1
|
Wu KLH, Wu CW, Tain YL, Chao YM, Hung CY, Tsai PC, Wang WS, Shih CD. Effects of high fructose intake on the development of hypertension in the spontaneously hypertensive rats: the role of AT 1R/gp91 PHOX signaling in the rostral ventrolateral medulla. J Nutr Biochem 2016; 41:73-83. [PMID: 28063367 DOI: 10.1016/j.jnutbio.2016.11.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 11/11/2016] [Accepted: 11/29/2016] [Indexed: 02/07/2023]
Abstract
Both genetic and dietary factors determine the development of hypertension. Whether dietary factor impacts the development of hereditary hypertension is unknown. Here, we evaluated the effect of daily high-fructose diet (HFD) on the development of hypertension in adolescent spontaneously hypertensive rats (SHR). Six-week-old SHR were randomly divided into two groups to receive HFD or normal diet (ND) for 3 weeks. The temporal profile of systolic blood pressure, alongside the sympathetic vasomotor activity, in the SHR-HFD showed significantly greater increases at 9-12 weeks of age compared with the age-matched SHR-ND group. Immunofluorescence was used to identify the distribution of reactive oxygen species (ROS), oxidants and antioxidants in rostral ventrolateral medulla (RVLM) where sympathetic premotor neurons reside. In RVLM of SHR-HFD, the levels of ROS accumulation and lipid peroxidation were elevated. The changes in protein expression were measured by Western blot. NADPH oxidase subunit gp91phox and angiotensin II type I receptor were up-regulated in RVLM neuron. On the other hand, the expression of extracellular superoxide dismutase was suppressed. Both molecular and hemodynamic changes in the SHR-HFD were rescued by oral pioglitazone treatment from weeks 7 to 9. Furthermore, central infusion with tempol, a ROS scavenger, effectively ameliorated ROS accumulation in RVLM and diminished the heightened pressor response and enhanced sympathetic activity in the SHR-HFD. Together, these results suggest that HFD intake at adolescent SHR may impact the development of hypertension via increasing oxidative stress in RVLM which could be effectively attenuated by pioglitazone treatment.
Collapse
Affiliation(s)
- Kay L H Wu
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China; Department of Senior Citizen Services, National Tainan Institute of Nursing, Tainan 700, Taiwan, Republic of China.
| | - Chih-Wei Wu
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - You-Lin Tain
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China; Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University, College of Medicine, Kaohsiung 833, Taiwan, Republic of China
| | - Yung-Mei Chao
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - Chun-Ying Hung
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - Pei-Chia Tsai
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - Wei-Sing Wang
- Institute for Translational Research in Biomedicine, Kaohsiung Chang Gung Memorial Hospital, Kaohsiung, 83301, Taiwan, Republic of China
| | - Cheng-Dean Shih
- Department of Pharmacy, Graduate Institute of Pharmaceutical Technology, Tajen University, Pingtung County 90741, Taiwan, Republic of China.
| |
Collapse
|
2
|
Chen CH, Wu CW, Shih CD, Lien WH, Huang SL, Huang CC. Attenuation of Isoflurane Preconditioning-Induced Acute Cardioprotection in Hypertensive Hypertrophied Hearts. J Cardiothorac Vasc Anesth 2016; 30:1317-23. [PMID: 27474329 DOI: 10.1053/j.jvca.2016.03.131] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Indexed: 01/19/2023]
Abstract
OBJECTIVES To evaluate the efficiency of isoflurane-induced anesthetic preconditioning and the role of mitochondrial manganese superoxide dismutase (MnSOD) in hypertensive hypertrophied hearts. DESIGN A prospective animal investigation. SETTING Medical center hospital research laboratory. PARTICIPANTS Male spontaneously hypertensive rats (SHRs) and normotensive control Wistar-Kyoto (WKY) rats. INTERVENTIONS All pentobarbital-anesthetized open-chest rats were subjected to a 45-minute left coronary artery occlusion followed by a 120-minute reperfusion. Before ischemia, both SHR and WKY rats were assigned randomly to receive a 30-minute exposure to 0.9% saline or 1.0 minimum alveolar concentration isoflurane. MEASUREMENTS AND MAIN RESULTS The myocardial infarct size, assessed as a percentage of the area at risk, was significantly greater in the hypertrophied SHRs than in the WKY rats (65.3%±8.7% v 51.8%±7.2%, p<0.05). Isoflurane preconditioning appreciably reduced the infarct size in the WKY hearts (30.9%±10.5%, p<0.05) but not in the SHR hearts. MnSOD protein expression and enzymatic activity were increased drastically in response to isoflurane exposure in the hearts of the WKY rats (p<0.05) but not in the SHRs. CONCLUSIONS Isoflurane-induced anesthetic preconditioning is attenuated in hypertensive hypertrophied hearts. This impairment may be associated with the loss of MnSOD augmentation during ischemia and reperfusion.
