Melatonin attenuates gray and white matter damage in a mouse model of transient focal cerebral ischemia

We have previously shown that melatonin reduces infarct volumes and enhances neurobehavioral and electrophysiological recoveries following transient middle cerebral artery (MCA) occlusion in rats. In the study, we examined whether melatonin would display neuroprotection against neuronal, axonal and oligodendrocyte pathology after 24 hr of reperfusion following 1 hr of MCA occlusion in mice. Melatonin (5 mg/kg) or vehicle was given intraperitoneally at the commencement of reperfusion. Neurological deficits were assessed 24 hr after ischemia. Gray matter damage was evaluated by quantitative histopathology. Axonal damage was determined with amyloid precursor protein and microtubule-associated protein tau-1 immunohistochemistry to identify postischemic disrupted axonal flow and oligodendrocyte pathology, respectively. Oxidative damage was assessed by 8-hydroxy-2'-deoxyguanosine (8-OHdG) and 4-hydroxynonenal (4-HNE) immunohistochemistry. Relative to controls, melatonin-treated animals not only had a significantly reduced volume of gray matter infarction by 42% (P<0.001), but also exhibited a decreased score of axonal damage by 42% (P<0.001) and a reduction in the volume of oligodendrocyte pathology by 58% (P<0.005). Melatonin-treated animals also had significantly reduced immunopositive reactions for 8-OHdG and 4-HNE by 53% (P<0.001) and 49% (P<0.001), respectively. In addition, melatonin improved sensory and motor neurobehavioral outcomes by 47 and 30%, respectively (P<0.01). Thus, delayed (1 hr) treatment with melatonin reduced both gray and white matter damage and improved neurobehavioral outcomes following transient focal cerebral ischemia in mice. The finding of reduced oxidative damage observed with melatonin suggests that its major mechanisms of action are mediated through its antioxidant and radical scavenging activity.     

Delayed treatment with melatonin enhances electrophysiological recovery following transient focal cerebral ischemia in rats

Melatonin has been reported to reduce infarct volumes induced by transient middle cerebral artery (MCA) occlusion. We examined whether melatonin could improve electrophysiological and neurobehavioral recoveries in rats after 72 hr of reperfusion following 1.5 hr of MCA occlusion. Melatonin (5 mg/kg) or vehicle was given intravenously at the commencement of reperfusion. Neurobehavioral outcome was serially examined, and somatosensory evoked potentials (SSEP) were recorded prior to ischemia and at 72 hr after the onset of reperfusion. Brain infarction was assessed upon killing. Before ischemia-reperfusion, stable SSEP waveforms were consistently recorded after individual fore- or hindpaw stimulation. The amplitude between the first positive (P1) and the first negative (N1) peaks and the P1 latency did not differ significantly between controls and melatonin-treated animals. At 72 hr of reperfusion, controls had severely depressant SSEPs recorded from ischemic fore- and hindpaw cortical fields, and the amplitudes decreased to 36 and 35% of baselines, respectively (P < 0.001). These animals also had transcallosal electrophysiological diaschisis in the SSEPs recorded at the contralateral hindpaw cortical field (P < 0.01). Relative to controls, melatonin-treated animals not only had significantly improved amplitudes of the SSEPs recorded from both ischemic fore- and hindpaw cortical fields, by 33 and 37% of baselines, respectively (P < 0.001), but also exhibited diminished transcallosal electrophysiological diaschisis following ischemia-reperfusion. In addition, melatonin improved sensory and motor neurobehavioral outcomes by 40 and 28%, respectively (P < 0.001), and reduced cortical and striatal infarct sizes by 32 and 40%, respectively (P < 0.05). Thus, delayed intravenous administration with melatonin both enhances electrophysiological and neurobehavioral recoveries and reduces cortical and striatal infarct sizes after cerebral ischemia and reperfusion injury.     

