[Application of high hip center technique in total hip arthroplasty in patients with Crowe typeâ ¡and â ¢ developmental dysplasia of hip and severe hip osteoarthritis].

OBJECTIVE: To explore the clinical efficacy of high hip center technique total hip arthroplasty （THA） for Crowe Ⅱand Ⅲ developmental dysplasia of hip （DDH） and severe hip osteoarthritis （HOA）. METHODS: From January 2018 to January 2020, 74 patients with Crowe typeⅡand Ⅲ DDH and severe HOA were admitted, and 37 cases of anatomical hip center reconstruction were taken as control group, including 7 males and 30 females, aged from 42 to 65 years old with an average of （58.40±4.98） years old, body mass index （BMI） ranged from 18 to 29 kg·m-2 with an average of （23.02±2.21） kg·m-2. Thirty-seven routine high hip center technical reconstruction were performed as study group, including 5 males and 32 females, aged from 41 to 65 years old with an average of （57.31±5.42） years old, BMI ranged from 18 to 29 kg·m-2 with an average of （23.14±2.07） kg·m-2. The patients presented with hip pain, limited function and range of motion, and gait instability before surgery. All patients underwent THA, the control group underwent intraoperative anatomical hip center reconstruction, and the study group underwent intraoperative high hip joint reconstruction. The perioperative indicators of the two groups were compared. The hip joint function, balance function and gait of the patients were evaluated before surgery, 3 months, 6 months, and 12 months after surgery. The length difference of both lower limbs, horizontal distance of rotation center, vertical distance of rotation center and femoral eccentricity were measured before operation and 1 year after operation. The incidence of complications in the two groups during the operation and postoperative follow-up was counted. RESULTS: The operation time of the study group was shorter than that of the control group, and the intraoperative blood loss was less than that of the control group （P<0.05）. After 12-months follow-up, 1 was lost to followvup in study group and 2 were lost to follow-up in control group. The Harris scores and Berg balance scale（BBS）, pace, stride frequency and single step length in the study group were higher than those in the control group at 3 months and 6 months after operation （P<0.05）；there was no statistically significant difference between the two groups in the indexes 12 months after operation （P>0.05）. The vertical distance of the center of rotation of the study group was greater than that of the control group 12 months after operation （P<0.05）, and there was no significant difference in the length difference of the lower limbs, the horizontal distance of the center of rotation, and the femoral eccentricity between two groups （P>0.05）. There were no complications in either group. CONCLUSION: The long-term effects of THA in patients with DDH and severe HOA were similar between the two central hip reconstruction methods, and the safety was good, and the high hip central reconstruction technique could shorten the operation time and reduce the amount of intraoperative blood loss.At the same time, it has certain advantages in early recovery of hip joint function, balance function and walking function of patients.

Use of customized 3-dimensional printed mandibular prostheses with a dental implant pressure-reducing device in mandibular body defect: A finite element study performing multiresponse surface methodology.

Background/purpose: Segmental body defects of the mandible result in the complete loss of the affected region. In our previous study, we investigated the clinical applicability of a customized mandible prosthesis (CMP) with a pressure-reducing device (PRD) in an animal study. In this study, we further incorporated dental implants into the CMP and explored the use of dental implant PRD (iPRD) designs. Materials and methods: By employing a finite element analysis approach, we created 4 types of CMP: CMP, CMP with iPRD, CMP-PRD, and CMP-PRD with iPRD. We developed 2 parameters for the iPRD: cone length (CL) in the upper part and spring pitch (SP) in the lower part. Using the response surface methodology (RSM), we determined the most suitable structural assignment for the iPRD. Results: Our results indicate that CMP-PRD had the highest von Mises stress value for the entire assembly (1076.26 MPa). For retentive screws and abutments, CMP with iPRD had the highest von Mises stress value (319.97 and 452.78 MPa, respectively). CMP-PRD had the highest principal stress (131.66 MPa) in the anterior mandible. The iPRD reduced principal stress in both the anterior and posterior mandible. Using the RSM, we generated 25 groups for comparison to achieve the most favorable results for the iPRD and we might suggest the CL to 12 mm and the SP to 0.4 mm in the further clinical trials. Conclusion: Use of the PRD and iPRD in CMP may resolve the challenges associated with CMP, thereby promoting its usage in clinical practice.

