SNAP29 mediates the assembly of histidine-induced CTP synthase filaments in proximity to the cytokeratin network.

Under metabolic stress, cellular components can assemble into distinct membraneless organelles for adaptation. One such example is cytidine 5'-triphosphate synthase (CTPS, for which there are CTPS1 and CTPS2 forms in mammals), which forms filamentous structures under glutamine deprivation. We have previously demonstrated that histidine (His)-mediated methylation regulates the formation of CTPS filaments to suppress enzymatic activity and preserve the CTPS protein under glutamine deprivation, which promotes cancer cell growth after stress alleviation. However, it remains unclear where and how these enigmatic structures are assembled. Using CTPS-APEX2-mediated in vivo proximity labeling, we found that synaptosome-associated protein 29 (SNAP29) regulates the spatiotemporal filament assembly of CTPS along the cytokeratin network in a keratin 8 (KRT8)-dependent manner. Knockdown of SNAP29 interfered with assembly and relaxed the filament-induced suppression of CTPS enzymatic activity. Furthermore, APEX2 proximity labeling of keratin 18 (KRT18) revealed a spatiotemporal association of SNAP29 with cytokeratin in response to stress. Super-resolution imaging suggests that during CTPS filament formation, SNAP29 interacts with CTPS along the cytokeratin network. This study links the cytokeratin network to the regulation of metabolism by compartmentalization of metabolic enzymes during nutrient deprivation.

Median nerve stimulation induces analgesia via orexin-initiated endocannabinoid disinhibition in the periaqueductal gray.

Adequate pain management remains an unmet medical need. We previously revealed an opioid-independent analgesic mechanism mediated by orexin 1 receptor (OX1R)-initiated 2-arachidonoylglycerol (2-AG) signaling in the ventrolateral periaqueductal gray (vlPAG). Here, we found that low-frequency median nerve stimulation (MNS) through acupuncture needles at the PC6 (Neiguan) acupoint (MNS-PC6) induced an antinociceptive effect that engaged this mechanism. In mice, MNS-PC6 reduced acute thermal nociceptive responses and neuropathy-induced mechanical allodynia, increased the number of c-Fos-immunoreactive hypothalamic orexin neurons, and led to higher orexin A and lower GABA levels in the vlPAG. Such responses were not seen in mice with PC6 needle insertion only or electrical stimulation of the lateral deltoid, a nonmedian nerve-innervated location. Directly stimulating the surgically exposed median nerve also increased vlPAG orexin A levels. MNS-PC6-induced antinociception (MNS-PC6-IA) was prevented by proximal block of the median nerve with lidocaine as well as by systemic or intravlPAG injection of an antagonist of OX1Rs or cannabinoid 1 receptors (CB1Rs) but not by opioid receptor antagonists. Systemic blockade of OX1Rs or CB1Rs also restored vlPAG GABA levels after MNS-PC6. A cannabinoid (2-AG)-dependent mechanism was also implicated by the observations that MNS-PC6-IA was prevented by intravlPAG inhibition of 2-AG synthesis and was attenuated in Cnr1-/- mice. These findings suggest that PC6-targeting low-frequency MNS activates hypothalamic orexin neurons, releasing orexins to induce analgesia through a CB1R-dependent cascade mediated by OX1R-initiated 2-AG retrograde disinhibition in the vlPAG. The opioid-independent characteristic of MNS-PC6-induced analgesia may provide a strategy for pain management in opioid-tolerant patients.

Therapeutic effects and mechanisms of actions of Descurainia sophia.

Descurainia sophia Webb ex Prantl has been used in traditional medicine globally. It has been shown that Descurainia sophia, together with many other bioactive compounds, can modulate the biological functions of various genes. We have viewed the clinical benefits and mechanisms of action of Descurainia sophia associated with its current uses and outlined potential further applications. There are many studies documenting its numerous clinical effects in cancer, respiratory, gastrointestinal, and cardiac systems. Further, Descurainia sophia has been shown to exhibit anti-inflammatory, anti-oxidative, and anthelmintic activities. The clinical studies did not indicate any significant adverse effects of Descurainia sophia, demonstrating that it is a safe and effective herbal medicine. However, more clinical studies demonstrating the therapeutic effects of Descurainia sophia are still warranted.

