OBJECTIVETo investigate the role of dopamine-1 receptor in the modulation of basic respiration rhythm.

METHODSNewborn SD rat (0-3 days, n=20) brain stem slices containing the medial region of the nucleus retrofacialis (mNRF) were prepared with the hypoglossal nerve roots retained. The respiratory rhythmical discharge activity (RRDA) of the hypoglossal nerve was recorded using suction electrodes on these preparations, and the effects of dopamine-1 receptor on RRDA were investigated by application of the specific agonist of dopamine-1 receptor A68930 at different concentrations (0, 1, 2, and 5 micromol/L) in the perfusion solution.

RESULTSThe respiratory cycles (RC) and the expiratory time (TE) decreased progressively with gradual increment of the integrated amplitude (IA) after A68930 administration, and their changes were the most conspicuous at 5 min after the administration. A68930 at the concentrations of 2 and 5 micromol/L resulted in the most obvious changes in RC, TE, and IA (P<0.05), but IA exhibited no significant variation at 1 min after perfusion with 2 micromol/L A68930 (P>0.05). RC and TE were gradually shortened after treatment with increasing concentrations of A68930, which also caused gradual increment of IA, and at the concentration of 5 micromol/L, RC, TE, and IA all showed the most obvious changes (P<0.01).

CONCLUSIONSDopamine-1 receptor plays a role in the modulation of RRDA in isolated neonatal rat brainstem slice. A68930 may increase the frequency of respiration by shortening TE and enhance the respiratory activity by increasing the amplitude of inspiratory discharge of the respiratory neurons.

Animals ; Animals, Newborn ; Cell Separation ; Chromans ; pharmacology ; Dopamine Agonists ; pharmacology ; In Vitro Techniques ; Medulla Oblongata ; cytology ; physiology ; Neurons ; cytology ; Rats ; Rats, Sprague-Dawley ; Receptors, Dopamine ; physiology ; Respiration ; drug effects

To explore the role of D(1)-dopamine receptor in the modulation of basic respiratory rhythm, neonatal (0-3 d) Sprague-Dawley rats of either sex were used. The medulla oblongata slice was prepared and the surgical procedure was performed in the modified Kreb's solution (MKS) with continuous ventilating 95% O2 and 5% CO2 and ended in 3 min. A 600-700 mum single transverse slice containing the hypoglossal nerve roots and some parts of the ventral respiratory group was cut. The preparation was quickly transferred to a recording chamber and continuously perfused with oxygen-saturated MKS at a rate of 4-6 mL/min at 27-29 degrees C. Ten medulla oblongata slice preparations were randomly divided into two groups. In group I, the preparations were perfused with perfusion solution containing D(1)-dopamine receptor specific agonist cis-(+/-)-1-(Aminomethyl)-3,4-dihydro-3-phenyl-1H-2-Benzopyran-5,6-Diolhy-drochlo-ride (A68930, 5 mumol/L) for 10 min first; after washing out, the preparations were then perfused with perfusion solution containing D(1)-dopamine receptor specific antagonist R(+)-7-Chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine hydrochloride (SCH-23390, 2 mumol/L) for 10 min. In group II, after perfusion with A68930 for 10 min, the preparations were perfused with additional A68930 + SCH-23390 for 10 min. Respiratory rhythmical discharge activity (RRDA) of the rootlets of hypoglossal nerve was recorded by suction electrodes. The results showed that A68930 shortened the respiratory cycle (RC) and expiratory time (TE) with an increase in the integral amplitude (IA). However, SCH-23390 significantly prolonged RC and TE, and decreased IA with a decrease in inspiratory time (TI). Moreover, the effect of A68930 on the respiratory rhythm was partially reversed by additional application of A68930 + SCH-23390. These results indicate that D(1)-dopamine receptor is possibly involved in the modulation of the RRDA in the isolated neonatal rat brainstem slice.
Animals ; Animals, Newborn ; Benzazepines ; pharmacology ; Biological Clocks ; Chromans ; pharmacology ; Female ; In Vitro Techniques ; Male ; Medulla Oblongata ; physiology ; Rats ; Rats, Sprague-Dawley ; Receptors, Dopamine ; physiology ; Respiration

OBJECTIVETo investigate the effect of PPARgamma1 gene overexpression on caveolin-1 mRNA and protein expressions in a murine macrophage cell line Raw264.7.

