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Pontes RB, Colombari DSA, De Paula PM, Colombari E, Andrade CAF, De Luca LA, Menani JV. Sympathetic and angiotensinergic activity in spontaneously hypertensive rats treated with 3-amino-1,2,4-triazole. Auton Neurosci 2023; 248:103107. [PMID: 37454409 DOI: 10.1016/j.autneu.2023.103107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/28/2023] [Accepted: 07/07/2023] [Indexed: 07/18/2023]
Abstract
Previous studies from our laboratory have shown that the pressor response to intracerebroventricular (icv) administered ANG II in normotensive rats or spontaneously hypertensive rats (SHRs) is attenuated by increased central H2O2 concentration, produced either by direct H2O2 icv injection or by increased endogenous H2O2 centrally in response to local catalase inhibition with 3-amino-1,2,4-triazole (ATZ). In the present study, we evaluated the effects of ATZ administered peripherally on arterial pressure and sympathetic and angiotensinergic activity in SHRs. Male SHRs weighing 280-330 g were used. Mean arterial pressure (MAP) and heart rate (HR) were recorded in conscious freely moving SHRs. Acute intravenous injection of ATZ (300 mg/kg of body weight) did not modify MAP and HR during the next 4 h, however, the treatment with ATZ (300 mg/kg of body weight twice per day) for 3 days reduced MAP (144 ± 6, vs. saline, 183 ± 13 mmHg), without changing HR. Intravenous hexamethonium (ganglionic blocker) produced a smaller decrease in MAP 4 h after ATZ (-25 ± 3, vs saline -38 ± 4 mmHg). Losartan (angiotensinergic AT1 receptor blocker) produced a significant depressor response 4 h after ATZ (-22 ± 4, vs. saline: -2 ± 4 mmHg) and in 3-day ATZ treated SHRs (-25 ± 5, vs. saline: -9 ± 4 mmHg). The results suggest that the treatment with ATZ reduces sympathetic activity in SHRs and simultaneously increases angiotensinergic activity.
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Affiliation(s)
- Roberto Braz Pontes
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Patrícia M De Paula
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Carina A F Andrade
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Laurival A De Luca
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - José V Menani
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
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Lauar MR, Colombari DSA, De Paula PM, Colombari E, Andrade CAF, De Luca LA, Menani JV. Chronic administration of catalase inhibitor attenuates hypertension in renovascular hypertensive rats. Life Sci 2023; 319:121538. [PMID: 36868399 DOI: 10.1016/j.lfs.2023.121538] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/18/2023] [Accepted: 02/24/2023] [Indexed: 03/05/2023]
Abstract
AIMS Reactive oxygen species like hydrogen peroxide (H2O2) are produced endogenously and may participate in intra- and extracellular signaling, including modulation of angiotensin II responses. In the present study, we investigated the effects of chronic subcutaneous (sc) administration of the catalase inhibitor 3-amino-1,2,4-triazole (ATZ) on arterial pressure, autonomic modulation of arterial pressure, hypothalamic expression of AT1 receptors and neuroinflammatory markers and fluid balance in 2-kidney, 1clip (2K1C) renovascular hypertensive rats. MATERIALS AND METHODS Male Holtzman rats with a clip occluding partially the left renal artery and chronic sc injections of ATZ were used. KEY FINDINGS Subcutaneous injections of ATZ (600 mg/kg of body weight/day) for 9 days in 2K1C rats reduced arterial pressure (137 ± 8, vs. saline: 182 ± 8 mmHg). ATZ also reduced the sympathetic modulation and enhanced the parasympathetic modulation of pulse interval, reducing the sympatho-vagal balance. Additionally, ATZ reduced mRNA expression for interleukins 6 and IL-1β, tumor necrosis factor-α, AT1 receptor (0.77 ± 0.06, vs. saline: 1.47 ± 0.26 fold change), NOX 2 (0.85 ± 0.13, vs. saline: 1.75 ± 0.15 fold change) and the marker of microglial activation, CD 11 (0.47 ± 0.07, vs. saline, 1.34 ± 0.15 fold change) in the hypothalamus of 2K1C rats. Daily water and food intake and renal excretion were only slightly modified by ATZ. SIGNIFICANCE The results suggest that the increase of endogenous H2O2 availability with chronic treatment with ATZ had an anti-hypertensive effect in 2K1C hypertensive rats. This effect depends on decreased activity of sympathetic pressor mechanisms and mRNA expression of AT1 receptors and neuroinflammatory markers possibly due to reduced angiotensin II action.
