Testis specific protein, Y-encoded-like 2 activates JAK2/STAT3 pathway in hypothalamic paraventricular nucleus to sustain hypertension.

BACKGROUND: In the hypothalamic paraventricular nucleus (PVN) of spontaneously hypertensive rats (SHRs), the expression of Testis specific protein, Y-encoded-like 2 (TSPYL2) and the phosphorylation level of Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) are higher comparing with the normotensive Wistar-Kyoto rats (WKY). But how they are involved in hypertension remains unclear. TSPYL2 may interact with JAK2/STAT3 in PVN to sustain the high blood pressure during hypertension. METHODS: Knockdown of TSPYL2 via adeno-associated virus (AAV) carrying shRNA was conducted through bilateral micro-injection into the PVN of SHR and WKY rats. JAK2/STAT3 inhibition was achieved by intraperitoneally or PVN injection of AG490 into the SHRs. Blood pressure (BP), plasma norepinephrine (NE), PVN inflammatory response, and PVN oxidative stress were measured. RESULTS: TSPYL2 knock-down in the PVN of SHRs but not WKYs led to reduced BP and plasma NE, and deactivation of JAK2/STAT3, decreased expression of pro-inflammatory cytokine IL-1ß, and increased expression of anti-inflammatory cytokine IL-10 in the PVN. Meanwhile, AG490 administrated in both ways reduced the blood pressure in the SHRs and deactivated JAK2/STAT3 but failed to change the expression of TSPYL2 in PVN. AG490 also downregulated expression of IL-1ß and upregulated expression of IL-10. Both knockdown of TSPYL2 and inhibition of JAK2/STAT3 can reduce the oxidative stress in the PVN of SHRs. CONCLUSION: JAK2/STAT3 is regulated by TSPYL2 in the PVN of SHRs, and PVN TSPYL2/JAK2/STAT3 is essential for maintaining high blood pressure in the hypertensive rats, making it a potential therapeutic target for hypertension.

Central administration of AICAR attenuates hypertension via AMPK/Nrf2 pathway in the hypothalamic paraventricular nucleus of hypertensive rats.

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-ß-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)-1ß 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.

Capsaicin improves hypertension and cardiac hypertrophy via SIRT1/NF-κB/MAPKs pathway in the hypothalamic paraventricular nucleus.

BACKGROUND: Hypertension has seriously affected a large part of the adult and elderly population. The complications caused by hypertension are important risk factors for cardiovascular disease accidents. Capsaicin, a pungent component of chili pepper has been revealed to improve hypertension. However, its potential mechanism in improving hypertension remains to be explored. PURPOSE: In the present study, we aimed to investigate whether capsaicin could attenuate the SIRT1/NF-κB/MAPKs pathway in the paraventricular nucleus of hypothalamus (PVN). METHODS: We used spontaneous hypertensive rats (SHRs) as animal model rats. Micro osmotic pump was used to give capsaicin through PVN for 28 days, starting from age12-week-old. RESULTS: The results showed that capsaicin significantly reduced blood pressure from the 16th day of infusion onward. At the end of the experimental period, we measured cardiac hypertrophy index and the heart rate (HR), and the results showed that the cardiac hypertrophy and heart rate of rats was significantly improved upon capsaicin chronic infusion. Norepinephrine (NE) and epinephrine (EPI) in plasma of SHRs treated with capsaicin were also decreased. Additionally, capsaicin increased the protein expression and number of positive cells of SIRT1 and the 67-kDa isoform of glutamate decarboxylase (GAD67), decreased the production of reactive oxygen species (ROS), number of positive cells of NOX2, those of Angiotensin Converting Enzyme (ACE) and p-IKKß, tyrosine hydroxylase (TH), the gene expression levels of NOX4 and pro-inflammatory cytokines. Capsaicin also decreased the relative protein expressions of protein in MAPKs pathway. CONCLUSION: Current data indicated that capsaicin within the PVN improves hypertension and cardiac hypertrophy via SIRT1/NF-κB/MAPKs pathway in the PVN of SHRs, supporting its potential as candidate drug for preventing and improving hypertension.

Hypothalamic Paraventricular Nucleus Hydrogen Sulfide Exerts Antihypertensive Effects in Spontaneously Hypertensive Rats via the Nrf2 Pathway.

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, gp91phox, p47phox, superoxide dismutase 1, interleukin (IL)-1ß, IL-6, IL-10, tumor necrosis factor-α, 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.

