Mitochondrial dysfunction and cardiac ischemia/reperfusion injury are attenuated by nandrolone: Role of JAK-STAT3 pathway.

AIM: To investigate the effect of acute treatment with the anabolic steroid (AS) nandrolone decanoate in mitochondrial homeostasis and JAK-STAT3 signaling during the progression of cardiac ischemia/reperfusion injury (IR). METHODS: Male Wistar rats (2 months old) were randomly allocated into four experimental groups: Control (CTRL), IR, AS, and AS + AG490. All animals were euthanized 3 days after a single intramuscular injection of nandrolone at 10 mg/kg (AS and AS + AG490 groups) or vehicle (CTRL and IR groups). Baseline mRNA expression of antioxidant enzymes superoxide dismutase (SOD) 1 and 2, glutathione peroxidase, catalase, and myosin heavy chain (MHC) α and ß were compared between CTRL and AS groups. Isolated hearts were submitted to ex vivo ischemia and reperfusion, except for hearts from the CTRL group. Before the IR protocol, the JAK-STAT3 inhibitor AG490 was perfused in hearts from the AS + AG490 group. Heart samples were collected during reperfusion to investigate the effects on mitochondrial function. Results Antioxidant enzyme mRNA expression was unaffected, whereas the AS group exhibited decreased ß- MHC/α-MHC ratio versus the CTRL group. Compared to the IR group, the AS group exhibited better recovery of post-ischemic left ventricular (LV) end-diastolic pressure and LV-developed pressure levels, while infarct size significantly decreased. Furthermore, mitochondrial production, transmembrane potential, and swelling were improved, whereas ROS formation was decreased versus the IR group. These effects were prevented by the perfusion of JAK-STAT3 inhibitor AG490. CONCLUSION: These findings suggest that acute nandrolone treatment can provide cardioprotection by recruiting the JAK-STAT3 signaling pathway and mitochondrial preservation.

Yerba mate consumption by ovariectomized rats alters white adipose tissue.

INTRODUCTION: Menopause and post-menopause are characterized by low levels of estrogen that can be associated with the emergence of metabolic diseases. While hormone replacement therapy can alleviate many symptoms, it can also exacerbate other diseases such as breast cancer. In the search for natural alternatives, Ilex paraguariensis (Yerba Mate) has been identified as a potential therapy for the onset of obesity. Here, the effect of MATE consumption on white adipose tissue (WAT) was studied in ovariectomized rats, an animal model for post-menopause hormone loss. METHODS: Four groups of animals were used: ovariectomy with MATE (OVX MATE) and without MATE (OVX), as well as sham surgery with MATE (Sham MATE) and without MATE (Sham). MATE was provided by gavage at 1 g/kg of body weight for eight weeks before measuring biochemical parameters in plasma and characterizing WAT morphology. RESULTS: The consumption of Yerba MATE significantly decreased weight gain in ovariectomized rats and presented near control levels of triglycerides, total cholesterol, and LDL. A morphometric analysis of WAT showed a significant decrease in the area occupied by adipocytes in the group that consumed MATE. Finally, MATE consumption increased the UCP1 content in the WAT of the ovariectomized group. Yerba MATE treatment was also associated with higher levels of SIRT1 protein. CONCLUSION: MATE consumption has a preventive effect on the weight gain observed in ovariectomized rats and potential benefits in naturally avoiding the onset of obesity post menopause.

Short-term consumption of Ilex paraguariensis extracts protects isolated hearts from ischemia/reperfusion injury and contradicts exercise-mediated cardioprotection.

