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D'Souza AW, Takeda R, Manabe K, Hissen SL, Washio T, Coombs GB, Sanchez B, Fu Q, Shoemaker JK. The interactive effects of age and sex on the neuro-cardiovascular responses during fatiguing rhythmic handgrip exercise. J Physiol 2023; 601:2877-2898. [PMID: 37083007 DOI: 10.1113/jp284517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Accepted: 03/30/2023] [Indexed: 04/22/2023] Open
Abstract
The impact of age on exercise pressor responses is equivocal, likely because of sex-specific neuro-cardiovascular changes with age. However, assessments of the interactive effects of age and sex on muscle sympathetic nerve activity (MSNA) responses to exercise are lacking. We tested the hypothesis that older females would exhibit exaggerated increases in blood pressure (BP) and MSNA discharge patterns during handgrip exercise compared with similarly aged males and young adults. Twenty-five young (25 (2) years; mean (SD)) males (YM; n = 12) and females (YF; n = 13) and 23 older (71 (5) years) males (OM; n = 11) and females (OF; n = 12) underwent assessments of BP, total peripheral resistance (TPR; Modelflow) and MSNA action potential (AP) discharge patterns (microneurography) during incremental rhythmic handgrip exercise and post-exercise circulatory occlusion (PECO). OM demonstrated larger ∆BP and ∆TPR from baseline than YM (both P < 0.001) despite smaller increases in ∆APs/burst (OM: 0.4 (3) vs. YM: 5 (3) spikes/burst, P < 0.001) and ∆AP clusters/burst (OM: 0.1 (1) vs. YM: 1.8 (1) clusters/burst, P < 0.001) during exercise. Testosterone was lower in OM than YM (P < 0.001) and was inversely related to ∆BP but positively related to ∆AP clusters/burst in males (both P = 0.03). Conversely, YF and OF demonstrated similar ∆BP and ∆AP discharge during exercise (range: P = 0.75-0.96). Age and sex did not impact haemodynamics or AP discharge during PECO (range: P = 0.08-0.94). Altogether, age-related changes in neuro-cardiovascular reactivity exist in males but not females during fatiguing exercise and seem to be related to testosterone. This sex-specific impact of age underscores the importance of considering biological sex when assessing age-related changes in neuro-cardiovascular control during exercise. KEY POINTS: Older males have the largest increase in blood pressure despite having the smallest increases in sympathetic vasomotor outflow during rhythmic handgrip exercise. Young males demonstrate greater increases in sympathetic action potential (AP) discharge compared with young females during rhythmic handgrip exercise. Older adults (regardless of sex) demonstrate smaller increases in muscle sympathetic nerve activity (MSNA) burst amplitude and total AP clusters compared with young adults during exercise, as well as smaller increases in integrated MSNA burst frequency, incidence and total MSNA activity during post-exercise circulatory occlusion (i.e. independent effect of age). Males, but not females (regardless of age), reflexively modify AP conduction velocity during exercise. Our results indicate that age and sex independently and interactively impact the neural and cardiovascular homeostatic adjustments to fatiguing small muscle mass exercise.