Luteolin Attenuates Hypertension via Inhibiting NF-κB-Mediated Inflammation and PI3K/Akt Signaling Pathway in the Hypothalamic Paraventricular Nucleus.

BACKGROUND: Luteolin is widely distributed among a number of vegetal species worldwide. The pharmacological effects of luteolin are diverse and amongst antioxidant, free radical scavenging, and anti-inflammatory activities. Preliminary study showed that luteolin can ameliorate hypertension. However, the precise mechanism needs further investigation. There is no evidence that luteolin affects the paraventricular nucleus of the hypothalamus (PVN), a brain nucleus associated with a critical neural regulator of blood pressure. Our main aim was to explore the effect of luteolin on the PI3K/Akt/NF-κB signaling pathway within the PVN of hypertensive rats. METHODS: spontaneously hypertensive rats (SHRs) and corresponding normotensive control rats, the Wistar Kyoto (WKY) rats were divided into four groups and subsequently treated for 4 weeks with bilateral PVN injections of either luteolin (20 µg/0.11 µL, volume: 0.11 µL/h) or vehicle (artificial cerebrospinal fluid). RESULTS: luteolin infusion to the PVN significantly decreased some hemodynamic parameters including the mean arterial pressure (MAP), heart rate (HR), circulating plasma norepinephrine (NE) and epinephrine (EPI). Additionally, there was a decrease in the expressions of the phosphatidylinositol 3-kinase (p-PI3K) and phosphorylated protein kinase-B (p-AKT), levels of reactive oxygen species (ROS), NAD(P)H oxidase subunit (NOX2, NOX4) in the PVN of SHRs. Meanwhile, the expression of inflammatory cytokines and the activity of nuclear factor κB (NF-κB) p65 in the PVN of SHRs were lowered. Furthermore, immunofluorescence results showed that injection of luteolin in the PVN reduced the expression of tyrosine hydroxylase (TH), and increased that of superoxide dismutase (SOD1) and the 67-kDa isoform of glutamate decarboxylase (GAD67) in the PVN of SHRs. CONCLUSION: Our novel findings revealed that luteolin lowered hypertension via inhibiting NF-κB-mediated inflammation and PI3K/Akt signaling pathway in the PVN.

Minocycline and Pyrrolidine Dithiocarbamate Attenuate Hypertension via Suppressing Activation of Microglia in the Hypothalamic Paraventricular Nucleus.

Proinflammatory cytokines, reactive oxygen species and imbalance of neurotransmitters are involved in the pathophysiology of angiotensin II-induced hypertension. The hypothalamic paraventricular nucleus (PVN) plays a vital role in hypertension. Evidences show that microglia are activated and release proinflammatory cytokines in angiocardiopathy. We hypothesized that angiotensin II induces PVN microglial activation, and the activated PVN microglia release proinflammatory cytokines and cause oxidative stress through nuclear factor-kappa B (NF-κB) pathway, which contributes to sympathetic overactivity and hypertension. Male Sprague-Dawley rats (weight 275-300 g) were infused with angiotensin II to induce hypertension. Then, rats were treated with bilateral PVN infusion of microglial activation inhibitor minocycline, NF-κB activation inhibitor pyrrolidine dithiocarbamate or vehicle for 4 weeks. When compared to control groups, angiotensin II-induced hypertensive rats had higher mean arterial pressure, PVN proinflammatory cytokines, and imbalance of neurotransmitters, accompanied with PVN activated microglia. These rats also had more PVN gp91phox (source of reactive oxygen species production), and NF-κB p65. Bilateral PVN infusion of minocycline or pyrrolidine dithiocarbamate partly or completely ameliorated these changes. This study indicates that angiotensin II-induced hypertensive rats have more activated microglia in PVN, and activated PVN microglia release proinflammatory cytokines and result in oxidative stress, which contributes to sympathoexcitation and hypertensive response. Suppression of activated PVN microglia by minocycline or pyrrolidine dithiocarbamate attenuates inflammation and oxidative stress, and improves angiotensin II-induced hypertension, which indicates that activated microglia promote hypertension through activated NF-κB. The findings may offer hypertension new strategies.

Resveratrol in the Hypothalamic Paraventricular Nucleus Attenuates Hypertension by Regulation of ROS and Neurotransmitters.