The use of customized 3D-printed mandibular prostheses with pressure-reducing device: A clinical trial.

BACKGROUND: Segmental bone defects of the mandible result in the complete loss of the affected region. We had incorporated the pressure-reducing device (PRD) designs into the customized mandible prostheses (CMP) and conducted a clinical trial to evaluate this approach. METHODS: Seven patients were enrolled in this study. We examined the association among the history of radiotherapy, the number of CMP regions, the number of chin regions involved, and CMP exposure. RESULTS: We included five men and two women with an average age of 55 years. We excised tumors with an average weight of 147.8 g and the average weight of the CMP was 68.5 g. No significant difference between the two weights was noted (p = 0.3882). Three patients received temporary dentures and the CMP remained stable in all patients. CONCLUSION: The use of PRD in CMP may address the previous challenges associated with CMP, but further research is necessary.

The Use of Customized Three-Dimensionally Printed Mandible Prostheses with a Pressure-Reducing Device: A Finite Element Analysis in Different Chewing Positions, Biomechanical Testing, and In Vivo Animal Study Using Lanyu Pigs.

Segmental bony defects of the mandible constitute a complete loss of the regional part of the mandible. Although several types of customized three-dimension-printed mandible prostheses (CMPs) have been developed, this technique has yet to be widely used. We used CMP with a pressure-reducing device (PRD) to investigate its clinical applicability. First, we used the finite element analysis (FEA). We designed four models of CMP (P1 to P4), and the result showed that CMP with posterior PRD deployment (P4 group) had the maximum total deformation in the protrusion and right excursion positions, and in clenching and left excursion positions, posterior screws had the minimum von Mises stress. Second, the P4 CMP-PRD was produced using LaserCUSING from titanium alloy (Ti-6Al-4V). The fracture test result revealed that the maximum static pressure that could be withstood was 189 N, and a fatigue test was conducted for 5,000,000 cycles. Third, animal study was conducted on five male 4-month-old Lanyu pigs. Four animals completed the experiment. Two animals had CMP exposure in the oral cavity, but there was no significant inflammation, and one animal had a rear wing fracture. According to a CT scan, the lingual cortex of the mandible crawled along the CMP surface, and a bony front-to-back connection was noted in one animal. A histological examination indicated that CMP was significantly less reactive than control materials (p = 0.0170). Adequate PRD deployment in CMP may solve a challenge associated with CMP, thus promoting its use in clinical practice.

Involvement of NMDA receptors in nicotine-mediated central control of hypotensive effects.

It is known that enrichment of glutamatergic transmission in the nucleus tractus solitarii (NTS) plays an important role in central cardiovascular regulation. Our previous study demonstrated that nicotine decreased blood pressure and heart rate in the NTS probably acting via the nicotinic acetylcholine receptors (nAChRs)-Ca²âº-calmodulin-eNOS-NO signaling pathway. The possible relationship between glutamate and nicotine in the NTS for cardiovascular regulation is poorly understood. This study investigated the involvement of glutamate receptors in the cardiovascular effects of nicotine in the NTS. Nicotine (a non-selective nAChRs agonist), MK801 (a non-competitive NMDA receptor antagonist), APV (a competitive NMDA receptor antagonist), or NBQX (a selective AMPA receptor antagonist) was microinjected into the NTS of anesthetized Wistar-Kyoto rats. Microinjection of nicotine (1.5 pmol) into the NTS produced decreases in blood pressure and heart rate. The hypotensive and bradycardic effects of nicotine were abolished by prior administration of MK801 (1 nmol) and APV (10 nmol), but was completely restored after 60 min of recovery. In contrast, prior administration of NBQX (10 pmol) into the NTS did not alter the cardiovascular effects of nicotine. The nitrate (served as total NO) production in response to nicotine microinjection into the NTS was suppressed by prior administration of APV. These results suggest that the hypotensive and bradycardic effects of nicotine in the NTS might be mediated through NMDA receptors, and that the nAChRs-NMDA receptor-NO pathway could be involved.

Central nicotinic acetylcholine receptor involved in Ca(2+) -calmodulin-endothelial nitric oxide synthase pathway modulated hypotensive effects.