The CCL5/CCR5 Axis Promotes Vascular Smooth Muscle Cell Proliferation and Atherogenic Phenotype Switching.

BACKGROUND/AIMS: Hyperlipidemia induces dysfunction in the smooth muscle cells (SMCs) of the blood vessels, and the vascular remodeling that ensues is a key proatherogenic factor contributing to cardiovascular events. Chemokines and chemokine receptors play crucial roles in vascular remodeling. Here, we examined whether the hyperlipidemia-derived chemokine CCL5 and its receptor CCR5 influence vascular SMC proliferation, phenotypic switching, and explored the underlying mechanisms. METHODS: Thoracoabdominal aorta were isolated from wild-type, CCL5 and CCR5 double-knockout mice (CCL5-/-CCR5-/-) fed a high-fat diet (HFD) for 12 weeks. Expression of the contractile, synthetic, and proliferation markers were assayed using immunohistochemical and western blotting. The effects of CCL5 and palmitic acid on cultured SMC proliferation and phenotypic modulation were evaluated using flow cytometry, bromodeoxyuridine (BrdU), and western blotting. RESULTS: Wild-type mice fed an HFD showed markedly increased total cholesterol, triglyceride, and CCL5 serum levels, as well as significantly increased CCL5 and CCR5 expression in the thoracoabdominal aorta vs. normal-diet-fed controls. HFD-fed CCL5-/-CCR5-/- mice showed significantly decreased expression of the synthetic phenotype marker osteopontin and the proliferation marker proliferating cell nuclear antigen, and increased expression of the contractile phenotype marker smooth muscle α-actin in the thoracoabdominal aorta vs. wild-type HFD-fed mice. Human aorta-derived SMCs stimulated with palmitic acid showed significantly increased expression of CCL5, CCR5, and synthetic phenotype markers, as well as increased proliferation. CCL5-treated SMCs showed increased cell cycle regulatory protein expression, paralleling increased synthetic and decreased contractile phenotype marker expression. Inhibition of CCR5 activity by the specific antagonist maraviroc or its expression using small interfering RNA significantly inhibited human aortic SMC proliferation and synthetic phenotype formation. Therefore, CCL5 induces SMC proliferation and phenotypic switching from a contractile to synthetic phenotype via CCR5. CCL5-mediated SMC stimulation activated ERK1/2, Akt/p70S6K, p38 MAPK, and NF-κB signaling. NF-κB inhibition significantly reduced CCR5 expression along with CCR5-induced SMC proliferation and synthetic phenotype formation. CONCLUSIONS: Hyperlipidemia-induced CCL5/CCR5 axis activation serves as a pivotal mediator of vascular remodeling, indicating that CCL5 and CCR5 are key chemokine-related factors in atherogenesis. SMC proliferation and synthetic phenotype transformation attenuation by CCR5 pharmacological inhibition may offer a new approach to treatment or prevention of atherosclerotic diseases associated with hyperlipidemia.

Spontaneously hypertensive rats have more orexin neurons in the hypothalamus and enhanced orexinergic input and orexin 2 receptor-associated nitric oxide signalling in the rostral ventrolateral medulla.