BACKGROUND: The hypothalamic paraventricular nucleus (PVN) is an important nucleus in the brain that plays a key role in regulating sympathetic nerve activity (SNA) and blood pressure. Silent mating-type information regulation 2 homolog-1 (sirtuin1, SIRT1) not only protects cardiovascular function but also reduces inflammation and oxidative stress in the periphery. However, its role in the central regulation of hypertension remains unknown. It is hypothesized that SIRT1 activation by resveratrol may reduce SNA and lower blood pressure through the regulation of intracellular reactive oxygen species (ROS) and neurotransmitters in the PVN. METHODS: The two-kidney one-clip (2K1C) method was used to induce renovascular hypertension in male Sprague-Dawley rats. Then, bilaterally injections of vehicle (artificial cerebrospinal fluid, aCSF, 0.4 µL) or resveratrol (a SIRT1 agonist, 160 µmol/L, 0.4 µL) into rat PVN were performed for four weeks. RESULTS: PVN SIRT1 expression was lower in the hypertension group than the sham surgery (SHAM) group. Activated SIRT1 within the PVN lowered systolic blood pressure and plasma norepinephrine (NE) levels. It was found that PVN of 2K1C animals injected with resveratrol exhibited increased expression of SIRT1, copper-zinc superoxide dismutase (SOD1), and glutamic acid decarboxylase (GAD67), as well as decreased activity of nuclear factor-kappa B (NF-κB) p65 and NAD(P)H oxidase (NOX), particularly NOX4. Treatment with resveratrol also decreased expression of ROS and tyrosine hydroxylase (TH). CONCLUSION: Resveratrol within the PVN attenuates hypertension via the SIRT1/NF-κB pathway to decrease ROS and restore the balance of excitatory and inhibitory neurotransmitters.

Exercise Training Attenuates Hypertension via Suppressing ROS/MAPK/NF-κB/AT-1R Pathway in the Hypothalamic Paraventricular Nucleus.

BACKGROUND: Aerobic exercise training (ExT) is beneficial for hypertension, however, its central mechanisms in improving hypertension remain unclear. Since the importance of the up-regulation of angiotensin II type 1 receptor (AT-1R) in the paraventricular nucleus (PVN) of the hypothalamic in sympathoexcitation and hypertension has been shown, we testified the hypothesis that aerobic ExT decreases blood pressure in hypertensive rats by down-regulating the AT-1R through reactive oxygen species (ROS)/mitogen-activated protein kinase (MAPK)/nuclear factors κB (NF-κB) pathway within the PVN. METHODS: Forty-eight male Sprague-Dawley (SD) rats were assigned to the following groups: sham operation (SHAM) + kept sedentary (Sed), SHAM + exercise training (ExT), two kidney-one clamp (2K1C) + Sed, and 2K1C + ExT groups. RESULTS: The 2K1C + Sed hypertensive rats showed higher systolic blood pressure (SBP), upregulated ROS, phosphorylated (p-) p44/42 MAPK, p-p38 MAPK, NF-κB p65 activity, and AT-1R expression in the PVN, and increased circulating norepinephrine (NE) than those of SHAM rats. After eight weeks of aerobic ExT, the 2K1C + ExT hypertensive rats showed attenuated NE and SBP levels, suppressed NF-κB p65 activity, and reduced expression of ROS, p-p44/42 MAPK, p-p38 MAPK, and AT-1R in the PVN, relatively to the 2K1C + Sed group. CONCLUSIONS: These data are suggestive of beneficial effects of aerobic ExT in decreasing SBP in hypertensive rats, via down-regulating the ROS/MAPK/NF-κB pathway that targets AT-1R in the PVN, and eventually ameliorating 2K1C-induced hypertension.

Imaging findings of vertebral osteomyelitis caused by nontuberculous mycobacterial organisms: Three case reports and literature review.