Intravenous administration of melatonin reduces the intracerebral cellular inflammatory response following transient focal cerebral ischemia in rats

We have previously shown that exogenous melatonin improves the preservation of the blood-brain barrier (BBB) and neurovascular unit following cerebral ischemia-reperfusion. Recent evidence indicates that postischemic microglial activation exaggerates the damage to the BBB. Herein, we explored whether melatonin mitigates the cellular inflammatory response after transient focal cerebral ischemia for 90 min in rats. Melatonin (5 mg/kg) or vehicle was given intravenously at reperfusion onset. Immunohistochemistry and flow cytometric analysis were used to evaluate the cellular inflammatory response at 48 hr after reperfusion. Relative to controls, melatonin-treated animals did not have significantly changed systemic cellular inflammatory responses in the bloodstream (P > 0.05). Melatonin, however, significantly decreased the cellular inflammatory response by 41% (P < 0.001) in the ischemic hemisphere. Specifically, melatonin effectively decreased the extent of neutrophil emigration (Ly6G-positive/CD45-positive) and macrophage/activated microglial infiltration (CD11b-positive/CD45-positive) by 51% (P < 0.01) and 66% (P < 0.01), respectively, but did not significantly alter the population composition of T lymphocyte (CD3-positive/CD45-positive; P > 0.05). This melatonin-mediated decrease in the cellular inflammatory response was accompanied by both reduced brain infarction and improved neurobehavioral outcome by 43% (P < 0.001) and 50% (P < 0.001), respectively. Thus, intravenous administration of melatonin upon reperfusion effectively decreased the emigration of circulatory neutrophils and macrophages/monocytes into the injured brain and inhibited focal microglial activation following cerebral ischemia-reperfusion. The finding demonstrates melatonin's inhibitory ability against the cellular inflammatory response after cerebral ischemia-reperfusion, and further supports its pleuripotent neuroprotective actions suited either as a monotherapy or an add-on to the thrombolytic therapy for ischemic stroke patients.     

Melatonin decreases neurovascular oxidative/nitrosative damage and protects against early increases in the blood-brain barrier permeability after transient focal cerebral ischemia in mice

We have recently shown that melatonin decreases the late (24 hr) increase in blood-brain barrier (BBB) permeability and the risk of tissue plasminogen activator-induced hemorrhagic transformation following ischemic stroke in mice. In the study, we further explored whether melatonin would reduce postischemic neurovascular oxidative/nitrosative damage and, therefore, improve preservation of the early increase in the BBB permeability at 4 hr after transient focal cerebral ischemia for 60 min in mice. Melatonin (5 mg/kg) or vehicle was given intraperitoneally at the beginning of reperfusion. Hydroethidine (HEt) in situ detection and immunohistochemistry for nitrotyrosine were used to evaluate postischemic accumulation in reactive oxygen and nitrogen species, respectively, in the ischemic neurovascular unit. BBB permeability was evaluated by spectrophotometric and microscopic quantitation of Evans Blue leakage. Relative to controls, melatonin-treated animals not only had a significantly reduced superoxide accumulation in neurovascular units in boundary zones of infarction, by reducing 35% and 54% cytosolic oxidized HEt in intensity and cell-expressing percentage, respectively (P < 0.001), but also exhibited a reduction in nitrotyrosine by 52% (P < 0.01). Additionally, melatonin-treated animals had significantly reduced early postischemic disruption in the BBB permeability by 53% (P < 0.001). Thus, melatonin reduced postischemic oxidative/nitrosative damage to the ischemic neurovascular units and improved the preservation of BBB permeability at an early phase following transient focal cerebral ischemia in mice. The findings further highlight the ability of melatonin in anatomical and functional preservation for the ischemic neurovascular units and its relevant potential in the treatment of ischemic stroke.     

依达拉奉对大鼠局灶性脑缺血再灌注后Caspase—3蛋白表达的影响

目的在大鼠脑缺血再灌注损伤发生后,用自由基清除剂依达拉奉对其进行治疗,监测再灌注不同时间点脑组织Cas-pase-3蛋白表达情况。研究依达拉奉对脑缺血再灌注损伤的保护作用。方法制作短暂、局灶性脑缺血再灌注模型。分为正常组及假手术组(对照组)、脑缺血再灌注对照组(缺血组)、依达拉奉治疗组(治疗组),分别于缺血1h后进行再灌注。治疗组于再灌注后30min腹腔内及皮下各注射依达拉奉1次(按依达拉奉3mg/kg),30min后重复一次。设再灌注后2h、6h、12h、24h、48h不同时间点,各时间点以0.4%戊巴比妥钠深度麻醉后快速断头法将大鼠处死,以4%多聚甲醛灌注固定后取脑,行免疫组化检测各时间点脑组织Caspase-3表达阳性细胞数。结果缺血组再灌注后2h在大脑额叶和顶叶皮质和海马即可见到Caspase-3蛋白表达的阳性细胞,12h达高峰,24h后开始下降。治疗组各时间点Caspase-3表达水平较对照组明显降低(P<0.01)。结论依达拉奉可抑制Caspase-3的表达,对缺血再灌注损害的脑组织有明显的保护作用。     