Collapse
Affiliation(s)
- Chen-Hsiu Chen
- Department of Anesthesiology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan; School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Chih-Wei Wu
- Department of Anesthesiology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Cheng-Dean Shih
- Department of Pharmacy and Master Program, Tajen University, Pingtung, Taiwan
| | - Wei-Hung Lien
- Department of Anesthesiology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Shiao-Lin Huang
- Department of Anesthesiology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan
| | - Cheng-Cheng Huang
- Department of Anesthesiology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan.
| |
Collapse
|
3
|
Wu KLH, Chen CH, Shih CD. Nontranscriptional activation of PI3K/Akt signaling mediates hypotensive effect following activation of estrogen receptor β in the rostral ventrolateral medulla of rats. J Biomed Sci 2012; 19:76. [PMID: 22897791 PMCID: PMC3438069 DOI: 10.1186/1423-0127-19-76] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2012] [Accepted: 08/01/2012] [Indexed: 12/22/2022] Open
Abstract
Background Estrogen acts on the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons are located, to elicit vasodepressor effects via an estrogen receptor (ER)β-dependent mechanism. We investigated in the present study nontranscriptional mechanism on cardiovascular effects following activation of ERβ in the RVLM, and delineated the involvement of phosphatidylinositol 3-kinase (PI3K)/serine/threonine kinase (Akt) signaling pathway in the effects. Methods In male Sprague–Dawley rats maintained under propofol anesthesia, changes in arterial pressure, heart rate and sympathetic neurogenic vasomotor tone were examined after microinjection bilaterally into RVLM of 17β-estradiol (E2β) or a selective ERα or ERβ agonist. Involvement of ER subtypes and PI3K/Akt signaling pathway in the induced cardiovascular effects were studied using pharmacological tools of antagonists or inhibitors, gene manipulation with antisense oligonucleotide (ASON) or adenovirus-mediated gene transfection. Results Similar to E2β (1 pmol), microinjection of ERβ agonist, diarylpropionitrile (DPN, 1, 2 or 5 pmol), into bilateral RVLM evoked dose-dependent hypotension and reduction in sympathetic neurogenic vasomotor tone. These vasodepressive effects of DPN (2 pmol) were inhibited by ERβ antagonist, R,R-tetrahydrochrysene (50 pmol), ASON against ERβ mRNA (250 pmol), PI3K inhibitor LY294002 (5 pmol), or Akt inhibitor (250 pmol), but not by ERα inhibitor, methyl-piperidino-pyrazole (1 nmol), or transcription inhibitor, actinomycin D (5 or 10 nmol). Gene transfer by microinjection into bilateral RVLM of adenovirus encoding phosphatase and tensin homologues deleted on chromosome 10 (5 × 108 pfu) reversed the vasodepressive effects of DPN. Conclusions Our results indicate that vasodepressive effects following activation of ERβ in RVLM are mediated by nongenomic activation of PI3K/Akt signaling pathway. This study provides new insight in the intracellular signaling cascades involved in central vasodepressive functions of estrogen.
