[Effects of 18β-sodium glycyrrhetinic acid on TNF-α expression in rats with allergic rhinitis]

Objective:To observe the effect of 18β-sodium glycyrrhetinic acid(18β-SGA) on the expression of TNF-α in nasal mucosa of rats with allergic rhinitis（AR）, and explore the intervention mechanism of 18β-SGA on AR. Method:One hundred and six SPF-level Wistar rats were randomly divided into control group, AR group, budesonide group, 18β-SGA low dose group and high dose group. After the AR rat model was constructed by ovalbumin, the rats were given drug intervention and sacrificed after 2 and 4 weeks of intervention. The nasal mucosa of the rats was taken for immunohistochemical staining, RT-qPCR and Western-blotting to localize and quantify the expression of TNF-α. Result:By immunohistochemistry, Western-blotting and RT-PCR, TNF-α was mainly found in the columnar epithelium, vascular endothelium, glandular and some inflammatory cytoplasm of nasal mucosa. And the expression of TNF-α in the nasal mucosa of AR rats was significantly increased than the normal group at the protein and mRNA levels (P<0.01). After intervention with different doses of 18β-SGA, the expression of TNF-α was significantly decreased (P<0.01), especially after 4 weeks of 18β-SGA low dose group(P<0.01). Conclusion:Different doses of 18β-SGA have therapeutic effects on AR, and its mechanism of action may be related to the inhibition of TNF-α expression.

Intracerebral hemorrhage induces edema and oxidative stress and alters N-methyl-D-aspartate receptor subunits expression

Intracerebral hemorrhage (ICH) induces brain edema formation via a variety of mechanisms including toxicity due to thrombin and erythrocyte lysis. However, the roles of oxidative damage and excitotoxicity have not been fully elucidated and they are examined in this rat ICH study. Adult male Sprague-Dawley rats received an intracaudate injection of 100 microl autologous whole blood and 5 U of thrombin. Rats were sacrificed at 1 hour, 1 and 3 days, and then the brains processed using Western blotting to quantify N-methyl-D-aspartate receptor (NR) subunit expression. At 3 days, animals were also sacrificed for assessment of protein oxidation using Western blot analysis for dinitrophenyl (DNP) and brain water content. Compared to the contralateral side, ipsilateral basal ganglia NR1 and NR2A subunit expression transiently increased at 1 hour after ICH and thrombin injection. From 24 hours there was a marked down-regulation. At 3 days, marked edema and DNP up-regulation were observed in ICH and thrombin injection groups. The present NR expression up-regulation at 1 hour may reflect the acute cell response after ICH. The down-regulation of NR subunits and upregulation of DNP may be associated with cell damage, towards which thrombin may contribute.

Aging enhances intracerebral hemorrhage-induced brain injury in rats

Age is an important factor affecting oxidative stress and plasticity after brain injury. The present study investigated the effects of aging on brain injury after intracerebral hemorrhage (ICH). Aging (18-month) and young (3-month) male Sprague-Dawley rats received an intracerebral infusion of 100-microl autologous blood. Age-related changes in brain edema and neurological deficits were examined and heat shock protein 27 (HSP27) and heat shock protein 32 (HSP32) levels were determined by Western blotting. Perihematomal brain swelling was more severe in aged rats compared to young rats at three days after ICH (P < 0.05). The behavioral tests used were forelimb placing test and forelimb use asymmetry test. There were more severe neurological deficits and a slower recovery in aged rats compared to those in young rats after ICH (P < 0.05). In addition, perihematomal HSP27 and HSP32 protein levels were higher (p < 0.05) in aged rats. In conclusion, ICH causes more severe brain swelling and neurological deficits in aged rats. Clarification of the mechanisms of brain injury after ICH in the aging brain should help develop new therapeutic strategies for hemorrhagic brain injury.