Melatonin attenuates the postischemic increase in blood-brain barrier permeability and decreases hemorrhagic transformation of tissue-plasminogen activator therapy following ischemic stroke in mice

Melatonin protects against transient middle cerebral artery (MCA) occlusion and may be suited as an add-on therapy of tissue plasminogen activator (t-PA) thrombolysis. Herein, we examined whether melatonin would reduce postischemic increase in the blood-brain barrier (BBB) permeability and, therefore, attenuate the risk of hemorrhagic transformation after t-PA therapy in experimental stroke. Twelve mice were subjected to transient occlusion of the MCA for 1 hr, followed by 24 hr of reperfusion. Melatonin (5 mg/kg, i.p.) or vehicle was given at the beginning of reperfusion. BBB permeability was evaluated by quantitation of Evans Blue leakage. An additional 32 mice underwent photothrombotic occlusion of the distal MCA, and were administered vehicle or t-PA (10 mg/kg, i.v.), alone or in combination with melatonin (5 mg/kg, i.p.), at 6 hr postinsult. The animals were then killed after 24 hr for the determination of infarct and hemorrhage volumes. Relative to controls, melatonin-treated animals had significantly reduced BBB permeability (by 52%; P < 0.001). Additionally, we found that at 6 hr after photo-irradiation, either t-PA or melatonin, or a combined administration of t-PA plus melatonin, did not significantly affect brain infarction (P > 0.05), compared with controls. Mice treated with t-PA alone, however, had significantly increased hemorrhagic formation (P < 0.05), and the event was effectively reversed by co-treatment with melatonin (P < 0.05). Thus, melatonin improved postischemic preservation of the BBB permeability and a decreased risk of adverse hemorrhagic transformation after t-PA therapy for ischemic stroke. The findings further highlight melatonin's potential role in the field of thrombolytic treatment for ischemic stroke patients.     

Melatonin improves presynaptic protein, SNAP-25, expression and dendritic spine density and enhances functional and electrophysiological recovery following transient focal cerebral ischemia in rats

Abstract: Synapto-dendritic dysfunction and rearrangement takes place over time at the peri-infarct brain after stroke, and the event plays an important role in post-stroke functional recovery. Here, we evaluated whether melatonin would modulate the synapto-dendritic plasticity after stroke. Adult male Sprague-Dawley rats were treated with melatonin (5 mg/kg) or vehicle at reperfusion onset after transient occlusion of the right middle cerebral artery (tMCAO) for 90 min. Local cerebral blood perfusion, somatosensory electrophysiological recordings and neurobehavioral tests were serially measured. Animals were sacrificed at 7 days after tMCAO. The brain was processed for Nissl-stained histology, Golgi–Cox-impregnated sections, or Western blotting for presynaptic proteins, synaptosomal-associated protein of 25 kDa (SNAP-25) and synaptophysin (a calcium-binding protein found on presynaptic vesicle membranes). Relative to controls, melatonin-treated animals had significantly reduced infarction volumes (P < 0.05) and improved neurobehavioral outcomes, as accessed by sensorimotor and rota-rod motor performance tests (P < 0.05, respectively). Melatonin also significantly improved the SNAP-25, but not synaptophysin, protein expression in the ischemic brain (P < 0.05). Moreover, melatonin significantly improved the dendritic spine density and the somatosensory electrophysiological field potentials both in the ischemic brain and the contralateral homotopic intact brain (P < 0.05, respectively). Together, melatonin not only effectively attenuated the loss of presynaptic protein, SANP-25, and dendritic spine density in the ischemic territory, but also improved the reductions in the dendritic spine density in the contralateral intact brain. This synapto-dendritic plasticity may partly account for the melatonin-mediated improvements in functional and electrophysiological circuitry after stroke.     

松龄血脉康预处理对脑缺血再灌注大鼠脑组织基质金属蛋白酶-9表达的影响

目的 探讨松龄血脉康预处理对脑缺血再灌注大鼠脑组织基质金属蛋白酶-9(matrix metalloproteinase-9,MMP-9)表达的影响.方法 45只雄性SD大鼠,随机分为松龄血脉康(SL-xmk)预处理组、假手术组和生理盐水对照组.SL-xmk预处理组采用SL-xmk悬浮液(937.5 mg/kg)对大鼠...     