RATIONALE: Prompt diagnosis of nontuberculous Mycobacterial (NTM) vertebral osteomyelitis is challenging, yet necessary to prevent serious morbidity and mortality. Here, we report 3 cases of vertebral osteomyelitis caused by NTM with imaging findings. PATIENT CONCERNS: Case 1, a 58-year-old male patient, was admitted to our hospital because of the presence of a pulmonary mass for 6 months with cough and chest pain.Case 2, a 50-year-old male patient, had fever and cough for 3 years and was diagnosed with tuberculosis. Antituberculosis treatment was ineffective, accompanied by lymph node enlargement and osteosclerotic changes involving vertebral bodies.Case 3, a 66-year-old female patient, was admitted to our hospital with a mass on the top of her head for 1 month, which ruptured in the last 2 weeks. DIAGNOSES: Case 1: Sputum culture revealed Mycobacterium (M.) avium.Case 2: The final culture results of the lymph node biopsy samples were M. intracellulare.Case 3: Culture results of the sputum and pus from the abscess were M. gordon.We found sclerosing lesions in the spine in all 3 NTM patients, which were easily misdiagnosed as metastatic tumors. In 2 cases, there was bone destruction in the ilium with limbic sclerosis, and there were abscesses near the ilium and in front of the sacrum in 1 case. INTERVENTIONS: Case 1 was transferred to other specialist hospital.Case 3 received surgical treatment for cranial lesions and abscess drainage.Case 2 and case 3 received targeted treatment for nontuberculous mycobacteria in our hospital. OUTCOME: The condition of case 1 was unknown.Recovery of case 2 was uneventful because of prolonged illness; however, inflammation gradually improved overall.Case 3 had no recurrence following surgical treatment. LESSONS: In our 3 cases of NTM vertebral osteomyelitis, bone lesions were often misdiagnosed as bony metastases because of the presence of multiple sclerotic lesions. Diagnoses were challenging and delayed. It is important to consider osteomyelitis by NTM when disseminated osteosclerosis with or without osteolytic bone lesions is present in conjunction with continuous inflammatory symptoms and signs. Moreover, an open biopsy of the lesion should be performed for a definitive diagnosis.

Blockade of Microglial Activation in Hypothalamic Paraventricular Nucleus Improves High Salt-Induced Hypertension.

BACKGROUND: It has been shown that activated microglia in brain releasing proinflammatory cytokines (PICs) contribute to the progression of cardiovascular diseases. In this study, we tested the hypothesis that microglial activation in hypothalamic paraventricular nucleus (PVN), induced by high-salt diet, increases the oxidative stress via releasing PICs and promotes sympathoexcitation and development of hypertension. METHODS: High-salt diet was given to male Dahl salt-sensitive rats to induce hypertension. Those rats were bilaterally implanted with cannula for PVN infusion of minocycline, a selective microglial activation blocker, or artificial cerebrospinal fluid for 4 weeks. RESULTS: High-salt diet elevated mean arterial pressure of Dahl salt-sensitive rats. Meanwhile, elevations of renal sympathetic nerve activity and central prostaglandin E2, as well as increase of plasma norepinephrine, were observed in those hypertensive rats. Tumor necrosis factor-α, interleukin-1ß (IL-1ß), and IL-6 increased in the PVN of those rats, associated with a significant activation of microglia and prominent disruption of redox balance, which was demonstrated by higher superoxide and NAD(P)H oxidase 2 (NOX-2) and NAD(P)H oxidase 4 (NOX-4), and lower Cu/Zn superoxide dismutase in PVN. PVN infusion of minocycline attenuated all hypertension-related alterations described above. CONCLUSION: This study indicates that high salt leads to microglial activation within PVN of hypertensive rats, and those activated PVN microglia release PICs and trigger the production of reactive oxygen species, which contributes to sympathoexcitation and development of hypertension. Blockade of PVN microglial activation inhibits inflammation and oxidative stress, therefore attenuating the development of hypertension induced by high-salt diet.

Na+/K+-ATPase Alpha 2 Isoform Elicits Rac1-Dependent Oxidative Stress and TLR4-Induced Inflammation in the Hypothalamic Paraventricular Nucleus in High Salt-Induced Hypertension.

BACKGROUND: Numerous studies have indicated that a high salt diet inhibits brain Na+/K+-ATPase (NKA) activity, and affects oxidative stress and inflammation in the paraventricular nucleus (PVN). Furthermore, Na+/K+-ATPase alpha 2-isoform (NKA α2) may be a target in the brain, taking part in the development of salt-dependent hypertension. Therefore, we hypothesized that NKA α2 regulates oxidative stress and inflammation in the PVN in the context of salt-induced hypertension. METHODS: Part I: We assessed NKA subunits (NKA α1, NKA α2, and NKA α3), Na+/K+-ATPase activity, oxidative stress, and inflammation in a high salt group (8% NaCl) and normal salt group (0.3% NaCl). Part II: NKA α2 short hairpin RNA (shRNA) was bilaterally microinjected into the PVN of salt-induced hypertensive rats to knockdown NKA α2, and we explored whether NKA α2 regulates downstream signaling pathways related to protein kinase C γ (PKC γ)-dependent oxidative stress and toll-like receptor 4 (TLR4)-induced inflammation in the PVN to promote the development of hypertension. RESULTS: High salt diet increased NKA α1 and NKA α2 protein expression in the PVN but had no effect on NKA α3 compared to the normal salt diet. Na+/K+-ATPase activity and ADP/ATP ratio was lower, but NAD(P)H activity and NF-κB activity in the PVN were higher after a high salt diet. Bilateral PVN microinjection of NKA α2 shRNA not only improved Na+/K+-ATPase activity and ADP/ATP ratio but also suppressed PKC γ-dependent oxidative stress and TLR4-dependent inflammation in the PVN, thus decreasing sympathetic activity in rats with salt-induced hypertension. CONCLUSIONS: NKA α2 in the PVN elicits PKC γ/Rac1/NAD (P)H-dependent oxidative stress and TLR4/MyD88/NF-κB-induced inflammation in the PVN, thus increasing MAP and sympathetic activity during the development of salt-induced hypertension.

