Background The paraventricular nucleus (PVN) of the hypothalamus is a key autonomic and cardiovascular regulatory center that contributes to neuroinflammation‐driven sympathetic excitation in heart failure. To define the cellular and transcriptional mechanisms underlying inflammatory signaling during heart failure progression, we performed single‐nucleus RNA sequencing of the PVN in rats 2 weeks after myocardial infarction (MI). Methods PVN tissues were collected 2 weeks post MI for single‐nucleus RNA sequencing analysis. Sequencing data were processed through alignment, dimensionality reduction, clustering, and marker‐gene identification to define cell populations and gene expression profiles. Gene Set Variation Analysis and transcriptional regulatory network analyses were performed to identify altered signaling pathways and key transcription factors. Results A total of 16 341 nuclei were classified into 5 major cell types: neurons, oligodendrocytes, astrocytes, oligodendrocyte progenitor cells, and microglia. Functional analyses identified microglia as the primary mediators of inflammatory responses in the PVN. Gene Set Variation Analysis revealed substantial pathway alterations across cell types, with microglia exhibiting marked activation of immune‐related and cytokine‐producing pathways in MI rats. Moreover, IRF5 (interferon regulatory factor 5) was identified as a master transcriptional regulator associated with inflammatory activation and was significantly upregulated in PVN microglia after MI. Increased IRF5 expression in PVN microglia was confirmed by immunofluorescence. Conclusions Single‐nucleus RNA sequencing identified distinct cell‐specific gene signatures, regulatory networks, and signaling pathways in the PVN during heart failure, with microglial IRF5 emerging as a central regulator of immune activation and inflammatory processes. Activated IRF5 promotes microglial activation and neuroinflammation, thereby enhancing PVN neuronal activity and driving sympathetic and neurohumoral dysregulation in rats with MI. Targeting IRF5 and its downstream pathways may therefore provide new insights into the central inflammatory mechanisms contributing to cardiac dysfunction during heart failure progression.

Endoplasmic reticulum (ER) stress in the brain has been implicated in the pathophysiology of hypertension and heart failure. We previously demonstrated that central inhibition of ER stress with tauroursodeoxycholic acid in heart failure rats reduces renin–angiotensin system activation and sympathetic overactivity. Mesencephalic astrocyte-derived neurotrophic factor (MANF) is a stress-responsive protein essential for maintaining cellular homeostasis and viability, particularly under ER stress, through its ability to modulate the unfolded protein response. Our prior work showed that MANF is selectively expressed in neurons, especially within neurohumoral and autonomic regulatory centers; however, its role in the brain in modulating cardiovascular function and sympathetic outflow remains unclear. In this study, we examined the impact of MANF on hemodynamic control and sympathetic drive using electrophysiological recordings in urethane-anesthetized male Sprague–Dawley rats. The ER stress inducer tunicamycin (3 μg), an AAV-mediated MANF siRNA, or recombinant human MANF (rhMANF) was administered via intracerebroventricular (ICV) injection. Mean arterial pressure (MAP, mmHg), heart rate (HR, bpm), and renal sympathetic nerve activity (RSNA, % change from baseline) were continuously monitored for 4–5 hours. Compared with vehicle controls, tunicamycin significantly (*p < 0.01) increased MAP (11.4 ± 3.9*), HR (73.2 ± 4.3*), and RSNA (68.3 ± 10.1*). Similarly, MANF knockdown elevated MAP (9.2 ± 4.7*), HR (54.3 ± 3.7*), and RSNA (28.6 ± 7.8*). In contrast, restoring central MANF levels with ICV rhMANF markedly blunted the excitatory responses induced by MANF deficiency, reducing MAP from 96.7 ± 4.3 to 82.2 ± 4.6*, HR from 382.6 ± 4.2 to 351.3 ± 3.3*, and RSNA from 21.3 ± 3.5 to 8.9 ± 1.4*. These results indicate that ER stress and neuronal MANF critically influence central regulation of hemodynamics and sympathetic outflow, and suggest that MANF functions as an endogenous protective factor that counteracts ER stress–driven cardiovascular dysregulation and sympathetic overactivity. Targeting MANF may represent a promising therapeutic strategy for conditions characterized by ER stress–associated neurohumoral activation and autonomic imbalance, including hypertension and heart failure. This study was supported by NIH R01 NIH R01 HL155091 to SG Wei. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Hypertension increases the risk for cardiovascular and cerebrovascular diseases and both its preventive and current therapeutics measures require extensive investigations. Despite that Gastrodin, a neuroprotective compound extracted from a Traditional Chinese medicine (TCM), reportedly has preventive and curative potentials in hypertensive patients, its molecular mechanisms in lowering blood pressure still remain obscure. This study was designed to test the hypothesis that gastrodin lowers blood pressure by targeting the PPAR-γ/NF-κB/NLRP3 signaling axis in the hypothalamic paraventricular (PVN). Gastrodin or vehicle (artificial cerebrospinal fluid, aCSF) was directly infused into the PVN through a mini osmotic pump for 28 days to Spontaneous hypertensive rats (SHRs) and Wistar Kyoto (WKY). Four groups of rats were set: WKY + PVN vehicle; WKY + PVN Gastrodin; SHR + PVN vehicle; and SHR + PVN Gastrodin. Blood pressure was monitored and at the conclusion of experiment, plasma and PVN samples were collected and processed for ELISA, PCR, Western blotting and Immunofluorescence analyses. SHRs had elevated blood pressure (BP), heart rate (HR) and plasmatic norepinephrine (NE) validating their hypertensive status. PVN micro-infusion of gastrodin markedly reversed these hypertensive features in SHRs. At molecular level, gastrodin attenuated the local production of reactive oxygen species (ROS), reduced NADPH Oxidases (NOX)2 and NOX4 messenger RNA (mRNA) level and attenuated the activation of PPAR-γ in the PVN. In addition, gastrodin reduced the inflammasome activation and the expression of interleukin-1β (IL-1β). Furthermore, pretreatment with gastrodin reduced the expression of caspase-1 p10 and inflammation (IL-1β and MCP-1), the ratio of phosphorylated kappa B kinase (p-IKK)/IKK, and that of p-p65/p65 in the PVN of SHRs. In conclusion, gastrodin-lowered blood pressure is associated with balanced PPAR-γ/NF-κB/NLRP3 signaling axis within the PVN local highlighting its promising properties in the management of hypertension. Schematic representation of the proposed molecular mechanism highlights that gastrodin effectively ameliorated blood pressure by targeting the PPAR-y/NF-kB/NLRP3 signaling axis in the hypothalamic paraventricular nucleus

Aims The potential of nanoparticles as effective drug delivery tools for treating failing hearts in heart failure remains a challenge. Leveraging the rapid infiltration of neutrophils into infarcted hearts after myocardial infarction (MI), we developed a nanoparticle platform engineered with neutrophil membrane proteins for the targeted delivery of TAPI-1, a TACE/ADAM17 inhibitor, to the inflamed myocardium, aiming to treat cardiac dysfunction and remodelling in rats with MI.Methods and results Neutrophil-mimic liposomal nanoparticles (Neu-LNPs) were constructed by integrating synthesized liposomal nanoparticles with LPS-stimulated neutrophil membrane fragments and then loaded with TAPI-1. MI rats were treated with TAPI-1 delivered via Neu-LNPs for 4 weeks. Left ventricular function was assessed by echocardiography and cardiac fibrosis was evaluated post-treatment. The novel Neu-LNPs maintained typical nanoparticle features, but with increased biocompatibility. Neu-LNPs demonstrated improved targeting ability and cellular internalization, facilitated by LFA1/Mac1/ICAM-1 interaction. Neu-LNPs displayed higher accumulation and cellular uptake by macrophages and cardiomyocytes in infarcted hearts post-MI, with a sustained duration. Treatments with TAPI-1-Neu-LNPs demonstrated greater protection against myocardial injury and cardiac dysfunction in MI rats compared to untargeted TAPI-1, along with reduced cardiac collagen deposition and expression of fibrosis biomarkers as well as altered immune cell compositions within the hearts.Conclusions Targeted treatment with TACE/ADAM17 inhibitor delivered via biomimetic nanoparticles exhibited pronounced advantages in improving left ventricle function, mitigating cardiac remodelling, and reducing inflammatory responses within the infarcted hearts. This study underscores the effectiveness of Neu-LNPs as a drug delivery strategy to enhance therapeutic efficacy in clinical settings.

