Optimal compatible doses and effects of ephedrine and naloxone on neural plasticity in cerebral ischemia/reperfusion rats

BACKGROUND: Ephedrine promotes neural plasticity in rats following cerebral ischemia/reperfusion injury. Ephedrine has been combined with naloxone in some studies, and it has been confirmed that their combination has synergistic effects on increasing neural plasticity following cerebral ischemia/reperfusion injury. OBJECTIVE: To investigate the effects of ephedrine combined with various doses of naloxone on neural plasticity and to find an optimal dose of naloxone in rats after cerebral ischemia/reperfusion injury by analyzing growth associated protein-43 (GAP-43), synaptophysin and β-endorphin expression in the hippocampal CA3 area. DESIGN, TIME AND SETTING: This immunohistochemical, randomized, controlled, animal experiment was performed at the Chongqing Research Institute of Pediatrics, China from September 2007 to June 2008. MATERIALS: Ephedrine hydrochloride injection and naloxone hydrochloride injection were respectively purchased from Shandong Lvliang Pharmaceutical Factory, China and Sichuan Jingwei Pharmaceutical Co., Ltd., China. A total of 192 healthy adult Sprague Dawley rats were used to establish models of left middle cerebral artery occlusion using the suture occlusion method. METHODS: At 2 hours following cerebral ischemia, the rats were intraperitoneally injected with 1.5 mg/kg/d ephedrine (ephedrine group), with 0.1, 0.2, or 0.3 mg/kg/d naloxone (low, moderate and high doses of naloxone groups), with 1.5 mg/kg/d ephedrine + 0.1, 0.2, or 0.3 mg/kg/d naloxone (ephedrine + low, moderate and high doses of naloxone groups), and with 0.5 mL saline (model group), respectively. MAIN OUTCOME MEASURES: GAP-43, synaptophysin and β-endorphin expression were detected in the hippocampal CA3 area using immunohistochemistry 1-4 weeks after surgery. Sensorimotor integration in rats was assessed using the beam walking test. RESULTS: GAP-43 and synaptophysin expression was greater in the ephedrine group, and in the ephedrine + moderate and high doses of naloxone groups compared with the model group. GAP-43 and synaptophysin expression was greatest in the ephedrine + high dose of naloxone group at 2 and 3 weeks after surgery. β-endorphin expression was significantly lower in the ephedrine group, and in the ephedrine + moderate and high doses of naloxone groups compared with the model group (P < 0.05). β-endorphin expression was persistently low in the ephedrine + high dose of naloxone group. At 1–3 weeks after surgery, the beam walking test score was significantly higher in the ephedrine group and ephedrine + various doses of naloxone groups than in the model group (P < 0.05). The score was higher in the ephedrine + moderate and high doses of naloxone groups than in the ephedrine group (P < 0.05). Moreover, the score was increased as the dose of naloxone increased in the ephedrine + various doses of naloxone groups. CONCLUSION: Ephedrine promotes GAP-43 and synaptophysin expression, inhibits β-endorphin expression in the hippocampal CA3 area, and improves motor function in rats following cerebral ischemia/reperfusion injury. Naloxone does not have the above-mentioned effects. During combined treatment with ephedrine and naloxone, however, the above-described effects are enhanced with an increased dose of naloxone. The combination of ephedrine (1.5 mg/kg/d) and naloxone (0.3 mg/kg/d) can produce optimal therapeutic efficacy in treatment of cerebral ischemic injury.

Side effects of different doses of ephedrine in rats with cerebral ischemia/reperfusion injury

Ephedrine has a protective effect against cerebral ischemia,but its side effects limit its clinical application. Results from a previous study showed that 1.5 mg/kg per day ephedrine can promote motion recovery in rats following cerebral ischemia/reperfusion without significant side effects. In the present study,ephedrine at doses of 3.0,2.5 and 2.0 mg/kg was used to treat rats with cerebral ischemia/reperfusion and the effects of ephedrine on the heart,liver,kidney and cerebrum were observed. Results showed that the blood pressure of rats with cerebral ischemia/reperfusion injury following ephedrine treatment was lower than in rats that recovered naturally from cerebral ischemia/reperfusion,but the pressure decreased with increasing doses of ephedrine. In addition,serum aspartate transaminase,alkaline phosphatase and creatinine concentration in rats with cerebral ischemia/reperfusion injury following ephedrine treatment were greater than in rats that recovered naturally from cerebral ischemia/reperfusion. The concentrations of these enzymes were decreased with increasing doses of ephedrine. Ephedrine-treated rats displayed hyperemia,degeneration and edema in the cerebrum,liver,heart and kidney. Results demonstrated that ephedrine exhibited side effects on the cerebrum,heart,liver and kidney in rats following cerebral ischemia/reperfusion in a dose-dependent manner.