BACKGROUND AND PURPOSE: Recent evidence has suggested that nicotine decreases blood pressure (BP) and heart rate (HR) in the nucleus tractus solitarii (NTS), indicating that nicotinic acetylcholine receptors (nAChRs) play an important role in BP control in the NTS. However, the signalling mechanisms involved in nAChR-mediated depressor effects in the NTS are unclear. Hence, the aim of this study was to investigate these signalling mechanisms. EXPERIMENTAL APPROACH: Depressor responses to nicotine microinjected into the NTS of Wistar-Kyoto rats were elicited in the absence and presence of an antagonist of α7 nAChR, the calcium chelator ethylene glycol tetraacetic acid, a calmodulin-specific inhibitor, nitric oxide (NO) synthase (NOS) inhibitor, endothelial NOS (eNOS)-selective inhibitor or neuronal NOS (nNOS)-specific inhibitor. KEY RESULTS: Microinjection of nicotine into the NTS produced a dose-dependent decrease in BP and HR, and increased nitrate levels. This depressor effect of nicotine was attenuated after pretreatment with a nAChR antagonist or blockers of the calmodulin-eNOS pathway. In contrast, N5-(1-Imino-3-butenyl)-L-ornithine (vinyl-L-NIO), nNOS-specific inhibitor, did not diminish these nicotine-mediated effects. Calmodulin was found to bind eNOS after nicotine injection into NTS. However, nicotine did not affect the eNOS phosphorylation level or eNOS upstream extracellular signal-regulated kinases (ERK)1/2 and Akt phosphorylation levels. Furthermore, pretreatment with an ERK1/2 or Akt inhibitor did not attenuate nicotine-induced depressor effects in the NTS. CONCLUSIONS AND IMPLICATIONS: These results suggest that the nAChR-Ca(2+) -calmodulin-eNOS-NO signalling pathway, but not nNOS, plays a significant role in central BP regulation, and neither the ERK1/2 nor Akt signalling pathway are significantly involved in the activation of eNOS by nAChRs in the NTS.

CXC-chemokine-ligand-10 gene therapy efficiently inhibits the growth of cervical carcinoma on the basis of its anti-angiogenic and antiviral activity.

Epidemiological studies have demonstrated that high-risk human papillomavirus (HPV) is involved in causing cervical carcinoma. The HPV oncoproteins E6 and E7 immortalize human keratinocytes is mostly resulted from inactivation of tumor suppressor proteins p53 and pRB, which also play an important role in regulating the expression of pro- and antiangiogenic factors. The present study was conducted to determine whether IFN--inducible protein 10 (IP-10)/CXC chemokine ligand 10(CXCL10), one of the potent antiangiogenic chemokines, can inhibit the growth of cervical cancer. Plasmid DNA encoding CXCL10 was encapsulated with cationic liposomes, mice were treated with DNA-liposome mixture 6 times with the 5-day interval. Our results demonstrated that CXCL10 could reduce the level of HPV oncoproteins E6 and E7 in cervical cancer cells. In vivo study showed that CXCL10 could inhibit the growth of tumor in the immunodeficiency mice. Immunohistology analysis revealed that CXCL10 downregulated the microvessel density and the expression of PCNA in tumor tissues. TUNEL staining demonstrated CXCL10 significantly increase the apoptotic rate. Our data suggest that CXCL10 can inhibit the growth of cervical carcinoma through modulating the formation of microvessel and the expression of HPV oncoproteins E6 and E7. The present findings also provide further evidence of the anti-tumor effects of CXCL10, and may be of importance for the further exploration of the potential application of this molecule in the treatment of cervical carcinoma.

Upregulation of AT1 receptor gene on activation of protein kinase Cbeta/nicotinamide adenine dinucleotide diphosphate oxidase/ERK1/2/c-fos signaling cascade mediates long-term pressor effect of angiotensin II in rostral ventrolateral medulla.