Background The RORγt (nuclear receptor retinoid‐related orphan receptor γt) has been identified as a master transcription factor critical for the differentiation of T helper 17 cells, the primary source of IL‐17A (interleukin‐17A). We previously demonstrated that IL‐17A promotes neuroinflammation and sympathetic excitation, contributing to cardiac dysfunction in heart failure and angiotensin II (ANG II)‐induced hypertension. The present study sought to determine whether inhibiting RORγt, thereby reducing IL‐17A production, could attenuate microglial activation, neuroinflammation, and sympathetic excitation by preserving the integrity of the blood–brain barrier (BBB) in ANG II‐induced hypertensive rats. Methods Rats underwent a 2‐week subcutaneous infusion of ANG II, with concurrent daily subcutaneous administration of the RORγt inhibitor digoxin or vehicle. Results Compared with controls, ANG II‐infused rats exhibited elevated IL‐17A levels in both the periphery and brain, along with increased blood pressure and sympathetic tone—effects that were significantly attenuated by inhibiting RORγt with digoxin. ANG II‐infused rats also displayed heightened BBB permeability, decreased expression of the BBB regulator Mfsd2a (major facilitator superfamily domain‐containing protein 2a), increased caveolar transcytosis, and degradation of tight junction proteins in BBB endothelial cells within the hypothalamic paraventricular nucleus, a key autonomic regulatory brain center, all of which were alleviated by digoxin. Additionally, ANG II‐infused rats showed marked microglial activation and elevated expression of proinflammatory cytokines within the paraventricular nucleus, both of which were mitigated by digoxin. Conclusions These findings suggest that RORγt inhibition reduces neuroinflammation and sympathetic activation to ameliorate ANG II‐induced hypertension, likely by mitigating IL‐17A‐induced BBB disruption and microglial activation in the paraventricular nucleus.

Inflammation is implicated in pathophysiology in cardiovascular diseases including hypertension and heart failure. Proinflammatory cytokines (PICs) in the brain substantially elevate blood pressure (BP), heart rate (HR), and renal sympathetic nerve activity (RSNA), suggesting that PICs-driven neuroinflammation plays a critical role in the regulation of cardiovascular function and sympathetic outflow. We recently identified that Src homology 2 domain-containing inositol polyphosphate 5-phosphatase 1 (SHIP1) is selectively expressed in microglia, particularly within the hypothalamic paraventricular nucleus, a critical cardiovascular/autonomic brain region. SHIP1 is an important signaling molecule regulating PI3K/Akt-mediated NLRP3 inflammasome activation and interleukin (IL)-1β and IL-18 production. However, its role in regulating hemodynamic responses and sympathetic activity remains unclear. Using electrophysiological recording technique, we examined the effects of SHIP1 on BP, HR, and RSNA under inflammatory conditions-induced by intravenous lipopolysaccharide (LPS, 20 mg/kg) in urethane-anesthetized male SD rats. Mean BP (MBP, mmHg), HR (beats/min), and RSNA (% change from baseline) were recorded continuously over 4-5 hours, with SHIP1 activator (AQX-1125) or inhibitor (3AC) administered intracerebroventricularly (ICV). Our results indicated that ICV 3AC significantly (*p<0.01) increased MBP (11.7 ± 9.1*), HR (76.9 ± 2.8*), and RSNA (64.6 ± 9.8*), with effects observed 20–30 minutes post-injection. Conversely, pretreatment with ICV SHIP1 activator AQX-1125 markedly attenuated LPS-induced increase (* p<0.01, LPS vs. LPS+AQX-1125) in MBP (23.7 ± 3.7* to 11.8 ± 5.2*), HR (135.6 ± 2.1* to 55.4 ± 1.3*), and RSNA (118.4 ± 4.7* to 92.2 ± 2.5*). These findings demonstrate that SHIP1 in the brain is a critical negative regulator of inflammation-driven hemodynamic responses and sympathetic overactivity. Targeting SHIP1 may provide a novel therapeutic approach for managing neuroinflammation-associated cardiovascular dysfunction in hypertension and heart failure. Supported by R01 HL-139521 and HL-155091 (to Dr Wei) This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.

Depressive disorder is a highly disabling condition that affects more than 300 million individuals worldwide, with women affected at a higher rate than men. With the aging of the population, the incidence of perimenopausal depression has risen markedly, seriously jeopardizing women's physical and mental health. Symptoms of perimenopausal depression include feelings of depression, stress, anxiety and endocrine dysfunctions, particularly hypogonadism and senescence. During perimenopause, estrogen and progesterone levels fluctuate erratically, adding to the risk of developing depression associated with perimenopause. As a result of these hormonal changes, proinflammatory mediators are produced and oxidative stress is induced, which finally leads to progressive neuronal damage. The present study mainly reviewed roles of neuroinflammation in perimenopausal depression and explained potential anti‑inflammatory and anti‑oxidative stress mechanisms for clinically effective therapeutic treatment.

