群多普利对大鼠脑缺血再灌注损伤的保护作用研究

目的 观察群多普利对大鼠局灶性脑缺血损伤的保护作用,并探究其可能作用机制。 方法 采用改良ZeaLonga's法制作大脑中动脉闭塞（middle c erebral a rtery o cclusion,MCAO）模型。将 健康雄性SD大鼠随机分成假手术组、模型组、群多普利低剂量组（5 mg/kg）、群多普利高剂量组 （10 mg/kg）等四组,观察各实验组大鼠神经功能评分、脑梗死体积、脑组织白细胞介素（i nterl euki n, IL）-1β及IL-10含量变化。 结果 与假手术相比,模型组神经功能缺损程度评分显著提高,脑组织IL-1β及IL-10含量显著增加 （P＜0.05）;与模型组比较,群多普利低剂量和高剂量均能显著减轻缺血再灌注损伤大鼠神经功能 缺损,减小脑梗死体积（P＜0.05）;群多普利低剂量和高剂量均能显著降低IL-1β的含量;群多普利 高剂量可进一步增加IL-10的含量。 结论 在脑缺血再灌注损伤大鼠中,群多普利可能通过调节IL-1β及IL-10的分泌,重建促炎因子与抗 炎因子之间的平衡,从而起到神经保护作用。     

Matrix Metalloproteinase-8 Inhibitor Ameliorates Inflammatory Responses and Behavioral Deficits in LRRK2 G2019S Parkinson’s Disease Model Mice

Parkinson’s disease (PD) is a neurodegenerative disorder that involves the loss of dopaminergic neurons in the substantia nigra (SN). Matrix metalloproteinases-8 (MMP-8), neutrophil collagenase, is a functional player in the progressive pathology of various inflammatory disorders. In this study, we administered an MMP-8 inhibitor (MMP-8i) in Leucine-rich repeat kinase 2 (LRRK2) G2019S transgenic mice, to determine the effects of MMP-8i on PD pathology. We observed a significant increase of ionized calcium-binding adapter molecule 1 (Iba1)-positive activated microglia in the striatum of LRRK2 G2019S mice compared to normal control mice, indicating enhanced neuro-inflammatory responses. The increased number of Iba1-positive activated microglia in LRRK2 G2019S PD mice was down-regulated by systemic administration of MMP-8i. Interestingly, this LRRK2 G2019S PD mice showed significantly reduced size of cell body area of tyrosine hydroxylase (TH) positive neurons in SN region and MMP-8i significantly recovered cellular atrophy shown in PD model indicating distinct neuro-protective effects of MMP-8i. Furthermore, MMP-8i administration markedly improved behavioral abnormalities of motor balancing coordination in rota-rod test in LRRK2 G2019S mice. These data suggest that MMP-8i attenuates the pathological symptoms of PD through anti-inflammatory processes.     

Parameters of optic nerve electrical stimulation affecting neuroprotection of axotomized retinal ganglion cells in adult rats

We previously showed the enhancement of survival of retinal ganglion cells (RGCs) by electrical stimulation (ES) of the optic nerve (ON) stump in adult rats. To elucidate the mechanisms underlying the survival enhancement, we determined whether the neuroprotective effect of ES is affected by the following parameters: stimulation time, frequency of current pulses and starting of ES. ES for 10 min immediately after ON transection was not effective in increasing the number of surviving RGCs 7 days after the transection, but that for 30 min was effective. ES at 20 Hz was the most effective, when applied just after axotomy. When the starting of ES to the ON was shifted either 3 h after or 4 h before the axotomy, the neuroprotective effect of ES was not observed. These results suggest that the electrical activation of RGCs and/or the transected ON interfere with early events after axotomy that leads to RGC death.     