Collapse
Affiliation(s)
- Kay L H Wu
- Department of Pharmacy, Graduate Institute of Pharmaceutical Technology, Tajen University, 20 Weishin Road, Yanpu Township, Pingtung County 90741, Taiwan
| | | | | |
Collapse
|
4
|
Wang JJ, Wang HY, Shih CD. Autonomic nervous system and nitric oxide in antihypertensive and cardiac inhibitory effects induced by red mold rice in spontaneously hypertensive rats. J Agric Food Chem 2010; 58:7940-7948. [PMID: 20527963 DOI: 10.1021/jf100339p] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The aim of this study was to investigate the antihypertensive activity of the ethanol extract (EE) of red mold rice (RMR) and to explore its mechanism of action. In comparison to EE of nonfermented rice, the EE of RMR contained higher levels of total phenolic, total flavonoids, gamma-aminobutyric acid, and monacolin K. Intravenous bolus administration of the EE (10-50 mg/kg) resulted in biphasic, dose-dependent antihypertensive effects and decreases in heart rate, cardiac contractility, and sympathetic vasomotor tone in spontaneously hypertensive rats. The initial and delayed antihypertensive responses, and the negative inotropic and chronotropic effects of EE treatment (30 mg/kg, i.v.) were significantly reduced by pretreatment with hexamethonium (30 mg/kg, i.v.) and N(G)-nitro-l-arginine methyl ester (20 mg/kg, i.v.). Pretreatment with methylatropine (1 mg/kg, i.v.), however, reversed the initial but not the delayed bradycardiac and negative inotropic effects of EE. We conclude that systemic administration of the EE of RMR elicited both transient and delayed antihypertensive actions that were mediated by the withdrawal of sympathetic tone and the production of nitric oxide (NO). The negative inotropic and chronotropic effects of EE may result from a direct sympathetic inhibition of the heart as well as an activation of the NO-dependent pathway.
Collapse
Affiliation(s)
- Jyh-Jye Wang
- Department of Nutrition and Health Science, Fooyin University, 151 Chinhsueh Road, Taliao Township, Kaohsiung County 83102, Taiwan, Republic of China
| | | | | |
Collapse
|
5
|
Shih CD. Activation of nitric oxide/cGMP/PKG signaling cascade mediates antihypertensive effects of Muntingia calabura in anesthetized spontaneously hypertensive rats. Am J Chin Med 2010; 37:1045-58. [PMID: 19938215 DOI: 10.1142/s0192415x0900748x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We previously reported that the leaf extract of Muntingia calabura L. (Tiliaceae) exerts a potent hypotensive effect in the normotensive rats. The antihypertensive activity of this plant extract, however, is currently unknown. In the present study, we investigated the antihypertensive effects of the n-butanol soluble fraction (BSF) from methanol leaf extract of M. calabura in spontaneously hypertensive rats (SHR), and delineated is underlying mechanisms. The intravenous bolus administration of the BSF (10-100 mg/kg) of M. calabura produced biphasic dose-related antihypertensive and bradycardiac effects in SHR. The BSF-induced initial cardiovascular depressive effects lasted for 10 min, and the delayed effects commenced 40 min and lasted for at least 120 min postinjection. These cardiovascular depressive effects of BSF treatments were greater in SHR than in normotensive Wistar-Kyoto (WKY) rats. Both the initial and delayed antihypertensive and bradycardiac effects of BSF (25 mg/kg, i.v.) in SHR, were significantly blocked by pretreatment with a nonselective nitric oxide (NO) synthase (NOS) inhibitor, a soluble guanylyl cyclase (sGC) inhibitor, or a protein kinase G (PKG) inhibitor. Moreover, the initial effects of BSF in SHR were inhibited by pretreatment with a selective endothelial NOS (eNOS) inhibitor; whereas the delayed effects were attenuated by a selective inducible NOS (iNOS) inhibitor. These results indicate that the BSF from the leaf of M. calabura elicited both transient and delayed antihypertensive and bradycardiac actions in SHR, which might be mediated through NO generated respectively by eNOS and iNOS. Furthermore, activation of sGC/cGMP/PKG signaling pathway may participate in the M. calabura-induced biphasic cardiovascular effects.
Collapse
Affiliation(s)
- Cheng-Dean Shih
- Graduate Institute of Pharmaceutical Technology, Tajen University, Pingtung County 90741, Taiwan.