Evidence that membrane-bound G protein-coupled melatonin receptors MT1 and MT2 are not involved in the neuroprotective effects of melatonin in focal cerebral ischemia

Melatonin is synthesized and released by the pineal gland in a circadian rhythm, and many of its peripheral actions are mediated via membrane MT1 and MT2 receptors. Apart from its metabolic functions, melatonin is a potent neuroprotective molecule owing to its antioxidative actions. The roles of MT1 and MT2 in the neuroprotective effects of melatonin and cell signaling after cerebral ischemia remain unknown. With the use of MT1 and MT2 knockout (mt1/2(-/-) ) mice treated with melatonin, we evaluated brain injury, edema formation, inducible nitric oxide synthase (iNOS) activity, and signaling pathways, including CREB, ATF-1, p21, Jun kinase (JNK)1/2, p38 phosphorylation, resulting from ischemia/reperfusion injury. We show that the infarct volume and brain edema do not differ between mt1/2(-/-) and wild-type (WT) animals, but melatonin treatment decreases infarct volume in both groups and brain edema in WT animals after middle cerebral artery occlusion. Notably, melatonin's neuroprotective effect was even more pronounced in mt1/2(-/-) animals compared to that in WT animals. We also demonstrate that melatonin treatment decreased CREB, ATF-1, and p38 phosphorylation in both mt1/2(-/-) and WT mice, while p21 and JNK1/2 were reduced only in melatonin-treated WT animals in the ischemic hemisphere. Furthermore, melatonin treatment lowered iNOS activity only in WT animals. We provide evidence that the absence of MT1 and MT2 has no unfavorable effect on ischemic brain injury. In addition, the neuroprotective effects of melatonin appear to be mediated through a mechanism independent of its membrane receptors. The underlying mechanism(s) should be further studied using selective melatonin receptor agonists and antagonists.     

Melatonin inhibits matrix metalloproteinase-9 (MMP-9) activation in the lipopolysaccharide (LPS)-stimulated RAW 264.7 and BV2 cells and a mouse model of meningitis

Abstract: We explored anti‐inflammatory potential of melatonin against the lipopolysaccharide (LPS)‐induced inflammation in vivo and in vitro. RAW 264.7 and BV2 cells were stimulated by LPS, followed by the treatment with melatonin or vehicle at various time intervals. In a mouse model of meningitis induced by LPS, melatonin (5 mg/kg) or vehicle was intravenously injected at 30 min postinsult. The activity of matrix metalloproteinase‐2 (MMP‐2) and metalloproteinase‐9 (MMP‐9) was determined by gelatin zymography. Nuclear factor‐kappa B (NFκB) translocation and binding activity were determined by immunocytochemistry and electrophoretic mobility shift assay (EMSA). Our results showed that either pretreatment or cotreatment with melatonin at 50–500 μm effectively inhibited the LPS‐induced proMMP‐9 activation in the RAW 264.7 and BV2 cells, respectively (P < 0.05). This melatonin‐induced proMMP‐9 inhibition remained effective when treatment was delayed up to 2 and 6 hr postinsult for RAW 264.7 and BV2 cells, respectively (P < 0.05 for both groups). Additionally, melatonin significantly attenuated the rises of circulatory and cerebral MMP‐9 activity, respectively (P < 0.05) and reduced the loss of body weight (P < 0.05) in mice with meningitis. Moreover, melatonin (50 μm ) effectively inhibited nuclear factor‐kappa B (NFκB) translocation and binding activity in the LPS‐treated RAW 264.7 and BV2 cells, respectively (P < 0.05). These results demonstrate direct inhibitory actions of melatonin against postinflammatory NFκB translocation and MMP‐9 activation and highlight its ability to inhibit systemic and cerebral MMP‐9 activation following brain inflammation.     