NEW FINDINGS: What is the central question of this study? Our previous study demonstrates that elevated orexin 2 receptor (OX2R) activity within the rostral ventrolateral medulla (RVLM) contributes to hypertension in spontaneously hypertensive rats (SHRs), and a lower OX2R protein level was detected in their RVLM. The present study aims to explore the mechanisms underlying elevated orexinergic activity in the RVLM of SHRs, compared with their normotensive counterparts, Wistar-Kyoto rats. What is the main finding and its importance? Increased orexinergic input into the RVLM and enhanced OX2R responsiveness in the RVLM, which was mainly mediated by augmented OX2R-neuronal nitric oxide synthase signalling, may underlie the elevated OX2R activity within the RVLM of SHRs. Our previous study showed that elevated orexin 2 receptor (OX2R) activity within the rostral ventrolateral medulla (RVLM) contributes to hypertension in spontaneously hypertensive rats (SHRs). Herein, we investigated the mechanism(s) underlying the elevated OX2R activity. The following results were found. (i) More hypothalamic orexin A-immunoreactive (OXA-IR) cells existed in SHRs than in Wistar-Kyoto (WKY) rats at either 4 (2217 ± 43 versus 1809 ± 69) or 16 weeks of age (1829 ± 59 versus 1230 ± 84). The number of OXA-IR cells that project to the RVLM was higher in 16-week-old SHRs than in WKY rats (91 ± 11 versus 52 ± 11). (ii) Higher numbers of OXA-IR and RVLM-projecting OXA-IR cells were found in the dorsomedial and perifornical hypothalamus of 16-week-old SHRs. (iii) Spontaneously hypertensive rats had higher levels of orexin A and B in the hypothalamus and higher levels of orexin A in the RVLM than did WKY rats. (iv) Unilateral intra-RVLM application of OX2R agonist, orexin A or [Ala(11), d-Leu(15)]-orexin B (50 pmol) induced a larger pressor response in SHRs than in WKY rats. (v) Intra-RVLM pretreatment with a neuronal nitric oxide synthase (NOS) inhibitor, 7-nitro-indazole (2.5 pmol), or a soluble guanylate cyclase inhibitor, methylene blue (250 pmol), reduced the intra-RVLM [Ala(11), d-Leu(15) ]-orexin B-induced pressor response in both WKY rats and SHRs. In contrast, an inducible NOS inhibitor, aminoguanidine (100 pmol), was ineffective. (vi) Neuronal NOS was co-expressed with OX2R in RVLM neurons. In conclusion, increased orexinergic input and enhanced OX2R-neuronal NOS signalling may underlie elevated OX2R activity in the RVLM and contribute to the pathophysiology of hypertension in SHRs.

Dihydroaustrasulfone alcohol inhibits PDGF-induced proliferation and migration of human aortic smooth muscle cells through inhibition of the cell cycle.

Dihydroaustrasulfone alcohol is the synthetic precursor of austrasulfone, which is a marine natural product, isolated from the Taiwanese soft coral Cladiella australis. Dihydroaustrasulfone alcohol has anti-inflammatory, neuroprotective, antitumor and anti-atherogenic properties. Although dihydroaustrasulfone alcohol has been shown to inhibit neointima formation, its effect on human vascular smooth muscle cells (VSMCs) has not been elucidated. We examined the effects and the mechanisms of action of dihydroaustrasulfone alcohol on proliferation, migration and phenotypic modulation of human aortic smooth muscle cells (HASMCs). Dihydroaustrasulfone alcohol significantly inhibited proliferation, DNA synthesis and migration of HASMCs, without inducing cell death. Dihydroaustrasulfone alcohol also inhibited platelet-derived growth factor (PDGF)-induced expression of cyclin-dependent kinases (CDK) 2, CDK4, cyclin D1 and cyclin E. In addition, dihydroaustrasulfone alcohol inhibited PDGF-induced phosphorylation of extracellular signal-regulated kinase 1/2 (ERK1/2), whereas it had no effect on the phosphorylation of phosphatidylinositol 3-kinase (PI3K)/(Akt). Moreover, treatment with PD98059, a highly selective ERK inhibitor, blocked PDGF-induced upregulation of cyclin D1 and cyclin E and downregulation of p27kip1. Furthermore, dihydroaustrasulfone alcohol also inhibits VSMC synthetic phenotype formation induced by PDGF. For in vivo studies, dihydroaustrasulfone alcohol decreased smooth muscle cell proliferation in a rat model of restenosis induced by balloon injury. Immunohistochemical staining showed that dihydroaustrasulfone alcohol noticeably decreased the expression of proliferating cell nuclear antigen (PCNA) and altered VSMC phenotype from a synthetic to contractile state. Our findings provide important insights into the mechanisms underlying the vasoprotective actions of dihydroaustrasulfone alcohol and suggest that it may be a useful therapeutic agent for the treatment of vascular occlusive disease.