METHODSReplication-deficient recombinant adenovirus expression vector of PPARgamma1 was constructed using the AdEasy system. Raw264.7 cells were randomly treated as follows: P group (PPARgamma1 gene overexpression), T group (Troglitazone 40 micromol/L in DMSO), PT group (PPARgamma1 gene overexpression and Troglitazone) and control group. Changes of PPARgamma1 and caveolin-1 at mRNA and protein levels were investigated.

RESULTSCaveolin-1 expression can be detected by RT-PCR in Raw264.7, by immunocytochemistry method in cell and nuclear membrane but not by immunoblotting at protein level. Caveolin-1 expression at mRNA and protein levels in Raw264.7 were significantly higher in P, T and PT groups compared to control group and the expression was also significantly higher in PT group than that in P group and T group (P < 0.05). PPARgamma expression was significantly increased in PT group and P group where remained unchanged in T group compared to control group.

CONCLUSIONPPARgamma1 overexpression can upregulate caveolin-1 expression in macrophages. Troglitazone upregulated caveolin-1 expression in the absence of increased PPARgamma1 expressions at mRNA and protein levels.

Adenoviridae ; genetics ; Animals ; Caveolin 1 ; metabolism ; Cell Line ; Chromans ; pharmacology ; Gene Expression ; Macrophages ; drug effects ; metabolism ; Mice ; PPAR gamma ; genetics ; RNA, Messenger ; metabolism ; Thiazolidinediones ; pharmacology

AIMTo clarify mechanisms that the antiarrhythmic effects of matrine and berbamine are weaker than those of amiodarone and RP58866.

METHODSExperimental arrhythmic models were induced by aconitine, coronary artery ligation and electric stimulation in rats and rabbits. Whole-cell patch-clamp techniques were used to record IK1, IKr, IKs and Ito.

RESULTSMatrine and berbamine significantly increased the dose of aconitine for induction of ventricular premature and ventricular tachycardia in rats, decreased the number of arrhythmias induced by coronary artery ligation in rats and increased ventricular fibrillation threshold (VFT) induced by electric stimulation in rabbits, but the anti-arrhythmic potency of matrine and berbamine was lower than that of amiodarone and RP58866. The inhibitory actions of matrine and berbamine on IK1, IKr, IKs, Ito were lower than those of amiodarone and RP58866. The IC50 of matrine for IK1, IKr, IKs, Ito were (46 +/- 3), (32.9 +/- 1.2), (37 +/- 8) and (7.6 +/- 0.5) mol x L(-1), respectively. The IC50 of amiodarone for IK1, IKr, IKs, Ito were (21 +/- 5) , (3.7 +/- 0.7), (5.9 +/- 0.9) and (5.9 +/- 0.6) mol x L(-1), respectively.

CONCLUSIONThe inhibitory actions of matrine and berbamine on IK1, IKr, IKs, Ito were lower than those of amiodarone and RP58866, which might be the reason that the antiarrhythmic effects of matrine and berbamine were weaker than those of amiodarone and RP58866.

