Mei Yuanwu

Cytokine-induced cell surface expression of adhesion molecules in vascular endothelial cells in vitro.

SummaryRegulation of the adhesion molecules expression by cytokine in vascular endothelial cells was investigated. Human umbilical vein endothelial cells (HUVEC) were stimulated with cytokines, TNF-α (1–250 U/ml) or IL-1ß (0. 1–50 U/ml) for 24 h. HUVEC were also cultured with cytokines, TNF-α (100 U/ml) or IL-1ß (10 U/ml), for 4–72 h, cell surface expression of adhesion molecules (ICAM-1 and VCAM-1) were detected and quantitated by immunocytochemical methods and computerized imaging analysis technique. Adhesion molecules expression were up-regulated by TNF-α, IL-1ß in a concentration- and time-dependent manner. Some significant differences were observed between the effects of cytokines on the ICAM-1 and on VCAM-1 expression. Cytokines might directly induce the expression of ICAM-1 and VCAM-1 in vascular endothelial cells. Our observations indicate differential functions of the two adhesion molecules during the evolution of inflammatory responses in stroke.

Expression of cytokines IL-2, IL-10 and TNF-α in mice with herpes simplex viral encephalitis

SummaryThe expression of the cytokines IL-2, IL-10, TNF-α and their roles in mice with herpes simplex viral encephalitis (HSE) were studied. By using semiquantitative reverse transcription polymerase chain reaction (RT-PCR), the expressions of IL-2, IL-10, and TNF-α mRNA in control group, HSE group and acyclovir (ACV)-treated group were detected and the pathological changes of brain were observed. It was found that after HSV1 infection, the cerebral lesions of haemorrhage and necrosis in mice were observed under the microscopy, and the levels of IL-2, IL-10 and TNF-α were increased remarkably. After treatment with ACV after HSV1 infection, the cerebral lesions in mice were improved, the level of IL-2 maintained stable, IL-10 was increased consistently, and TNF-α was decreased significantly as compared with those in HSE group. In acute HSE, many cytokines are upregulated, including IL-2, IL-10 and TNF-α to eliminate virus and TH1 type response is dominant. In convalescence, there is a shift in the cytokine expression profile from TH1 profile to TH2 profile and the shift can inhibit the overexpression of immune response in animals. ACV has remarkable effects in the treatment of HSE.

The protective effect of rosuvastatin on ischemic brain injury and its mechanism

SummaryTo study the protective effect of rosuvastatin on ischemic brain injury and its mechanism, focal cerebral ischemia/reperfusion was induced by occlusion of the middle cerebral artery (MCA) using the intra-luminal filament technique. The cerebral blood flow was monitored with laser-Doppler flowmetry (LDF). The slices of brain tissue were stained with cresyl-violet. The cerebral volume of infarction and edema were quantified with ImageJ software. The expressions of endothelial NO synthase (eNOS) and activated caspase-3 were detected with Western blot. The inducible NO synthase (iNOS) positive cells were immunohistochemically observed. The results demonstrated that rosuvastatin (20 mg/kg) could remarkably decrease infarct volume and cerebral edema after MCAO 90 min/reperfusion 24 h. Western blots showed that the expression of eNOS in cerebral cortex before and after ischemia was (100±43.3) %, (1668.9±112.2) % respectively (P<0.001), rosuvastatin significantly up-regulated the expression of eNOS in non-ischemic cortex (P<0.001), whereas in ischemic cortex of rosuvastatin group the expression of eNOS was (1678.8±121.3) %. There was no expression of activated caspase-3 in non-ischemic cortex, nonetheless the expression of activated caspase-3 increased after ischemia, and rosuvastatin significantly diminished it (P<0.01). Immunohistochemistry revealed no iNOS-positive cells in non-ischemic brain area, while in ischemic brain area the number of iNOS positive cells went up, and rosuvastatin could significantly reduced them. Consequently, the mechanisms of rosuvastatin’s neural protection on ischemic brain injury are to enhance expression of eNOS, to inhibit expression of iNOS and activated caspase-3.

The effect of beta-amyloid on neurons and the influence of glucocorticoid and age on such effect

SummaryTo explore the relationship between β-amyloid (Aβ) and the pathogenesis of Alzheimer disease (AD), after injection of β-amyloid into the rat brain, the apoptosis of nerve cells and acetylcholine (Ach) content in rat hippocampus were examined by employing TUNEL technique and base hydroxylamine colorimetry respectively. The influence of age and glucocorticoid on the neurotoxic effect of Aβ was also analyzed. Aβ peptide could strongly induce the apoptosis of neurons in hippocampus, cortex and striate body (P<0.05 orP<0.01). In addition, the senility and glucocorticoid pre-treatment could enhance the toxic effect of Aβ(P<0.05 orP<0.01). It is concluded that Aβ may play an important role in the pathogenesis of Alzheimer disease via its induction of apoptosis of neurons and by decreasing the content of the Ach.

