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To characterize the temporal activation of the renin-angiotensin system after myocardial infarction (MI) in rabbits, we examined cardiac ANG It type 1 receptor (AT1R) expression and ANG II levels from 3 h to 35 days. The effects of losartan (12.5 mgkg-1· day-1) on functional and histomorphometric parameters when treatment was initiated early (3 h) and late (day 15) post-MI and maintained for different periods of time [short term (4 days), midterm (20 days), and long term (35 days)] were also studied. AT1R expression increased in the MI zone at 15 and 35 days (P < 0.05). ANG II levels increased (P < 0.05) in the non-MI zone at 24 h and in the MI zone as well as in plasma at 4 days and then progressively decreased until 35 days. The survival rate was significantly lower in untreated MI and early long-term-treated animals. Diastolic pressure-volume curves in MI at 35 and 56 days shifted to the right (P < 0.05). This shift was even more pronounced in long-term-treated groups (P < 0.05). Contractility decreased (P < 0.05 vs. sham) in the untreated and long-term-treated groups and was attenuated in the midterm-treated group. The early administration of losartan reduced RAM 11-positive macrophages from 4.15 ± 0.05 to 3.05 ± 0.02 cells/high-power field (HPF; P < 0.05) and CD45 RO-positive lymphocytes from 2.23 ± 0.05 to 1.48 ± 0.01 cells/HPF (P < 0.05) in the MI zone at 4 days. Long-term treatment reduced the scar collagen (MI: 70.50 ± 2.35% and MI + losartan: 57.50 ± 2.48, P < 0.05), determined the persistency of RAM 11-positive macro- phages (3.02 ± 0.13 cells/HPF) and CD45 RO-positive lymphocytes (2.77 ± 0.58 cells/HPF, P < 0.05 vs. MI), and reduced the scar thinning ratio at 35 days (P < 0.05). Consequently, the temporal expressions of cardiac AT1R and ANG II post-MI in rabbits are different from those described in other species. Long-term treatment unfavorably modified post-MI remodeling, whereas midterm treatment attenuated this harmful effect. The delay in wound healing (early reduction and late persistency of inflammatory infiltrate) and adverse remodeling observed in long-term-treated animals might explain the unfavorable effect observed in rabbits. [ABSTRACT FROM AUTHOR]

Background/aims: Aging is accompanied by progressive and adverse cardiac remodeling characterized by myocardial hypertrophy, fibrosis, and dysfunction. We previously reported that galectin-3 (Gal-3) is a critical regulator of inflammation and fibrosis associated with hypertensive heart disease and myocardial infarction. Nevertheless, the role and mechanism of Gal-3 in age-related cardiac remodeling have not been previously investigated. We hypothesized that Gal-3 plays a critical role in cardiac aging and that its deficiency exacerbates the underlying mechanisms of myocardial hypertrophy and fibrosis., Methods: Male C57BL/6 (control) (n=24) and Gal-3 knockout (KO) (n=29) mice were studied at 24 months of age to evaluate the role of Gal-3 in cardiac aging. We assessed 1) survival rate; 2) systolic blood pressure (SBP) by plethysmography; 3) myocardial hypertrophy, apoptosis, and fibrosis by quantification of histological and immunohistochemical analysis; 4) cardiac expression of angiotensin (Ang) II, Ang (1-7) by Radioimmunoassay; 5) transforming growth factor-β (TGF-β), sirtuin (SIRT) 1, SIRT 7 and metalloproteinase 9 (MMP-9) by RT-qPCR and 6) ventricular remodeling and function by echocardiography., Results: We found that aged Gal-3 KO mice had a lower survival rate and exhibited exacerbated myocardial hypertrophy and fibrosis without changes in SBP. Similarly, myocardial apoptosis and MMP-9 mRNA expression was significantly increased in the hearts of Gal-3 KO mice compared to controls. Additionally, cardiac Ang II and TGF-β expression were higher in aged Gal-3 KO mice while SIRT1 and SIRT7 expression were reduced., Conclusion: Our findings strongly suggest that Gal-3 is involved in age-related cardiac remodeling by regulating critical mechanisms associated with the development of pathological hypertrophy. The gene deletion of Gal-3 reduced the lifespan and markedly increased age-dependent mechanisms of myocardial hypertrophy, apoptosis, and fibrosis, including Ang-II, TGF-β, and MMP-9. At the same time, there was diminished cardiac-specific expression of SIRT1 and SIRT7, which are extensively implicated in delaying age-dependent cardiomyopathies., Competing Interests: The authors declare that no conflicts of interest exist., (© Copyright by the Author(s). Published by Cell Physiol Biochem Press.)