OBJECTIVE: Angiotensin II induces the phosphorylation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK) 1/2 via the activation of nicotinamide adenine dinucleotide diphosphate (NADPH) oxidase on stimulation of the angiotensin subtype 1 receptor (AT1R) in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons for the maintenance of vasomotor tone and blood pressure are located. Angiotensin II-activated p38 MAPK in RVLM promotes a short-term pressor effect via augmented glutamatergic neurotransmission. We tested the hypothesis that the NADPH oxidase-dependent phosphorylation of ERK1/2 after the activation of conventional protein kinase C (PKC) mediates the AT1R-dependent long-term pressor effects of angiotensin II via transcriptional induction of the proto-oncogene c-fos gene in RVLM. METHODS AND RESULTS: In Sprague-Dawley rats, a microinjection of angiotensin II bilaterally into the RVLM induced membrane-bound translocation of the conventional PKCalpha, PKCbeta or PKCgamma isoform, phosphorylation of the p47 subunit of NADPH oxidase and ERK1/2, followed by phosphorylation of the transcription factor cyclic adenosine monophosphate response element binding protein (CREB), and c-fos induction. The PKC inhibitor antagonized angiotensin II-induced p47 phosphorylation, and an antisense oligonucleotide (ASON) complementary to PKCbeta messenger RNA suppressed angiotensin II-induced ERK1/2 activation, phosphorylation or DNA binding activity of CREB, and upregulation of c-fos mRNA expression in the ventrolateral medulla. Furthermore, a microinjection of ERK1/2, CREB or c-fos ASON into the RVLM significantly reduced the long-term pressor effect and augmented AT1R expression in the ventrolateral medulla induced by intracerebroventricular infusion of angiotensin II. CONCLUSION: We concluded that the PKCbeta/NADPH oxidase/ERK1/2/CREB/c-fos cascade represents a novel signaling cascade that mediates the long-term pressor effect induced by angiotensin II in the RVLM.

Protein kinase C-dependent mitochondrial translocation of proapoptotic protein Bax on activation of inducible nitric-oxide synthase in rostral ventrolateral medulla mediates cardiovascular depression during experimental endotoxemia.

Sympathetic premotor neurons for the maintenance of vasomotor tone are located in rostral ventrolateral medulla (RVLM). We demonstrated previously that overproduction of nitric oxide (NO) by inducible NO synthase (iNOS) in RVLM, leading to caspase 3-dependent apoptotic cell death, plays a pivotal role in cardiovascular depression during endotoxemia induced by intravenous administration of Escherichia coli lipopolysaccharide. The interposing intracellular events remain unknown. We evaluated the hypothesis that these events encompass protein kinase C (PKC) activation, which triggers activation and translocation of Bax that opens mitochondrial permeability transition pore by interacting with adenine nucleotide translocase (ANT) or voltage-dependent anion protein (VDAC), followed by cytosolic release of cytochrome c. In Sprague-Dawley rats, coimmunoprecipitation and Western blot analyses revealed sequential manifestations during endotoxemia of membrane-bound translocation of PKC, dissociation of cytosolic PKC/Bax complex, mitochondrial translocation of activated Bax, augmented Bax/ANT or Bax/VDAC association, elevated cytosolic cytochrome c and caspase 3, and DNA fragmentation in ventrolateral medulla. Microinjection of iNOS inhibitor into bilateral RVLM significantly retarded PKC and Bax activation. The induced association of translocated Bax with ANT or VDAC and the triggered mitochondrial apoptotic signaling cascade were blunted by blockade in RVLM of PKC, mitochondrial translocation of Bax, Bax channels, ANT, or caspase 3, alongside significant amelioration of cardiovascular depression. We conclude that formation of mitochondrial Bax/ANT or Bax/VDAC complex that initiates caspase 3-dependent apoptosis in the RVLM as a result of PKC-dependent mitochondrial translocation of activated Bax activated by iNOS-derived NO plays a pivotal role in the manifestation of endotoxin-induced cardiovascular depression.

NADPH oxidase-derived superoxide anion mediates angiotensin II-induced pressor effect via activation of p38 mitogen-activated protein kinase in the rostral ventrolateral medulla.

The rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons are located, is a central site via which angiotensin II (Ang II) elicits its pressor effect. We tested the hypothesis that NADPH oxidase-derived superoxide anion (O2*-) in the RVLM mediates Ang II-induced pressor response via activation of mitogen-activated protein kinase (MAPK) signaling pathways. Bilateral microinjection of Ang II into the RVLM resulted in an angiotensin subtype 1 (AT1) receptor-dependent phosphorylation of p38 MAPK and extracellular signal-regulated protein kinase (ERK)1/2, but not stress-activated protein kinase/Jun N-terminal kinase (SAPK/JNK), in the ventrolateral medulla. The Ang II-induced p38 MAPK or ERK1/2 phosphorylation was attenuated by application into the RVLM of a NADPH oxidase inhibitor, diphenyleneiodonium chloride (DPI), an antisense oligonucleotide that targets against p22phox or p47phox subunit of NADPH oxidase mRNA, or the superoxide dismutase mimetic tempol. DPI or antisense p22phox or p47phox oligonucleotide treatment also attenuated the AT1 receptor-dependent increase in O2*- production in the ventrolateral medulla elicited by Ang II at the RVLM. Functionally, Ang II-elicited pressor response in the RVLM was attenuated by DPI, tempol, or a p38 MAPK inhibitor, SB203580. The AT1 receptor-mediated enhancement of the frequency of glutamate-sensitive spontaneous excitatory postsynaptic currents induced by Ang II in RVLM neurons was also abolished by SB203580. These results suggest that NADPH oxidase-derived O2*- underlies the activation of p38 MAPK or ERK1/2 by Ang II in the ventrolateral medulla. Furthermore, the p38 MAPK signaling pathway may mediate Ang II-induced pressor response via enhancement of presynaptic release of glutamate to RVLM neurons.

Nitric oxide- and superoxide-dependent mitochondrial signaling in endotoxin-induced apoptosis in the rostral ventrolateral medulla of rats.

This study evaluated the hypothesis that the repertoire of cellular events that underlie circulatory fatality during endotoxemia may entail mitochondrial respiratory enzyme dysfunction, followed by the release of cytochrome c to the cytosol that triggers the activation of caspase cascades, leading to apoptotic cell death in the rostral ventrolateral medulla (RVLM) where sympathetic premotor neurons responsible for maintaining vasomotor tone are located. In adult Sprague-Dawley rats maintained under propofol anesthesia, nucleosomal DNA fragmentation was detected in the RVLM in a temporal profile that coincided positively with the progression of cardiovascular depression during experimental endotoxemia induced by Escherichia coli lipopolysaccharide (LPS). LPS also induced nitric oxide (NO) and superoxide (O(2)(-)) production, depressed mitochondrial Complex I and IV activity, promoted the release of cytochrome c from mitochondria to cytosol, upregulated the cytosolic expression of activated caspase-9 and -3, or increased caspase-3 enzyme activity in the RVLM. Microinjection bilaterally into the RVLM of an inducible nitric oxide synthase (iNOS) blocker, S-methylisothiourea, or a superoxide dismutase mimetic, Tempol, significantly blunted these apoptotic cellular events and antagonized the cardiovascular depression during endotoxemia. We conclude that caspase-dependent apoptotic cell death that results from NO- and O(2)(-)-associated mitochondrial signaling in the RVLM may underlie fatal cardiovascular depression during endotoxemia.

Increased superoxide anion in rostral ventrolateral medulla contributes to hypertension in spontaneously hypertensive rats via interactions with nitric oxide.

Oxidative stress because of an excessive production of superoxide anion (O2*-) is associated with hypertension. The present study evaluated the hypothesis that in the rostral ventrolateral medulla (RVLM), where the premotor neurons for the maintenance of vascular vasomotor activity are located, increased O2*- contributes to hypertension in spontaneously hypertensive rats (SHR) by modulating the cardiovascular depressive actions of nitric oxide (NO). Compared with normotensive Wistar-Kyoto (WKY) rats, SHR manifested significantly increased basal O2*- production, along with reduced manganese superoxide dismutase (MnSOD) expression and activity, in the RVLM. The magnitude of hypotension, bradycardia, or suppression of sympathetic neurogenic vasomotor tone elicited by microinjection bilaterally into the RVLM of a membrane-permeable SOD mimetic, Mn(III)-tetrakis-(4-benzoic acid) porphyrin (MnTBAP), was also significantly larger in SHR. Transfection bilaterally into the RVLM of adenoviral vectors encoding endothelial nitric oxide synthase resulted in suppression of arterial pressure, heart rate, and sympathetic neurogenic vasomotor tone in both WKY rats and SHR. Microinjection of MnTBAP into the RVLM of SHR further normalized those cardiovascular parameters to the levels of WKY rats. We conclude that an elevated level of O2*- in the RVLM is associated with hypertension in SHR. More importantly, this elevated O2*- may contribute to hypertension by reducing the NO-promoted cardiovascular depression.