Aconitine ; Alkaloids ; pharmacology ; Amiodarone ; pharmacology ; Animals ; Anti-Arrhythmia Agents ; pharmacology ; Arrhythmias, Cardiac ; chemically induced ; physiopathology ; prevention & control ; Benzylisoquinolines ; pharmacology ; Chromans ; pharmacology ; Dogs ; Female ; Guinea Pigs ; Male ; Piperidines ; pharmacology ; Potassium Channels ; drug effects ; Quinolizines ; Rabbits ; Rats

Oxidized LDL (OxLDL), a causal factor in atherosclerosis, induces the expression of heat shock proteins (Hsp) in a variety of cells. In this study, we investigated the role of CD36, an OxLDL receptor, and peroxisome proliferator-activated receptor gamma (PPAR gamma) in OxLDL-induced Hsp70 expression. Overexpression of dominant-negative forms of CD36 or knockdown of CD36 by siRNA transfection increased OxLDL-induced Hsp70 protein expression in human monocytic U937 cells, suggesting that CD36 signaling inhibits Hsp70 expression. Similar results were obtained by the inhibition of PPAR gamma activity or knockdown of PPAR gamma expression. In contrast, overexpression of CD36, which is induced by treatment of MCF-7 cells with troglitazone, decreased Hsp70 protein expression induced by OxLDL. Interestingly, activation of PPAR gamma through a synthetic ligand, ciglitazone or troglitazone, decreased the expression levels of Hsp70 protein in OxLDL-treated U937 cells. However, major changes in Hsp70 mRNA levels were not observed. Cycloheximide studies demonstrate that troglitazone attenuates Hsp70 translation but not Hsp70 protein stability. PPAR gamma siRNA transfection reversed the inhibitory effects of troglitazone on Hsp70 translation. These results suggest that CD36 signaling may inhibit stress- induced gene expression by suppressing translation via activation of PPAR gamma in monocytes. These findings reveal a new molecular basis for the anti-inflammatory effects of PPAR gamma.
Antigens, CD36/*physiology ; Cell Line, Tumor ; Chromans/pharmacology ; Cycloheximide/pharmacology ; HSP70 Heat-Shock Proteins/*biosynthesis ; Humans ; Lipoproteins, LDL/pharmacology/*physiology ; Monocytes/drug effects/metabolism ; PPAR gamma/agonists/antagonists & inhibitors/*physiology ; Protein Synthesis Inhibitors/pharmacology ; Signal Transduction ; Thiazolidinediones/pharmacology

Estrogen replacement therapy in postmenopausal women may reduce the risk of Alzheimer's disease, possibly by ameliorating neuronal degeneration. In the present study, we examined the neuroprotective spectrum of estrogen against excitotoxicity, oxidative stress, and serum-deprivation-induced apoptosis of neurons in mouse cortical cultures. 17beta-estradiol as well as 17alpha-estradiol and estrone attenuated oxidative neuronal death induced by 24 hr exposure to 100 microM FeCl2, excitotoxic neuronal death induced by 24 hr of exposure to 30 microM N-methyl-D-aspartate (NMDA) and serum-deprivation induced neuronal apoptosis. Furthermore, estradiol attenuated neuronal death induced by Abeta25-35. However, all these neuroprotective effects were mediated by the anti-oxidative action of estrogens. When oxidative stress was blocked by an antioxidant trolox, estrogens did not show any additional protection. Addition of a specific estrogen receptor antagonist ICI182,780 did not reverse the protection offered by estrogens. These findings suggest that high concentrations of estrogen protect against various neuronal injuries mainly by its anti-oxidative effects as previously shown by Behl et al. Our results do not support the view that classical estrogen receptors mediate neuroprotection.
Amyloid beta-Protein/pharmacology ; Animal ; Antioxidants/pharmacology* ; Antioxidants/metabolism ; Apoptosis/drug effects* ; Cells, Cultured ; Chelating Agents/pharmacology ; Chromans/pharmacology ; Estradiol/pharmacology ; Estrogens/pharmacology* ; Estrogens/metabolism ; Estrone/pharmacology ; Ethylenediamines/pharmacology ; Excitatory Amino Acid Agonists/pharmacology ; Ferric Compounds/pharmacology ; Lactate Dehydrogenase/analysis ; Mice ; N-Methylaspartate/pharmacology ; Neurons/metabolism ; Neurons/drug effects* ; Neurons/cytology ; Organ of Corti/cytology ; Peptide Fragments/pharmacology ; Staurosporine/pharmacology