This study aimed to evaluate renal morphology and the renal renin-angiotensin system in 6- and 81-day-old male and female offspring exposed to zinc deficiency during fetal life, lactation and/or postnatal growth. Female Wistar rats were fed low- or control zinc diets from pregnancy to offspring weaning. Afterwards, offspring were fed a low- or a control zinc diet until 81 days of life. In 6- and/or 81-day-old offspring, we evaluated systolic blood pressure, renal morphology, renal angiotensin II and angiotensin 1-7 concentration, and AT1 and AT2 receptors and angiotensin-converting enzymes protein and/or mRNA expression. At 6 days, zinc-deficient male offspring showed decreased glomerular filtration areas, remodelling of renal arteries, greater number of renal apoptotic cells, increased levels of Angiotensin II, higher Angiotensin II/Angiotensin 1-7 ratio and increased angiotensin-converting enzyme 1, AT1 and AT2 receptors mRNA and/or protein expression. Exacerbation of the renal Ang II/AT1 receptor axis and remodelling of renal arteries were also observed in adult zinc-deficient male offspring. An adequate zinc diet during post-weaning life did not improve all the alterations induced by zinc deficiency in early stages of development. Female offspring would appear to be less sensitive to zinc deficiency with no increase in blood pressure or significant alterations in renal morphology and the renin-angiotensin system. Moderate zinc deficiency during critical periods of prenatal and postnatal development leads to early morphological renal alterations and to permanent and long-term changes in the renal renin-angiotensin system that could predispose to renal and cardiovascular diseases in adult life., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest, (Copyright © 2020 Elsevier Inc. All rights reserved.)

The deleterious effects of ethanol (EtOH) on the brain have been widely described, but its effects on the neuronal cytoskeleton during differentiation have not yet been firmly established. In this context, our aim was to investigate the direct effect of EtOH on cortical neurons during the period of differentiation. Primary cultures of cortical neurons obtained from 1-day-old rats were exposed to EtOH after 7days of culture, and viability and morphology were analyzed at structural and ultrastructural levels after 24-h EtOH exposure. EtOH caused a significant reduction of 73±7% in the viability of cultured cortical neurons, by preferentially inducing apoptotic cellular death. This effect was accompanied by an increase in caspase 3 and 9 expression. Furthermore, EtOH induced a reduction in total dendrite length and in the number of dendrites per cell. Ultrastructural studies showed that EtOH increased the number of lipidic vacuoles, lysosomes and multilamellar vesicles and induced a dilated endoplasmatic reticulum lumen and a disorganized Golgi apparatus with a ring-shape appearance. Microtubules showed a disorganized distribution. Apposition between pre- and postsynaptic membranes without a defined synaptic cleft and a delay in presynaptic vesicle organization were also observed. Synaptophysin and PSD95 expression, proteins pre- and postsynaptically located, were reduced in EtOH-exposed cultures. Overall, our study shows that EtOH induces neuronal apoptosis and changes in the cytoskeleton and membrane proteins related with the establishment of mature synapses. These direct effects of EtOH on neurons may partially explain its effects on brain development., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The aim was to study the effects of C-type natriuretic peptide (CNP) on mean arterial pressure (MAP) and the cardiovascular nitric oxide (NO) system in spontaneously hypertensive rats (SHR), and to investigate the signaling pathways involved in this interaction. SHR and WKY rats were infused with saline or CNP. MAP and nitrites and nitrates excretion (NO(x)) were determined. Catalytic NO synthase (NOS) activity and endothelial (eNOS), neuronal (nNOS) and inducible NOS (iNOS) were measured in the heart and aorta artery. NOS activity induced by CNP was determined in presence of: iNOS or nNOS inhibitors, NPR-A/B natriuretic peptide receptors blocker and Gi protein and calmodulin inhibitors. CNP diminished MAP and increased NO(x) in both groups. Cardiovascular NOS activity was higher in SHR than in WKY. CNP increased NOS activity, but this activation was lower in SHR. CNP had no effect on NOS isoforms expression. iNOS and nNOS inhibitors did not modify CNP-induced NOS activity. NPR-A/B blockade induced no changes in NOS stimulation via CNP in both tissues. Cardiovascular NOS response to CNP was reduced by Gi protein and calmodulin inhibitors in both groups. CNP interacts with NPR-C receptors, activating Ca-calmodulin eNOS via Gi protein. NOS response to CNP is impaired in the heart and aorta of SHR. Alterations in the interaction between CNP and NO would be involved in the maintenance of high blood pressure in this model of hypertension., (Copyright 2010 Elsevier Inc. All rights reserved.)