Receptor-independent activation of GABAergic neurotransmission and receptor-dependent nontranscriptional activation of phosphatidylinositol 3-kinase/protein kinase Akt pathway in short-term cardiovascular actions of dexamethasone at the nucleus tractus solitarii of the rat.

Whereas glucocorticoids are important blood pressure regulators via an action on peripheral circulation, their roles in central cardiovascular regulation are less known. This study evaluated the short-term cardiovascular effect of glucocorticoid in the nucleus tractus solitarii (NTS) and delineated the underlying molecular mechanisms. In Sprague-Dawley rats maintained under propofol anesthesia, microinjection bilaterally into the NTS of a synthetic glucocorticoid, dexamethasone (Dex; 12.5, 25, 50, or 100 pmol), elicited hypertensive and tachycardiac responses. The initial cardiovascular responses, which lasted 15 to 30 min, were blunted by coadministration of a selective GABA(A) or GABA(B) receptor antagonist, bicuculline (15 pmol) or 2-hydroxy saclofen (150 pmol). The delayed responses, which endured at least 90 min and entailed maintained hypertension and tachycardia, were reversed by selective glucocorticoid type II receptor (GR) antagonist mifepristone (100 or 200 pmol), phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 [2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one] (20 nmol), or nitric-oxide synthase inhibitor N(G)-monomethyl-l-arginine acetate (5 nmol), but not by the RNA synthesis inhibitor actinomycin D (20 nmol). Moreover, Dex induced an association of GR with the regulatory subunit of PI3K, p85alpha, in a ligand-dependent manner and promoted serine/threonine kinase Akt phosphorylation that was blocked by coadministration of mifepristone or LY294002. These cardiovascular and molecular responses occurred when translocation of activated GR into the nucleus was minimal. Our results indicate that Dex acts on the NTS to elicit hypertension and tachycardia via both a GR-independent interaction with GABA(A) and GABA(B) receptors and a GR-dependent but nontranscriptional mechanism that involves activation of PI3K/Akt pathway.

Heat shock protein 70 confers cardiovascular protection during endotoxemia via inhibition of nuclear factor-kappaB activation and inducible nitric oxide synthase expression in the rostral ventrolateral medulla.

BACKGROUND: Overproduction of nitric oxide (NO) by inducible NO synthase (iNOS) in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons are located, plays a pivotal role in the manifestation of fatal cardiovascular depression during endotoxemia. The iNOS gene is regulated transcriptionally by nuclear factor-kappaB (NF-kappaB) activation. The present study tested the hypothesis that heat shock protein 70 (HSP70) may confer protection against sepsis-induced circulatory fatality via inhibition of iNOS gene expression in the RVLM through prevention of NF-kappaB activation. METHODS AND RESULTS: Adult male Sprague-Dawley rats subjected to a brief hyperthermic heat shock (42 degrees C for 15 minutes) exhibited significant upregulation of HSP70 in the RVLM. Brief heat shock preconditioning also significantly suppressed iNOS mRNA or protein surge and alleviated hypotension, bradycardia, and reduction in neurogenic sympathetic vasomotor activity manifested during experimental endotoxemia induced by intravenous administration of Escherichia coli lipopolysaccharide. An increase in DNA binding activity and nuclear translocation of transcription factor NF-kappaB were detected during endotoxemia. Heat shock preconditioning significantly decreased DNA binding activity of NF-kappaB, which was reversed by microinjection of an hsp70 antisense oligonucleotide bilaterally into the RVLM. Heat shock preconditioning also blocked inhibitory kappaB (IkappaB) kinase activity or degradation of IkappaB in the RVLM during endotoxemia. CONCLUSIONS: We conclude that HSP70 confers protection against sepsis-related circulatory fatality via inhibition of iNOS gene expression in the RVLM through prevention of NF-kappaB activation in cellular processes that include prevention of IkappaB kinase activation and inhibition of IkappaBalpha degradation.

Downregulation of angiotensin subtype 1 receptor in rostral ventrolateral medulla during endotoxemia.