Neuromedin B (NMB) has potentially great impacts on the development of cardiovascular diseases by promoting hypertensive and sympatho-excitation effects. However, studies regarding the NMB function in paraventricular nucleus (PVN) are lacking. With selective neuromedin B receptor (NMBR) antagonist, BIM-23127, we aim to determine whether the blockade of NMB function in PVN could alleviate central inflammation and attenuate hypertensive responses. Spontaneously hypertensive rats (SHR) and Wistar Kyoto rats (WKY) were chronically infused with BIM-23127 in the PVN for 6 weeks. Mean arterial pressure (MAP) was assessed with tail cuff and electrophysiological acquisition systems. PVN tissues were collected to analyze expressions of Fra-LI, inflammatory cytokines (IL-1β, TNF-α, IL-6, IL-10, and IL-4), renin-angiotensin system (angiotensin-converting enzyme (ACE), ACE2, and AT1-reporter (AT1-R)) and oxidative stress (reactive oxygen species (ROS), superoxide dismutase (SOD)1, NADPH oxidase (NOX)2, and NOX4). ELISA was used to detect inflammation indices, norepinephrine (NE), and nuclear factor κB (NF-κB) p65 in plasma and PVN tissue homogenate. Compared to WKY, SHR exhibited higher mean arterial pressure (MAP), plasma NE, and pro-inflammatory cytokines (PICs). Higher PVN levels of Fra-LI, PICs, ACE, AT1-R, ROS, NOX2, NOX4, and NF-κB p65, while lower central levels of anti-inflammatory cytokines (AICs), ACE2, and SOD1 were observed in SHR. Administration of BIM-23127 in PVN reversed all these changes in SHR. In SHR, blockade of NMBR in the PVN inhibited sympatho-excitation and attenuated hypertensive response. The attenuation mechanism may involve reducing inflammation and the RAS/ROS/ NF-κB pathways in PVN.

BACKGROUND:Oxidative stress and inflammatory cytokines in the hypothalamus paraventricular nucleus (PVN) have been implicated in sympathetic nerve activity and the development of hypertension, but the specific mechanisms underlying their production in the PVN remains to be elucidated. Previous studies have demonstrated that activation of nuclear transcription related factor-2 (Nrf2) in the PVN reduced the production of reactive oxygen species (ROS) and inflammatory mediators. Moreover, AMP-activated protein kinase (AMPK), has been observed to decrease ROS and inflammatory cytokine production when activated in the periphery. 5-amino-1-β-D-ribofuranosyl-imidazole-4-carboxamide (AICAR) is an AMPK agonist. However, little research has been conducted on the role of AMPK in the PVN during hypertension. Therefore, we hypothesized that AICAR in the PVN is involved in regulating AMPK/Nrf2 pathway, affecting ROS and inflammatory cytokine expression, influencing sympathetic nerve activity.METHODS:Adult male Sprague-Dawley rats were utilized to induce two-kidney, one-clip (2K1C) hypertension via constriction of the right renal artery. Bilateral PVN was microinjected with either artificial cerebrospinal fluid or AICAR once a day for 4 weeks.RESULTS:Compared to the SHAM group, the PVN of 2K1C hypertensive rats decreased p-AMPK and p-Nrf2 expression, increased Fra-Like, NAD(P)H oxidase (NOX)2, NOX4, tumor necrosis factor-α and interleukin (IL)-1β expression, elevated ROS levels, decreased superoxide dismutase 1 and IL-10 expression, and elevated plasma norepinephrine levels. Bilateral PVN microinjection of AICAR significantly ameliorated these changes.CONCLUSION:These findings suggest that repeated injection of AICAR in the PVN suppresses ROS and inflammatory cytokine production through the AMPK/Nrf2 pathway, reducing sympathetic nerve activity and improving hypertension.