Atrial natriuretic factor (ANF) and dopamine (DA) are both important regulators of sodium and water transport across renal proximal tubules. Many evidences suggest that some of ANF inhibitory effects on sodium and water reabsorption are mediated by dopaminergic mechanisms. We have previously reported that ANF stimulates extraneuronal DA uptake in external renal cortex by activation of NPR-A receptors coupled to cGMP signal and PKG. Moreover, ANF enhanced DA-induced inhibition of Na(+)-K(+) ATPase activity. The aim of the present study was to evaluate if ANF could alter also renal DA release, catabolism and turn over. The results indicate that ANF did not affect basal secretion of the amine in external renal cortex or its KCl-induced release, but diminished DA turn over. Moreover, ANF diminished COMT and did not alter MAO activity. In conclusion, present results as well as previous findings show that ANF modifies DA metabolism in rat external renal cortex by enhancing DA uptake and decreasing COMT activity. All those effects, taken together, may favor DA accumulation into renal cells and increase its endogenous content and availability. This would permit D1 receptor recruitment and stimulation and in turn, Na(+), K(+)-ATPase activity over inhibition that results in decreased sodium reabsorption. Therefore, ANF and DA could act via a common pathway to enhance natriuresis and diuresis.

Objective: Several studies suggest the importance of the interaction between the renin angiotensin and sympathetic nervous systems in blood pressure control, especially in clinical situations such as the metabolic syndrome. Previously, we have demonstrated changes in noradrenergic hypothalamic control of blood pressure in an animal model of insulin resistance and hypertension. The aim of the present study was to evaluate the effects of the interaction between the noradrenergic and angiotensinergic systems on hypothalamic blood pressure regulation in fructose hypertensive rats., Methods: In control (C) and fructose-fed hypertensive (F) rats, we studied: 1) the effects of hypothalamic perfusion of irbesartan (AT(1) angiotensin receptor antagonist, 50 and 500 microg ml(-1)) and metoprolol (beta(1) adrenergic receptor antagonist, 10 and 100 microg ml(-1)) on blood pressure, heart rate and noradrenaline intrahypothalamic levels, by means of the microdialysis technique; and 2) the effects of intrahypothalamic microinjection of angiotensin II alone or after metoprolol pre-administration, on blood pressure and heart rate., Results: Meanwhile irbesartan perfusion did not modify neither mean arterial pressure (MAP) nor heart rate or noradrenaline hypothalamic levels in the C group, its highest dose diminished MAP (DeltaMAP: F: - 16.3+/-1 mm Hg, p<0.05) and noradrenaline levels (% of basal levels: 58+/-7%, p<0.05) in the F group, without affecting heart rate. Intrahypothalamic perfusion of metoprolol diminished MAP only in the F group (DeltaMAP: F: -12.1+/-1.1 mm Hg, p<0.05), but did not modify heart rate in both groups. On the other hand, it diminished noradrenaline hypothalamic levels in C (% of basal levels: 53+/-6%, p<0.05) but not in the F group. The pressor response to angiotensin II microinjection was increased in F rats (DeltaMAP: F: 13.3+/-1.5 mm Hg vs. C: 6.9+/-1.8 mm Hg; p<0.05). Previous administration of metoprolol markedly abolished this increment., Conclusions: Our results suggest the existence of an increase in AT(1) and beta(1) adrenergic receptors tone in the hypothalamus of F rats, which could be related to the increase in blood pressure present in this experimental model. On the other hand, considering that the enhanced pressor response to angiotensin II intrahypothalamic injection in F rats was abolished by previous administration of a beta(1) adrenergic receptor antagonist, these results would indicate that beta(1) adrenergic receptors activation participates in the pressor response to angiotensin II in this experimental model of insulin resistance and hypertension.

