RESUMO
Liver is the central metabolic organ of the body and diet is considered one of the main environmental factors that can impact on aging liver. In the elderly stage liver function is relatively well conserved although there are a variety of not well defined morphological changes related to liver fibrosis which is commonly associated with an inflammatory state. The aim of this paper is to study these alterations during the physiological process of aging in Wistar rats and also test if caloric restriction (CR) could ameliorate them. As fibrosis is associated to hepatic stellate cell (HSC) function we also analyzed these cells during aging. Livers from five groups of male Wistar rats (3-, 8-, 24-months old ad libitum and 8- and 24-months caloric restricted rats) were used in this study. Histological analysis, expression of genes implicated in liver fibrosis and the status of inflammatory step-pathways as p38 mitogen-activated protein kinase (p38-MAPK), c-Jun N-terminal kinase (JNK) and the nuclear factor kappa B (NFkB) isoforms, p50 and p65, in cytosolic and nuclear fractions were performed. During elderly, associated with morphological change of HSC, there is a progressive increase in collagen deposition due to an inhibition in collagen degradation. Higher expression of cytokines and the activation of inflammatory pathways are associated with aging. CR ameliorates these circumstances being more effective when it started in middle age. In conclusion elderly stage is associated to a mild fibrotic and inflammatory state in the liver which could be ameliorated after CR.
Assuntos
Envelhecimento , Restrição Calórica , Cirrose Hepática Experimental/etiologia , Animais , Proteína Glial Fibrilar Ácida/análise , Células Estreladas do Fígado/fisiologia , Masculino , Estresse Oxidativo , Ratos , Ratos WistarRESUMO
BACKGROUND AND PURPOSE: Toll-like receptor 4 (TLR4) signalling contributes to inflammatory cardiovascular diseases, but its role in hypertension and the associated vascular damage is not known. We investigated whether TLR4 activation contributed to angiotensin II (AngII)-induced hypertension and the associated vascular structural, mechanical and functional alterations. EXPERIMENTAL APPROACH: AngII was infused (1.44 mg · kg(-1) · day(-1), s.c.) for 2 weeks in C57BL6 mice, treated with a neutralizing anti-TLR4 antibody or IgG (1 µg · day(-1); systolic BP (SBP) and aortic cytokine levels were measured. Structural, mechanical and contractile properties of aortic and mesenteric arterial segments were measured with myography and histology. RT-PCR and Western blotting were used to analyse these tissues and cultured vascular smooth muscle cells (VSMC) from hypertensive rats (SHR). KEY RESULTS: Aortic TLR4 mRNA levels were raised by AngII infusion. Anti-TLR4 antibody treatment of AngII-treated mice normalised: (i) increased SBP and TNF-α, IL-6 and CCL2 levels; (ii) vascular structural and mechanical changes; (iii) altered aortic phenylephrine- and ACh-induced responses; (iv) increased NOX-1 mRNA levels, superoxide anion production and NAD(P)H oxidase activity and effects of catalase, apocynin, ML-171 and Mito-TEMPO on vascular responses; and (v) reduced NO release and effects of L-NAME on phenylephrine-induced contraction. In VSMC, the MyD88 inhibitor ST-2825 reduced AngII-induced NAD(P)H oxidase activity. The TLR4 inhibitor CLI-095 reduced AngII-induced increased phospho-JNK1/2 and p65 NF-κB subunit nuclear protein expression. CONCLUSIONS AND IMPLICATIONS: TLR4 up-regulation by AngII contributed to the inflammation, endothelial dysfunction, vascular remodelling and stiffness associated with hypertension by mechanisms involving oxidative stress. MyD88-dependent activation and JNK/NF-κB signalling pathways participated in these alterations.