Beneficial effects of metformin supplementation in hypothalamic paraventricular nucleus and arcuate nucleus of type 2 diabetic rats.

Background Oxidative stress and inflammation play important roles in the development of diabetes. Metformin (MET) is considered as the first-line therapy for patients with type 2 diabetes (T2D). Hypothalamic paraventricular nucleus (PVN) and hypothalamic arcuate nucleus (ARC) are vital in obesity and diabetes. However, there have been few studies on the effects of MET on inflammatory reaction and oxidative stress in the PVN and ARC of T2D diabetic rats. Methods Male Sprague-Dawley (SD) rats were fed with high-fat diet (HFD), and intraperitoneally injected with low-dose streptozotocin (STZ, 30 mg/kg) at 6th week to induce T2D diabetes. After injection of STZ, they were fed with HFD continually. Starting from the 8th week of HFD feeding, T2D rats received intragastrical administration of MET (150 mg/kg/day) in addition to the HFD for another 8 weeks. At the end of the 15th week, the rats were anaesthetized to record the sympathetic nerve activity and collect blood and tissue samples. Results In comparison with control rats, T2D diabetic rats had higher levels of pro-inflammatory cytokines (PICs) and excessive oxidative stress in the PVN and ARC, accompanied with more activated astrocytes. The renal sympathetic nerve activity (RSNA) and the plasma norepinephrine (NE) increased in T2D diabetic rats. The expression of tyrosine hydroxylase (TH) increased and the expression of 67-kDa isoform of glutamate decarboxylase (GAD67) decreased in T2D diabetic rats. Supplementation of MET decreased blood glucose, suppressed RSNA, decreased PICs (TNF-α, IL-1ß and IL-6) in PVN and ARC, attenuated oxidative stress and activation of astrocytes in ARC and PVN of T2D diabetic rats, as well as restored the balance of neurotransmitter synthetase. The number of Fra-LI (chronic neuronal excitation marker) positive neurons in the ARC and PVN of T2D diabetic rats increased. Chronic supplementation of MET also decreased the number of Fra-LI positive neurons in the ARC and PVN of T2D diabetic rats. Conclusion These findings suggest that the PVN and ARC participate in the beneficial effects of MET in T2D diabetic rats, which is possibly mediated via down-regulating of inflammatory molecules, attenuating oxidative stress and restoring the balance of neurotransmitter synthetase by MET in the PVN and ARC.

Bilateral Paraventricular Nucleus Upregulation of Extracellular Superoxide Dismutase Decreases Blood Pressure by Regulation of the NLRP3 and Neurotransmitters in Salt-Induced Hypertensive Rats.

Aims: Long-term salt diet induces the oxidative stress in the paraventricular nucleus (PVN) and increases the blood pressure. Extracellular superoxide dismutase (Ec-SOD) is a unique antioxidant enzyme that exists in extracellular space and plays an essential role in scavenging excessive reactive oxygen species (ROS). However, the underlying mechanism of Ec-SOD in the PVN remains unclear. Methods: Sprague-Dawley rats (150-200 g) were fed either a high salt diet (8% NaCl, HS) or normal salt diet (0.9% NaCl, NS) for 6 weeks. Each group of rats was administered with bilateral PVN microinjection of AAV-Ec-SOD (Ec-SOD overexpression) or AAV-Ctrl for the next 6 weeks. Results: High salt intake not only increased mean arterial blood pressure (MAP) and the plasma noradrenaline (NE) but also elevated the NAD(P)H oxidase activity, the NAD(P)H oxidase components (NOX2 and NOX4) expression, and ROS production in the PVN. Meanwhile, the NOD-like receptor protein 3 (NLRP3)-dependent inflammatory proteins (ASC, pro-cas-1, IL-ß, CXCR, CCL2) expression and the tyrosine hydroxylase (TH) expression in the PVN with high salt diet were higher, but the GSH level, Ec-SOD activity, GAD67 expression, and GABA level were lower than the NS group. Bilateral PVN microinjection of AAV-Ec-SOD decreased MAP and the plasma NE, reduced NAD(P)H oxidase activity, the NOX2 and NOX4 expression, and ROS production, attenuated NLRP3-dependent inflammatory expression and TH, but increased GSH level, Ec-SOD activity, GAD67 expression, and GABA level in the PVN compared with the high salt group. Conclusion: Excessive salt intake not only activates oxidative stress but also induces the NLRP3-depensent inflammation and breaks the balance between inhibitory and excitability neurotransmitters in the PVN. Ec-SOD, as an essential anti-oxidative enzyme, eliminates the ROS in the PVN and decreases the blood pressure, probably through inhibiting the NLRP3-dependent inflammation and improving the excitatory neurotransmitter release in the PVN in the salt-induced hypertension.