Effects of RING-SH2Grb², a chimeric protein containing the E3 ligase domain of Cbl, on the EGFR pathway.

The E3 ubiquitin-protein ligase Casitas B-lineage lymphoma protein (Cbl) negatively regulates epidermal growth factor receptor (EGFR) signaling pathway in many organisms, and has crucial roles in cell growth, development and human pathologies, including lung cancers. RING-SH2Grb² a chimeric protein of 215 amino acids containing the RING domain of Cbl that provides E3 ligase activity, and the SH2 domain of Grb2 that serves as an adaptor for EGFR. In this study, we demonstrated that RING-SH2Grb² could promote the ubiquitinylation and degradation of EGFR in a human non-small cell lung carcinoma cell line H1299. Moreover, we discovered that the RING-SH2Grb² chimera promoted the internalization of ligand-bound EGFR, inhibited the growth of H1299 cells, and significantly suppressed tumor growth in a xenograft mouse model. In summary, our results revealed a potential new cancer therapeutic approach for non-small cell lung cancer.

The impact of index futures crash risk on bitcoin futures returns and volatility.

This study examines the relationship between E-mini S&P 500 futures' crash risk and Bitcoin futures' returns and volatility using data from 2017 to 2021. While E-mini S&P 500's crash risk doesn't significantly influence Bitcoin returns, it correlates with its volatility, especially during events like the COVID-19 pandemic and U.S. elections. Furthermore, as global and emerging market indices rise, Bitcoin futures volatility decreases, suggesting its role as a hedging tool. These findings are pivotal for investors aiming to construct informed trading strategies, leverage Bitcoin futures as a hedging asset during economic instability, and keep tabs on traditional market indicators like E-mini S&P 500 crash risk for anticipating fluctuations in Bitcoin futures.

Blockade of central orexin 2 receptors reduces arterial pressure in spontaneously hypertensive rats.

Orexins can raise arterial pressure and sympathetic activity and are involved in tonic and phasic control of cardiovascular homeostasis. We hypothesized that elevated central orexinergic activity contributes to the maintenance of hypertension in spontaneously hypertensive rats (SHRs). We examined this hypothesis by suppressing central orexinergic activity in SHRs and Wistar-Kyoto rats (WKYs) with specific antagonists or antibodies against orexin 1 (OX1R) and 2 receptors (OX2R). Intracerebroventricular administration of an OX1R antagonist, SB-334867 (30 and 100 nmol), induced no significant change in mean arterial pressure (MAP) and heart rate (HR) in SHRs and WKYs except that at 100 nmol it reduced HR in WKYs. In contrast, an OX2R antagonist, TCS-OX2-29 (3-30 nmol) induced long-lasting reductions of MAP and HR in SHRs (21 ± 3 mmHg and 22 ± 2 beats min(-1) at 30 nmol), but not in WKYs. Intracerebroventricular anti-OX2R IgG, but not anti-OX1R IgG or non-immune goat IgG, significantly lowered MAP and HR in SHRs. None of the three IgGs affected MAP or HR in WKYs. The OX2R protein level in the rostral ventrolateral medulla (RVLM) was lower in SHRs than in WKYs, whereas no differences were found between SHRs and WKYs in the paraventricular hypothalamic nucleus, dorsomedial-perifornical hypothalamic area or caudal nucleus tractus solitarii. The OX1R protein levels in these four regions did not differ between SHRs and WKYs. Injection of TCS-OX2-29 (50 pmol) into the RVLM produced a larger reduction of MAP in SHRs than in WKYs. We conclude that elevated OX2R-mediated activity in the brain, especially in the RVLM, may contribute to hypertension in SHRs.