| |
Collapse
|
6
|
Shih CD, Chen JJ, Lee HH. Activation of nitric oxide signaling pathway mediates hypotensive effect of Muntingia calabura L. (Tiliaceae) leaf extract. Am J Chin Med 2010; 34:857-72. [PMID: 17080550 DOI: 10.1142/s0192415x0600434x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The cardiovascular effect of the crude methanol extract from the leaf of Muntingia calabura L. (Tiliaceae) was investigated in the anesthetized rats. The crude methanol extract was sequentially fractionated to obtain the water-soluble extract (WSE). Intravenous administration of the WSE (10, 25, 50, 75 or 100 mg/kg) produced an initial followed by a delayed decrease in systemic arterial pressure (SAP) in a dose-dependent manner. The M. calabura-induced initial hypotension lasted for 10 min and the delayed depressor effect commenced after 90 min and lasted for at least 180 min post-injection. The same treatment, on the other hand, had no appreciable effect on heart rate (HR) or the blood gas/electrolytes concentrations. Both the initial and delayed hypotensive effects of WSE (50 mg/kg, i.v.) were significantly blocked by pre-treatment with a nonselective nitric oxide (NO) synthase (NOS) inhibitor, N(G)-nitro-L-arginine methyl ester ((L)-NAME, 0.325 mg/kg/min for 5 min) or a soluble guanylate cyclase (sGC) inhibitor, 1H-[1,2,4]oxadiazole[4,3-alpha]quinoxalin-1-one (ODQ, 0.2 mg/kg/min for 5 min). Moreover, whereas the initial depressor effect of WSE was inhibited by pre-treatment with a selective endothelial NOS (eNOS) inhibitor, N5-(1-Iminoethyl)-L-ornithine ((L)-NIO, 1 mg/kg/min for 5 min), the delayed hypotension was attenuated by a selective inducible NOS (iNOS) inhibitor, S-methylisothiourea (SMT, 0.5 mg/kg/min for 5 min). Administration of WSE also produced an elevation in plasma nitrate/nitrite concentration, as well as an increase in the expression of iNOS protein in the heart and thoracic aorta. These results indicate that WSE from the leaf of M. calabura elicited both a transient and delayed hypotensive effect via the production of NO. Furthermore, activation of NO/sGC/cGMP signaling pathway may mediate the M. calabura-induced hypotension.
Collapse
Affiliation(s)
- Cheng-Dean Shih
- Department of Pharmacy and Graduate Institute of Pharmaceutical Technology, Pingtung 907, Taiwan, ROC.
| | | | | |
Collapse
|
7
|
Shih CD. Activation of estrogen receptor beta-dependent nitric oxide signaling mediates the hypotensive effects of estrogen in the rostral ventrolateral medulla of anesthetized rats. J Biomed Sci 2009; 16:60. [PMID: 19583861 PMCID: PMC2717931 DOI: 10.1186/1423-0127-16-60] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2009] [Accepted: 07/07/2009] [Indexed: 12/02/2022] Open
Abstract
Background Apart from their well-known peripheral cardiovascular effects, emerging evidence indicates that estrogen acts as a modulator in the brain to regulate cardiovascular functions. The underlying mechanisms of estrogen in central cardiovascular regulation, however, are poorly understood. The present study investigated the cardiovascular effects of 17β-estradiol (E2β) in the rostral ventrolateral medulla (RVLM), where sympathetic premotor neurons are located, and delineated the engagement of nitric oxide (NO) in E2β-induced cardiovascular responses. Methods In male Sprague-Dawley rats maintained under propofol anesthesia, the changes of blood pressure, heart rate and sympathetic vasomotor tone after microinjection bilaterally into the RVLM of a synthetic estrogen, E2β were examined for at least 120 min. The involvement of ERα and/or ERβ subtypes was determined by microinjection of selective ERα or ERβ agonist into bilateral RVLM. Different NO synthase (NOS) inhibitors were used to evaluate the involvement of differential of NOS isoforms in the cardiovascular effects of E2β. Results Bilateral microinjection of E2β (0.5, 1, or 5 pmol) into the RVLM dose-dependently decreased systemic arterial pressure (SAP) and the power density of the vasomotor components of SAP signals, our experimental index for sympathetic neurogenic vasomotor tone. These cardiovascular depressive effects of E2β (1 pmol) were abolished by co-injection of ER antagonist ICI 182780 (0.25 or 0.5 pmol), but not a transcription inhibitor actinomycin D (10 nmol). Like E2β, microinjection bilaterally into the RVLM of a selective ERβ agonist 2,3-bis(4-hydroxyphenyl) propionitrile (DPN, 1, 2, or 5 pmol) induced significant decreases in these hemodynamic parameters in a dose-dependent manner. In contrast, the selective ERα agonist 1,3,5-tris(4-hydroxyphenyl)-4-propyl-1H-pyrazole (5 pmol) did not influence the same cardiovascular parameters. Co-administration bilaterally into the RVLM of NOS inhibitor NG-nitro-L-arginine methyl ester (5 nmol) or selective inducible NOS (iNOS) inhibitor S-methylisothiourea (25 pmol), but not selective neuronal NOS inhibitor 7-nitroindazole (0.5 pmol) or endothelial NOS inhibitor N5-(1-Iminoethyl)-L-ornithine (2.5 pmol), significantly attenuated the cardiovascular depressive effects elicited by DPN (2 pmol). Conclusion Our results indicate that E2β in the RVLM elicited short-term cardiovascular depressive effects via an ERβ-dependent nontranscriptional mechanism. These vasodepressor effects of E2β are likely to be mediated by the iNOS-derived NO in the RVLM.
