonomic neural function in mice.

BACKGROUND

Insulin resistant diabetes is associated with hypertension and autonomic dysfunction. There is evidence that the increasing incidence of diabetes may be related to dietary changes, including consumption of high levels of fructose.

DESIGN/METHODS

C57/BL mice, instrumented with radiotelemetric arterial catheters, were fed a control or high fructose diet (60%). Cardiovascular parameters measured were light/dark pattern of mean arterial pressure (MAP), heart rate (HR) and variability (time and frequency domain). We also measured plasma insulin, glucose, lipids and angiotensin II (Ang II) as well as glucose tolerance. In situ hybridization was used to measure brainstem expression of tyrosine hydroxylase (TH) and Ang AT1a mRNA.

RESULTS

Fructose diet (8 weeks) produced an increase in MAP, variance and low frequency domain (14+/-3 vs. 33+/-4 mm Hg(2), variance and 10+/-2 vs. 26+/-4 mm Hg(2), LF, control vs. fructose, P<0.01). The changes occurred only at night, a period of activity for mice. Glucose tolerance was attenuated in the fructose group. Fructose also increased plasma cholesterol (80+/-1 vs. 126+/-2 mg/dl, control vs. fructose, P<0.05) and plasma Ang II (18+/-5 vs.65+/-12 pg/ml, control vs. fructose, P<0.05). Depressor responses to alpha(1)-adrenergic blockade with prasozin were augmented in fructose-fed mice. Using quantitative in situ hybridization, we found that Ang AT1a receptor and TH mRNA expression were significantly increased in the brainstem locus coeruleus.

CONCLUSION

A high fructose diet in mice produced nocturnal hypertension and autonomic imbalance which may be related to activation of sympathetic and angiotensin systems.

New mass spectrometric assay for angiotensin-converting enzyme 2 activity

A novel assay was developed for evaluation of mouse angiotensin-converting enzyme (ACE) 2 and recombinant human ACE2 (rACE2) activity. Using surface-enhanced laser desorption/ionization time of flight mass spectrometry (MS) with ProteinChip Array technology, ACE1 and ACE2 activity could be measured using natural peptide substrates. Plasma from C57BL/6 mice, kidney from wild-type and ACE2 knockout mice, and rACE2 were used for assay validation. Plasma or tissue extracts were incubated with angiotensin I (Ang I; 1296 m/z) or angiotensin II (Ang II; 1045 m/z). Reaction mixtures were spotted onto the ProteinChips WCX2 and peptides detected using surface-enhanced laser desorption/ionization time of flight MS. MS peaks for the substrates, Ang I and Ang II, and the generated peptides, Ang (1-7) and Ang (1-9), were monitored. The ACE2 inhibitor MLN 4760 (0.01 to 100 micromol/L) significantly inhibited rACE2 activity (IC50=3 nmol/L). Ang II was preferably cleaved by rACE2 (km=5 mumol/L), whereas Ang I was not a good substrate for rACE2. There was no detectable ACE2 activity in plasma. Assay specificity was validated in a model of ACE2 gene deletion. In kidney extract from ACE2-deficient mice, there was no generation of Ang (1-7) from Ang II. However, Ang (1-7) was produced when Ang I was used as a substrate. In conclusion, we developed a specific and sensitive assay for ACE2 activity, which used the natural endogenous peptide substrate Ang II. This approach allows for the rapid screening for ACE2, which has applications in drug testing, high-throughput enzymatic assays, and identification of novel substrates/inhibitors of the renin-angiotensin system.

Relação entre a administração de esteróide anabólico androgênico, treinamento físico aeróbio e supercompensação do glicogênio

A supercompensação do glicogênio é uma das adaptações induzidas pelo treinamento físico. Visando potencializar este fenômeno, muitos atletas utilizam doses suprafisiológicas de esteróides anabólicos androgênicos (EAA). O objetivo deste estudo foi avaliar em ratos os efeitos da nandrolona e do exercício aeróbio sobre o peso corporal, triglicerídeos, glicose e reservas de glicogênio. Ratos Wistar machos foram aleatoriamente divididos em quatro grupos: sedentário + veículo (SV), treinado + veículo (TV), sedentário + EAA (SEAA) e treinado + EAA (TEAA, n = 7-14/grupo). Receberam injeção i.m. de nandrolona ou veículo durante nove semanas e durante o mesmo período os animais treinados foram submetidos a exercício aeróbio. Os dados foram analisados por ANOVA bifatorial e Tukey (p < 0,05). Os grupos SEAA, TV e TEAA apresentaram menor peso corporal do que o grupo SV (SEAA: 339 ± 10 = TV: 342 ± 14 = TEAA: 332 ± 6 < SV: 398 ± 9g). O treinamento físico reduziu significativamente a concentração plasmática de triglicerídeos [(TV: 46 ± 4 = TEAA: 44 ± 3) < (SV: 104 ± 1 = SEAA: 101 ± 6mg/dL)] e de glicogênio hepático [(TV: 3,38 ± 0,57 = TEAA: 2,62 ± 0,34) < (SV: 4,95 ± 0,11 = SEAA: 4,43 ± 0,23mg/100mg)] e aumentou a concentração cardíaca de glicogênio [(TV: 0,38 ± 0,04 = TEAA: 0,42 ± 0,03) > (SV: 0,2 ± 0,02 = SEAA: 0,21 ± 0,02mg/100mg)]. A glicemia e as reservas de glicogênio do sóleo permaneceram inalteradas. O uso de doses suprafisiológicas de nandrolona não potencializou nenhum dos efeitos obtidos em resposta ao treinamento aeróbio.