[Guiding mechanism of platycodin D in treatment of mouse lung cancer with doxorubicin].

This study is to observe whether platycodin D has the guiding role in treatment of mouse lung cancer with doxorubicin and explore its guiding mechanism. In vitro, platycodin D and doxorubicin(alone or in combination) were added into Lewis lung cancer(LLC) cells to detect the cell proliferation and doxorubicin uptake. Cell morphological changes were analyzed by cell holographic analysis system; cell gap junctional intercellular communication(GJIC) was tested by fluorescent yellow tracer; lyso-tracker red was used to examine lysosomal function; LC-3 B(Light chain 3 beta)and P62(heat shock 90-like protein)staining were used to test auto-phagy and autophagic degradation respectively; and P-glycoprotein(P-gp) expression was examined by Western blot. In vivo, lung solid tumor was formed in mouse LLC cells via intravenous injection. Platycodin D and doxorubicin(alone or in combination) were used to treat tumor-bearing mice for four weeks, and then the tumor size was examined, mouse survival time was recorded, doxorubicin uptake in lung tissues was tested, and lung tissues were stained for observation by HE(hematoxylin-eosin) and immunohistochemistry. The results showed that platycodin D at the experimental concentration had no effect on LLC cell proliferation but decreased LLC cell volume, promoted the cells to uptake doxorubicin and enhanced the inhibitory action of doxorubicin on cell proliferation. Platycodin D could promote GJIC and lysosomal function, increase autophagy and autophagic degradation and suppress P-gp expression. Platycodin D at the experimental dose in this study had no effect on LLC lung solid tumors in mice, increased doxorubicin uptake in lung tissues and enhanced the therapeutic efficacy of doxorubicin on lung solid tumors. Platycodin D could improve the extracellular matrix deposition in lung solid tumors, decreased the lung mucin 5 AC secretion and pulmonary vessel permeability. In summary, platycodin D had the guiding role in treating mouse lung cancer with doxorubicin, and its guiding mechanism may be associated with the promotion of cell communication, lysosomal function, and improvement of extracellular environment.

Hydroxysafflor Yellow A Shows Protection against PPARγ Inactivation in Nitrosative Neurons.

Peroxynitrite-mediated nitrosative stress in the brain has been associated with various neurodegenerative disorders. Recent evidence highlights peroxisome proliferator-activated receptor γ (PPARγ) as a critical neuroprotective factor in neurodegenerative diseases. Here, we observed the effect of the herb hydroxysafflor yellow A (HSYA) during nitrosative stress in neurons and investigated the mechanism based on PPARγ protection. We found that a single exposure of primary neurons to peroxynitrite donor SIN-1 caused neuronal injury, which was accompanied by the increase of PPARγ nitration status and lack of activation of the receptor, as measured by PPARγ DNA-binding activity, by agonist (15d-PGJ2 or rosiglitazone) stimulation. The crucial role of PPARγ in neuronal defense against nitrosative stress was verified by showing that pretreatment with 15d-PGJ2 or rosiglitazone attenuated SIN-1-induced neuronal injury but pretreatment with GW9662, a PPARγ antagonist, aggravated SIN-1-induced neuronal injury. The addition of HSYA not only inhibited SIN-1-induced neuronal damage but prevented PPARγ nitrative modification and resumed PPARγ activity stimulated by either 15d-PGJ2 or rosiglitazone. Furthermore, HSYA also showed the ability to rescue the neuroprotective effect of 15d-PGJ2 or rosiglitazone when the agonists were coincubated with SIN-1. Finally, in vivo experiments demonstrated that the administration of HSYA also efficiently blocked PPARγ nitration and loss of activity in the SIN-1-injected hippocampus and reversed the increased neuronal susceptibility which was supported by the inhibition of Bcl-2 protein downregulation induced by SIN-1. The results suggest that HSYA protects neurons from nitrosative stress through keeping PPARγ as a functional receptor, allowing a more effective activation of this neuroprotective factor by the endogenous or exogenous agonist. Our findings provide new clues in understanding the role of the neuroprotective potential of the herbal HSYA.

12/15-Lipoxygenase metabolites of arachidonic acid activate PPARγ: a possible neuroprotective effect in ischemic brain.

The enzyme 12/15-lipoxygenase (LOX) oxidizes various free fatty acids, including arachidonic acid (AA). In the brain, the principal 12/15-LOX metabolites of AA are 12(S)-HETE and 15(S)-HETE. PPARγ is a nuclear receptor whose activation is neuroprotective through its anti-inflammatory properties. In this study, we investigate the involvement of 12(S)- and 15(S)-HETE in the regulation of PPARγ following cerebral ischemia and their effects on ischemia-induced inflammatory response. We show here the increased expression of 12/15-LOX, predominantly in neurons, and elevated production of 12(S)-HETE and 15(S)-HETE in ischemic brain. The exogenous 12(S)- and 15(S)-HETE increase PPARγ protein level, nuclear translocation, and DNA-binding activity in ischemic rats, suggesting the activation of PPARγ. This effect was further confirmed by showing the increased PPARγ transcriptional activity in primary cortical neurons when incubated with 12(S)- or 15(S)-HETE. Moreover, both 12(S)- and 15(S)-HETE potently inhibited the induction of nuclear factor-κB, inducible NO synthase, and cyclooxygenase-2 in ischemic rats, and elicited neuroprotection. The reversal of the effects of 12(S)- and 15(S)-HETE on pro-inflammatory factors by PPARγ antagonist GW9662 indicated their actions were mediated via PPARγ. Thus, the induction of 12(S)- and 15(S)-HETE during brain ischemia suggests that endogenous signals of neuroprotection may be generated.