Collapse
Affiliation(s)
- Cheng-Dean Shih
- Department of Pharmacy & Graduate Institute of Pharmaceutical Technology, Tajen University, Pingtung 90741, Taiwan, Republic of China.
| |
Collapse
|
8
|
Shih CD, Kuo DH, Huang CW, Gu YH, Chen FA. Autonomic nervous system mediates the cardiovascular effects of Rhodiola sacra radix in rats. J Ethnopharmacol 2008; 119:284-290. [PMID: 18692558 DOI: 10.1016/j.jep.2008.07.016] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2007] [Revised: 06/03/2008] [Accepted: 07/13/2008] [Indexed: 05/26/2023]
Abstract
ETHNOPHARMACOLOGICAL RELEVANCE Rhodiola sacra (Crassulaceae) exhibits cardiovascular bioactivities and is used in Tibetan medicine for promoting circulation and preventing hypertension. However, the underlying mechanisms of its cardiovascular effects are poorly understood. AIM OF THE STUDY The aim of this study was therefore to evaluate the cardiovascular activity of water-soluble fraction (WtF) and n-butanol-soluble fraction (BtF) of Rhodiola sacra radix and to explore its mechanism of action in propofol anesthetized Sprague-Dawley rats. MATERIALS AND METHODS The changes of blood pressure, heart rate and cardiac contractility after systemic administration of the extracts (10-75 mg/kg) were examined for at least 40 min. Different antagonists were used to evaluate the mechanisms of cardiovascular effects of the extracts. RESULTS Intravenous injection of the WtF (10, 25, 35, 50 or 75 mg/kg) exhibited dose-dependent hypotension and increases in heart rate and cardiac contractility. In contrast, mild alterations in the same cardiovascular parameters were detected only at high dose (75 mg/kg) BtF. The WtF-induced hypotensive, positive inotropic and chronotropic effects were significantly abolished by pretreatment with hexamethonium (30 mg/kg, i.v.) or reserpine (5 mg/kg, i.v.), whereas the hypotensive, but not the positive inotropic or chronotropic effect was potentiated by captopril (2.5 mg/kg, i.v.). Pretreatment with methylatropine (1 mg/kg, i.v.), on the other hand, reversed the positive inotropic and chronotropic but not the hypotensive effects of WtF. The WtF-induced cardiovascular responses were not affected in rats pretreated with N(G)-nitro-l-arginine methyl ester (20 mg/kg, i.v.). CONCLUSIONS We conclude that systemic administration of the WtF of Rhodiola sacra radix elicited a potent hypotensive effect that was mediated by the withdrawal of sympathetic vasomotor tone and interaction with the circulatory angiotensin system. The positive inotropic and chronotropic effects of WtF may result from a direct vagal inhibition on the heart.
Collapse
Affiliation(s)
- Cheng-Dean Shih
- Department of Pharmacy and Graduate Institute of Pharmaceutical Technology, Tajen University, 20 Weishin Road, Yanpu Township, Pingtung County 90741, Taiwan.
| | | | | | | | | |
Collapse
|
9
|
Chen JJ, Lee HH, Shih CD, Liao CH, Chen IS, Chou TH. New dihydrochalcones and anti-platelet aggregation constituents from the leaves of Muntingia calabura. Planta Med 2007; 73:572-7. [PMID: 17516329 DOI: 10.1055/s-2007-967196] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Two new dihydrochalcones, 2,3-dihydroxy-4,3',4',5'-tetramethoxydihydrochalcone (1) and 4,2',4'-trihydroxy-3'-methoxydihydrochalcone (2), and a new flavanone, (2R,3R)-(-)-3,5-dihydroxy-6,7-dimethoxyflavanone (3), together with nineteen known compounds have been isolated from the leaves of Muntingia calabura. The structures of three new compounds were determined through spectral analyses including extensive 2D-NMR data. Among the isolates, 2,3-dihydroxy-4,3',4',5'-tetramethoxydihydrochalcone, 5,7-dihydroxy-3-methoxyflavone, 5,7-dihydroxy-6-methoxyflavone, 5,4'-dihydroxy-3,7-dimethoxyflavone, (2S)-7,8,3',4',5'-pentamethoxyflavan, (2S)-5'-hydroxy-7,8,3',4'-tetramethoxyflavan, and methyl gallate exhibited significant anti-platelet aggregation activity in vitro.
