Effect of psoralen on rat osteoblasts injuries induced by TCP wear particles in vitro and its mechanism / 中国应用生理学杂志

To investigate the effect and mechanism of psoralen on calvarial osteoblasts injuries caused by tricalcium phosphate (TCP) wear particles in vitro. Primary osteoblasts were obtained from the calvaria of neonatal SD rat by the series of digestion and were identified with ALP staining. Calvarial osteoblasts were treated with TCP wear particles for 48 h to establish the in vitro model of osteoblasts injuries. The rat osteoblasts were randomly divided into control group, TCP wear particles (0.1 mg/ml) group, psoralen treated (at the concentrations of 10, 10, 10 mol/L) groups. WST assay and the flow cytometry were used to detect the cell viability of osteoblasts and apoptosis, respectively. Chemical colorimetry was performed to examine ALP activity of osteobalsts. When the osteoblasts were treated for 14 day, mineral nodules formation was observed with alizarin red S staining. Western blot was applied to examine protein expressions of glucose regulated protein78/94(GRP78/94), inositol dependent enzyme 1 alpha (IREα), spliced X-box binding protein 1 (XBP1s) and phosphorylated c-Jun N-terminal kinase (p-JNK) in calvarial osteoblasts. Compared with control group, the cell viability of osteoblasts, ALP activity and mineral nodules formation in TCP group were decreased significantly (P＜0.05), while the percentage of apoptosis and protein expressions of GRP78/94, IRE1α, XBP1 and p-JNK were obviously increased in calvarial osteoblasts (P＜0.05). Compared with TCP group, the injuries of calvarial osteoblasts and cell apoptosis in psoralen treated groups were obviously decreased (P＜0.05), and the expression levels of GRP78/94, IRE1α, XBP1 and p-JNK were down-regulated remarkably (P＜0.05). Psoralen prevents osteoblasts injuries caused by TCP wear particles through IRE1α-XBP1s-JNK signaling pathway activation.

Effect of oxidative stress on periprosthetic osteolysis induced by TCP wear particles in mouse calvaria and its mechanism / 中国应用生理学杂志

OBJECTIVE@#To explore the effect of oxidative stress on periprosthetic osteolysis induced by TCP wear particles in mouse calvaria and its mechanism.@*METHODS@#Thirty-six male ICR mice were randomly divided into three groups (=12):sham group, TCP wear particles (TCP) group and N-acetyl-L-cysteine (NAC) group. Aperiprosthetic osteolysis model in mouse was established by implanting 30 mg of TCP wear particles onto the surface of bilateral parietal bones following removal of the periosteum. On the 2nd day post-operation, NAC (1.0 mg/kg) was locally injected to the calvarium under the periosteum every other day for 2 weeks. Then, all the mice were sacrificed to obtain blood and the calvaria. Periprosthetic osteolysis in the mouse calvaria was observed by tartrate resistant acid phosphatase (TRAP) staining; serum levels of tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), interleukin-6 (IL-6); total anti-oxidation capacity (T-AOC) and superoxide dismutase (SOD) activity were examined by ELISA and chemical colorimetry, respectively; protein levels of glucose-regulated protein 78 (GRP78), protein kinase R-like ER kinase (PERK), phospho-PERK (p-PERK), eukaryotic initiation factor 2α (eIF2α) and phospho-eIF2α (p-eIF2α) in periprosthetic bone tissue were detected by Western blot.@*RESULTS@#Compared with sham group, serum levels of TNF-α, IL-1β and IL-6, and osteolysis area were increased obviously in TCP group (<0.05), and serum level of T-AOC and SOD activity were decreased significantly in TCP group (<0.05), GRP78 expression, the ratio of p-PERK and PERK, p-eIF2α and eIF2α in the mouse calvaria of TCP group were up-regulated markedly. Compared with TCP group, serum levels of TNF-α, IL-1β and IL-6, and osteolysis area were decreased markedly in NAC group (<0.05), serum level of T-AOC and SOD activity were increased obviously in NAC group (<0.05), and GRP78 expression, the ratio of p-PERK/PERK and p-eIF2α/eIF2α were obviously down-regulated.@*CONCLUSIONS@#Inhibition of oxidative stress can prevent periprosthetic osteolysis induced by TCP wear particles, which may be mediated by inactivation of PERK/eIF2α signaling pathway.

The study of effects and mechanism of U50, 488H on electrical coupling during ischemia in the perfused isolated rat heart / 中国应用生理学杂志