Background Elevated inflammatory cytokines in the periphery have been identified as active contributors to neuroinflammation and sympathetic overactivity in heart failure (HF). Yet, the exact mechanisms by which these cytokines breach the blood‐brain barrier (BBB) to exert their effects on the brain remain elusive. Interleukin 17A has been linked to BBB disruption in various neurologic disorders, and its levels were significantly augmented in circulation and the brain in HF. The present study aimed to determine whether the BBB integrity was compromised within the hypothalamic paraventricular nucleus (PVN), and if so, whether interleukin 17A contributes to BBB disruption in myocardial infarction–induced HF. Methods and Results Male Sprague‐Dawley rats underwent coronary artery ligation to induce HF or sham surgery. Some HF rats received bilateral PVN microinjections of an interleukin 17 receptor A small interfering RNA or a scrambled small interfering RNA adeno‐associated virus. Four weeks after coronary artery ligation, the permeability of the BBB was evaluated by intracarotid injection of fluorescent dyes (fluorescein isothiocyanate–dextran 10 kDa+rhodamine‐dextran 70 kDa). Compared with sham‐operated rats, HF rats exhibited an elevated extravasation of fluorescein isothiocyanate–dextran 10 kDa within the PVN but not in the brain cortex. The plasma interleukin 17A levels were positively correlated with fluorescein isothiocyanate 10 kDa extravasation in the PVN. The expression of caveolin‐1, a transcytosis marker, was augmented, whereas the expression of tight junction proteins was diminished in HF rats. Interleukin 17 receptor A was identified within the endothelium of PVN microvessels. Treatment with interleukin 17 receptor A small interfering RNA led to a significant attenuation of fluorescein isothiocyanate 10 kDa extravasation in the PVN and reversed expression of caveolin‐1 and tight junction–associated proteins in the PVN. Conclusions Collectively, these data indicate that BBB permeability within the PVN is enhanced in HF and is likely attributable to increased interleukin 17A/interleukin 17 receptor A signaling in the BBB endothelium, by promoting caveolar transcytosis and degradation of tight junction complexes.

The hypothalamic paraventricular nucleus (PVN), as an important integrating center, plays a prominent role in the pathogenesis of hypertension, in maintaining the stability of cardiovascular activity through peripheral sympathetic nervous activity and secretion of various humoral factors. Acknowledging that the mechanistic targets of the endocannabinoid type 1 receptor (CB1R) are the key signaling systems involved in the regulation of hypertension, we sought to clarify whether inhibition of CB1R within the PVN ameliorates hypertension through Wnt/β-catenin/RAS pathway. Spontaneously hypertensive rats (SHRs) and Wistar Kyoto rats were randomly assigned to different groups and treated with bilateral PVN injections of AM251 (CB1R antagonist, 10 µg/h) or vehicle (artificial cerebrospinal fluid, aCSF) for four weeks. Bilateral PVN injections of AM251 significantly decreased the heart rate, the body weight and the mean arterial pressure in SHRs. AM251 lowered the expression of CB1R, Wnt3, active-β-catenin, p-IKKβ, RAS components, pro-inflammatory cytokines and elevated the expression level of Glycogen synthase kinase3β and Superoxide Dismutase in the PVN of hypertensive rats. Our findings suggest that inhibition of CB1R in the PVN ameliorates hypertension through Wnt/β-catenin/RAS pathway and broaden our current understanding of the pathological mechanism and clinical treatment of hypertension.

Alamandine (Ala), a relatively recent addition to the renin-angiotensin system (RAS), is a heptapeptide sharing structural similarities with angiotensin-(1-7). This peptide has garnered significant attention due to its distinctive antihypertensive, vasodilatory, and antifibrotic effects. In this study, we sought to determine whether Ala acts as a counter-regulatory agent against angiotensin II-induced cardiac hypertrophy, fibrosis, and inflammation in rats. Male SD rats (n=6 in each group) received a two-week subcutaneous infusion of vehicle (saline), angiotensin II (ANG II, 150 ng/kg/min), or a combination of ANG II and Ala (50 ng/kg/min) via mini osmotic pumps. Left ventricular (LV) function was evaluated through echocardiography. Histological analysis of cardiac hypertrophy and fibrosis was conducted