Dopamine (DA) and atrial natriuretic factor (ANF) share a number of physiological effects. We hypothesized that ANF and the renal dopaminergic system could interact and enhance the natriuretic and diuretic effects of the peptide. We have previously reported that the ANF-stimulated DA uptake in renal tubular cells is mediated by the natriuretic peptide type-A receptor (NPR-A). Our aim was to investigate the signaling pathways that mediate ANF effects on renal 3H-DA uptake. Methylene blue (10 microM), an unspecific inhibitor of guanylate cyclase (GC), blunted ANF elicited increase of DA uptake. ODQ (10 microM) a specific inhibitor of soluble GC, did not modify DA uptake and did not reverse ANF-induced increase of DA uptake; then the participation of nitric oxide-dependent pathways must be discarded. The second messenger was the cGMP since the analogous 125 microM 8-Br-cGMP mimicked ANF effects. The specific inhibitor of the protein kinase G (PKG), KT 5823 (1 microM) blocked ANF effects indicating that PKG is involved. We examined if ANF effects on DA uptake were able to modify Na+, K+ -adenosine triphosphatase (Na+, K+ -ATPase) activity. The experiments were designed by means of inhibition of renal DA synthesis by carbidopa and neuronal DA uptake blocked by nomifensine. In these conditions renal Na+, K+ -ATPase activity was increased, in agreement with the decrease of DA availability. When in similar conditions, exogenous DA was added to the incubation medium, the activity of the enzyme tended to decrease, following to the restored availability of DA. The addition of ANF alone had similar effects to the addition of DA on the sodium pump, but when both were added together, the activity of Na(+), K(+)-ATPase was decreased. Moreover, the extraneuronal uptake blocker, hydrocortisone, inhibited the latter effect. In conclusion, ANF stimulates extraneuronal DA uptake in external cortex tissues by activation of NPR-A receptors coupled to GC and it signals through cGMP as second messenger and PKG. Dopamine and ANF may achieve their effects through a common pathway that involves reversible deactivation of renal tubular Na+, K+ -ATPase activity. This mechanism demonstrates a DA-ANF relationship involved in the modulation of both decreased sodium reabsorption and increased natriuresis.

The objective of our work was to study the intrahypothalamic actions of irbesartan, an angiotensin receptor antagonist, on blood pressure and dopaminergic and serotoninergic neurotransmission in sham operated (SO) and aortic coarctated (ACo) rats by using the microdialysis perfusion technique. We also studied a possible enhanced pressor response to angiotensin II in aortic coarctated rats in the anterior and posterior hypothalamic area. Wistar urethane-chloralose anaesthetised rats were used. A cannula was inserted in the carotid artery. A concentric microdialysis probe was implanted into the anterior hypothalamus or posterior hypothalamus and irbesartan (6 microg ml(-1)) was perfused through the probe. Changes of mean arterial pressure (MAP) were measured. 3,4-Dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) levels were measured in dialysate samples by HPLC-EC. A greater response to irbesartan perfusion in the anterior hypothalamic area of aortic coarctated rats was observed (SO rats, DMAP: -4.3+/-2.3 mm Hg; ACo rats, DMAP: -11.4+/-1.5 mm Hg, P<0.05). The pressor response to angiotensin II in the anterior hypothalamic area (SO rats, DMAP: 4.2+/-1.2 mm Hg; ACo rats, DMAP: 21.7+/-3.7 mm Hg, P<0.05) but not in the posterior hypothalamic area was enhanced in aortic coarctated rats. The perfusion of irbesartan in the anterior hypothalamic area did not modify the extracellular levels of 5-HIAA in both experimental groups, but induced a slightly reduction of DOPAC levels in sham operated rats. The results suggest that the angiotensin system in the anterior hypothalamic area is involved in the maintenance of hypertension in ACo rats and it appears that the increased pressor reactivity to angiotensin II is related to this enhanced function. On the other hand, the effect of irbesartan on DOPAC dialysate levels suggests that the drug produces an alteration of the dopaminergic neurotransmission in the SO rats.