We reported recently that an upregulation of the inducible nitric oxide synthase (iNOS) in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons are located, is a crucial determinant for the elicitation of cardiovascular depression during experimental endotoxemia. The current study evaluated the hypothesis that a downregulation of the molecular synthesis and functional expression of angiotensin subtype 1 receptor (AT1R) in the RVLM is consequential to this upregulated iNOS. In adult Sprague-Dawley rats maintained under propofol anesthesia, intravenous administration of Escherichia coli lipopolysaccharide (15 mg/kg) elicited a reduction, followed by an augmentation and a secondary decrease in sympathetic vasomotor outflow, together with progressive hypotension and bradycardia. There was also a progressive increase in iNOS mRNA and protein level in the ventrolateral medulla. This was followed by a significant downregulation of both mRNA and protein levels of AT1R in the ventrolateral medulla, alongside reduced efficacy of angiotensin II (50 pmol) to induce an increase in systemic arterial pressure, heart rate, or sympathetic vasomotor outflow on unilateral microinjection into the RVLM. Pretreatment with microinjection of a selective iNOS inhibitor, S-methylisothiourea (250 pmol) bilaterally into the RVLM significantly reversed the reduction in both synthesis and activity of AT1R. We conclude that a downregulation of molecular synthesis and functional expression of AT1R in the ventrolateral medulla is consequential to the overproduction of NO through upregulation of iNOS in the RVLM and may underlie the cardiovascular depression that takes place during experimental endotoxemia.

Downregulation of basal iNOS at the rostral ventrolateral medulla is innate in SHR.

We demonstrated recently that a significant reduction in both the molecular synthesis and functional expression of inducible nitric oxide synthase (iNOS) in the rostral ventrolateral medulla (RVLM), the medullary origin of sympathetic vasomotor outflow, underlies the augmented sympathetic vasomotor tone during hypertension. This study further evaluated the hypothesis that this downregulation of basal iNOS at the RVLM during hypertension is innate. In adult spontaneously hypertensive rats (SHR) treated for 4 weeks with the antihypertensive captopril to normalize elevated blood pressure or in young prehypertensive SHR, the significantly lower iNOS mRNA and protein levels at the ventrolateral medulla under basal conditions or on activation by microinjection bilaterally into the RVLM of lipopolysaccharide (10 ng) remained unaltered. The retarded efficacy of lipopolysaccharide (10 ng) to elicit cardiovascular depression (hypotension, bradycardia, and reduction in sympathetic vasomotor tone) also persevered in captopril-treated adult or young normotensive SHR. On the other hand, compared with Wistar-Kyoto normotensive rats, the magnitude of cardiovascular depression induced in adult SHR by local administration into the RVLM of the NO precursor l-arginine (40 nmol) was significantly smaller. In addition, microinjection bilaterally into the RVLM of a selective iNOS inhibitor, aminoguanidine (125 or 250 pmol), was discernibly less efficacious in unmasking hypertension, tachycardia, and the increase in sympathetic vasomotor tone in adult SHR. We conclude that a predisposed reduction in molecular synthesis and functional expression of basal iNOS in the RVLM is associated with the sympathetic vasomotor overactivity during hypertension.

Differential engagements of glutamate and GABA receptors in cardiovascular actions of endogenous nNOS or iNOS at rostral ventrolateral medulla of rats.

1. We evaluated in Sprague-Dawley rats anaesthetized with propofol the engagement of soluble guanylyl cyclase (sGC)/cGMP cascade, glutamatergic and GABAergic neurotransmission in the cardiovascular actions of endogenous nitric oxide (NO) at the rostral ventrolateral medulla (RVLM). 2. Microinjection bilaterally into the RVLM of a selective iNOS inhibitor, S-methylisothiourea (SMT, 250 pmoles), or a selective nNOS inhibitor, 7-nitroindazole (7-NI, 5 pmoles), induced respectively an enhancement or a reduction in systemic arterial pressure, heart rate and power density of the vasomotor components in the spectrum of arterial blood pressure signals, our experimental index for sympathetic neurogenic vasomotor tone. 3. The cardiovascular actions of SMT or 7-NI in the RVLM were significantly antagonized by co-administration into the RVLM of the sGC inhibitor, 1H-[1,2,4]Oxadiazole[4,3-alpha]quinoxalin-1-one (ODQ, 250 or 500 pmoles). 4. The cardiovascular excitatory effects after blockade of endogenous iNOS activity were significantly attenuated when N-methyl-D-aspartate (NMDA) receptor antagonist, dizocilpine (20 or 50 pmoles), or non-NMDA receptor antagonist, 6-cyano-7-nitroquinoxaline-2,3-dione (250 or 500 pmoles), was co-microinjected bilaterally into the RVLM. 5. On the other hand, the cardiovascular depressive responses to blockade of endogenous nNOS activity were significantly antagonized on co-administration of GABA(A) receptor antagonist, bicuculline methiodine (5 or 10 pmoles), but not GABA(B) receptor antagonist, 2-hydroxy saclofen (50 or 100 pmoles). 6. We conclude that the cardiovascular actions of endogenous NO in the RVLM engage the sGC/cGMP pathway. In addition, whereas NO derived from nNOS induced sympathoexcitation via both NMDA and non-NMDA receptors in the RVLM, NO generated by iNOS elicited sympathoinhibition via GABA(A) receptors.