Collapse
Affiliation(s)
- Jih-Jung Chen
- Graduate Institute of Pharmaceutical Technology, Tajen University, Pingtung, Taiwan.
| | | | | | | | | | | |
Collapse
|
10
|
Shih CD, Au LC, Chan JYH. Differential role of leptin receptors at the hypothalamic paraventricular nucleus in tonic regulation of food intake and cardiovascular functions. J Biomed Sci 2003; 10:367-78. [PMID: 12824696 DOI: 10.1159/000071156] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2003] [Accepted: 03/10/2003] [Indexed: 11/19/2022] Open
Abstract
Leptin plays an important role in the central regulation of body weight and arterial pressure via activation of leptin receptors (Ob-Rs) in the hypothalamic area, including the hypothalamic paraventricular nucleus (PVN). The present study was undertaken to investigate whether endogenous leptin in the PVN plays a dual role in the tonic regulation of body weight and arterial pressure. Adult, male normal-weight Sprague-Dawley rats, which were anesthetized and maintained with propofol, were used. A direct bilateral microinjection into the PVN of an antisense oligonucleotide against Ob-R mRNA (ASON1, 50 pmol) significantly increased the daily food intake and body weight gain, effects which lasted for at least 14 days. The same treatment, on the other hand, had no appreciable effect on the basal mean systemic arterial pressure (SAP), heart rate (HR), or power density of the vasomotor components of SAP signals, the experimental index of neurogenic sympathetic vasomotor tone. ASON1 treatment also exerted an insignificant effect on the baroreceptor reflex control of HR. Western blot analysis revealed that a bilateral microinjection into the PVN of ASON1 (50 pmol) significantly decreased the expression of the Ob-R protein in the hypothalamus. The same treatment also attenuated hypertension, tachycardia, and the increase in the power density of the vasomotor components of the SAP signals induced by exogenous bilateral application of leptin (5 or 50 ng) into the PVN. Control application of sense (SON, 50 pmol) or a scrambled antisense Ob-R oligonucleotide (ASON2, 50 pmol) into the bilateral PVN promoted no discernible effect on Ob-R protein expression in the hypothalamus, on daily food intake, or on cardiovascular performance. Our results indicate that whereas the Ob-Rs in the PVN are involved in the tonic regulation of food intake, they might not be actively involved in the tonic regulation of cardiovascular functions.
Collapse
Affiliation(s)
- Cheng-Dean Shih
- Department of Pharmacy, Tajen Institute of Technology, Pintung, Taiwan, ROC
| | | | | |
Collapse
|
11
|
Shih CD, Au LC, Chen JYH. Differential role of leptin receptors at the hypothalamic paraventricular nucleus in tonic regulation of food intake and cardiovascular functions. J Biomed Sci 2003. [DOI: 10.1007/bf02256428] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
|
12
|
Abstract
We evaluated the hypothesis that basal Fos protein at the nucleus tractus solitarii (NTS), the primary terminal site for baroreceptor afferents, exerts a tonic inhibitory modulation on the spontaneous baroreceptor reflex (BRR) control machinery, which is responsible for beat-to-beat regulation of resting systemic arterial pressure (SAP). In adult male Sprague-Dawley rats anesthetized and maintained with pentobarbital sodium, microinjection bilaterally into the caudal NTS of a 15-mer antisense oligonucleotide that targets against the initiation codon of c-fos mRNA (5'-129 to 143-3') significantly enhanced the spontaneous BRR response, as determined by transfer function analysis of SAP and heart rate signals. The same treatment also diminished baseline Fos-like immunoreactivity in the absence of acute cardiovascular perturbation. Control treatments with artificial cerebrospinal fluid, sense cDNA, or antisense oligonucleotides that either target against a different site of the c-fos mRNA (5'-135 to 149-3') or with three mismatched nucleotides in the antisense sequence, were ineffective. These observations support the notion that, under minimal cardiovascular perturbation, basal expression of Fos protein in the NTS may represent an early step in the cascade of intracellular events that leads to long-term inhibitory modulation of beat-to-beat baroreflex control of blood pressure.