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Affiliation(s)
- Andrew W D'Souza
- Neurovascular research laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Ryosuke Takeda
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Kazumasa Manabe
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sarah L Hissen
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Takuro Washio
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Geoff B Coombs
- Neurovascular research laboratory, School of Kinesiology, Western University, London, Ontario, Canada
| | - Belinda Sanchez
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas, USA
- Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - J Kevin Shoemaker
- Neurovascular research laboratory, School of Kinesiology, Western University, London, Ontario, Canada
- Department of Physiology and Pharmacology, Western University, London, Ontario, Canada
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DeLalio LJ, Stocker SD. Impact of anesthesia, sex, and circadian cycle on renal afferent nerve sensitivity. Am J Physiol Heart Circ Physiol 2021; 320:H117-H132. [PMID: 33216622 PMCID: PMC7847066 DOI: 10.1152/ajpheart.00675.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2020] [Revised: 11/17/2020] [Accepted: 11/17/2020] [Indexed: 01/09/2023]
Abstract
Elevated renal afferent nerve (ARNA) activity or dysfunctional reno-renal reflexes via altered ARNA sensitivity contribute to hypertension and chronic kidney disease. These nerves contain mechano- and chemosensitive fibers that respond to ischemia, changes in intrarenal pressures, and chemokines. Most studies have utilized various anesthetized preparations and exclusively male animals to characterize ARNA responses. Therefore, this study assessed the impact of anesthesia, sex, and circadian period on ARNA responses and sensitivity. Multifiber ARNA recordings were performed in male and female Sprague-Dawley rats (250-400 g) and compared across decerebrate versus Inactin, isoflurane, and urethane anesthesia groups. Intrarenal artery infusion of capsaicin (0.1-50.0 μM, 0.05 mL) produced concentration-dependent increases in ARNA; however, the ARNA sensitivity was significantly greater in decerebrate versus Inactin, isoflurane, and urethane groups. Increases in renal pelvic pressure (0-30 mmHg, 30 s) produced pressure-dependent increases in ARNA; however, ARNA sensitivity was again greater in decerebrate and Inactin groups versus isoflurane and urethane. Acute renal artery occlusion (30 s) increased ARNA, but responses did not differ across groups. Analysis of ARNA responses to increased pelvic pressure between male and female rats revealed significant sex differences only in isoflurane and urethane groups. ARNA responses to intrarenal capsaicin infusion were significantly blunted at nighttime versus daytime; however, ARNA responses to increased pelvic pressure or renal artery occlusion were not different between daytime and nighttime. These results demonstrate that ARNA sensitivity is greatest in decerebrate and Inactin-anesthetized groups but was not consistently influenced by sex.NEW & NOTEWORTHY We determined the impact of anesthesia, sex, and circadian cycle on renal afferent nerve (ARNA) sensitivity to chemical and mechanical stimuli. ARNA sensitivity to renal capsaicin infusion was greatest in decerebrate > Inactin > urethane or isoflurane groups. Elevated renal pelvic pressure significantly increased ARNA; decerebrate and Inactin groups exhibited the greatest ARNA sensitivity. Sex differences in renal afferent responses were not consistently observed. Circadian cycle altered chemosensory but not mechanosensory responses.
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Affiliation(s)
- Leon J DeLalio
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sean D Stocker
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
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Hajmohammadi M, Khaksari M, Soltani Z, Shahrokhi N, Najafipour H, Abbasi R. The Effect of Candesartan Alone and Its Combination With Estrogen on Post-traumatic Brain Injury Outcomes in Female Rats. Front Neurosci 2019; 13:1043. [PMID: 31849571 PMCID: PMC6901902 DOI: 10.3389/fnins.2019.01043] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2018] [Accepted: 09/13/2019] [Indexed: 01/31/2023] Open
Abstract
Aim: The aim of this study was to evaluate the effect of candesartan (angiotensin II type I receptor blocker) alone and its combination with estrogen on the changes in brain edema, intracranial pressure (ICP), and cerebral perfusion pressure (CPP) following diffuse traumatic brain injury (TBI) in female rats. Methods: TBI was induced in ovariectomized female rats using Marmarou's method. The treatment groups received low-dose (LC) and high-dose (HC) candesartan, estrogen (E2), a combination of estrogen vehicle and candesartan vehicle (oil + vehicle), or a combination of estrogen with low-dose (E2 + LC), or with high-dose (E2 + HC) candesartan. ICP and CPP were measured before and several times after TBI, and the brain water content (brain edema) was measured 24 h after TBI. Results: After the TBI, brain edema and ICP in the estrogen group were lower than in the vehicle and TBI groups. Brain edema and ICP in the HC group were lower than in the vehicle group after TBI. Although there was no significant difference in brain edema and ICP between the LC and vehicle groups, significant differences in these variables were observed when the E2 + LC and E2 + HC groups were compared with the oil + vehicle group after TBI. A significant increase in CPP was observed in the estrogen group 4 and 24 h post-TBI, while this increase was found in the HC and E2 + LC groups 24 h post-TBI. Conclusions: A low dose of candesartan did not exert a protective effect on TBI outcomes, but such an effect did appear after combination with estrogen. This finding suggests that interaction between low-dose candesartan and estrogen improves TBI-induced consequences.