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Affiliation(s)
- Mariana R Lauar
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Patrícia M De Paula
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Carina A F Andrade
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - Laurival A De Luca
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil
| | - José V Menani
- Department of Physiology and Pathology, School of Dentistry, São Paulo State University, UNESP, Araraquara, SP, Brazil.
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Anti-hypertensive effect of hydrogen peroxide acting centrally. Hypertens Res 2020; 43:1192-1203. [PMID: 32461634 DOI: 10.1038/s41440-020-0474-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Revised: 04/20/2020] [Accepted: 04/29/2020] [Indexed: 11/09/2022]
Abstract
Intracerebroventricular (icv) injection of hydrogen peroxide (H2O2) or the increase of endogenous H2O2 centrally produced by catalase inhibition with 3-amino-1,2,4-triazole (ATZ) injected icv reduces the pressor responses to central angiotensin II (ANG II) in normotensive rats. In the present study, we investigated the changes in the arterial pressure and in the pressor responses to ANG II icv in spontaneously hypertensive rats (SHRs) and 2-kidney, 1-clip (2K1C) hypertensive rats treated with H2O2 injected icv or ATZ injected icv or intravenously (iv). Adult male SHRs or Holtzman rats (n = 5-10/group) with stainless steel cannulas implanted in the lateral ventricle were used. In freely moving rats, H2O2 (5 μmol/1 μl) or ATZ (5 nmol/1 μl) icv reduced the pressor responses to ANG II (50 ng/1 µl) icv in SHRs (11 ± 3 and 17 ± 4 mmHg, respectively, vs. 35 ± 6 mmHg) and 2K1C hypertensive rats (3 ± 1 and 16 ± 3 mmHg, respectively, vs. 26 ± 2 mmHg). ATZ (3.6 mmol/kg of body weight) iv alone or combined with H2O2 icv also reduced icv ANG II-induced pressor response in SHRs and 2K1C hypertensive rats. Baseline arterial pressure was also reduced (-10 to -15 mmHg) in 2K1C hypertensive rats treated with H2O2 icv and ATZ iv alone or combined and in SHRs treated with H2O2 icv alone or combined with ATZ iv. The results suggest that exogenous or endogenous H2O2 acting centrally produces anti-hypertensive effects impairing central pressor mechanisms activated by ANG II in SHRs or 2K1C hypertensive rats.