Complement inhibition attenuates brain edema and neurological deficits induced by thrombin

The present study examined whether thrombin activates the complement cascade in the brain and whether N-acetylheparin, an inhibitor of complement activation, attenuates brain injury induced by thrombin. There were three sets of studies. In the first set, rats had an intracerebral infusion of either five-unit thrombin or a needle insertion. Brains were sampled at 24 hours for Western blot analysis and immuno-histochemistry. In the second set, rats received either five-unit thrombin+saline, five-unit thrombin+25 microg N-acetylheparin or five-unit thrombin+100 microg N-acetylheparin infusion. Brains were sampled 24 hours later for water content measurement. In the third set, rats received either five-unit thrombin+saline or five-unit thrombin+ 100 microg N-acetylheparin. Behavioral tests sensitive to unilateral striatal damage were carried out for two weeks. Western blotting demonstrated that complement C9 and clusterin levels increase 24 hours after thrombin infusion (P < 0.01). Both C9 and clusterin positive cells were found around the injection site. High-dose (100-microg) but not low-dose (25-microg) N-acetylheparin attenuated thrombin-induced brain edema (81.5 +/- 0.4% vs. 83.7 +/- 0.3% in the vehicle, P < 0.05). Behavior was also significantly improved by N-acetylheparin (P < 0.05). In conclusion, thrombin-induced edema formation and neurological deficits were both reduced by N-acetylheparin. This suggests that inhibition may be a novel treatment for the thrombin-induced brain injury that occurs in intracerebral hemorrhage.

Systemic use of argatroban reduces tumor mass, attenuates neurological deficits and prolongs survival time in rat glioma models

Our previous studies showed that intracerebral infusion of argatroban, a specific thrombin inhibitor, reduces brain edema and neurological deficits in a C6 glioma model. The present study investigated whether systemic argatroban administration can reduce glioma mass and neurological deficits and extend survival time in C6 and F98 gliomas. Rat C6 or F98 glioma cells were infused into the right caudate of adult male Fischer 344 rats. Osmotic minipump loaded with argatroban (0.3 mg/hour) or vehicle was implanted into abdomen immediately after glioma implantation. Tumor mass was determined at day 9. Over the period of the experiment, the animals underwent behavioral testing (forelimb placing and forelimb use asymmetry). In addition, survival time was tested in the F98 glioma model. In C6 glioma, argatroban reduced glioma mass (p < 0.05) and neurological deficits (p < 0.05) at day 9. In F98 glioma, agratroban prolonged the survival time (p < 0.05) and reduced the body weight loss (84 +/- 15 gram vs. 99 +/- 2 gram in the vehicle group, P < 0.05). In conclusion, systemic use of argatroban reduced tumor mass and neurological deficits, and prolonged survival time. These results suggest that thrombin plays a key role in glioma growth and thrombin inhibition with argatroban may be a novel treatment for gliomas.

Effects of naloxone on tissue oxygen supply and somatosensory evoked potentials in cat brain during focal cerebral ischemia

The effects of naloxone on local tissue oxygen partial pressure (pO2) and on the somatosensory evoked potentials (SEP) were studied in the brain of cat during focal cerebral ischemia. Ischemia, produced by clamping of the middle cerebral artery (MCA) by a transorbital approach, was performed in two series of cats for 3 h. In one group of cats (n = 5), naloxone 5 mg.kg-1 was injected i.v. 0.5 h after clamping. The pO2 was continuously recorded on different depths (0-5000 microns) of the median gyrus by a polarographic oxygen microelectrode. After MCA clamping, pO2 (depth of 0-1000 microns) decreased markedly and hypoxia occurred in the ischemic area. But in the deeper brain (1001-5000 microns) pO2 did not change significantly. The amplitude of SEP decreased after MCA clamping, while the conduction time of SEP did not significantly decrease. The mean pO2 values in the ischemic area were increased as compared to the control group after naloxone, especially at the depths of 0-1000 microns, and the hypoxia was improved. The amplitude of SEP was increased after naloxone in comparison to the situation of ischemia without naloxone. The conduction time of SEP was not improved significantly. We conclude that naloxone can improve the oxygen supply and the electrical activity of neurons in the ischemic region of the brain.