using Hematoxylin Eosin and Trichome-Mason staining, respectively. Compared to the vehicle group, treatment with Ala significantly (*p<0.05) attenuated ANG II-induced cardiac mass (659.27 ± 54.26* vs. 824.48 ± 40.38 mg) with reduced LV thickness and end-diastolic volume. Ala treatment also improved cardiac function, as indicated by reduced global longitudinal strain and myocardial performance index. Histological images revealed that Ala treatment markedly reduced cardiomyocyte area (383.63* ± 7.20 vs 490.59 ± 13.13 μm²) and fibrosis area (5.22* ± 0.93 vs. 9.64 ± 0.36%) in rats treated with ANG II, along with reduced mRNA expression of pro-hypertrophic markers such as brain natriuretic peptide (4.29 ± 0.50* vs 7.53 ± 0.68, fold change) and β-myosin heavy chain (6.11 ± 0.61* vs 10.29 ± 1.02), as well as pro-fibrosis markers collagen 1 (5.72 ± 0.59* vs 10.56 ± 1.69), fibronectin (2.18 ± 0.34* vs 4.69 ± 0.70), and α-smooth muscle actin (2.14 ± 0.42* vs 3.85 ± 0.06), when compared to the rats treated with ANG II alone. Flow cytometry analysis also showed that Ala treatment significantly reduced ANG II-induced immune responses in the heart by reducing immune cell populations including CD4, CD8 T cells, B cells and NK cells, and increasing presence of anti-inflammatory M2 monocytes. Additionally, the mRNA levels of interlukin-6, CD 68, and chemokine monocyte chemoattractant protein-1 were significantly decreased in Ala-treated rats. Furthermore, treatment with Ala reversed ANG II-induced alterations in the mRNA expression of angiotensin-converting enzyme (ACE, 2.05 ± 0.16* vs. 3.08 ± 0.25), angiotensin type 1 receptor (1.45 ± 0.22* vs. 2.56 ± 0.31), and ACE 2 (1.08 ± 0.10** vs. 0.38 ± 0.06) in the LV of the heart. Taken together, these findings demonstrate that alamandine exerts a protective effect against ANG II-induced cardiac dysfunction, hypertrophy, fibrosis, and inflammation, potentially acting as a protective component of the RAS to counteract the adverse effects of ANG II. Alamandine might be a potential therapeutic agent in the treatment of cardiovascular disorders. Supported by NIH grants R01 HL139521 & 155091. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Objective: Alamandine, a recently identified component of the renin-angiotensin system (RAS), is an endogenous heptapeptide derived from angiotensin-(1-7) or angiotensin A. Synthesized primarily through the enzymatic actions of angiotensin-converting enzyme 2 and aspartate decarboxylase, alamandine exerts its effects by binding to the Mas-related G protein-coupled receptor (MrgD). In contrast to the well-studied angiotensin II (ANG II), alamandine exhibits vasodilatory, anti-inflammatory, and anti-fibrotic properties, thereby representing a novel player in the cardioprotective axis of RAS, countering the detrimental effects associated with classical RAS activation. However, the role of alamandine in regulating sympathetic outflow remains unclear. Design and method: The present study sought to examine the effects of systemic alamandine on hemodynamic and sympathetic responses in rats and determine whether alamandine counteracts ANG II-caused hypertension. Blood pressure (BP, mmHg), heart rate (HR, beats/min), and renal sympathetic nerve activity (RSNA, % change) were recorded in urethane-anesthetized male Sprague Dawley rats. Results: While intravenous (IV) vehicle (n=6) did not induce a significant change, IV injection of alamandine (n=6) elicited a substantial (p<0.05) reduction in BP (from 91.5 ± 3.4 to 77.6 ± 3.1∗), HR (from 313 ± 7 to 274 ± 6∗), and RSNA (25.1 ± 2.4% change∗), beginning within 10-15 mins after IV injection. The responses peaked at 45-60 min and returned to baseline within 120 min. Additionally, while a two-week subcutaneous infusion of ANG II significantly elevated BP, concurrent treatment with alamandine obviously attenuated ANG II-induced pressor response (from 115.9 ± 4.7 to 90.1 ± 3.2∗). Conclusions: These results indicate that systemic alamandine has inhibitory effects on sympathetic drive and ANG II-induced hypertension. The diminished impact of alamandine on sympathetic outflow may play a role in the attenuation of pressor responses. Further study to elucidate its molecular mechanisms and physiological implications holds significant potential for advancing our understanding of RAS regulation and identifying novel therapeutic targets in the treatment of cardiovascular disorders such as hypertension and heart failure.