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Lauar MR, Colombari DSA, Colombari E, De Paula PM, De Luca LA, Menani JV. Catalase blockade reduces the pressor response to central cholinergic activation. Brain Res Bull 2019; 153:266-272. [PMID: 31545999 DOI: 10.1016/j.brainresbull.2019.09.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 09/16/2019] [Accepted: 09/18/2019] [Indexed: 02/06/2023]
Abstract
Intracerebroventricular (icv) injection of hydrogen peroxide (H2O2), a reactive oxygen species, or the blockade of catalase (enzyme that degrades H2O2 into H2O and O2) with icv injection of 3-amino-1,2,4-triazole (ATZ) reduces the pressor effects of angiotensin II also injected icv. In the present study, we investigated the effects of ATZ injected icv or intravenously (iv) on the pressor responses induced by icv injections of the cholinergic agonist carbachol, which similar to angiotensin II induces pressor responses that depend on sympathoexcitation and vasopressin release. In addition, the effects of H2O2 icv on the pressor responses to icv carbachol were also tested to compare with the effects of ATZ. Normotensive non-anesthetized male Holtzman rats (280-300 g, n = 8-9/group) with stainless steel cannulas implanted in the lateral ventricle were used. Previous injection of ATZ (5 nmol/1 μl) or H2O2 (5 μmol/1 μl) icv similarly reduced the pressor responses induced by carbachol (4 nmol/1 μl) injected icv (13 ± 4 and 12 ± 4 mmHg, respectively, vs. vehicle + carbachol: 30 ± 5 mmHg). ATZ (3.6 mmol/kg of body weight) injected iv also reduced icv carbachol-induced pressor responses (21 ± 2 mmHg). ATZ icv or iv and H2O2 icv injected alone produced no effect on baseline arterial pressure. The treatments also produced no significant change of heart rate. The results show that ATZ icv or iv reduced the pressor responses to icv carbachol, suggesting that endogenous H2O2 acting centrally inhibits the pressor mechanisms (sympathoactivation and/or vasopressin release) activated by central cholinergic stimulation.
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Affiliation(s)
- Mariana R Lauar
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Débora S A Colombari
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Patrícia M De Paula
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - Laurival A De Luca
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil
| | - José V Menani
- Department of Physiology and Pathology, Dentistry School, São Paulo State University (UNESP), Araraquara, SP, Brazil.
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El-Mas MM, Abdel-Rahman AA. Role of Alcohol Oxidative Metabolism in Its Cardiovascular and Autonomic Effects. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1193:1-33. [PMID: 31368095 PMCID: PMC8034813 DOI: 10.1007/978-981-13-6260-6_1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Several review articles have been published on the neurobehavioral actions of acetaldehyde and other ethanol metabolites as well as in major alcohol-related disorders such as cancer and liver and lung disease. However, very few reviews dealt with the role of alcohol metabolism in the adverse cardiac and autonomic effects of alcohol and their potential underlying mechanisms, particularly in vulnerable populations. In this chapter, following a brief overview of the dose-related favorable and adverse cardiovascular effects of alcohol, we discuss the role of ethanol metabolism in its adverse effects in the brainstem and heart. Notably, current knowledge dismisses a major role for acetaldehyde in the adverse autonomic and cardiac effects of alcohol because of its low tissue level in vivo. Contrary to these findings in men and male rodents, women and hypertensive individuals are more sensitive to the adverse cardiac effects of similar amounts of alcohol. To understand this discrepancy, we discuss the autonomic and cardiac effects of alcohol and its metabolite acetaldehyde in a model of hypertension, the spontaneously hypertensive rat (SHR) and female rats. We present evidence that enhanced catalase activity, which contributes to cardioprotection in hypertension (compensatory) and in the presence of estrogen (inherent), becomes detrimental due to catalase catalysis of alcohol metabolism to acetaldehyde. Noteworthy, studies in SHRs and in estrogen deprived or replete normotensive rats implicate acetaldehyde in triggering oxidative stress in autonomic nuclei and the heart via (i) the Akt/extracellular signal-regulated kinases (ERK)/nitric oxide synthase (NOS) cascade and (ii) estrogen receptor-alpha (ERα) mediation of the higher catalase activity, which generates higher ethanol-derived acetaldehyde in female heart. The latter is supported by the ability of ERα blockade or catalase inhibition to attenuate alcohol-evoked myocardial oxidative stress and dysfunction. More mechanistic studies are needed to further understand the mechanisms of this public health problem.
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Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology and Toxicology, Faculty of Pharmacy, Alexandria University, Alexandria, Egypt
| | - Abdel A Abdel-Rahman
- Department of Pharmacology and Toxicology, The Brody School of Medicine, East Carolina University, Greenville, NC, USA.