尤瑞克林注射液对脑梗死患者血清基质金属蛋白酶9及预后的影响

目的研究尤瑞克林注射液对脑梗死患者血清基质金属蛋白酶9(matrix metalloproteinase-9,MMP-9)及预后的影响,探讨尤瑞克林注射液治疗脑梗死的作用机制。方法采用随机、双盲的方法,将发病48 h内入院的大面积脑梗死患者50例分为对照组和尤瑞克林组(尤瑞克林注射液0.15 PNA/d),每组25例,连续用药14 d。治疗前后检测血清MMP-9水平,应用美国国立卫生研究院脑卒中量表(NIHSS)及日常生活活动量表Barthel指数(BI)记分法对入院后当天及3个月时神经功能缺损程度进行评分。结果除尤瑞克林组1例患者用药后血压下降,无其他不良反应。对照组和尤瑞克林组治疗后14 d血清MMP-9水平明显降低,且尤瑞克林组较对照组明显降低,差异有统计学意义(P<0.01);对照组和尤瑞克林组治疗后3个月神经功能缺损程度评分较治疗前明显改善,且尤瑞克林组神经功能缺损程度评分改善明显优于对照组(P<0.01)。结论短期应用尤瑞克林注射液可以改善脑梗死患者的预后,其机制可能与降低血清MMP-9水平有关。     

急性脑梗死溶栓患者血清基质金属蛋白酶-9的动态变化及临床意义

目的观察基质金属蛋白酶-9（MMP-9）在急性脑梗死溶栓治疗患者血清中的动态变化并探讨其临床意义。方法采取30例急性脑梗死溶栓患者（溶栓前、溶栓后6h、24h、7d、14d）的肘静脉血，检测其不同时期血清MMP-9水平，以同期收住院30例脑供血不足患者的血清MMP-9水平作为基线参考。同时对脑梗死患者溶栓前及溶栓后14d行NIHSS评分，溶栓前及溶栓后90d行日常生活能力评分（mRS）以作为近中期疗效判断指标，并按评分改善程度分组比较其MMP-9水平的差异。结果急性脑梗死患者溶栓前及溶栓后6h、24h、7d、14d血清MMP-9水平均较基线水平有显著提高，且呈动态变化，在溶栓后7d达高峰。溶栓后14dNIHSS评分改善程度与MMP-9峰值水平存在负相关（r=0．65），90dmRS评分不同改善程度组其血清MMP-9峰值水平存在差异。结论急性脑梗死溶栓患者血清MMP-9水平呈动态变化，7d达高峰。血清MMP-9峰值水平可以初步预测脑梗死患者溶栓近中期疗效。     

实验性脑出血大鼠脑内基质金属蛋白酶-9的表达作用研究

目的　动态观察实验性脑出血大鼠脑内基质金属蛋白酶 9(MMP 9)表达水平的变化及其作用。方法　 4 5只大鼠随机分为正常对照组、脑出血模型组和假手术组 ,采用胶原酶复制大鼠脑出血模型 ,通过免疫组织化学和原位杂交技术动态测定不同时间点鼠脑内血肿周围脑组织中MMP 9的表达变化 ;同时另选 4 5只大鼠随机分组同上 ,进行脑含水量的测定 ,以观察MMP 9的表达变化与脑水肿程度的相关性。结果　大鼠正常对照组和假手术组均无MMP 9的蛋白和mRNA表达 ,脑出血模型组在 2 4～ 4 8hMMP 9的蛋白和mRNA表达达高峰 ,以后逐渐下降 ,6～ 96h手术侧其蛋白和mRNA表达量与脑含水量呈正相关。结论　实验性大鼠脑出血早期能诱导血肿周围MMP 9的蛋白和mRNA表达增强 ,可能参与了其脑水肿的形成。     

褪黑素对脑出血大鼠基质金属蛋白酶表达及神经功能的影响

目的观察褪黑素对脑出血大鼠神经功能缺损及血肿周围组织基质金属蛋白酶(MMP)表达的影响。方法将SD雄性大鼠85只,随机分为正常组10只、假手术组25只、模型组25只、褪黑素组25只;后2组建立脑出血模型,后3组随机于12h、1、2、4和7d处理,每个时间点5只。修正神经功能缺损评分(NSS)对各组大鼠进行神经功能评估;透射电子显微镜观察出血侧皮质微血管形态;RT-PCR技术定量分析脑组织MMP-2、MMP-9mRNA表达。结果褪黑素组1⁷dNSS低于模型组(P<0.05);褪黑素组和模型组12h7dNSS低于模型组(P<0.05);褪黑素组和模型组12h⁴dMMP-2mRNA水平均逐渐升高,褪黑素组7dMMP-2mRNA明显低于模型组(P<0.05);模型组MMP-9mRNA 2d显著升高,褪黑素组MMP-9mRNA峰值1d出现,7d再次升高,并明显高于模型组(P<0.05)。结论褪黑素能够改善脑出血大鼠神经功能,对脑出血具有保护作用,其机制可能与褪黑素通过调控MMP-2和MMP-9转录,减轻血管源性脑水肿相关。     