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Affiliation(s)
- Mojdeh Hajmohammadi
- Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohammad Khaksari
- Endocrinology and Metabolism Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran
| | - Zahra Soltani
- Endocrinology and Metabolism Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran
| | - Nader Shahrokhi
- Physiology Research Center, Institute of Neuropharmacology, Kerman University of Medical Sciences, Kerman, Iran
| | - Hamid Najafipour
- Cardiovascular Research Center, Institute of Basic and Clinical Physiology Sciences, Kerman University of Medical Sciences, Kerman, Iran
| | - Reza Abbasi
- Neuroscience Research Center, Neuropharmacology Institute, Kerman University of Medical Sciences, Kerman, Iran
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Almeida-Pereira G, Vilhena-Franco T, Coletti R, Cognuck SQ, Silva HVP, Elias LLK, Antunes-Rodrigues J. 17β-Estradiol attenuates p38MAPK activity but not PKCα induced by angiotensin II in the brain. J Endocrinol 2019; 240:345-360. [PMID: 30508412 DOI: 10.1530/joe-18-0095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 11/30/2018] [Indexed: 01/11/2023]
Abstract
17β-Estradiol (E2) has been shown to modulate the renin-angiotensin system in hydromineral and blood pressure homeostasis mainly by attenuating angiotensin II (ANGII) actions. However, the cellular mechanisms of the interaction between E2 and angiotensin II (ANGII) and its physiological role are largely unknown. The present experiments were performed to better understand the interaction between ANGII and E2 in body fluid control in female ovariectomized (OVX) rats. The present results are the first to demonstrate that PKC/p38 MAPK signaling is involved in ANGII-induced water and sodium intake and oxytocin (OT) secretion in OVX rats. In addition, previous data from our group revealed that the ANGII-induced vasopressin (AVP) secretion requires ERK1/2 signaling. Therefore, taken together, the present observations support a novel concept that distinct intracellular ANGII signaling gives rise to distinct neurohypophyseal hormone release. Furthermore, the results show that E2 attenuates p38 MAPK phosphorylation in response to ANGII but not PKC activity in the hypothalamus and the lamina terminalis, suggesting that E2 modulates ANGII effects through the attenuation of the MAPK pathway. In conclusion, this work contributes to the further understanding of the interaction between E2 and ANGII signaling in hydromineral homeostasis, as well as it contributes to further elucidate the physiological relevance of PKC/p38 MAPK signaling on the fluid intake and neurohypophyseal release induced by ANGII.
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Affiliation(s)
- G Almeida-Pereira
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
| | - T Vilhena-Franco
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
| | - R Coletti
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
| | - S Q Cognuck
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
| | - H V P Silva
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
| | - L L K Elias
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
| | - J Antunes-Rodrigues
- Department of Physiology, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, Brazil
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Santollo J, Daniels D. Anorexigenic effects of estradiol in the medial preoptic area occur through membrane-associated estrogen receptors and metabotropic glutamate receptors. Horm Behav 2019; 107:20-25. [PMID: 30462987 PMCID: PMC6348004 DOI: 10.1016/j.yhbeh.2018.11.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 11/01/2018] [Accepted: 11/03/2018] [Indexed: 11/22/2022]
Abstract
Activation of membrane-associated estrogen receptors (mER) decreases food and water intake in female rats. Additional studies suggest these effects are mediated, at least in part, by membrane-associated estrogen receptor alpha (ERα). Nevertheless, the critical site of action and the intracellular signaling required for the ingestive effects of ERα remain unclear. Estradiol given to the medial preoptic area (mPOA) decreases ingestive behaviors, and membrane-associated ERα has been shown to affect intracellular signaling through interactions with metabotropic glutamate receptor (mGluR) subtypes, but an involvement of this signaling pathway, in the mPOA, in ingestive behavior remains untested. To address these open questions, we first showed that activation of mER in the mPOA decreased both overnight food and water intake, and did so in a time course consistent with a genomic mechanism of action. Next, we tested the requirement of mGluR1a signaling in the mPOA for the anorexigenic and anti-dipsogenic effects of estradiol. As expected, estradiol in the mPOA decreased food intake, but only in the absence of an mGluR1a antagonist. The same was not true for estradiol effects on water intake, which were unaffected by an mGluR1a antagonist. These results suggest that estrogens require mGluR activation for at least some of their effects on ingestive behaviors, and indicate that the mPOA is a critical site of action. The results also reveal an interesting divergence in the estrogenic control of ingestive behavior by which mGluR signaling in the mPOA plays a role in the control of food intake, but not water intake.
