l-2286 and Hypertension

During oxidative stress mitochondria become the main source of endogenous reactive oxygen species (ROS) production. In the present study, we aimed to clarify the effects of pharmacological PARP-1 inhibition on mitochondrial function and quality control processes.. L-2286, a quinazoline-derivative PARP inhibitor, protects against cardiovascular remodeling and heart failure by favorable modulation of signaling routes. We examined the effects of PARP-1 inhibition on mitochondrial quality control processes and function in vivo and in vitro. Spontaneously hypertensive rats (SHRs) were treated with L-2286 or placebo. In the in vitro model, 150 μM H. PARP-inhibition prevented the development of left ventricular hypertrophy in SHRs. The interfibrillar mitochondrial network were less fragmented, the average mitochondrial size was bigger and showed higher cristae density compared to untreated SHRs. Dynamin related protein 1 (Drp1) translocation and therefore the fission of mitochondria was inhibited by L-2286 treatment. Moreover, L-2286 treatment increased the amount of fusion proteins (Opa1, Mfn2), thus preserving structural stability. PARP-inhibition also preserved the mitochondrial genome integrity. In addition, the mitochondrial biogenesis was also enhanced due to L-2286 treatment, leading to an overall increase in the ATP production and improvement in survival of stressed cells.. Our results suggest that the modulation of mitochondrial dynamics and biogenesis can be a promising therapeutical target in hypertension-induced myocardial remodeling and heart failure.

Topics: Animals; Cells, Cultured; Citrate (si)-Synthase; DNA, Mitochondrial; Electrocardiography; Glutathione; Hypertension; Hypertrophy, Left Ventricular; Male; Membrane Potential, Mitochondrial; Mitochondria, Heart; Mitochondrial Proteins; Myocytes, Cardiac; Natriuretic Peptide, Brain; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Quinazolines; Rats, Inbred SHR; Rats, Wistar

Vascular remodeling during chronic hypertension may impair the supply of tissues with oxygen, glucose and other compounds, potentially unleashing deleterious effects. In this study, we used Spontaneously Hypertensive Rats and normotensive Wistar-Kyoto rats with or without pharmacological inhibition of poly(ADP-ribose)polymerase-1 by an experimental compound L-2286, to evaluate carotid artery remodeling and consequent damage of neuronal tissue during hypertension. We observed elevated oxidative stress and profound thickening of the vascular wall with fibrotic tissue accumulation induced by elevated blood pressure. 32 weeks of L-2286 treatment attenuated these processes by modulating mitogen activated protein kinase phosphatase-1 cellular levels in carotid arteries. In hypertensive animals, vascular inflammation and endothelial dysfunction was observed by NF-κB nuclear accumulation and impaired vasodilation to acetylcholine, respectively. Pharmacological poly(ADP-ribose)polymerase-1 inhibition interfered in these processes and mitigated Apoptosis Inducing Factor dependent cell death events, thus improved structural and functional alterations of carotid arteries, without affecting blood pressure. Chronic poly(ADP-ribose)polymerase-1 inhibition protected neuronal tissue against oxidative damage, assessed by nitrotyrosine, 4-hydroxinonenal and 8-oxoguanosine immunohistochemistry in the area of Cornu ammonis 1 of the dorsal hippocampus in hypertensive rats. In this area, extensive pyramidal cell loss was also attenuated by treatment with lowered poly(ADP-ribose)polymer formation. It also preserved the structure of fissural arteries and attenuated perivascular white matter lesions and reactive astrogliosis in hypertensive rats. These data support the premise in which chronic poly(ADP-ribose)polymerase-1 inhibition has beneficial effects on hypertension related tissue damage both in vascular tissue and in the hippocampus by altering signaling events, reducing oxidative/nitrosative stress and inflammatory status, without lowering blood pressure.

Topics: Animals; Blood Pressure; Carotid Arteries; Hippocampus; Hypertension; Male; Oxidative Stress; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Quinazolines; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Vascular Remodeling

Oxidative stress and neurohumoral factors play important role in the development of hypertension-induced vascular remodeling, likely by disregulating kinase cascades and transcription factors. Oxidative stress activates poly(ADP-ribose)-polymerase (PARP-1), which promotes inflammation and cell death. We assumed that inhibition of PARP-1 reduces the hypertension-induced adverse vascular changes. This hypothesis was tested in spontaneously hypertensive rats (SHR).. Ten-week-old male SHRs and wild-type rats received or not 5mg/kg/day L-2286 (a water-soluble PARP-inhibitor) for 32 weeks, then morphological and functional parameters were determined in their aortas. L-2286 did not affect the blood pressure in any of the animal groups measured with tail-cuff method. Arterial stiffness index increased in untreated SHRs compared to untreated Wistar rats, which was attenuated by L-2286 treatment. Electron and light microscopy of aortas showed prominent collagen deposition, elevation of oxidative stress markers and increased PARP activity in SHR, which were attenuated by PARP-inhibition. L-2286 treatment decreased also the hypertension-activated mitochondrial cell death pathway, characterized by the nuclear translocation of AIF. Hypertension activated all three branches of MAP-kinases. L-2286 attenuated these changes by inducing the expression of MAPK phosphatase-1 and by activating the cytoprotective PI-3-kinase/Akt pathway. Hypertension activated nuclear factor-kappaB, which was prevented by PARP-inhibition via activating its nuclear export.. PARP-inhibition has significant vasoprotective effects against hypertension-induced vascular remodeling. Therefore, PARP-1 can be a novel therapeutic drug target for preventing hypertension-induced vascular remodeling in a group of patients, in whom lowering the blood pressure to optimal range is harmful or causes intolerable side effects.