Dantrolene antagonizes the glycineB site of the NMDA receptor

In this study we tested the hypothesis that dantrolene, an established inhibitor of the skeletal muscle isoform of the ryanodine receptor, may interfere with activity of NMDA receptors in neurons. We assessed the effects of dantrolene on [(3)H]MK-801 and [(3)H]glycine binding to isolated rat cortical membranes. Dantrolene inhibited [(3)H]MK-801 binding in the presence of 100 microM NMDA with an IC(50) of 58.4 microM. The IC(50) value increased to 99.6, 343.0 and 364.6 microM in the presence of 10, 30 and 50 microM glycine, respectively, suggesting that dantrolene competes with glycine for binding site at the NMDA receptor complex. A binding assay using [(3)H]glycine confirmed this supposition: dantrolene inhibited strychnine-insensitive glycine binding in a dose-dependent way. Thus, our results show that dantrolene at concentrations of 50-100 microM and higher blocks the glycine binding site of the NMDA receptor complex and in this way inhibits activation of the NMDA ion channel. These data reveal a new mechanism of dantrolene action in neuronal tissue. Our results also suggest that the neuroprotective effect of dantrolene may be at least partly explained by its activity as a non-competitive antagonist of NMDA receptors.     

Genistein attenuates oxidative stress and neuronal damage following transient global cerebral ischemia in rat hippocampus

Oxidative stress is believed to contribute to neuronal damage induced by cerebral ischemia/reperfusion (I/R) injury. The present study was undertaken to evaluate the possible antioxidant neuroprotective effect of genistein against neuronal death in hippocampal CA1 neurons following transient global cerebral ischemia in the rat. Transient global cerebral ischemia was induced in male Sprague-Dawley rats by four-vessel-occlusion for 10min. At various times of reperfusion, the histopathological changes and the levels of mitochondria-generated reactive oxygen species (ROS), malondialdehyde (MDA), cytosolic cytochrome c and caspase-3 activity in hippocampus were measured. We found extensive neuronal death in the CA1 region at day 5 after I/R. The ischemic changes were preceded by increases in ROS generation and MDA concentration and followed by increased cytosolic cytochrome c, and subsequently caspase-3 activation and apoptosis. Treatment with genistein (15mg/kg, i.p.) significantly attenuated ischemia-induced neuronal death. Genistein administration also decreased ROS generation, MDA concentration and the apoptotic indices. These results suggest that genistein protects neurons from transient global cerebral I/R injury in rat hippocampus by attenuating oxidative stress, lipid peroxidation and the signaling cascade leading to apoptotic cell death.     

Progesterone blocks estrogen neuroprotection from kainate in middle-aged female rats

The neuroprotective effects of estrogen in young adult rodents are well established. Less well understood is how estrogen neuroprotection is affected by aging and interactions with progesterone. In this study, we investigated the effects of estrogen and continuous progesterone, both alone and in combination, on hippocampal neuron survival following kainate lesion in 14-month-old female rats entering reproductive senescence. Our results show that ovariectomy-induced hormone depletion did not significantly affect the extent of kainate-induced neuron loss. Treatment of ovariectomized rats with estrogen significantly reduced neuron loss, however this effect was blocked by co-administration of continuous progesterone. Treatment of ovariectomized rats with progesterone alone did not significantly affect kainate toxicity. These results provide new insight into factors that regulate estrogen neuroprotection, which has important implications for hormone therapy in postmenopausal women.     

Melatonin attenuates the decrement of dendritic protein MAP-2 immuno-staining in the hippocampal CA1 and CA3 fields of the aging male rat