Estrogen replacement therapy in postmenopausal women may reduce the risk of Alzheimer's disease, possibly by ameliorating neuronal degeneration. In the present study, we examined the neuroprotective spectrum of estrogen against excitotoxicity, oxidative stress, and serum-deprivation-induced apoptosis of neurons in mouse cortical cultures. 17beta-estradiol as well as 17alpha-estradiol and estrone attenuated oxidative neuronal death induced by 24 hr exposure to 100 microM FeCl2, excitotoxic neuronal death induced by 24 hr of exposure to 30 microM N-methyl-D-aspartate (NMDA) and serum-deprivation induced neuronal apoptosis. Furthermore, estradiol attenuated neuronal death induced by Abeta25-35. However, all these neuroprotective effects were mediated by the anti-oxidative action of estrogens. When oxidative stress was blocked by an antioxidant trolox, estrogens did not show any additional protection. Addition of a specific estrogen receptor antagonist ICI182,780 did not reverse the protection offered by estrogens. These findings suggest that high concentrations of estrogen protect against various neuronal injuries mainly by its anti-oxidative effects as previously shown by Behl et al. Our results do not support the view that classical estrogen receptors mediate neuroprotection.
Amyloid beta-Protein/pharmacology ; Animal ; Antioxidants/pharmacology* ; Antioxidants/metabolism ; Apoptosis/drug effects* ; Cells, Cultured ; Chelating Agents/pharmacology ; Chromans/pharmacology ; Estradiol/pharmacology ; Estrogens/pharmacology* ; Estrogens/metabolism ; Estrone/pharmacology ; Ethylenediamines/pharmacology ; Excitatory Amino Acid Agonists/pharmacology ; Ferric Compounds/pharmacology ; Lactate Dehydrogenase/analysis ; Mice ; N-Methylaspartate/pharmacology ; Neurons/metabolism ; Neurons/drug effects* ; Neurons/cytology ; Organ of Corti/cytology ; Peptide Fragments/pharmacology ; Staurosporine/pharmacology

OBJECTIVEIn order to investigate the potential mechanisms in troglitazone-induced apoptosis in HT29 cells, the effects of PPARγ and POX-induced ROS were explored.

METHODS[3- (4, 5)-dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide (MTT) assay, Annexin V and PI staining using FACS, plasmid transfection, ROS formation detected by DCFH staining, RNA interference, RT-PCR & RT-QPCR, and Western blotting analyses were employed to investigate the apoptotic effect of troglitazone and the potential role of PPARγ pathway and POX-induced ROS formation in HT29 cells.

RESULTSTroglitazone was found to inhibit the growth of HT29 cells by induction of apoptosis. During this process, mitochondria related pathways including ROS formation, POX expression and cytochrome c release increased, which were inhibited by pretreatment with GW9662, a specific antagonist of PPARγ. These results illustrated that POX upregulation and ROS formation in apoptosis induced by troglitazone was modulated in PPARγ-dependent pattern. Furthermore, the inhibition of ROS and apoptosis after POX siRNA used in troglitazone-treated HT29 cells indicated that POX be essential in the ROS formation and PPARγ-dependent apoptosis induced by troglitazone.

CONCLUSIONThe findings from this study showed that troglitazone-induced apoptosis was mediated by POX-induced ROS formation, at least partly, via PPARγ activation.

Antineoplastic Agents ; pharmacology ; Apoptosis ; drug effects ; Chromans ; pharmacology ; Cytochromes c ; genetics ; metabolism ; Gene Expression Regulation, Neoplastic ; HT29 Cells ; Humans ; PPAR gamma ; metabolism ; Proline Oxidase ; metabolism ; Reactive Oxygen Species ; metabolism ; Thiazolidinediones ; pharmacology

OBJECTIVETo investigate the effect of troglitazone, a proliferator-activated receptor-γ (PPARγ) agonist, on the expressions of intercellular adhesion molecule-1 (ICAM-1) and matrix metalloproteainse-9 (MMP-9) and cell proliferation in HeLa cells.