Assuntos
Angiotensina II/administração & dosagem , Hipertensão/fisiopatologia , Receptor 4 Toll-Like/metabolismo , Remodelação Vascular/fisiologia , Animais , Aorta/metabolismo , Pressão Sanguínea , Endotélio Vascular/patologia , Hipertensão/genética , Inflamação/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/metabolismo , NF-kappa B/metabolismo , Estresse Oxidativo/fisiologia , Ratos , Ratos Endogâmicos SHR , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Receptor 4 Toll-Like/genética , Regulação para CimaRESUMO
The effect of phorbol 12-myristate, 13-acetate (PMA), an activator of protein kinase C, on noradrenaline (NA) release from cat cerebral arteries preincubated with [3H]NA was investigated in order to examine the role of that enzyme in this secretion. PMA (3 microM) potentiated tritium release elicited by electrical stimulation (2 Hz, 0.3 ms) without modification of spontaneous secretion, whereas 4 alpha-phorbol 12,13 didecanoate (3 microM), an inactive compound, had no effect. Tritium release evoked by tyramine was not modified by PMA. The electrically evoked tritium secretion was reduced by clonidine (1 microM) or B-HT 920 (0.1 microM), alpha 2-adrenoceptor agonists, and unaffected by yohimbine (1 microM), an alpha 2-adrenoceptor antagonist. The presence of clonidine, B-HT 920 or yohimbine reduced the action of PMA. The facilitatory effect of PMA was not increased by the Ca2+ ionophore A23187 (5 microM). These results suggest that: (1) protein kinase C of perivascular adrenergic nerve endings participates in the exocytotic release of NA; (2) the effects of PMA could be partially due to an interference with prejunctional autoinhibitory alpha 2-adrenoceptors, and (3) the increase of intracellular Ca2+ produced by A23187 appears to be inadequate for potentiating the action of PMA.
Assuntos
Artérias Cerebrais/fisiologia , Norepinefrina/metabolismo , Ésteres de Forbol/farmacologia , Acetato de Tetradecanoilforbol/farmacologia , Agonistas alfa-Adrenérgicos/farmacologia , Animais , Azepinas/farmacologia , Gatos , Artérias Cerebrais/efeitos dos fármacos , Clonidina/farmacologia , Estimulação Elétrica , Feminino , Masculino , Norepinefrina/sangue , Proteína Quinase C/metabolismo , Ioimbina/farmacologiaRESUMO
The uptake of [3H]5-hydroxytryptamine (5-HT) in bovine cerebral arteries was reduced by cocaine (1 microM), ouabain (100 microM), pretreatment with 6-hydroxydopamine (6-OHDA) (1.46 mM, 10 min) and metitepine (1 microM). Electrically-stimulated tritium release was decreased by tetrodotoxin (0.8 microM), Ca-free medium, denervation with 6-OHDA (1.46 mM, 10 min), 5-HT (10 microM), noradrenaline (1 microM) and the agonist of alpha 2-adrenoceptors B-HT 920 (0.1 and 1 microM), enhanced by metitepine (1 microM, antagonists of presynaptic 5-HT1 receptors) and rauwolscine (1 microM, antagonist at alpha 2-adrenoceptors, and also of 5-HT1D receptors) and not affected by ketanserin (1 microM, antagonist of 5-HT2 receptors), methysergide (0.1 microM, antagonist of 5-HT1 and 5-HT2 receptors) and phentolamine (1 and 3 microM antagonist of alpha-adrenoceptors and less potent of 5-HT1 receptors). The inhibitory action of 10 microM 5-HT was partially reversed by phentolamine (3 microM) and cocaine (1 microM) and completely reversed by both metitepine (1 microM) and rauwolscine (1 microM). Ketanserin (1 microM), methysergide (0.1 microM) or phentolamine (1 microM) had no effect. Rauwolscine (1 microM) antagonized the inhibition induced by both noradrenaline (1 microM) and B-HT 920 (0.1 and 1 microM). 5-HT induced tritium release which was inhibited by cocaine (an antagonist of 5-HT3 receptors) and denervation with 6-OHDA.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Artérias Cerebrais/metabolismo , Receptores Adrenérgicos alfa/fisiologia , Receptores de Serotonina/fisiologia , Serotonina/metabolismo , Agonistas alfa-Adrenérgicos/farmacologia , Antagonistas Adrenérgicos alfa/farmacologia , Animais , Bovinos , Artérias Cerebrais/efeitos dos fármacos , Estimulação Elétrica , Técnicas In Vitro , Oxidopamina/farmacologia , Serotonina/análise , Serotonina/farmacologia , Antagonistas da Serotonina/farmacologia , Inibidores Seletivos de Recaptação de Serotonina/farmacologia , TrítioRESUMO