Effects of Nrf1 in Hypothalamic Paraventricular Nucleus on Regulating the Blood Pressure During Hypertension.

The incidence rate and mortality of hypertension increase every year. Hypothalamic paraventricular nucleus (PVN) plays a critical role on the pathophysiology of hypertension. It has been demonstrated that the imbalance of neurotransmitters including norepinephrine (NE), glutamate (Glu) and γ-aminobutyric acid (GABA) are closely related to sympathetic overactivity and pathogenesis of hypertension. N-methyl-D-aspartate receptor (NMDAR), consisting of GluN1 and GluN2 subunits, is considered to be a glutamate-gated ion channel, which binds to Glu, and activates neuronal activity. Studies have found that the synthesis of respiratory chain enzyme complex was affected and mitochondrial function was impaired in spontaneously hypertensive rats (SHR), further indicating that mitochondria is associated with hypertension. Nuclear respiratory factor 1 (Nrf1) is a transcription factor that modulates mitochondrial respiratory chain and is related to GluN1, GluN2A, and GluN2B promoters. However, the brain mechanisms underlying PVN Nrf1 modulating sympathoexcitation and blood pressure during the development of hypertension remains unclear. In this study, an adeno-associated virus (AAV) vector carrying the shRNA targeting rat Nrf1 gene (shNrf1) was injected into bilateral PVN of male rats underwent two kidneys and one clip to explore the role of Nrf1 in mediating the development of hypertension and sympathoexcitation. Administration of shNrf1 knocked down the expression of Nrf1 and reduced the expression of excitatory neurotransmitters, increased the expression of inhibitory neurotransmitters, and reduced the production of reactive oxygen species (ROS), and attenuated sympathoexcitation and hypertension. The results indicate that knocking down Nrf1 suppresses sympathoexcitation in hypertension by reducing PVN transcription of NMDAR subunits (GluN1, GluN2A, and GluN2B), rebalancing PVN excitatory and inhibitory neurotransmitters, inhibiting PVN neuronal activity and oxidative stress, and attenuating sympathetic activity.

Astaxanthin Ameliorates Blood Pressure in Salt-Induced Prehypertensive Rats Through ROS/MAPK/NF-κB Pathways in the Hypothalamic Paraventricular Nucleus.

Astaxanthin (AST) has a variety of biochemical effects, including anti-inflammatory, antioxidative, and antihypertensive functions. The aim of the present study was to determine whether AST ameliorates blood pressure in salt-induced prehypertensive rats by ROS/MAPK/NF-κB pathways in hypothalamic paraventricular nucleus.To explore the central effects of AST on the development of blood pressure, prehypertensive rats were induced by a high-salt diet (HS, 8% NaCl) and its control groups were treated with normal-salt diet (NS, 0.3% NaCl). The Dahl salt-sensitive (S) rats with HS diet for 6 weeks received AST or vehicle by gastric perfusion for 6 weeks. Compared to those with NS diet, rats with HS diet exhibited increased mean arterial pressure (MAP) and heart rate (HR). These increases were associated with higher plasma level of norepinephrine (NE), interleukin 1ß (IL-1ß), and interleukin 6 (IL-6); elevated PVN level of reactive oxygen species (ROS), NOX2, and NOX4, that of IL-1ß, IL-6, monocyte chemotactic protein 1 (MCP-1), tyrosine hydroxylase (TH), phosphorylation extracellular-signal-regulated kinase (p-ERK1/2), phosphorylation Jun N-terminal kinases (p-JNK), nuclear factor-kappa B (NF-κB) activity; and lower levels of IL-10, superoxide dismutase (SOD), and catalase (CAT) in the PVN. In addition, our data demonstrated that chronic AST treatment ameliorated these changes in the HS but not NS diet rats. These data suggested that AST could alleviate prehypertensive response in HS-induced prehypertension through ROS/MAPK/NF-κB pathways in the PVN.