METHODSMTT assay was used to measure the cell viability at different time points (0, 24, 48 and 72 h) after exposure to troglitazone. RT-PCR and Western blotting were employed to detect the mRNA and protein expressions of ICAM-1, MMP-9 and PPARγ in the cells. Electrophoretic mobility shift assay (EMSA) was performed to assess the changes in DNA binding activity of PPARγ.

RESULTSThe viability of HeLa cells were time-dependently inhibited by troglitazone, which also significantly reduced the mRNA and protein expressions of ICAM-1 and MMP-9 and increased PPARγ expression. The effects of troglitazone in inhibiting the cell viability and reducing ICAM-1 and MMP-9 expressions were antagonized by the application of the PPARγ antagonist GW9662. The result of EMSA also showed significantly increased DNA binding activity of PPARγ in the cells exposed to troglitazone.

CONCLUSIONThe PPARγ agonist troglitazone can inhibit the expression of ICAM-1 and MMP-9 in HeLa cells by up-regulating PPARγ.

Anilides ; Cell Proliferation ; Cell Survival ; Chromans ; pharmacology ; Gene Expression Regulation ; HeLa Cells ; Humans ; Intercellular Adhesion Molecule-1 ; metabolism ; Matrix Metalloproteinase 9 ; metabolism ; PPAR gamma ; metabolism ; RNA, Messenger ; Thiazolidinediones ; pharmacology ; Up-Regulation

15-deoxy-delta12,14-PGJ2(15d-PGJ2) is a natural ligand that activates the peroxisome proliferators-activated receptor (PPAR) gamma, a member of nuclear receptor family implicated in regulation of lipid metabolism and adipocyte differentiation. Recent studies have shown that 15d-PGJ2 is the potent anti-inflammatory agent functioning via PPARgamma-dependent and -independent mechanisms. Most postulated mechanisms for anti-inflammatory action of PPARgamma agonists are involved in inhibiting NF-kappaB signaling pathway. We examined the possibility that IL-6 signaling via the Jak-Stat pathway is modulated by 15d-PGJ2 in lymphocytes and also examined whether the inhibition of IL-6 signaling is dependent of PPARgamma. 15d-PGJ2 blocked IL-6 induced Stat1 and Stat3 activation in primary human lymphocytes, Jurkat cells and immortalized rheumatoid arthritis B cells. Inhibition of IL-6 signaling was induced rapidly within 15 min after treatment of 15d-PGJ2. Other PPARgamma-agonists, such as troglitazone and ciglitazone, did not inhibit IL-6 signaling, indicating that 15d-PGJ2 affect the IL-6-induced Jak-Stat signaling pathway via PPARgamma-independent mechanism. Although cycloheximide reversed 15d-PGJ2-mediated inhibition of Stat3 activation, actinomycin D had no effect on 15d-PGJ2-mediated inhibition of IL-6 signaling, indicating that inhibition of IL-6 signaling occur independent of de novo gene expression. These results show that 15d-PGJ2 specifically inhibit Jak-Stat signaling pathway in lymphocytes, and suggest that 15d-PGJ2 may regulate inflammatory reactions through the modulation of different signaling pathway other than NF-kappaB in lymphocytes.
Arthritis, Rheumatoid/metabolism/pathology ; Chromans/pharmacology ; Cycloheximide/pharmacology ; DNA-Binding Proteins/*metabolism ; Dactinomycin/pharmacology ; Gene Expression Regulation ; Humans ; Hypoglycemic Agents/pharmacology ; Interleukin-6/*pharmacology ; Jurkat Cells/metabolism/pathology ; Lymphocytes/cytology/*drug effects/*metabolism ; NF-kappa B/metabolism ; PPAR gamma/metabolism ; Phosphorylation ; Prostaglandin D2/*analogs & derivatives/pharmacology ; Protein Synthesis Inhibitors/pharmacology ; Research Support, Non-U.S. Gov't ; *Signal Transduction ; Thiazolidinediones/pharmacology ; Trans-Activators/*metabolism