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Sá JM, Barros MC, Melo MR, Colombari E, Menani JV, Colombari DSA. Endogenous hydrogen peroxide affects antidiuresis to cholinergic activation in the medial septal area. Neurosci Lett 2018; 694:51-56. [PMID: 30448293 DOI: 10.1016/j.neulet.2018.11.023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 10/29/2018] [Accepted: 11/15/2018] [Indexed: 02/04/2023]
Abstract
Cholinergic activation of the medial septal area (MSA) with carbachol produces thirst, natriuresis and antidiuresis. Hydrogen peroxide (H2O2) injected into the medial septal area (MSA) impairs behavioral and renal responses induced by carbachol at the same site, suggesting the exogenous H2O2 may modulate the responses to cholinergic activation in the MSA. In the present study, we investigated if the accumulation of endogenous H2O2 in the MSA after the injection of the catalase inhibitor 3-amino-1,2,4-triazole (ATZ) also affects cholinergic responses. In addition, the effects of the combination of ATZ with a non-effective dose of H2O2 in the MSA were also tested. Male Holtzman rats (280-320 g) with stainless steel cannulas implanted in the MSA were used. The treatment with ATZ (10 nmol) into the MSA partially reverted the antidiuretic effect of carbachol (10.5 ± 0.7, vs. saline + carbachol: 7.3 ± 0.6 ml/120 min), without changing carbachol-induced water intake (9.5 ± 1.9, vs. saline + carbachol: 10.7 ± 1.6 ml/60 min). The combination of a low dose of ATZ (2.5 nmol) with an ineffective dose of H2O2 (0.5 μmol) into the MSA reduced carbachol-induced thirst (7.5 ± 2.0, vs. saline + carbachol: 14.9 ± 1.2 ml/15 min) and reverted the antidiuresis (8.1 ± 1.1, vs. saline + carbachol: 5.3 ± 0.9 ml/120 min). Sodium and potassium excretion were not modified regardless the treatment. Although exogenous H2O2 injected in the MSA may affect most of the responses to cholinergic activation of the MSA, the antidiuresis is the response clearly modulated by endogenous H2O2.
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Affiliation(s)
- Jéssica Matheus Sá
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - Milena Cassolatti Barros
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - Mariana Rosso Melo
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - Eduardo Colombari
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
| | - José Vanderlei Menani
- Department of Physiology and Pathology, School of Dentistry, UNESP - São Paulo State University, Araraquara, SP, Brazil
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Chronic high-sodium diet intake after weaning lead to neurogenic hypertension in adult Wistar rats. Sci Rep 2017; 7:5655. [PMID: 28720883 PMCID: PMC5515999 DOI: 10.1038/s41598-017-05984-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 06/06/2017] [Indexed: 02/07/2023] Open
Abstract
In this study, we investigated some mechanisms involved in sodium-dependent hypertension of rats exposed to chronic salt (NaCl) intake from weaning until adult age. Weaned male Wistar rats were placed under high (0.90% w/w, HS) or regular (0.27% w/w, Cont) sodium diets for 12 weeks. Water consumption, urine output and sodium excretion were higher in HS rats compared to control. Blood pressure (BP) was directly measured by the arterial catheter and found 13.8% higher in HS vs Cont rats. Ganglionic blockade with hexamethonium caused greater fall in the BP of HS rats (33%), and central antagonism of AT1 receptors (losartan) microinjected into the lateral ventricle reduced BP level of HS, but not of Cont group. Heart rate variability analysis revealed sympathetic prevalence on modulation of the systolic interval. HS diet did not affect creatinine clearance. Kidney histological analysis revealed no significant change in renal corpuscle structure. Sodium and potassium concentrations in CSF were found higher in HS rats despite no change in plasma concentration of these ions. Taken together, data suggest that animals exposed to chronic salt intake to a level close to that reported for human' diet since weaning lead to hypertension, which appears to rely on sodium-driven neurogenic mechanisms.