Perfusion of hearts with extracts of Ilex paraguariensis (IP/mate) appears to reduce ischemia/reperfusion (I/R) injury. To determine if oral consumption of IP/mate can provide similar cardioprotection, short-term consumption was investigated alone or in association with exercise in rats. Animals were grouped into control (C), IP/mate consumption (M), exercise (E), and exercise with mate (E+M). M and E+M groups consumed IP/mate (1 g·kg-1 body weight in 1 mL water) by gavage. E and E+M groups swam 7× per week for 30 min carrying an additional 5% of body weight. After 1 week, hearts were tested ex vivo to measure left ventricle developed pressure (LVDP), systolic and end diastolic pressure (LVSP/LVEDP), maximum velocity of contraction and relaxation (dP/dt+ and dP/dt-) during I/R and infarction size. In addition, cardiac tissue was analyzed for oxidative stress by lipid peroxidation and protein carbonyl levels along with activity of catalase and superoxide dismutase (SOD). LVDP was higher in hearts from M and E groups as well as decreased infarction sizes than others. At the end of reperfusion, dP/dt+ was increased in E and M and dP/dt- was higher in M. LVSP was higher in M and E compared with C. Protein carbonyl and thiobarbituric acid reactive substances levels were higher in M while SOD activity was increased in E. No differences were observed in other activities. The results suggest that short-term consumption of IP/mate has protective effects on heart I/R injury similar to exercise, but the combination of these interventions appears to contradict the beneficial adaptations from exercise.

Antibodies with beta-adrenergic activity from chronic chagasic patients modulate the QT interval and M cell action potential duration.

AIMS: The aim of this study was to investigate whether the sera from chronic chagasic patients (CChPs) with beta-1 adrenergic activity (Ab-beta) can modulate ventricular repolarization. Beta-adrenergic activity has been described in CChP. It increases the L-type calcium current and heart rate in isolated hearts, but its effects on ventricular repolarization has not been described. METHODS AND RESULTS: In isolated rabbit hearts, under pacing condition, QT interval was measured under Ab-beta perfusion. Beta-adrenergic activity was also tested in guinea pig ventricular M cells. Furthermore, the immunoglobulin fraction (IgG-beta) of the Ab-beta was tested on Ito, ICa, and Iks currents in rat, rabbit, and guinea pig myocytes, respectively. Beta-adrenergic activity shortened the QT interval. This effect was abolished in the presence of propranolol. In addition, sera from CChP without beta-adrenergic activity (Ab-beta) did not modulate QT interval. The M cell action potential duration (APD) was reversibly shortened by Ab-beta. Atenolol inhibited this effect of Ab-beta, and Ab- did not modulate the AP of M cells. Ito was not modulated by isoproterenol nor by IgG-beta. However, IgG-beta increased ICa and IKs. CONCLUSION: The shortening of the QT interval and APD in M cells and the increase of IKs and ICa induced by IgG-beta contribute to repolarization changes that may trigger malignant ventricular arrhythmias observed in patients with chronic chagasic or idiopathic cardiomyopathy.

Human chagasic IgGs bind to cardiac muscarinic receptors and impair L-type Ca2+ currents.

OBJECTIVES: Antibodies against cardiac G protein-coupled receptors have been reported in sera from chronic chagasic patients (CChP) and other non-parasitic cardiomyopathies, but the effects and underlying mechanism of interaction between these antibodies and heart cells are not fully established. To address this point, binding of antibodies purified from sera of CChP patients and normal blood donors (NBD) to cardiac muscarinic acetylcholine receptors (mAChR) and their effect on L-type Ca(2+) currents were examined. METHODS AND RESULTS: Saturation [3H]NMS binding experiments with porcine atrial membranes showed that B(max) in the presence of CChP-immunoglobulin G (IgG) decreased from 280.2+/-16.08 fmol/mg (control) to 91.00+/-5.98 fmol/mg, with no apparent change in K(D), while NBD-IgG did not significantly alter these parameters. At the single channel level, CChP-IgG decreased both the fast and slow mean open times and P(o) (from 0.074+/-0.023 to 0.025+/-0.007) without changes in single channel conductance. I/V plots of isoproterenol-stimulated whole-cell L-type Ca(2+) currents (I(Ca)) from rabbit ventricular cardiomyocytes showed a significant reduction in peak I(Ca) during perfusion with CChP-IgG (at 0 mV: from 10.61+/-2.97 to 8.45+/-2.54 pA/pF). NBD-IgGs had no effect on I(Ca). A CChP-IgG purified against a peptide corresponding to the second extracellular loop of the M(2) receptor also impaired L-type Ca(2+) currents. All effects of CChP-IgG were blocked by atropine. CONCLUSIONS: Our results show that antibodies from CChP bind to mAChR in a non-competitive manner and are able to activate the receptor in an agonist-like form resulting in L-type Ca(2+) current inhibition.