CEO cultural background and overinvestment decisions: The north-south divide in China.

This study addresses an under-researched area in corporate behavior by examining the impact of a CEO's cultural background on corporate overinvestment decisions. We focus on the unique cultural dichotomy between northern and southern China as our context of study. Additionally, we scrutinize the interactions between a CEO's age and the type of company ownership in influencing overinvestment tendencies. Our aim is to enrich theoretical understanding of factors influencing corporate overinvestment, offering practical implications for businesses within and beyond China. By filling this gap in the literature, our study sheds light on the nuanced determinants of overinvestment decisions, aiding businesses in refining their investment strategies and governance mechanisms.

The Contribution of DNA Ligase 4 Genetic Variations to Taiwanese Lung Cancer.

BACKGROUND/AIM: Impaired non-homologous end-joining DNA repair capacity may have a significant role in maintaining genome integrity and triggering carcinogenesis. However, the specific impact of DNA ligase 4 (Lig4) genotypes remains unclear. This study aimed to assess the contribution of Lig4 genotypes to the risk of developing lung cancer. MATERIALS AND METHODS: Polymerase chain reaction-restriction fragment length polymorphism analysis was used to examine the genotypes of Lig4 rs1805388, and their association with lung cancer risk was evaluated in a case-control study consisting of 358 lung cancer cases and 716 age- and sex-matched cancer-free control subjects. RESULTS: The distribution of CC, CT, and TT genotypes for Lig4 rs1805388 among the cases was 45.0%, 41.6%, and 13.4%, respectively, compared to 58.0%, 36.3%, and 5.7% among the controls (p for trend=1.98×10-6). Allelic analysis indicated that individuals carrying the T-allele for Lig4 rs1805388 had a 1.66-fold higher risk of developing lung cancer compared to those carrying the wild-type C-allele [95% confidence interval (CI)=1.36-2.02, p=4.04×10-7]. Moreover, a significant interaction was observed between the Lig4 rs1805388 genotype and smoking status (p=1.32×10-7). CONCLUSION: These findings suggest that the CT and TT variant genotypes of Lig4 rs1805388, combined with cigarette smoking, may contribute to a higher risk of developing lung cancer.

Effect of the Universal Health Coverage Healthcare System on Stock Returns During COVID-19: Evidence From Global Stock Indices.

The increased uncertainty caused by a sudden epidemic disease has had an impact on the global financial market. We aimed to assess the primary healthcare system of universal health coverage (UHC) during the coronavirus disease (COVID-19) pandemic and its relationship with the financial market. To this end, we employed the abnormal returns of 68 countries from January 2, 2019, to December 31, 2020, to test the impact of the COVID-19 outbreak on abnormal returns in the stock market and determine how a country's UHC changes the impact of a sudden pandemic on abnormal returns. Our findings show that the sudden onset of an epidemic disease results in unevenly distributed medical system resources, consequently diminishing the impact of UHC on abnormal returns.

The roles of sodium-potassium-chloride cotransporter isoform-1 in acute lung injury.