1. Since we previously reported that angiotensin-(1-7) [Ang-(1-7)] increases or inhibits norepinephrine (NE) release in rat atria or hypothalamus, respectively, the present work was undertaken to investigate the effect of the heptapeptide on NE neuronal uptake and metabolism in atria and hypothalamus isolated from rats. 2. Ang II (1-10 microM) caused a decrease in neuronal NE uptake in both atria and hypothalami isolated from rats. On the contrary, tissues incubated with [3H]NE in the presence of 0.1-10 microM Ang-(1-7) showed no modification in [3H]NE content with respect to the control group, suggesting that the heptapeptide did not modify [3H]NE neuronal uptake. 3. To study the effect of the heptapeptide on NE catabolism, monoamine-oxidase (MAO) and catechol-O-methyltransferase (COMT) activities were determined. Pretreatment of the tissue with Ang-(1-7) (0.1-1.0 microM) showed a tendency to diminish MAO activity in rat atria, while no significant changes were observed in hypothalamic MAO activity. Moreover, the heptapeptide (0.1-1.0 microM) did not affect central COMT activity with respect to the control group. 4. Present results allow us to conclude that Ang-(1-7) interacts with noradrenergic neurotransmission by increasing or inhibiting NE release at the peripheral and central levels, respectively, without affecting either the neurotransmitter neuronal uptake or catabolism.

Significant angiotensin (Ang) (1-7) production occurs in kidney and effects on renal function have been observed. The present study was undertaken to investigate binding characteristics of the heptapeptide to Ang II receptors present in rat renal cortex. [125I]-Ang II binding to rat glomeruli membranes was analyzed in the presence of increasing concentrations of Ang II, Ang-(1-7), DUP 753 and PD 123319. Linearity of the Scatchard plot of the [125I]-Ang II specific binding to rat glomeruli membranes indicated a single population of receptors, with a Kd value of 0.7 +/- 0.1 nM and a Bmax of 198 +/- 0.04 fmol/mg protein. DUP 753, an specific AT1 receptor antagonist, totally displaced the specific binding of [125I]-radiolabelled hormone with a Ki of 15.8 +/- 0.9 nM, while no changes were observed in the presence of the selective AT2 receptor antagonist, PD 123319. The specific [125I]-Ang II binding to rat glomerular membranes was displaced by Ang-(1-7) with high affinity (Ki = 8.0 +/- 3.2 nM). We conclude that radioligand binding assays in the presence of selective Ang II antagonists DUP 753 and PD 123319 suggest the unique presence of AT1, receptors in rat glomeruli and a possible role in the control of the biological renal effects of Ang-(1-7).

The present investigation was undertaken to determine whether Ang-(1-7) is able to modify ATPase activities in membrane fractions prepared from several tissues. In the presence of 10(-6) M Ang-(1-7), total (Na , K+, Mg2+)-ATPase activity decreased 31% in rat atrium and 13% in sheep atrium but was unmodified in sheep liver, rat ventricle or crude brain membranes. In rat brain synaptosomal membranes, Ang-(1-7) at 10(-8) and 10(-7) M concentrations activated Na+, K+-ATPase 20 and 24%, respectively. Rat kidney Na+, K+-ATPase activity decreased roughly 40-70% with 10(-10)-10(-6) M Ang-(1-7)), but increased 22% with 10(-12) M peptide concentration, thus indicating a biphasic effect. Our findings showing that ATPase from several tissues responds differently to Ang-(1-7) are attributable to enzyme tissue specificity.