<p><b>OBJECTIVE</b>To determine the effect of activation of lambda-opioid receptor with U50, 488H, a selective kappa-opioid receptor agonist, on the changes in electrical coupling during prolonged ischemia and to explore the possible mechanism.</p><p><b>METHODS</b>The isolated rat heart was perfused in a Langendorff apparatus. The effect of U50, 488H on electrical coupling parameters including onset of uncoupling, plateau time, slope and fold increase in r(t) was observed in isolated perfused rat heart subjected to global no-flow ischemia. The effect of U50, 488H on connexin 43 (Cx43) expression of ventricular muscle during ischemia was determined by immunohistochemistry.</p><p><b>RESULTS</b>In the prolonged ischemia model, U50, 488H concentration dependently delayed the onset of uncoupling, increased time to plateau, and decreased the maximal rate of uncoupling during ischemia. The effect of U50, 488H on electrical uncoupling parameters during ischemia was abolished by a selective kappa-opioid receptor antagonist nor-BNI or a PKC inhibitor chelerythrine. The amount of Cx43 immunoreactive signal in ventricular muscle was greatly reduced after ischemia. U50, 488H markedly increased Cx43 expression during ischemia and its effect was also attenuated by nor-BNI or chelerythrine.</p><p><b>CONCLUSION</b>These results demonstrated that U50, 488H delayed the onset of uncoupling and plateau time, decreased the maximal rate of uncoupling and increased Cx43 expression of ventricular muscle during ischemia, and these effects of U50, 488H were mediated by kappa-opioid receptor, in which activation of PKC was involved. The effect of U50, 488H on electrical coupling during ischemia was probably correlated with preservation of Cx43 in cardiac muscle.</p>

Effect of gap junction on the cardioprotection of ischemic postconditioning in rat heart / 中国应用生理学杂志

<p><b>AIM</b>To determine whether the cardioprotection of ischemic postconditioning and heptanol in ischemic heart against ischemia/reperfusion (I/R) is mediated by gap junction.</p><p><b>METHODS</b>The effect of ischemic postconditioning, heptanol at different doses (0.03, 0.06, 0.30, and 0.60 mg/kg) and AAP10 (10 mg/kg) on the intact rat heart during 30 min ischemia and 2 h of reperfusion was observed. Ischemic postconditioning was achieved by 3 cycles of 10 s reperfusion/10 s regional ischemia starting at the beginning of the reperfusion. The infarct size and the arrhythmia scores were measured. The effect of ischemic postconditioning, heptanol at different doses (0.05, 0.10, 0.50 and 1.00 mmol/L) and AAP10 (1 x 10(-7)mol/L) on the isolated heart during 30 min ischemia and 2 h of reperfusion was observed. Ischemic postconditioning was achieved by 6 cycles of 10 s reperfusion/10 s global ischemia starting at the beginning of the reperfusion. The arrhythmia scores and conduction velocity of ventricle muscle were measured.</p><p><b>RESULTS</b>In the intact rat heart model, ischemic postconditioning and heptanol reduced infarct size and arrhythmia scores. In the Langendorff perfused rat heart model, ischemic postconditioning and heptanol reduced arrhythmia scores and conduction velocity of ventricle muscle. Administration of AAP10, an opener of gap junction attenuated the cardioprotection of ischemic postconditioning and heptanol.</p><p><b>CONCLUSION</b>The cardioprotection of ischemic postconditioning and heptanol may be related to the attenuation of gap junction communication on myocardiac ischemia/reperfusion injury.</p>

Delayed electrical uncoupling is involved in kappa-opioid receptor activation -induced cardioprotective effect in the isolated rat heart / 中国应用生理学杂志

<p><b>AIM</b>To determine whether activation of kappa-opioid receptor with U50,488H, a selective kappa-opioid receptor agonist, produces any changes in electrical uncoupling during prolonged ischemia and whether these changes in electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation, and to explore the possible mechanism.</p><p><b>METHODS</b>(1) To observe the effect of U50,488H (10(-7), 10(-6), 3 x10(-6) and 10(-5) mol/L), a selective kappa-opioid receptor agonist, or with a selective kappa-opioid receptor antagonist nor-BNI (5 x 10(-6) mol/L), or with a mitochondrial K(ATP) channel inhibitor 5-HD on myocardium during ischemia/reperfusion in isolated perfused rat heart. Parameters of measurements include hemodynamic data, formazan content, heart rate, coronary flow, and lactate dehydrogenase (LDH). (2) To examine the effect of U50,488H of different concentration on electrical coupling parameters (including onset of uncoupling, plateau time, slope, and fold increase in r1) during 70 min myocardial ischemia in isolated perfused rat heart.</p><p><b>RESULTS</b>(1) Pretreatment with U50,488H concentration dependently increased formazan content and reduced LDH release induced by 30 min of ischemia and 120 min of reperfusion. (2) The onset of electrical uncoupling and plateau time during prolonged ischemia was delayed by kappa-opioid receptor activation with U50,488H. (3) Linear regression analysis shown that the increase in formazan content and decrease in LDH release produced by kappa-opioid receptor activation was associated with delayed electrical uncoupling during prolonged ischemia. (4) The effects of U50,488H on formazan content, LDH release and on electrical coupling were abolished by nor-BNI, or 5-HD.</p><p><b>CONCLUSION</b>This results demonstrate that the onset of electrical uncoupling during prolonged ischemia is delayed by kappa-opioid receptor activation with a selective kappa-opioid receptor agonist U50,488H, and that delayed electrical uncoupling is associated with the cardioprotection induced by kappa-opioid receptor activation with U50,488H. These effects of kappa-opioid receptor activation with U50,488H are mediated by mitochondrial K(ATP) channels.</p>