Neuroprotection of hydroxysafflor yellow A in the transient focal ischemia: inhibition of protein oxidation/nitration, 12/15-lipoxygenase and blood-brain barrier disruption.

Hydroxysafflor yellow A (HSYA) is the main component of the safflower yellow pigments, the aqueous extract of safflower florets. We report here an experimental study for evaluating HSYA for their neuroprotective qualities on rats subjected to middle cerebral artery occlusion (60 min) and reperfusion (24h), an experimental model in which excessive production of reactive oxygen and nitrogen species has been found. In our data, biochemical analysis of tissue proteins showed that cerebral ischemia/reperfusion (I/R) injury resulted in significant elevation of carbonyl groups and nitrotyrosine in the brain of I/R in comparison to sham controls, indicating the occurrence of oxidative/nitrative modification to brain proteins. HSYA-treatment (1, 5 and 10mg/kg) inhibited I/R-induced protein oxidation and nitration. 12/15-Lipoxygenase (12/15-LOX), the enzyme implicated in oxidative stress of cerebral I/R, displayed overexpression in I/R rats. Elevated 12/15-LOX activity, estimated by the level of its metabolite 15-hydroxyeicosatetraenoic acid (15-HETE), was also induced by the challenge of cerebral I/R. Administration of HSYA 1, 5 and 10mg/kg reduced the upregulation of 12/15-LOX expression and activity in a dose-dependent manner. Moreover, the increase in blood-brain barrier (BBB) permeability evaluated by IgG leakage, Evans blue extravasation, and brain water content, respectively, was markedly alleviated by HSYA, indicating its protection against BBB disruption and brain edema following I/R insult. Taken together, these results demonstrate the neuroprotective properties of HSYA, which may be at least in part due to its potential to reduce protein oxidation and nitration, inhibit the upregulation of 12/15-LOX, and attenuate BBB breakdown.

12/15-Lipoxygenase inhibitor baicalein suppresses PPAR gamma expression and nuclear translocation induced by cerebral ischemia/reperfusion.

Accumulating evidences have demonstrated the beneficial actions of peroxisome proliferator-activated receptor gamma (PPAR gamma) in a variety of animal stroke models. Following middle cerebral artery occlusion (60 min) and 2-24 hr reperfusion in rats, we observed cerebral ischemia/reperfusion (I/R) induced up-regulation of PPAR gamma protein expression and translocation from the cytoplasm into the nucleus in a time-dependent manner. We also found that PPAR gamma agonist rosiglitazone enhanced whereas PPAR gamma antagonist GW9662 inhibited the alteration of PPAR gamma stimulated by I/R, suggesting that the changes of PPAR gamma may result from the activation by endogenous ligands. Moreover, the link between the 12/15-lipoxygenase and the production of activating ligands for PPAR gamma has been proved in various tissues. However, the relation of them in brain tissue has not been identified. We demonstrated that the I/R-induced PPAR gamma alteration was reversed by baicalein, the specific inhibitor of 12/15-lipoxygenase. Baicalein treatment significantly inhibited the up-regulation of PPAR gamma expression and, furthermore, suppressed PPAR gamma nuclear accumulation as well as maintained PPAR gamma cytoplasmic retention. Together, these results suggest that I/R induces both PPAR gamma expression and translocation, probably through the activation by endogenous ligands in a 12/15-lipoxygenase inhibitor-sensitive way.

[Major ionic features and their sources in the Nam Co Basin over the Tibetan Plateau].

A preliminary study of major ions in water of three rivers (Niyaqu, Qugaqie, Angqu) in the Nam Co Basin has been carried out in June-October 2006. An obvious difference is found among these rivers, whose ionic characteristics are mainly influenced by the length of rivers and their supply sources. Among the three rivers, the contents of total dissolve solids (TDS) is 79.48 mg/L, 23.44 mg/L, and 111 mg/L in the Niyaqu, Qugaqie, and Angqu, respectively. The hydro-chemical type is CCa for the Qugaqie, between CNa and CCa for the Angqu, and between the Angqu and Qugaqie for the Qugaqie. Changes in ionic concentrations are also related with discharges of the rivers. According to principal component analysis and correlation analysis, the main chemical contents derive from Ca2+ and HCO3(-) in carbonate for the Niyaqu, glacier meltwater and carbonate for the Qugaqie, and Na+, Mg2+ and Cl(-) in evaporates for the Angqu.