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Affiliation(s)
- Jessica Santollo
- Department of Biology, University of Kentucky, Lexington, KY 40506, USA.
| | - Derek Daniels
- Behavioral Neuroscience Program, Department of Psychology, The State University of New York at Buffalo, Buffalo, New York 14260, USA
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Khaksari M, Hajmohammadi M, Sepehri G. The effect of angiotensin receptor type 2 inhibition and estrogen on experimental traumatic brain injury. Arch Trauma Res 2018. [DOI: 10.4103/atr.atr_51_17] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Abstract
The central nervous system (CNS) in concert with the heart and vasculature is essential to maintaining cardiovascular (CV) homeostasis. In recent years, our understanding of CNS control of blood pressure regulation (and dysregulation leading to hypertension) has evolved substantially to include (i) the actions of signaling molecules that are not classically viewed as CV signaling molecules, some of which exert effects at CNS targets in a non-traditional manner, and (ii) CNS locations not traditionally viewed as central autonomic cardiovascular centers. This review summarizes recent work implicating immune signals and reproductive hormones, as well as gasotransmitters and reactive oxygen species in the pathogenesis of hypertension at traditional CV control centers. Additionally, recent work implicating non-conventional CNS structures in CV regulation is discussed.
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Affiliation(s)
- Pauline M Smith
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L3N6, Canada
| | - Alastair V Ferguson
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L3N6, Canada
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8
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Abstract
Hypertension is a major contributor to worldwide morbidity and mortality rates related to cardiovascular disease. There are important sex differences in the onset and rate of hypertension in humans. Compared with age-matched men, premenopausal women are less likely to develop hypertension. However, after age 60, the incidence of hypertension increases in women and even surpasses that seen in older men. It is thought that changes in levels of circulating ovarian hormones as women age may be involved in the increase in hypertension in older women. One of the key mechanisms involved in the development of hypertension in both men and women is an increase in sympathetic nerve activity (SNA). Brain regions important for the regulation of SNA, such as the subfornical organ, the paraventricular nucleus and the rostral ventral lateral medulla, also express specific subtypes of oestrogen receptors. Each of these brain regions has also been implicated in mechanisms underlying risk factors for hypertension such as obesity, stress and inflammation. The present review brings together evidence that links actions of oestrogen at these receptors to modulate some of the common brain mechanisms involved in the ability of hypertensive risk factors to increase SNA and blood pressure. Understanding the mechanisms by which oestrogen acts at key sites in the brain for the regulation of SNA is important for the development of novel, sex-specific therapies for treating hypertension.