Acute lung injury (ALI) is often characterized by severe lung inflammation and pulmonary edema with poor gas exchange and hypoxemia. Alveolar inflammation and water flooding are, in fact, notable features of ALI pathogenesis. The sodium-potassium-chloride co-transporter isoform 1 (NKCC1), localized at the basolateral surface of the lung epithelium, drives water transport via back transport of Na+ and Cl- to the alveolar air space. NKCC1, therefore, is crucial in regulating alveolar fluid. Increased expression of NKCC1 results in increased alveolar fluid secretion and impaired alveolar fluid clearance. During ALI, the with no lysine kinase (WNK), oxidative stress responsive kinase 1 (OSR1), and STE20/SPS1-related proline/alanine-rich kinase (SPAK) pathways are activated, which upregulates NKCC1 expression. Proinflammatory cytokines also enhance the expression of NKCC1 via c-Jun N-terminal kinase-and p38-dependent pathways. NKCC1 activation also increases the expression of proinflammatory cytokines via cell rupture and activation of macrophages. Increased proinflammatory cytokines, in turn, recruit inflammatory cells to the site of injury and cause further lung damage. Animals with high expression of NKCC1 show more severe lung injury with presentations of more severe pulmonary edema and microvascular permeability, higher expression of proinflammatory cytokines, and greater neutrophilic infiltration. In contrast, animals with low expression of NKCC1 or those treated with NKCC1 inhibitors show less severe lung injury with milder levels of presentations of ALI. These reports collectively highlight a novel role of NKCC1 in ALI pathogenesis. Manipulation of NKCC1 expression levels could, therefore, represent novel modalities for effective ALI treatment.

Coronavirus disease outbreak and supply chain disruption: Evidence from Taiwanese firms in China.

This study applies an empirical analysis to examine whether supply chain disruption is caused by the outbreak of the coronavirus disease (COVID-19) that was first reported in Wuhan, China, on December 31, 2019. The study's findings indicate a link between the COVID-19 outbreak and the disruption of logistics and supply chains along with negative cumulative abnormal returns within Taiwanese firms manufacturing products in China and marketing them globally. This is the first study to examine the outbreak of the COVID-19 and the disruption of the supply chain and its effect on the stock market. The empirical results provide insights for business management in reconsidering their global supply chain strategies for the risk of disruption caused by similar epidemics occurs in the future.

The Effect of COVID-19 on Herding Behavior in Eastern European Stock Markets.

Unlike past health crises that were more localized, the highly contagious coronavirus disease 2019 (COVID-19) crisis is impacting the world to an unprecedented extent. This is the first study examining how and whether the COVID-19 pandemic affects herding behavior in the Eastern European stock markets. Using samples from the stock markets of Russia, Poland, the Czech Republic, Hungary, Croatia, and Slovenia from January 1, 2010 to March 10, 2021, we demonstrate that the COVID-19 pandemic has increased herding behavior in all the sample stock markets. Our results show that the COVID-19 crisis reinforces the impact of global market returns on herding behavior in these specific stock markets. We find that COVID-19 strengthens the spillover effect of regional herding on herding behavior. Thus, financial authorities should monitor investors in the stock market to avoid the increase in herding behavior as well as the reinforcement of the global market returns and regional return dispersion on herding during the period of pandemic.

Orexin-A directly depolarizes dorsomedial hypothalamic neurons, including those innervating the rostral ventrolateral medulla.

The dorsomedial hypothalamus (DMH) receives dense orexinergic innervation. Intra-DMH application of orexins increases arterial pressure and heart rate in rats. We studied the effects of orexin-A on DMH neurons, including those innervating the medullary cardiovascular center, the rostral ventrolateral medulla (RVLM), by using whole-cell recordings in brain slices. In the presence of tetrodotoxin, orexin-A (30-1000 nM) depolarized 56% of DMH neurons (EC50 82.4 ± 4.4 nM). Under voltage-clamp recording, orexin-A (300 nM) induced three types of responses characterized by different current-voltage relationships, namely unchanged, increased, and decreased slope conductance in 68%, 14%, and 18% of orexin-A-responsive neurons, respectively. The reversal potential of the decreased-conductance response was near the equilibrium potential of K+ and became more positive in a high-K+ solution, suggesting that K+ conductance blockade is the underlying mechanism. In a low-Na+ solution, unchanged-, increased-, and decreased-conductance responses were observed in 56%, 11%, and 33% of orexin-A-responsive neurons, respectively, implying that a non-selective cation current (NSCC) underlies orexin-A-induced responses in a small population of DMH neurons. KBR-7943 (70 µM), an inhibitor of Na+-Ca2+ exchanger (NCX), suppressed orexin-A-induced depolarization in 7 of 10 neurons. In the presence of KBR-7943, the majority of orexin-A-responsive neurons exhibited decreased-conductance responses. These findings suggest that NCX activation may underlie orexin-A-induced depolarization in the majority of orexin-responsive DMH neurons. Of 19 RVLM-projecting DMH neurons identified by retrograde labeling, 17 (90%) were orexin-A responsive. In conclusion, orexin-A directly excited over half of DMH neurons, including those innervating the RVLM, through decreasing K+ conductance, activating NCX, and/or increasing NSCC.