Collapse
Affiliation(s)
- J Y Chan
- Department of Medical Research, Veterans General Hospital-Taipei, Taiwan, Republic of China
| | | | | |
Collapse
|
13
|
Shih CD, Chan SH, Chan JY. Participation of Fos protein at the nucleus tractus solitarius in inhibitory modulation of baroreceptor reflex response in the rat. Brain Res 1996; 738:39-47. [PMID: 8949925 DOI: 10.1016/0006-8993(96)00771-8] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
We investigated the physiologic role of Fos protein at the nucleus tractus solitarius (NTS) in the modulation of baroreceptor reflex (BRR) in adult, male Sprague-Dawley rats that were anesthetized and maintained with pentobarbital sodium (40 mg/kg, i.p., with 10 mg/kg/h i.v. infusion supplements). Repeated and scheduled activation of the baroreceptors by transient hypertension induced by i.v. administration of phenylephrine (2.5, 5.0 or 10.0 micrograms/kg) resulted in a significant increase in Fos-like immunoreactivity (Fos-LI), primarily in the caudal part of the NTS. This increase in Fos-LI in the barosensitive NTS neurons was appreciably reduced by bilateral microinjection into the caudal NTS of an antisense oligonucleotide (20 pmol, 20 nl) designed to target a region of the c-fos mRNA that flanks the initiation codon (5'-129 to 143-3'). The same treatment also discernibly enhanced the BRR response, but elicited no appreciable effect on systemic arterial pressure or heart rate. On the other hand, bilateral application to the NTS of the corresponding sense oligonucleotide (20 pmol, 20 nl) or an antisense cDNA (20 pmol, 20 nl) that targeted a different site of the c-.fos mRNA (5'-135 to 149-3') was ineffective. These results suggest that expression of the inducible c-fos gene in the NTS may represent an early step in the cascade of intracellular events that leads to long-term inhibitory modulation of baroreflex control of blood pressure.
Collapse
Affiliation(s)
- C D Shih
- Institute of Physiology, National Yang-Ming University, Taipei, Taiwan, ROC
| | | | | |
Collapse
|
14
|
Abstract
We evaluated the potential participation of endogenous brain galanin (GAL) in the suppression of baroreceptor reflex (BRR) response by locus coeruleus (LC), using adult male Sprague-Dawley rats anesthetized with pentobarbital sodium (40 mg/kg, i.p., with 15 mg/kg/h i.v. infusion supplements). Our physiologic and pharmacologic results demonstrated that bilateral microinjection of GAL antiserum (1:20, 20 nl) into the nucleus tractus solitarii (NTS), the terminal site for baroreceptor afferent fibers, significantly attenuated the suppressive effect of LC on the BRR response. Pretreatment with the same amount of normal rabbit serum (1:20) or heat-inactivated GAL antiserum (1:20), on the other hand, was ineffective. Microinjection of GAL (100 pmol) into the bilateral NTS also appreciably depressed the BRR response. Histochemically, retrogradely labeled neurons were distributed in the LC following microinjection of fast blue into the NTS. Immunofluorescent staining further revealed that some of these fast blue labeled LC neurons also showed positive immunoreactivity to GAL. These results suggest that a direct galaninergic projection to the NTS may participate in the suppression of BRR response by the LC.
Collapse
Affiliation(s)
- C D Shih
- Department of Medical Research, Veterans General Hospital-Taipei, Taiwan, Republic of China
| | | | | |
Collapse
|
15
|
Shih CD, Chan SH, Chan JY. Participation of hypothalamic paraventricular nucleus in locus ceruleus-induced baroreflex suppression in rats. Am J Physiol 1995; 269:H46-52. [PMID: 7631873 DOI: 10.1152/ajpheart.1995.269.1.h46] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
We evaluated the potential role of the paraventricular nucleus (PVN) of the hypothalamus in the suppression of baroreceptor reflex (BRR) response by locus ceruleus (LC), using adult male Sprague-Dawley rats anesthetized with pentobarbital sodium. Electrical stimulation of histologically verified sites in the LC elicited significant reduction in the BRR response. This suppressive effect of LC on BRR response was appreciably antagonized by bilateral electrolytic lesions of the PVN and reversibly blocked by bilateral microinjection of 2% lidocaine into similar hypothalamic loci. Local administration of the alpha 1-adrenoceptor antagonist, prazosin (50 pmol), or an antiserum directed against neuropeptide Y (NPY) (1:20) into the bilateral PVN also significantly attenuated the suppression elicited by LC on BRR response. In contrast, treatments with the alpha 2-adrenoceptor blocker, yohimbine (50 pmol), heat-inactivated NPY antiserum (1:20), artificial cerebrospinal fluid, or normal rabbit serum (1:20) produced no discernible effect. These results suggest that the PVN may constitute part of the efferent pathways through which LC elicits its inhibition on the BRR response. Furthermore, LC may activate this pathway via alpha 1-adrenoceptors and NPY receptors in the PVN.