Effect of diazepam on the contents of amino acids and free radical during ischemia /reperfusion injury

SummaryThe protective effect and mechanism of diazepam on ischemia neurons during cerebral ischemia and reperfusion were studied. Sixty-three Wistar rats were divided randomly into nine groups: control group (n=7), ischemia (is) groups including subgroups of is3h, is3-h/repl-h, is3-h/rep2-h, is3-h/rep3-h(n = 7 in each group), diazepam treated groups (10 mg/kg, i. p.), including subgroups of is3-h, is3-h/repl-h, is3-h/rep2-h, is3-h/rep3-h (n=7 in each group) with Zea longa’s animal model of middle cerebral artery occlusion. The comparison between the ischemia group and diazepam-treated group showed that diazepam could obviously decrease the production of glutamate, asparate, MDA and increase the synthesis and release of GABA, SOD and GSH-PX. It was concluded that diazepam exerted its protective effects on neurons through complex mechanisms of regulating the synthesis and release of excitotary/inhibitory amino acids and free radicals.

Experimental Study on Parkinson Disease Model of Rats

Objective: To observe the characteristics of praxiology of Parkinson disease (PD) rats. Methods: At 1d, 7d, 14d after PD rats’ model were successful; we observed the markers of rotational behavior of Parkinson disease (PD) rats. For example: start time, continuous time, maximum turning, etc. Results: From 1d to 14d, PD rats, start time of the rotational behavior elongated gradually, continuous time shortened by degrees, maximum rotational speed and the number of the rotational behavior were invariable. Conclusions: Improved method of PD is scientific, reliable, and simple. Substantial nigral pathology of PD rats makes the foundation of the rotational behavior. The injury of substantial nigral can be reflected by maximum rotational speed and the number of the rotational behavior of PD rats.

Experimental Study on the Connection of Nigral Apoptosis of Normal Rats and Rats of Parkinson Disease with Different Doses of Levodopa

Objective: To evaluate the neuronal toxicical effects induced by levodopa and explore the method in which PD can be treated reasonably with levodopa. Method: The rat models of Parkinson disease (PD) were made by injecting stereotaxically 6-OHDA to right side of the mesencephic ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). The PD rats were treated intraperitoneally with different dosages (10 mg/kg/d, 50 mg/kg/d, 100 mg/kg/d) and different durations (1 d, 3 d, 5 d, 7 d) of levodopa. At the same time, we observed the injury of substantia nigral by the way of treating PD rats with levodopa for 7 days and then stopped for 7 days. In this study, we used TUNEL to detect the injury of substantia nigra by different doses and durations of levodopa. Results: The number of substantia nigral apoptosis was increased with the changes of doses and durations of levodopa. Conclusions: If we use levodopa intermittently or as little as possible, the toxical action of levodopa may be reduced.

Rapid inhibition of the glutamate-induced increase of intracellular free calcium by magnesium in rat hippocampal neurons

SummaryBy using Fura-2/AM, the effects of magnesium (Mg2+) on the glutamate-induced increase of intracellular free calcium ([Ca2+]i) in the cultured hippocampal neurons and the features were investigated by integrated photoelectric detecting system. The experiments were designed to three groups (The drug was spit to the cells for 20 s): Group A receiving 1×10−5 mol/L glutamate; Group B receiving 1×10−5 mol/L glutamate and 1×10−5 mol/L Mg2+ simultaneously; Group C receiving 1×10−5 mol/L glutamate again after [Ca2+]i in group B back to the baseline. The results showed that in group A, [Ca2+]i was obviously increased. In group B, the changes in [Ca2+] i and the peak value were significantly decreased. Moreover, the elevation of Phase 1 was slowed down and Phase 2 was shortened to some extent, and the plateau phase between them was relatively prolonged. In group C, calcium oscillation similar to that in group A occurred, but both the Phase 1 and Phase 2 were shortened and the Δ[Ca2+]i was slightly decreased. It was suggested that Mg2+ could quickly inhibit the rise of [Ca2+]i induced by glutamate in the cultured hippocampal neurons in rats.