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Zanella RC, Melo MR, Furuya WI, Colombari E, Menani JV, Colombari DSA. Hydrogen peroxide centrally attenuates hyperosmolarity-induced thirst and natriuresis. Neurosci Lett 2016; 610:129-34. [DOI: 10.1016/j.neulet.2015.10.067] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Revised: 10/14/2015] [Accepted: 10/27/2015] [Indexed: 11/25/2022]
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David RB, Roncari CF, Lauar MR, Vendramini RC, Antunes-Rodrigues J, Menani JV, De Luca LA. Sodium intake, brain c-Fos protein and gastric emptying in cell-dehydrated rats treated with methysergide into the lateral parabrachial nucleus. Physiol Behav 2015; 151:111-20. [DOI: 10.1016/j.physbeh.2015.07.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 06/11/2015] [Accepted: 07/10/2015] [Indexed: 10/23/2022]
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Hydrogen peroxide attenuates the dipsogenic, renal and pressor responses induced by cholinergic activation of the medial septal area. Neuroscience 2014; 284:611-621. [PMID: 25453778 DOI: 10.1016/j.neuroscience.2014.10.024] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 09/22/2014] [Accepted: 10/14/2014] [Indexed: 02/07/2023]
Abstract
Cholinergic activation of the medial septal area (MSA) with carbachol produces thirst, natriuresis, antidiuresis and pressor response. In the brain, hydrogen peroxide (H2O2) modulates autonomic and behavioral responses. In the present study, we investigated the effects of the combination of carbachol and H2O2 injected into the MSA on water intake, renal excretion, cardiovascular responses and the activity of vasopressinergic and oxytocinergic neurons in the hypothalamic paraventricular (PVN) and supraoptic (SON) nuclei. Furthermore, the possible modulation of carbachol responses by H2O2 acting through K+ATP channels was also investigated. Male Holtzman rats (280-320 g) with stainless steel cannulas implanted in the MSA were used. The pre-treatment with H2O2 in the MSA reduced carbachol-induced thirst (7.9±1.0, vs. carbachol: 13.2±2.0 ml/60 min), antidiuresis (9.6±0.5, vs. carbachol: 7.0±0.8 ml/120 min,), natriuresis (385±36, vs. carbachol: 528±46 μEq/120 min) and pressor response (33±5, vs. carbachol: 47±3 mmHg). Combining H2O2 and carbachol into the MSA also reduced the number of vasopressinergic neurons expressing c-Fos in the PVN (46.4±11.2, vs. carbachol: 98.5±5.9 c-Fos/AVP cells) and oxytocinergic neurons expressing c-Fos in the PVN (38.5±16.1, vs. carbachol: 75.1±8.5 c-Fos/OT cells) and in the SON (57.8±10.2, vs. carbachol: 102.7±7.4 c-Fos/OT cells). Glibenclamide (K+ATP channel blocker) into the MSA partially reversed H2O2 inhibitory responses. These results suggest that H2O2 acting through K+ATP channels in the MSA attenuates responses induced by cholinergic activation in the same area.