Collapse
Affiliation(s)
- C D Shih
- Institute of Physiology, National Yang-Ming University, Taipei, Taiwan, Republic of China
| | | | | |
Collapse
|
16
|
Chan JY, Shih CD, Chan SH. Participation of endogenous neuropeptide Y in the suppression of baroreceptor reflex response by locus coeruleus in the rat. Regul Pept 1993; 48:293-300. [PMID: 8278622 DOI: 10.1016/0167-0115(93)90157-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We evaluated the potential participation of endogenous brain neuropeptide Y (NPY) in the suppression of baroreceptor reflex (BRR) response by locus coeruleus (LC), using adult male Sprague-Dawley rats anesthetized with pentobarbital sodium (40 mg/kg, i.p.). Bilateral microinjection of an antiserum against NPY (1:20, 20 nl) into the caudal one-third level of the nucleus tractus solitarii (NTS), the terminal site for baroreceptor afferent fibers, significantly reversed the suppressive effect of electrical or chemical activation of the LC on the BRR response. Treatments with NPY (4.65 pmol, 20 nl), normal rabbit serum, aCSF and heat-inactivated NPY or NPY antiserum, on the other hand, were ineffective. The LC-promoted inhibition of the BRR response was also attenuated by the alpha 1-adrenoceptor antagonist prazosin (50 pmol, 20 nl), either microinjected alone or in combination with NPY antiserum into the bilateral NTS. Mathematical treatment of our data revealed that the depressive effect on the BRR response of NPY or NE released at the NTS following LC activation manifested different time-course and magnitude. The one by endogenous NPY maximized at 40 min and amounted to no more than 20% of, whereas that by NE peaked at 10 min and contributed no less than 30% to, the suppression. These results suggest that both endogenous NPY and NE may participate in the suppression of BRR response by the LC at the NTS.
Collapse
Affiliation(s)
- J Y Chan
- Department of Medical Research, Veterans General Hospital-Taipei, Taiwan, ROC
| | | | | |
Collapse
|
17
|
Shih CD, Chan JY, Chan SH. Tonic suppression of baroreceptor reflex response by endogenous neuropeptide Y at the nucleus tractus solitarius of the rat. Neurosci Lett 1992; 148:169-72. [PMID: 1300491 DOI: 10.1016/0304-3940(92)90831-q] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
We evaluated the potential participation of endogenous brain neuropeptide Y (NPY) in central cardiovascular regulation, using adult male Sprague-Dawley rats anesthetized with pentobarbital sodium (40 mg/kg, i.p.). Bilateral microinjection of NPY (4.65 pmol) into the caudal one-third level of the nucleus tractus solitarius (NTS), the terminal site for baroreceptor afferent fibers, promoted a significant suppression of the baroreceptor reflex (BRR) response. The maximal inhibition occurred at 30-40 min postinjection, and amounted to -42.7 +/- 8.6% (mean +/- S.E.M., n = 9). The same treatment, however, only caused transient (approximately 5 min) hypotension and bradycardia. Blocking the endogenous NPY activity at the NTS with its antiserum appreciably enhanced the sensitivity of BRR response (+ 59.2 +/- 18.8%, mean +/- S.E.M., n = 6), but had no appreciable effect on systemic arterial pressure or heart rate. These results suggest that neurons that contain NPY may participate in central cardiovascular regulation by tonically suppressing the BRR response, possibly by exerting an influence on the baroreceptive neurons at the NTS.
Collapse
Affiliation(s)
- C D Shih
- Institute of Pharmacology, National Yang-Ming Medical College, Taipei, Taiwan, ROC
| | | | | |
Collapse
|