Increased inflammatory cytokines in the circulation act in the brain to promote neuroinflammation and sympathetic excitation in myocardial infarction-induced heart failure (HF). However, the mechanisms by which proinflammatory cytokines interrupt blood-brain barrier (BBB) to reach brain remain unclear. We recently reported that the levels of interleukin (IL)-17A, a key inflammatory mediator of immune responses, are significantly elevated in circulation and the brain in HF. IL-17A has been shown to disrupt the integrity of BBB in in vitro model and in vivo rodent model of experimental autoimmune encephalomyelitis. The present study sought to determine whether BBB in hypothalamic paraventricular nucleus (PVN), a key cardiovascular/autonomic region of the brain within the BBB, was damaged in HF and if so, whether IL-17A contributes to BBB disruption in this disease setting. Adult male Sprague Dawley rats underwent coronary artery ligation to induce HF or sham surgery (Sham). Some HF rats were pretreated with bilateral PVN microinjections of an IL-17 receptor A (IL-17RA) siRNA AAV virus or a scrambled siRNA control. The left ventricular function and infarction size were evaluated by echocardiography. Four weeks after coronary artery ligation, BBB permeability was assessed with fluorescein isothiocyanate (FITC, 10 kDa)-dextran extravasation and molecular measurements of its biomarkers. FITC was injected through left carotid artery at a rate of 300 μl/min (10 mg/ml, 3 ml/kg) and allowed to circulate for 30 min. We found that HF rats displayed noticeable FITC extravasation within the PVN area when compared with brain cortex after injections. FITC extravasation was not observed in the PVN and brain cortex in Sham rats. Compared with Sham rats, HF rats had significantly increased PVN mRNA expression of caveolin-1 (1.05± 0.13 vs 3.30 ± 0.48*, fold changes; *P<0.05), a molecular marker of transcytosis, and decreased PVN mRNA levels of occludin and zonula occludens-1 (1.05± 0.14 vs 0.57 ± 0.13*; 1.05± 0.10 vs 0.54 ± 0.03*, respectively), two important tight junction-associated molecules. However, the mRNA expression of caveolin-1, occludin or zonula occludens-1 did not display significant difference in the brain cortex between HF and Sham rats. Pretreatment with IL-17RA siRNA, substantially reduced FITC extravasation within the PVN and reversed mRNA expression of caveolin-1 (1.08 ± 0.20 vs. 0.51 ± 0.09*), occludin (1.07 ± 0.15 vs. 1.86 ± 0.18*) or zonula occludens-1 (1.02 ± 0.08 vs.1.84 ± 0.24*) in HF rats when compared with HF rats pretreated with a scrambled siRNA control. These data indicated that BBB permeability is increased in the PVN in myocardial infarction-induced HF. The activated IL-17A/IL-17RA signaling in BBB endothelium in the PVN in HF may play an important role in disrupting BBB, probably by a molecular mechanism to augment transcellular transport and reduce tight junction protein expression. Supported by NIH grants R01 HL-139521 & HL-155091 to SGW This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Alamandine, a newly identified derivative of angiotensin II has been shown to exert antihypertensive and vasodilative actions, and may represent a novel component of cardioprotective axis of renin angiotensin system. We sought to determine the protective effects of alamandine on isoproterenol (ISO) induced cardiac remodeling and dysfunction in rats. Male SD rats (n=6 in each group) received a two-week subcutaneous infusion of vehicle, ISO (10 mg/kg/day) or a combination of ISO and alamandine (50 ng/kg/min). Compared with vehicle group, the ratio of heart/body weight (mg/g) in ISO treated rats was significantly (*P<0.05) elevated (3.93 ± 0.18 vs. 3.07 ± 0.08*), which was markedly attenuated by alamandine (3.50 ± 0.08*). Echocardiographic assessment showed that alamandine improved ISO-induced left ventricular (LV) dysfunction evidenced by reducing LV thickness (1.68 ± 0.07* vs 1.90 ± 0.02 mm), end diastolic and systolic volume. Rats treated with alamandine had reduced E/E' ratio (15.16 ± 1.04* vs 26.81 ± 3.79) and increased E'/A' ratio (1.09 ± 0.05 vs 0.57 ± 0.07 ** P<0.01), indicating the improved diastolic cardiac function. The reduced myocardial performance index (0.74 ± 0.06* vs. 1.24 ± 0.15) in alamandine treated rats demonstrated an improvement of global cardiac dysfunction. Histological analysis also revealed that alamandine attenuated ISO induced increase in cardiomyocyte size (372.46 ± 11.13** vs 551.99 ± 11.79 μm 2 ) and myocardial fibrosis (1.39 ± 0.16 ** vs 4.57 ± 0.35), along with reduced mRNA expression of hypertrophy biomarkers atrial natriuretic peptide (2.45 ± 0.71** vs 8.08 ± 0.74), brain natriuretic peptide (2.86 ± 0.35 ** vs 12.53 ± 1.12), beta myosin heavy chain (1.71 ± 0.25* vs 5.38 ± 0.95) and fibrosis genes – collagen-1 (1.97 ± 0.45* vs 4.25 ± 0.6), fibronectin (2.04 ± 0.32** vs 5.05 ± 0.74), α-smooth muscle actin (1.53 ± 0.1** vs 2.71 ± 0.17). Flow cytometry analysis unveiled that alamandine reduced neutrophil, CD8 T cells and M1 monocytes, but increased M2 monocytes of left ventricle, implying the reduction of inflammation of the heart. These data suggest that alamandine plays a cardioprotective role in improving cardiac hypertrophy and fibrosis, probably via an immune mechanism to alleviate inflammatory responses during cardiac remodeling.