1. Field electrical stimulation induced tritium release from cat cerebral arteries preincubated with [3H]serotonin (5-HT). 2. This release was markedly reduced by tetrodotoxin (0.8 microM), B-HT 920 (1 microM), denervation with 6-OH-dopamine (6-OHDA) and OCa2+, and increased by phentolamine (1 microM) and phorbol 12,13-dibutyrate (1 and 3 microM). 3. 5-HT (10 and 100 microM) and NA (0.1, 1 and 10 microM) caused concentration-dependent tritium release in control arteries, but not in those denervated with 6-OHDA. 4. [3H]5-HT uptake was greatly reduced by preincubation of arteries with cocaine (10 microM), ouabain (100 microM) or denervation with 6-OHDA. 5. 5-HT did not amplify contractions elicited by noradrenaline (NA) in middle cerebral arteries. 6. These data indicate: (1) 5-HT is mainly accumulated in adrenergic nerve endings; (2) 5-HT release is modulated by presynaptic alpha 2-adrenoceptors; (3) protein kinase C of perivascular adrenergic nerve endings participates in 5-HT release, and (4) 5-HT did not amplify NA responses.
Assuntos
Músculo Liso Vascular/metabolismo , Serotonina/metabolismo , Animais , Azepinas/farmacologia , Gatos , Artérias Cerebrais/metabolismo , Cocaína/farmacologia , Estimulação Elétrica , Feminino , Técnicas In Vitro , Masculino , Contração Muscular/efeitos dos fármacos , Norepinefrina/metabolismo , Ouabaína/farmacologia , Fentolamina/farmacologia , Dibutirato de 12,13-Forbol/farmacologia , Proteína Quinase C/metabolismo , Simpatectomia Química , Tetrodotoxina/farmacologiaRESUMO
1. The aim of the present study was to analyse, in segments of human placental veins, the effect of the Ca2+ channel agonist Bay K 8644 (0.1 microM) and Ca2+ channel antagonists nifedipine (0.1 microM) and diltiazem (1 microM) on vascular contractility and 45Ca2+ uptake. 2. The Ca2+ channel agonist Bay K 8644 (0.1 microM) caused small concentration dependent contractions that were increased by a moderate membrane depolarization with 7.5 mM K+. This increase was reversed by nifedipine and diltiazem. Ca2+ addition to segments previously depolarized with 75 mM K+ and exposed to a Ca(2+)-free medium caused contractile responses that were increased by 0.1 microM Bay K 8644; such an increase was blocked by 0.1 microM nifedipine and 1 microM diltiazem. 3. K+ and 5-HT induced concentration dependent contractile responses which were increased by Bay K 8644 (0.1 microM). Both 0.1 microM nifedipine and 1 microM diltiazem inhibited the increasing effect of Bay K 8644. Bay K 8644 (30 nM and 0.1 microM) caused an enhancement in 45Ca2+ accumulation over the basal value, that was increased by membrane depolarization with K+ (7.5, 15 and 30 nM) and inhibited by nifedipine (0.1 microM). K+ (15 and 30, but not 7.5 mM) and 5-HT (1 microM) induced 45Ca2+ uptake over the basal level that was increased by Bay K 8644 (0.1 microM). Such an increase was antagonized by nifedipine (0.1 microM). 4. These data indicate that: (1) a small depolarization with K+ is needed for Bay K 8644 to be able to produce consistent contractile responses, suggesting that voltage gated Ca2+ channels (VGCCs) are not activated in a basal situation in placental veins; (2) the increase of 5-HT contraction by Bay K 8644 may be produced by either the capability of this amine to depolarize the membrane of smooth muscle cells and subsequent facilitation of Ca2+ influx through VGCCs or direct activation by Bay K 8644 of receptor (5-HT) operated Ca2+ channels (ROCs), and (3) the increasing effect of Bay K 8644 appears to be due to a Ca2+ entry activation through VGCCs.