Effects of exogenous ganglioside-1 on learning and memory in a neonatal rat model of hypoxia-ischemia brain injury

BACKGROUND:Exogenous ganglioside-1(GM1) can cross the blood-brain barrier and play a protective role against hypoxia-ischemia-induced brain damage.OBJECTIVE:To examine the possible mechanisms of exogenous GM1 protection in hypoxia-ischemia-induced brain damage in a neonatal rat model by measuring changes in brain mass,pathological morphology,growth-associated protein-43 expression,and neurobehavioral manifestations.DESIGN,TIME AND SETTING:A randomized block-design study was performed at the Immunohistochemistry Laboratory of the Pediatric Research Institute,Children's Hospital of Chongqing Medical University from August 2005 to August 2006.MATERIALS:A total of 36 neonatal,7-day-old,Sprague Dawley rats were used in this experiment.The hypoxia-ischemia-induced brain damage model was established by permanently occluding the right carotid artery,followed by oxygen inhalation at a low concentration(8% O2,92% N2) for 2 hours.METHODS:All rats were randomly divided into the following groups:GM1,model,and sham operation,with 12 rats each group.Rats in the GM1 and model groups received hypoxic/ischemic-induced brain damage.Rats in the GM1 group received injections of GM1(i.p.,20 mg/kg) at 0,24,48,72,96,120,and 144 hours following models established,and rats in the model group were administered(i.p.) the same amount of saline.The right carotid artery was separated,but not ligated,in the sham operation group rats.MAIN OUTCOME MEASURES:At 1 week after surgery,expression of growth-associated protein-43,a marker of neural development and plasticity,was detected in the hippocampal CA3 region by immunohistochemistry.Brain mass was measured,and the pathological morphology was observed.At 4 weeks after surgery,behavioral changes in the remaining rats were tested by Morris water maze,and growth-associated protein-43 expression was measured.RESULTS:(1) In the GM1 and sham operation groups,growth-associated protein-43 expression was greater in the hippocampal CA3 region compared to the model group 1 week after surgery(P < 0.05).In all three groups,brain weight of the right hemisphere was significantly less than the left hemisphere,in particular in the model group(P < 0.05).In the GM1 group,the weight difference between two hemispheres,as well as the extent of damage in the right hemisphere,was less than the model group(P < 0.01).In the sham operation group,brain tissue consisted of integrated structures and ordered cells.In the model group,the cerebral cortex layers of the right hemisphere were not defined,neurons were damaged,and neurons were disarranged in the hippocampal area.In the GM1 group,neurons were dense in the right cerebral cortex and hippocampal area,with no significant change in glial proliferation.(2) The average time of escape latency in the GM1 group was shortened 4 weeks after surgery,and significantly less than the model group(P < 0.05).In addition,the frequency platform passing in the GM1 group was significantly greater than the model group(P < 0.01).CONCLUSION:Exogenous GM1 may reduce brain injury and improve learning and memory in hypoxia-ischemia-induced brain damage rats.This protection may be associated with increased growth-associated protein-43 expression,which is involved in neuronal remodeling processes.

海洋固氮菌和解磷菌的分离鉴定及发酵条件优化

【目的】从西沙喜盐草根际沉积物中分离纯化得到具有高效固氮能力及解磷能力的菌株。优化其发酵培养条件,研究其制备海洋微生物菌剂的可能性。【方法】从形态学特征、生理生化、16S rDNA及功能基因水平进行鉴定,通过乙炔还原法、钼锑抗显色法检测菌株的固氮酶活性和解磷能力,单因素法和响应面法优化其发酵培养条件,溶血试验和急性毒性实验鉴定菌株的安全性。【结果】结果表明,菌株AZ16属于星箭头菌(Sagittula stellate),革兰氏阴性菌,选择性固氮培养基中菌落呈黄圆形黏稠状,固氮酶活性达34.63 nmol C2H2/(mL·h),最适生长条件为:盐度25‰、pH 7.5、温度33°C、接种量5.0%;菌株XT37为海洋芽孢杆菌(Bacillus sp.),革兰氏阳性菌,选择性固氮培养基中菌落呈深黄色圆形褶皱,植酸酶活性达239.49μg/L,最适合生长条件为:盐度25‰、pH 6.7、温度28°C、接种量5.0%。溶血实验和急性毒性实验证明两株菌属实际无毒级别。【结论】两株菌具有高效的固氮解磷功能,以及抗高盐、强碱等环境的能力,安全无毒,因此有潜力应用于多功能混合微生物菌剂的研制。

Light amplified oxidative stress in tumor microenvironment by carbonized hemin nanoparticles for boosting photodynamic anticancer therapy

Photodynamic therapy(PDT),which utilizes light excite photosensitizers(PSs)to generate reactive oxygen species(ROS)and consequently ablate cancer cells or diseased tissue,has attracted a great deal of attention in the last decades due to its unique advantages.However,the advancement of PDT is restricted by the inherent characteristics of PS and tumor microenvironment(TME).It is urgent to explore high-performance PSs with TME regulation capability and subsequently improve the therapeutic outcomes.Herein,we reported a newly engineered PS of polymer encapsulated carbonized hemin nanoparticles(P-CHNPs)via a facile synthesis procedure for boosting photodynamic anticancer therapy.Solvothermal treatment of hemin enabled the synthesized P-CHNPs to enhance oxidative stress in TME,which could be further amplified under light irradiation.Excellent in vitro and in vivo PDT effects were achieved due to the improved ROS(hydroxyl radicals and singlet oxygen)generation efficiency,hypoxia relief,and glutathione depletion.Moreover,the superior in vitro and in vivo biocompatibility and boosted PDT effect make the P-CHNPs a potential therapeutic agent for future translational research.