Neuronal death during brain aging results, at least in part, from the disruption of synaptic connectivity caused by oxidative stress. Synaptic elimination might be caused by increased instability of the neuronal processes. In vitro evidence shows that melatonin increases MAP-2 expression, a protein that improves the stability of the dendritic cytoskeleton, opening the possibility that melatonin could prevent synaptic elimination by increasing dendritic stability. One way to begin exploring this issue in vivo is to evaluate whether long-term melatonin treatment changes the intensity of MAP-2 immuno-staining in areas commonly afflicted by aging that are rich in dendritic processes. Accordingly, we evaluated the effects of administering melatonin for 6 or 12 months on the intensity of MAP-2 immuno-staining in the strata oriens and lucidum of the hippocampal CA1 and CA3 fields of aging male rats, through semi-quantitative densitometry. Melatonin treated rats showed a relative increment in the intensity of MAP-2 immuno-staining in both regions after 6 or 12 months of treatment, as compared with age matched control rats. Although melatonin untreated and treated rats showed a decrease of MAP-2 immuno-staining in the hippocampus with increasing age, such decrement was less pronounced following melatonin treatment. These findings were confirmed by qualitative Western blot analyses. The melatonin effect seems specific because MAP-2 staining in the primary somatosensory cortex was not affected by the treatment. Thus, chronic melatonin administration increases MAP-2 immuno-staining and attenuates its decay in the adult aging hippocampus. These results are compatible with the idea that melatonin could improve dendritic stability and thus diminish synaptic elimination in the aging brain.     

Protective effect of alpha7 nAChR: Behavioural and morphological features on neuropathy

Traumatic, toxic or metabolic damage to the nervous system is the etiological foundation of neuropathic pain. Neuropathies are extremely difficult to treat and available drugs rarely joint an anti-hyperalgesic with a neurorestorative effect. From the literature, evidences support the alpha7 nicotinic receptor (nAChR) subtype as having a role in neuropathic pain as well as possessing neuroprotective properties. Aimed to inquire the anti-neuropathic effect of the alpha7 nAChR stimulation, we evaluated the pharmacological profile of the alpha7 nAChR agonist PNU-282987 on pain and on morphological alterations induced in the rat sciatic nerve by loose ligation (CCI).     

The cyclooxygenase and lipoxygenase inhibitor BW755C protects rats against kainic acid-induced seizures and neurotoxicity

In this study the effect of the anti-inflammatory drugs indomethacin, ibuprofen, ebselen (PZ 51, 2-phenyl-1,2-benzoiso-selenazol-3(2H)-one), and BW755C (3-amino-1-(m-(trifluoromethyl-phenyl)-2-pyrazoline) on kainic acid (KA)-induced behavioral and neurochemical changes in rats was investigated. Rats injected with KA (10 mg/kg s.c.) developed seizure activity with a 20% mortality within the first 4 h and neuronal degeneration in the limbic system after 3 days. Pretreatment with the cyclooxygenase inhibitor indomethacin (10 mg/kg i.p.) augmented KA-induced epileptic activity and increased the mortality in status epilepticus to 80%. Another cyclooxygenase inhibitor, ibuprofen (20 mg/kg i.p.), and the lipoxygenase inhibitor ebselen (20 mg/kg i.p.) showed no effect on KA-induced symptoms and neurochemical changes. Application of the cyclooxygenase/lipoxygenase inhibitor BW775C (40 mg/kg i.p.) reduced the severity of seizures and protected significantly from irreversible brain lesions induced by KA. The marked reduction of glutamate decarboxylase (GAD; 53.3 ± 12.2% of control) and choline acetyltransferase (ChAT; 60.9 ± 9.1% of control) activities in amygdala/pyriform cortex and GAD activity in hippocampus (69.4 ± 5.6% of control) observed 3 days after KA injection was abolished by BW755C treatment. Histopathological analyses of brain tissue showed that treatment with BW755C prevented the KA-induced nerve cell degeneration, edema, hemorrhages, and tissue necrosis in amygdala/pyriform cortex. However, some cell loss in the hippocampus was present, predominantly in its CA3 sector, and to a mild extent also in insular cortex and entorhinal/pyriform cortex. Our results indicate that BW755C may inhibit seizure-induced brain damage either through the blockade of both prostaglandin and leukotriene synthesis or by its action as an oxygen radical scavenger.