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Pinkham MI, Whalley GA, Guild SJ, Malpas SC, Barrett CJ. Arterial baroreceptor reflex control of renal sympathetic nerve activity following chronic myocardial infarction in male, female, and ovariectomized female rats. Am J Physiol Regul Integr Comp Physiol 2015; 309:R169-78. [PMID: 25994953 DOI: 10.1152/ajpregu.00026.2015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There is controversy regarding whether the arterial baroreflex control of renal sympathetic nerve activity (SNA) in heart failure is altered. We investigated the impact of sex and ovarian hormones on changes in the arterial baroreflex control of renal SNA following a chronic myocardial infarction (MI). Renal SNA and arterial pressure were recorded in chloralose-urethane anesthetized male, female, and ovariectomized female (OVX) Wistar rats 6-7 wk postsham or MI surgery. Animals were grouped according to MI size (sham, small and large MI). Ovary-intact females had a lower mortality rate post-MI (24%) compared with both males (38%) and OVX (50%) (P < 0.05). Males and OVX with large MI, but not small MI, displayed an impaired ability of the arterial baroreflex to inhibit renal SNA. As a result, the male large MI group (49 ± 6 vs. 84 ± 5% in male sham group) and OVX large MI group (37 ± 3 vs. 75 ± 5% in OVX sham group) displayed significantly reduced arterial baroreflex range of control of normalized renal SNA (P < 0.05). In ovary-intact females, arterial baroreflex control of normalized renal SNA was unchanged regardless of MI size. In males and OVX there was a significant, positive correlation between left ventricle (LV) ejection fraction and arterial baroreflex range of control of normalized renal SNA, but not absolute renal SNA, that was not evident in ovary-intact females. The current findings demonstrate that the arterial baroreflex control of renal SNA post-MI is preserved in ovary-intact females, and the state of left ventricular dysfunction significantly impacts on the changes in the arterial baroreflex post-MI.
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Joyner MJ, Barnes JN, Hart EC, Wallin BG, Charkoudian N. Neural control of the circulation: how sex and age differences interact in humans. Compr Physiol 2015; 5:193-215. [PMID: 25589269 DOI: 10.1002/cphy.c140005] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The autonomic nervous system is a key regulator of the cardiovascular system. In this review, we focus on how sex and aging influence autonomic regulation of blood pressure in humans in an effort to understand general issues related to the cardiovascular system as a whole. Younger women generally have lower blood pressure and sympathetic activity than younger men. However, both sexes show marked interindividual variability across age groups with significant overlap seen. Additionally, while men across the lifespan show a clear relationship between markers of whole body sympathetic activity and vascular resistance, such a relationship is not seen in young women. In this context, the ability of the sympathetic nerves to evoke vasoconstriction is lower in young women likely as a result of concurrent β2-mediated vasodilation that offsets α-adrenergic vasoconstriction. These differences reflect both central sympatho-inhibitory effects of estrogen and also its influence on peripheral vasodilation at the level of the vascular smooth muscle and endothelium. By contrast postmenopausal women show a clear relationship between markers of whole body sympathetic traffic and vascular resistance, and sympathetic activity rises progressively in both sexes with aging. These major findings in humans are discussed in the context of differences in population-based trends in blood pressure and orthostatic intolerance. The many areas where there is little sex-specific data on how the autonomic nervous system participates in the regulation of the human cardiovascular system are highlighted.
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Affiliation(s)
| | - Jill N Barnes
- School of Physiology and Pharmacology, University of Bristol, Bristol, United Kingdom
| | - Emma C Hart
- Institute of Neuroscience and Physiology, The Sahlgren Academy at Gothenburg University, Gothenburg, Sweden
| | - B Gunnar Wallin
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Nisha Charkoudian
- Thermal and Mountain Medicine Division, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
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Abstract
Body fluid homeostasis is maintained by a complex network of central and peripheral systems that regulate blood pressure, fluid and electrolyte excretion, and fluid intake. The behavioral components, which include well regulated water and saline intake, are influenced by a number of hormones and neuropeptides. Since the early 1970s, it has been known that the ovarian estrogens play an important role in regulating fluid intake in females by decreasing water and saline intake under a variety of hypovolemic conditions. Behavioral, electrophysiological, gene and protein expression studies have identified nuclei in the hypothalamus, along with nearby forebrain structures such as the subfornical organ (SFO), as sites of action involved in mediating these effects of estrogens and, importantly, all of these brain areas are rich with estrogen receptors (ERs). This review will discuss the multiple ER subtypes, found both in the cell nucleus and associated with the plasma membrane, that provide diversity in the mechanism through which estrogens can induce behavioral changes in fluid intake. We then focus on the relevant brain structures, hypothesized circuits, and various peptides, such as angiotensin, oxytocin, and vasopressin, implicated in the anti-dipsogenic and anti-natriorexigenic actions of the estrogens.