Topics: Animals; Aorta; Blood Pressure; Cell Death; Collagen; Hypertension; Male; Mitochondria; Mitogen-Activated Protein Kinases; NF-kappa B; Oxidative Stress; Phosphatidylinositol 3-Kinase; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Proto-Oncogene Proteins c-akt; Quinazolines; Rats; Rats, Inbred SHR; Rats, Wistar; Signal Transduction

Spontaneously hypertensive rat (SHR) is a suitable model for studies of the complications of hypertension. It is known that activation of poly(ADP-ribose) polymerase enzyme (PARP) plays an important role in the development of postinfarction as well as long-term hypertension induced heart failure. In this study, we examined whether PARP-inhibitor (L-2286) treatment could prevent the development of hypertensive cardiopathy in SHRs. 6-week-old SHR animals were treated with L-2286 (SHR-L group) or placebo (SHR-C group) for 24 weeks. Wistar-Kyoto rats were used as aged-matched, normotensive controls (WKY group). Echocardiography was performed, brain-derived natriuretic peptide (BNP) activity and blood pressure were determined at the end of the study. We detected the extent of fibrotic areas. The amount of heat-shock proteins (Hsps) and the phosphorylation state of Akt-1(Ser473), glycogen synthase kinase (GSK)-3β(Ser9), forkhead transcription factor (FKHR)(Ser256), mitogen activated protein kinases (MAPKs), and protein kinase C (PKC) isoenzymes were monitored. The elevated blood pressure in SHRs was not influenced by PARP-inhibitor treatment. Systolic left ventricular function and BNP activity did not differ among the three groups. L-2286 treatment decreased the marked left ventricular (LV) hypertrophy which was developed in SHRs. Interstitial collagen deposition was also decreased by L-2286 treatment. The phosphorylation of extracellular signal-regulated kinase (ERK)1/2(Thr183-Tyr185), Akt-1(Ser473), GSK-3β(Ser9), FKHR(Ser256), and PKC ε(Ser729) and the level of Hsp90 were increased, while the activity of PKC α/βII(Thr638/641), ζ/λ(410/403) were mitigated by L-2286 administration. We could detect signs of LV hypertrophy without congestive heart failure in SHR groups. This alteration was prevented by PARP inhibition. Our results suggest that PARP-inhibitor treatment has protective effect already in the early stage of hypertensive myocardial remodeling.

Topics: Animals; Blood Pressure; Extracellular Signal-Regulated MAP Kinases; Forkhead Transcription Factors; Gene Expression Regulation; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Heart Failure; HSP90 Heat-Shock Proteins; Hypertension; Hypertrophy, Left Ventricular; Isoenzymes; Male; Natriuretic Peptide, Brain; Nerve Tissue Proteins; Phosphorylation; Piperidines; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Protein Kinase C; Proto-Oncogene Proteins c-akt; Quinazolines; Rats; Rats, Inbred SHR; Rats, Inbred WKY; Signal Transduction

Oxidative stress followed by abnormal signalling can play a critical role in the development of long-term, high blood pressure-induced cardiac remodelling in heart failure (HF). Since oxidative stress-induced poly(ADP-ribose)polymerase (PARP) activation and cell death have been observed in several experimental models, we investigated the possibility that inhibition of nuclear PARP improves cardiac performance and delays transition from hypertensive cardiopathy to HF in a spontaneously hypertensive rat (SHR) model of HF.. SHRs were divided into two groups: one received no treatment (SHR-C) and the other (SHR-L) received 5 mg/kg/day L-2286 (PARP-inhibitor) orally for 46 weeks. A third group was a normotensive age-matched control group (CFY) and a fourth was a normotensive age-matched group receiving L-2286 treatment 5 mg/kg/day (CFY+L). At the beginning of the study, systolic function was similar in both CFY and SHR groups. In the SHR-C group at the end of the study, eccentric hypertrophy with poor left ventricular (LV) systolic function was observed, while PARP inhibitor treatment preserved systolic LV function. Due to these favourable changes, the survival rate of SHRs was significantly improved (P < 0.01) by the administration of the PARP inhibitor (L-2286). The PARP inhibitor used did not affect the elevated blood pressure of SHR rats, but moderated the level of plasma-BNP (P < 0.01) and favourably influenced all the measured gravimetric parameters (P < 0.05) and the extent of myocardial fibrosis (P < 0.05). The inhibition of PARP increased the phosporylation of Akt-1/GSK-3beta (P < 0.01), ERK 1/2 (P < 0.01), and PKC epsilon (P < 0.01), and decreased the phosphorylation of JNK (P < 0.05), p-38 MAPK (P < 0.01), PKC pan betaII and PKC zeta/lambda (P < 0.01), and PKC alpha/betaII and delta (P < 0.05).. These data demonstrate that chronic inhibition of PARP induces long-term favourable changes in the most important signalling pathways related to oxidative stress. PARP inhibition also prevents remodelling, preserves systolic function, and delays transition of hypertensive cardiopathy to HF in SHRs.

Topics: Administration, Oral; Animals; Blood Pressure; Cardiovascular Agents; Disease Models, Animal; Disease Progression; Enzyme Inhibitors; Extracellular Signal-Regulated MAP Kinases; Fibrosis; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Heart Failure; Hypertension; Hypertrophy, Left Ventricular; Isoenzymes; JNK Mitogen-Activated Protein Kinases; Male; Myocardium; Natriuretic Peptide, Brain; Oxidative Stress; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Piperidines; Poly (ADP-Ribose) Polymerase-1; Poly(ADP-ribose) Polymerase Inhibitors; Poly(ADP-ribose) Polymerases; Protein Kinase C; Proto-Oncogene Proteins c-akt; Quinazolines; Rats; Rats, Inbred SHR; Signal Transduction; Time Factors; Ventricular Function, Left; Ventricular Remodeling