Orexins depolarize rostral ventrolateral medulla neurons and increase arterial pressure and heart rate in rats mainly via orexin 2 receptors.

An injection of orexin A or B into the cisterna magna or the rostral ventrolateral medulla (RVLM), where bulbospinal vasomotor neurons are located, elevated arterial pressure (AP) and heart rate (HR). We examined how orexins affected RVLM neurons to regulate cardiovascular functions by using in vitro recordings of neuronal activity of the RVLM and in vivo measurement of cardiovascular functions in rats. Orexin A and B concentration-dependently depolarized RVLM neurons. At 100 nM, both peptides excited 42% of RVLM neurons. Tetrodotoxin failed to block orexin-induced depolarization. In the presence of N-(2-methyl-6-benzoxazolyl)-N'-1, 5-naphthyridin-4-yl urea (SB-334867), an orexin 1 receptor (OX(1)R) antagonist, orexin A depolarized 42% of RVLM neurons with a smaller, but not significantly different, amplitude (4.9 +/- 0.8 versus 7.2 +/- 1.1 mV). In the presence of (2S)-1- (3,4-dihydro-6,7-dimethoxy-2(1H)-isoquinolinyl)-3,3-dimethyl-2-[(4-pyridinylmethyl)amino]-1-butanone hydrochloride (TCS OX2 29), an orexin 2 receptor (OX(2)R) antagonist, orexin A depolarized 25% of RVLM neurons with a significantly smaller amplitude (1.7 +/- 0.5 mV). Coapplication of both antagonists completely eliminated orexin A-induced depolarization. An OX(2)R agonist, [Ala(11),D-Leu(15)]-orexin B, concentration-dependently depolarized RVLM neurons. Regarding neuronal phenotypes, orexins depolarized 88% of adrenergic, 43% of nonadrenergic, and 36 to 41% of rhythmically firing RVLM neurons. Intracisternal TCS OX2 29 (3 and 10 nmol) suppressed intracisternal orexin A-induced increases of AP and HR, whereas intracisternal SB-334867 (3 and 10 nmol) had no effect on the orexin A-induced increase of HR but suppressed the orexin A-induced pressor response at 10 nmol. We concluded that orexins directly excite RVLM neurons, which include bulbospinal vasomotor neurons, and regulate cardiovascular function mainly via the OX(2)R, with a smaller contribution from the OX(1)R.

Mechanisms of orexin 2 receptor-mediated depolarization in the rat paraventricular nucleus of the hypothalamus.