Altered temporal profile of heat shock factor 1 phosphorylation and heat shock protein 70 expression induced by heat shock in nucleus tractus solitarii of spontaneously hypertensive rats.

BACKGROUND: We demonstrated recently that heat shock (HS)-induced heat shock protein 70 (HSP70) expression in bilateral nucleus tractus solitarii (NTS), the terminal site in the brain stem for primary baroreceptor afferents, confers cardiovascular protection against heatstroke by potentiating baroreceptor reflex (BRR) response. This study evaluated the hypothesis that altered regulation of HSP70 expression may be associated with the heightened susceptibility to heatstroke during hypertension. METHODS AND RESULTS: Spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats anesthetized with propofol were used. Compared with WKY rats, significant induction in HSP70 or phosphorylation of heat shock factor 1 (HSF1), but not HSF2, in the NTS and potentiation of BRR response in SHR occurred earlier (4 versus 8 hours), reaching peak magnitude sooner (16 versus 24 hours), and declined more rapidly after a brief hyperthermic HS (42+/-0.5 degrees C for 15 minutes). The protection conferred by HS against hypotension and bradycardia during the onset of heatstroke (45 degrees C for 60 minutes), although effective, was less effective in SHR. Microinjection bilaterally into the NTS of the selective protein kinase A (PKA) inhibitor H-89 (100 pmol) or the selective PKC inhibitor calphostin C (100 pmol) significantly attenuated all of the above events induced in SHR by HS. However, only H-89 was effective in WKY rats. CONCLUSIONS: An altered temporal profile of HS-induced HSP70 expression or potentiation of BRR response by concurrent activation via both PKA and PKC pathways of phosphorylation of HSF1 in the NTS may be associated with greater susceptibility to heatstroke during hypertension.

Augmented upregulation by c-fos of angiotensin subtype 1 receptor in nucleus tractus solitarii of spontaneously hypertensive rats.

Our laboratory demonstrated previously that spontaneously hypertensive rats (SHR) exhibited an elevated basal Fos expression in the nucleus tractus solitarii (NTS), the terminal site for primary baroreceptor afferents, and that Fos protein is required for the re-expression of angiotensin subtype 1 receptor (AT1R) mRNA in the NTS after baroreceptor activation. The present study evaluated the hypothesis that this re-expression of AT1R is augmented in SHR and is promoted by the heightened Fos expression. Reverse transcription-polymerase chain reaction analysis revealed that baroreceptor activation via sustained increase in systemic arterial pressure resulted in a discernible reduction in the expression of AT1R mRNA at the dorsomedial medulla of SHR and normotensive Wistar-Kyoto rats. However, SHR manifested an appreciably larger magnitude of decline, followed by a faster time course of re-expression in AT1R mRNA. Parallel findings were obtained from the pressor response induced by microinjection unilaterally of angiotensin II (40 pmol) into the NTS. Whereas the re-expression of AT1R at both transcriptional and functional expression levels after baroreceptor activation was discernibly blunted by prior bilateral application into the NTS of an antisense c-fos oligonucleotide (50 pmol), the suppression in SHR was again significantly more intense. Control pretreatment with the corresponding sense or scrambled c-fos oligonucleotide was ineffective. We conclude that the heightened Fos expression in SHR is causatively related to the augmented re-expression of AT1R in the NTS at both transcriptional and functional levels.