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Affiliation(s)
- Jessica Santollo
- Department of Psychology, University at Buffalo SUNY Buffalo, NY, USA
| | - Derek Daniels
- Department of Psychology, University at Buffalo SUNY Buffalo, NY, USA
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Abstract
The role of the brain in hypertension between the sexes is known to be important especially with regards to the effects of circulating sex hormones. A number of different brain regions important for regulation of sympathetic outflow and blood pressure express estrogen receptors (ERα and ERβ). Estradiol, acting predominantly via the ERα, inhibits angiotensin II activation of the area postrema and subfornical organ neurons and inhibits reactive oxygen generation that is required for the development of Angiotensin II-induced neurogenic hypertension. Estradiol activation of ERβ within the paraventricular nucleus and the rostral ventral lateral medulla inhibits these neurons and inhibits angiotensin II, or aldosterone induced increases in sympathetic outflow and hypertension. Understanding the cellular and molecular mechanisms underlying ERα and ERβ actions within key brain regions regulating blood pressure will be essential for the development of "next generation" selective estrogen receptor modulators (SERMS) that can be used clinically for the treatment of neurogenic hypertension.
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Affiliation(s)
- Meredith Hay
- Department of Physiology, University of Arizona, 1501 N Campbell Rd Bldg 201, Rm 4103, Tucson, AZ, 85724, USA,
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Xue B, Zhang Z, Beltz TG, Guo F, Hay M, Johnson AK. Genetic knockdown of estrogen receptor-alpha in the subfornical organ augments ANG II-induced hypertension in female mice. Am J Physiol Regul Integr Comp Physiol 2014; 308:R507-16. [PMID: 25552661 DOI: 10.1152/ajpregu.00406.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The present study tested the hypotheses that 1) ERα in the brain plays a key role in the estrogen-protective effects against ANG II-induced hypertension, and 2) that the subfornical organ (SFO) is a key site where ERα mediates these protective actions. In this study, a "floxed" ERα transgenic mouse line (ERα(flox)) was used to create models in which ERα was knocked down in the brain or just in the SFO. Female mice with ERα ablated in the nervous system (Nestin-ERα(-) mice) showed greater increases in blood pressure (BP) in response to ANG II. Furthermore, females with ERα knockdown specifically in the SFO [SFO adenovirus-Cre (Ad-Cre) injected ERα(flox) mice] also showed an enhanced pressor response to ANG II. Immunohistochemical (IHC), RT-PCR, and Western blot analyses revealed a marked reduction in the expression of ERα in nervous tissues and, in particular, in the SFO. These changes were not present in peripheral tissues in Nestin-ERα(-) mice or Ad-Cre-injected ERα(flox) mice. mRNA expression of components of the renin-angiotensin system in the lamina terminalis were upregulated in Nestin-ERα(-) mice. Moreover, ganglionic blockade on day 7 after ANG II infusions resulted in a greater reduction of BP in Nestin-ERα(-) mice or SFO Ad-Cre-injected mice, suggesting that knockdown of ERα in the nervous system or the SFO alone augments central ANG II-induced increase in sympathetic tone. The results indicate that interfering with the action of estrogen on SFO ERα is sufficient to abolish the protective effects of estrogen against ANG II-induced hypertension.
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Affiliation(s)
- Baojian Xue
- Departments of Psychology, University of Iowa, Iowa City, Iowa; and
| | - Zhongming Zhang
- Zhang Zhongjing College of Chinese Medicine, Nanyang Institute of Technology, Henan, China
| | - Terry G Beltz
- Departments of Psychology, University of Iowa, Iowa City, Iowa; and
| | - Fang Guo
- Departments of Psychology, University of Iowa, Iowa City, Iowa; and
| | - Meredith Hay
- Department of Physiology, University of Arizona, Tucson, Arizona; Evelyn F. McKnight Brain Institute, Tucson, Arizona; and
| | - Alan Kim Johnson
- Departments of Psychology, University of Iowa, Iowa City, Iowa; and Department of Pharmacology, University of Iowa, Iowa City, Iowa; François M. Abboud Cardiovascular Research Center, University of Iowa, Iowa City, Iowa
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