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Li P, Zhang F, Zhou YB, Cui BP, Han Y. Superoxide anions modulate the effects of angiotensin-(1–7) in the rostral ventrolateral medulla on cardiac sympathetic afferent reflex and sympathetic activity in rats. Neuroscience 2012; 223:388-98. [DOI: 10.1016/j.neuroscience.2012.07.048] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 06/28/2012] [Accepted: 07/19/2012] [Indexed: 11/15/2022]
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Cardoso LM, Colombari E, Toney GM. Endogenous hydrogen peroxide in the hypothalamic paraventricular nucleus regulates sympathetic nerve activity responses to L-glutamate. J Appl Physiol (1985) 2012; 113:1423-31. [PMID: 22984242 DOI: 10.1152/japplphysiol.00912.2012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The hypothalamic paraventricular nucleus (PVN) is important for maintenance of sympathetic nerve activity (SNA) and cardiovascular function. PVN-mediated increases of SNA often involve the excitatory amino acid L-glutamate (L-glu), whose actions can be positively and negatively modulated by a variety of factors, including reactive oxygen species. Here, we determined modulatory effects of the highly diffusible reactive oxygen species hydrogen peroxide (H(2)O(2)) on responses to PVN L-glu. Renal SNA (RSNA), arterial blood pressure, and heart rate were recorded in anesthetized rats. L-Glu (0.2 nmol in 100 nl) microinjected unilaterally into PVN increased RSNA (P < 0.05), without affecting mean arterial blood pressure or heart rate. Effects of endogenously generated H(2)O(2) were determined by comparing responses to PVN L-glu before and after PVN injection of the catalase inhibitor 3-amino-1,2,4-triazole (ATZ; 100 nmol/200 nl, n = 5). ATZ alone was without effect on recorded variables, but attenuated the increase of RSNA elicited by PVN L-glu (P < 0.05). PVN injection of exogenous H(2)O(2) (5 nmol in 100 nl, n = 4) and vehicle (artificial cerebrospinal fluid) were without affect, but H(2)O(2), like ATZ, attenuated the increase of RSNA to PVN L-glu (P < 0.05). Tonic effects of endogenous H(2)O(2) were determined by PVN injection of polyethylene glycol-catalase (1.0 IU in 200 nl, n = 5). Whereas polyethylene glycol-catalase alone was without effect, increases of RSNA to subsequent PVN injection of L-glu were increased (P < 0.05). From these data, we conclude that PVN H(2)O(2) tonically, but submaximally, suppresses RSNA responses to L-glu, supporting the idea that a change of H(2)O(2) availability within PVN could influence SNA regulation under physiological and/or disease conditions.
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Affiliation(s)
- Leonardo M Cardoso
- Department of Physiology, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229, USA
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El-Mas MM, Abdel-Rahman AA. Enhanced catabolism to acetaldehyde in rostral ventrolateral medullary neurons accounts for the pressor effect of ethanol in spontaneously hypertensive rats. Am J Physiol Heart Circ Physiol 2012; 302:H837-44. [PMID: 22159996 PMCID: PMC3353783 DOI: 10.1152/ajpheart.00958.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Accepted: 12/01/2011] [Indexed: 11/22/2022]
Abstract
We have previously shown that ethanol microinjection into the rostral ventrolateral medulla (RVLM) elicits sympathoexcitation and hypertension in conscious spontaneously hypertensive rats (SHRs) but not in Wistar-Kyoto (WKY) rats. In this study, evidence was sought to implicate the oxidative breakdown of ethanol in this strain-dependent hypertensive action of ethanol. Biochemical experiments revealed significantly higher catalase activity and similar aldehyde dehydrogenase (ALDH) activity in the RVLM of SHRs compared with WKY rats. We also investigated the influence of pharmacological inhibition of catalase (3-aminotriazole) or ALDH (cyanamide) on the cardiovascular effects of intra-RVLM ethanol or its metabolic product acetaldehyde in conscious rats. Compared with vehicle, ethanol (10 μg/rat) elicited a significant increase in blood pressure in SHRs that lasted for the 60-min observation period but had no effect on blood pressure in WKY rats. The first oxidation product, acetaldehyde, played a critical role in ethanol-evoked hypertension because 1) catalase inhibition (3-aminotriazole treatment) virtually abolished the ethanol-evoked pressor response in SHRs, 2) intra-RVLM acetaldehyde (2 μg/rat) reproduced the strain-dependent hypertensive effect of intra-RVLM ethanol, and 3) ALDH inhibition (cyanamide treatment) uncovered a pressor response to intra-RVLM acetaldehyde in WKY rats similar to the response observed in SHRs. These findings support the hypothesis that local production of acetaldehyde, due to enhanced catalase activity, in the RVLM mediates the ethanol-evoked pressor response in SHRs.
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Affiliation(s)
- Mahmoud M El-Mas
- Department of Pharmacology and Toxicology, School of Medicine, East Carolina University, Greenville, NC 27834, USA.
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