Curcumin ameliorates hypertension via gut-brain communication in spontaneously hypertensive rat.

Gut dysbiosis and dysregulation of gut-brain communication have been identified in hypertensive patients and animal models. Previous studies have shown that probiotic or prebiotic treatments exert positive effects on the pathophysiology of hypertension. This study aimed to examine the hypothesis that the microbiota-gut-brain axis is involved in the antihypertensive effects of curcumin, a potential prebiotic obtained from Curcuma longa. Male 8- to 10-week-old spontaneously hypertensive rats (SHRs) and Wistar Kyoto (WKY) rats were divided into four groups: WKY rats and SHRs treated with vehicle and SHRs treated with curcumin in dosage of 100 or 300 mg/kg/day for 12 weeks. Our results show that the elevated blood pressure of SHRs was markedly decreased in both curcumin-treated groups. Curcumin treatment also altered the gut microbial composition and improved intestinal pathology and integrity. These factors were associated with reduced neuroinflammation and oxidative stress in the hypothalamus paraventricular nucleus (PVN). Moreover, curcumin treatment increased butyrate levels in the plasma, which may be the result of increased butyrate-producing gut microorganisms. In addition, curcumin treatment also activated G protein-coupled receptor 43 (GPR 43) in the PVN. These results indicate that curcumin reshapes the composition of the gut microbiota and ameliorates the dysregulation of the gut-brain communication to induce antihypertensive effects.

Inhibition of Maternal c-Src Ameliorates the Male Offspring Hypertension by Suppressing Inflammation and Neurotransmitters in the Paraventricular Nucleus.

Long-term maternal salt intake induces the hypertension in offspring. Numerous studies have also indicated that high-salt diet causes the inflammation and an imbalance in neurotransmitters in the paraventricular nucleus (PVN) which increases the blood pressure and sympathetic activity. This study aimed to explore whether maternal salt intake induces hypertension in their male offspring by increasing the inflammation and changing the neurotransmitters balance in the paraventricular nucleus of offspring. This study includes two parts: Part I to explore the effect of high-salt diet on pregnant rats and the changes in inflammation and neurotransmitters in their male offspring PVN; Part II to reveal the influence on their offspring of bilateral PVN infusion of c-Src inhibitor dasatinib (DAS) in pregnant rats fed a high-salt diet. Maternal high-salt diet intake during copulation, pregnancy, and lactation impacted the offspring mean arterial pressure (MAP) and elevated the offspring PVN levels of p-Src, proinflammatory cytokines, and excitatory neurotransmitters. Bilateral PVN infusion of a c-Src inhibitor combined with maternal high-salt diets decreased MAP in the offspring. The infusion was also shown to suppress the Src-induced MAPK/NF-κB signaling pathway (p38 MAPK, JNK, Erk1/2), which attenuates inflammatory reactions. Finally, bilateral PVN infusion of the Src inhibitor in pregnant rat with high-salt diets improved the levels of inhibitory neurotransmitters in offspring PVN, which restored the excitatory-inhibitory neurotransmitter balance in male offspring. High-salt diets increase sympathetic activity and blood pressure in adult offspring, probably by activating the c-Src/MAPKs/NF-κB signaling pathway-induced inflammation. Moreover, NF-κB disrupts the downstream excitatory-inhibitory neurotransmitter balance in the PVN of male offspring.

Apigenin Improves Hypertension and Cardiac Hypertrophy Through Modulating NADPH Oxidase-Dependent ROS Generation and Cytokines in Hypothalamic Paraventricular Nucleus.