Assuntos
Éster Metílico do Ácido 3-Piridinacarboxílico, 1,4-Di-Hidro-2,6-Dimetil-5-Nitro-4-(2-(Trifluormetil)fenil)/farmacologia , Agonistas dos Canais de Cálcio/farmacologia , Contração Muscular/efeitos dos fármacos , Placenta/irrigação sanguínea , Éster Metílico do Ácido 3-Piridinacarboxílico, 1,4-Di-Hidro-2,6-Dimetil-5-Nitro-4-(2-(Trifluormetil)fenil)/antagonistas & inibidores , Cálcio/farmacologia , Bloqueadores dos Canais de Cálcio/farmacologia , Diltiazem/farmacologia , Relação Dose-Resposta a Droga , Feminino , Humanos , Músculo Liso Vascular/efeitos dos fármacos , Nifedipino/farmacologia , Potássio/farmacologia , Gravidez , Fluxo Sanguíneo Regional , Serotonina/farmacologia , Veias/efeitos dos fármacosRESUMO
1. Bay K 8644 (0.1 microM induced weak contractions in human placental artery segments that were increased in the presence of 7.5 mM K+. K+ and serotonin (5-HT) induced contractions that were enhanced by preincubation of segments with Bay K 8644. These enhancements were reduced by nifedipine (0.1 microM) and diltiazem (1 microM). 2. Bay K 8644 induced a 45Ca2+ uptake increase which was potentiated by depolarization with K+ (less than 30 mM) and antagonized by nifedipine. K+ (15 and 30 mM) and 5-HT (1 microM) induced 45Ca2+ uptake that was enhanced by Bay K 8644. 3. These results suggest that Bay K 8644: (1) is unable to activate the quiescent potential-operated Ca2+ channels (POCs) of these arteries, and (2) activates receptor (5-HT)-operated Ca2+ channels or facilitates Ca2+ influx through POCs activated by 5-HT.
Assuntos
Éster Metílico do Ácido 3-Piridinacarboxílico, 1,4-Di-Hidro-2,6-Dimetil-5-Nitro-4-(2-(Trifluormetil)fenil)/farmacologia , Agonistas dos Canais de Cálcio/farmacologia , Músculo Liso Vascular/efeitos dos fármacos , Placenta/irrigação sanguínea , Artérias/efeitos dos fármacos , Artérias/metabolismo , Cálcio/metabolismo , Bloqueadores dos Canais de Cálcio/farmacologia , Radioisótopos de Cálcio , Feminino , Humanos , Técnicas In Vitro , Contração Isométrica/efeitos dos fármacos , Contração Muscular/efeitos dos fármacos , Músculo Liso Vascular/metabolismo , Placenta/efeitos dos fármacos , Placenta/metabolismo , Potássio/farmacologia , Gravidez , Fluxo Sanguíneo Regional/efeitos dos fármacos , Serotonina/metabolismoRESUMO
The influence of vascular endothelium on ouabain-induced contractions and sodium pump activity in aortic segments of Wistar-Kyoto (WKY) and spontaneously hypertensive rat (SHR) was analyzed. De-endothelialization increased and reduced ouabain-induced contractions in WKY and SHR segments, respectively. The effects of de-endothelialization were not reproduced by pretreatment of the segments with NG-nitro-L-arginine methyl ester, indomethacin, or 5, 8, 11, 14-eicosatetraenoic acid, acetyl salicylic acid, dazoxiben, phosphoramidon, BQ-123, or superoxide dismutase. Bioassay experiments suggest that ouabain releases a diffusible factor from endothelial cells that inhibits or facilitates digitalis-induced contractions in WKY and SHR segments, respectively. In a potassium-free solution, potassium-induced relaxation in segments of both strains was abolished by ouabain in de-endothelialized aortas and reduced in intact ones. Ouabain-sensitive 86Rb+ uptake was significantly reduced by de-endothelialization both in WKY and in SHR. These results suggest that the vascular endothelium of WKY and SHR aortas releases a diffusible factor that stimulates the sodium pump and/or protects it from ouabain blockade. Ouabain also releases a diffusible endothelium-derived factor in SHR aortas that facilitates ouabain-induced contractions.