Objective: Inflammation has been implicated in the pathophysiology of cardiovascular dysfunction and neurohumoral activation in cardiovascular diseases. Our previous work has demonstrated that proinflammatory cytokines (PICs) in cardiovascular/autonomic brain regions contribute significantly to the sympathetic excitation and cardiac dysfunction in heart failure and hypertension. Notably, the chronic inflammatory conditions in these disease settings are caused by numerous inflammatory cytokines and chemokines. Given that the elevated levels of a single effector cytokine in the pathophysiological condition are insufficient to cause a significant change in hemodynamic and sympathetic responses, how PIC-driven neuroinflammation promotes sympathetic activation remains unclear. This work sought to determine whether PICs in the brain have a synergistic action to exaggerate their inflammatory effects on hemodynamic and sympathetic responses in rats. Design and method: Blood pressure (BP, mmHg), heart rate (HR, beats/min) and renal sympathetic nerve activity (RSNA, % change) were continuously recorded for 4-5 hours in urethane anesthetized male Sprague Dawley rats. The inflammatory cytokines tumor necrosis factor-↑ (TNF-↑), interleukin (IL)-1↓, IL-6 and vehicle were injected intracerebroventricularly (ICV). Results: We found that while ICV injection of TNF-↑, IL-1↓ or IL-6 alone at a low dose (10 ng, respectively) did not induce significant changes in BP, HR and RSNA, the combined injection of all three cytokines at the same dose (10 ng) elicited a substantial (*p<0.05) increase in BP (18.2 ± 2.1*), HR (62 ± 7*) and RSNA (94.5 ± 5.2 %*), that began within 15-20 mins. These responses peaked at 2-3 hours after ICV injection and remained elevated for the rest of the recording period. Additionally, ICV injection of TNF-↑, IL-1↓ or IL-6 alone at a high dose (50 ng, respectively), produced a dramatic and long-lasting increase in BP, HR and RSNA, that closely resembles the time course and response pattern induced by ICV injection of all three cytokines concurrently at the low dose (10 ng). Conclusions: These data suggest a synergistically excitatory action of PICs in the brain on sympathetic outflow. Interventions that simultaneously target multiple cytokines may have an extended anti-inflammatory effect of reducing sympathetic excitation in hypertension and heart failure.

Background Hydrogen sulfide (H2S) is widely distributed throughout the nervous system with various antioxidant and anti-inflammatory properties. Hypertension involves an increase in reactive oxygen species (ROS) and inflammation in the hypothalamic paraventricular nucleus (PVN). However, it is unclear how H2S in PVN affects hypertension. Methods Our study used spontaneously hypertensive rats (SHR) and control Wistar Kyoto (WKY) rats, microinjected with adenovirus-associated virus (AAV)-CBS (cystathionine beta-synthase overexpression) or AAV-ZsGreen in bilateral PVN, or simultaneously injected with virus-carrying nuclear factor erythroid 2-related factor 2 (Nrf2)-shRNA for 4 weeks. Blood pressure (BP) and plasma noradrenaline level were detected, and the PVN was collected. Finally, levels of CBS, H2S, Nrf2, Fra-LI, ROS, gp91(phox), p47(phox), superoxide dismutase 1, interleukin (IL)-1 beta, IL-6, IL-10, tumor necrosis factor-alpha, tyrosine hydroxylase, and glutamate decarboxylase 67 were measured. Results We found that AAV-CBS increased H2S in the PVN, and BP, neuronal activation, oxidative stress, and inflammation of PVN were substantially reduced. Furthermore, endogenous H2S in the PVN activated Nrf2 and corrected the PVN's imbalance of excitatory and inhibitory neurotransmitters. However, Nrf2 knockdown in the PVN was similarly observed to abolish the beneficial effect of H2S on hypertension. Conclusions The findings imply that endogenous H2S in SHR PVN is reduced, and PVN endogenous H2S can alleviate hypertension via Nrf2-mediated antioxidant and anti-inflammatory effects.