The paraventricular nucleus of the hypothalamus (PVN) contains dense orexin 2 (OX2) receptor. We examined the mechanisms of OX2 receptor-mediated excitation on electrophysiologically identified type I (putative magnocellular), low-threshold spikes (LTS)-expressing type II (putative preautonomic), and non-LTS type II (putative parvocellular neuroendocrine) neurons. In the presence of tetrodotoxin, an OX2 receptor agonist, ALOXB (30-1000 nM) depolarized 56% of type I, and 73-75% of type II neurons. In type I neurons, ALOXB-induced inward current displayed increased-conductance current-voltage (I-V) relationship and reversed polarity at -27.5 ± 4.8 mV. A Na+-Ca2+ exchanger (NCX) inhibitor, KBR-7943, attenuated ALOXB responses in the majority of type I neurons, while no attenuation was observed in nearly all type II neurons. Type II neurons exhibited three types of I-V relationships in response to ALOXB, characterized by decreased, increased, and unchanged conductance, respectively. The reversal potential of the decreased-conductance responses was near the equilibrium potential of K+ (Ek+) and became more positive in a high-K+ solution, suggesting that K+ conductance blockade is involved. In a low-Na+ solution, non-reversed I-V curves of increased-conductance responses became decreased-conductance responses and reversed polarity near Ek+, suggesting the involvement of both K+ conductance and non-selective cation conductance (NSCC). Approximately 35% of LTS-expressing type II neurons were vasopressin-immunoreactive and 71% of them responded to ALOXB. In conclusion, orexins may activate OX2 receptor on PVN neurons and cause depolarization by promoting NCX and/or NSCC in magnocellular neurons, and by decreasing K+ conductance and/or increasing NSCC in parvocellular neurons. Furthermore, the majority of vasopressinergic preautonomic neurons are under OX2 receptor regulation.

Significant Association of MMP2 Promoter Genotypes to Asthma Susceptibility in Taiwan.

BACKGROUND/AIM: Matrix metalloproteinase 2 (MMP2) is reported to be overexpressed in asthma; however, its genotypic contribution to asthma is not well studied. Therefore, we examined the association of MMP2 genotypes with asthma risk among Taiwanese. MATERIALS AND METHODS: One hundred and ninety-eight asthma patients and 453 non-asthmatic subjects were determined with respect to their MMP2 -1306 (rs243845) and -735 (rs2285053) genotypes. RESULTS: CT and TT at MMP2 rs243845 are 17.7% and 1.5% among asthma cases, whereas their presence in healthy subjects is at 28.1% and 2.4%, respectively (p for trend=0.0118). In detail, the CT genotype in MMP2 rs243845 was associated with a decreased asthma risk [adjusted odds ratio (OR)=0.57, 95% confidence interval (CI)=0.37-0.78, p=0.0040], and the T allele conferred a significantly lower asthma risk compared to the wild-type C allele (adjusted OR=0.55, 95%CI=0.43-0.77, p=0.0042). No significance was found for MMP2 rs2285053. CONCLUSION: The genotype of CT in MMP2 rs243845 may serve as a novel biomarker in determining susceptibility to asthma in Taiwan.

Role of the orexin 2 receptor in palatable-food consumption-associated cardiovascular reactivity in spontaneously hypertensive rats.

Hypertensive subjects often exhibit exaggerated cardiovascular reactivity. An overactive orexin system underlies the pathophysiology of hypertension. We examined orexin's roles in eating-associated cardiovascular reactivity in spontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats. Results showed eating regular chow or palatable food (sucrose agar) was accompanied by elevated arterial pressure and heart rate. In both SHRs and WKY rats, the cardiovascular responses associated with sucrose-agar consumption were greater than that with regular-chow consumption. Additionally, SHRs exhibited greater cardiovascular responses than WKY rats did to regular-chow and palatable food consumption. Central orexin 2 receptor (OX2R) blockade attenuated sucrose-agar consumption-associated cardiovascular response only in SHRs. In both SHRs and WKY rats, OX2R blockade did not affect regular-chow consumption-associated cardiovascular responses. Greater numbers of c-Fos-positive cells in the rostral ventrolateral medulla (RVLM) and of c-Fos-positive orexin neurons in the dorsomedial hypothalamus (DMH) were detected in sucrose agar-treated SHRs, compared to regular chow-treated SHRs and to sucrose agar-treated WKY rats. Central OX2R blockade reduced the number of c-Fos-positive cells in the RVLM only in sucrose agar-treated SHRs. We concluded that in SHRs, orexin neurons in the DMH might be overactive during eating palatable food and may further elicit exaggerated cardiovascular responses via an OX2R-RVLM pathway.