Apigenin, identified as 4', 5, 7-trihydroxyflavone, is a natural flavonoid compound that has many interesting pharmacological activities and nutraceutical potential including anti-inflammatory and antioxidant functions. Chronic, low-grade inflammation and oxidative stress are involved in both the initiation and progression of hypertension and hypertension-induced cardiac hypertrophy. However, whether or not apigenin improves hypertension and cardiac hypertrophy through modulating NADPH oxidase-dependent reactive oxygen species (ROS) generation and inflammation in hypothalamic paraventricular nucleus (PVN) has not been reported. This study aimed to investigate the effects of apigenin on hypertension in spontaneously hypertensive rats (SHRs) and its possible central mechanism of action. SHRs and Wistar-Kyoto (WKY) rats were randomly assigned and treated with bilateral PVN infusion of apigenin or vehicle (artificial cerebrospinal fluid) via osmotic minipumps (20 µg/h) for 4 weeks. The results showed that after PVN infusion of apigenin, the mean arterial pressure (MAP), heart rate, plasma norepinephrine (NE), Beta 1 receptor in kidneys, level of phosphorylation of PKA in the ventricular tissue and cardiac hypertrophy, perivascular fibrosis, heart level of oxidative stress, PVN levels of oxidative stress, interleukin 1ß (IL-1ß), interleukin 6 (IL-6), iNOS, monocyte chemotactic protein 1 (MCP-1), tyrosine hydroxylase (TH), NOX2 and NOX4 were attenuated and PVN levels of interleukin 10 (IL-10), superoxide dismutase 1 (Cu/Zn-SOD) and the 67-kDa isoform of glutamate decarboxylase (GAD67) were increased. These results revealed that apigenin improves hypertension and cardiac hypertrophy in SHRs which are associated with the down-regulation of NADPH oxidase-dependent ROS generation and inflammation in the PVN.

Chronic Blockade of NMDAR Subunit 2A in the Hypothalamic Paraventricular Nucleus Alleviates Hypertension Through Suppression of MEK/ERK/CREB Pathway.

BACKGROUND: N-Methyl-d-aspartate receptor (NMDAR) in the hypothalamic paraventricular nucleus (PVN) plays critical roles in regulating sympathetic outflow. Studies showed that acute application of the antagonists of NMDAR or its subunits would reduce sympathetic nerve discharges. However, little is known about the effect of long-term management of NMDAR in hypertensive animals. METHODS: PEAQX, the specific antagonist of NMDAR subunit 2A (GluN2A) was injected into both sides of the PVN of two-kidney, one-clip (2K1C) renal hypertensive rats and control (normotensive rats) for 3 weeks. RESULTS: Three weeks of PEAQX infusion significantly reduced the blood pressure of the 2K1C rats. It managed to resume the balance between excitatory and inhibitory neural transmitters, reduce the level of proinflammatory cytokines and reactive oxygen species in the PVN, and reduce the level of norepinephrine in plasma of the 2K1C rats. PEAQX administration also largely reduced the transcription and translation levels of GluN2A and changed the expression levels of NMDAR subunits 1 and 2B (GluN1 and GluN2B). In addition, NMDAR was known to function through activating the extracellular regulated protein kinases (ERK) or phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) pathways. In our study, we found that in the PVN of 2K1C rats treated with PEAQX, the phosphorylation levels of mitogen-activated protein kinase kinase (MEK), ERK1/2, and cAMP-response element-binding protein (CREB) significantly reduced, while the phosphorylation level of PI3K did not change significantly. CONCLUSIONS: Chronic blockade of GluN2A alleviates hypertension through suppression of MEK/ERK/CREB pathway.

Paraventricular Nucleus Infusion of Oligomeric Proantho Cyanidins Improves Renovascular Hypertension.

Oxidative stress plays an important role in the pathogenesis of hypertension. Oligomeric proantho cyanidins (OPC) is the main polyphenol presents in grape seed and is known for its potent antioxidant and anti-inflammatory properties. In the present study, we hypothesize that OPC can attenuate oxidative stress in the paraventricular nucleus of hypothalamus (PVN), ameliorate neurotransmitter imbalance, decrease the blood pressure and sympathetic activity in renovascular hypertensive rats. After induction of renovascular hypertension by the two-kidney one-clip (2K-1C) method, male Sprague-Dawley rats received chronic bilateral PVN infusion of OPC (20 µg/h) or vehicle via osmotic minipump for 4 weeks. We found that hypertension induced by 2K-1C was associated with the production of reactive oxygen species (ROS) in the PVN. Infusion of OPC in the PVN significantly reduced the systolic blood pressure and norepinephrine in plasma of 2K-1C rats. In addition, PVN infusion of OPC decreased the level of ROS and the expression of stress-related nicotinamide adenine dinucleotide phosphate (NADPH) oxidases subunit NOX4, increased the levels of nuclear factor E2-related factor 2 (Nrf2) and antioxidant enzyme, balanced the content of cytokines, increased expression of glutamic acid decarboxylase and decreased the expression of tyrosine hydroxylase in the PVN of 2K-1C rats. Our findings provided strong evidence that PVN infusion of OPC inhibited the progression of renovascular hypertension through its potent anti-oxidative and anti-inflammatory function in the PVN.