Melatonin inhibits matrix metalloproteinase‐9 activity by binding to its active site

The zinc‐dependent matrix metalloproteinases (MMPs) are key enzymes associated with extracellular matrix (ECM) remodeling; they play critical roles under both physiological and pathological conditions. MMP‐9 activity is linked to many pathological processes, including rheumatoid arthritis, atherosclerosis, gastric ulcer, tumor growth, and cancer metastasis. Specific inhibition of MMP‐9 activity may be a promising target for therapy for diseases characterized by dysregulated ECM turnover. Potent MMP‐9 inhibitors including an indole scaffold were recently reported in an X‐ray crystallographic study. Herein, we addressed whether melatonin, a secretory product of pineal gland, has an inhibitory effect on MMP‐9 function. Gelatin zymographic analysis showed a significant reduction in pro‐ and active MMP‐9 activity in vitro in a dose‐ and time‐dependent manner. In addition, a human gastric adenocarcinoma cell line (AGS) exhibited a reduced (~50%) MMP‐9 expression when incubated with melatonin, supporting an inhibitory effect of melatonin on MMP‐9. Atomic‐level interaction between melatonin and MMP‐9 was probed with computational chemistry tools. Melatonin docked into the active site cleft of MMP‐9 and interacted with key catalytic site residues including the three histidines that form the coordination complex with the catalytic zinc as well as proline 421 and alanine 191. We hypothesize that under physiological conditions, tight binding of melatonin in the active site might be involved in reducing the catalytic activity of MMP‐9. This finding could provide a novel approach to physical docking of biomolecules to the catalytic site of MMPs, which inhibits this protease, to arrest MMP‐9‐mediated inflammatory signals.     

脑缺血预处理对脑缺血再灌注大鼠血脑屏障通透性和基质金属蛋白酶-9表达的影响

目的 探讨脑缺血预处理(ischemic preconditioning,IP)对脑缺血再灌注大鼠血脑屏障通透性和基质金属蛋白酶-9(matrix metalloproteinase-9,MMP-9)表达的影响.方法 154只Wistar大鼠随机分为假手术组(14只)、非缺血预处理(non-ischemic preconditioning,NIP)组(70只)和IP组(70只),后两组再随机分为5个亚组,每组14只.线栓法建立大脑中动脉闭塞模型,缺血预处理10 min,分别在IP后1、3、7、14和21 d进行再次缺血2 h再灌注22 h.采用2,3,5-氯化三苯基四氮唑(2,3,5-triphenyltetrazolium chloride,TTC)染色测定脑梗死体积,通过测定渗出血管外的伊文思蓝(Evans blue,EB)含量评价血脑屏障通透性,采用于湿重法评价脑水肿程度,免疫组化染色和原位杂交法检测MMP-9蛋白和mRNA表达.结果 与NIP组相应亚组比较,IP组缺血预处理1、3和7 d亚组神经功能缺损评分显著降低,脑梗死体积显著缩小,EB含量和脑水含量显著降低,MMP-9蛋白和mRNA表达均显著下调(P＜0.05或P＜0.01).IP组1、3和7 d亚组梗死体积和MMP-9 mRNA表达较IP组14 d和21 d亚组显著缩小或下调,3 d和7 d亚组EB含量、脑水含量和MMP-9蛋白表达较其他亚组显著降低,其中以3 d亚组降低最显著(P＜0.05).结论 缺血预处理诱导的血脑屏障通透性改变和MMP-9表达下调在脑缺血耐受中发挥着重要作用.     

人参皂甙Rg1对脑缺血-再灌注大鼠基质金属蛋白酶2和9表达的影响

目的探讨人参皂甙Rg1对脑缺血-再灌注大鼠脑组织基质金属蛋白酶2（MMP-2）和基质金属蛋白酶9（MMP-9）表达的影响。方法取健康雄性SD大鼠60只。将其随机分为假手术组,模型组,尼莫地平组,人参皂甙Rg110、20、40mg/kg组,每组10只。采用线栓法栓塞2h制作大脑中动脉模型。4个药物组于术前5d至取材当日,每日清晨于腹腔注射人参皂甙Rg1（10、20、40mg/kg）及尼莫地平1mg/kg（均溶于1.5ml的等渗盐水中）,其余各组于同一时间点注射1.5ml等渗盐水,1次/d。观察再灌注24h后神经功能缺损评分;应用免疫组化、免疫印迹法检测海马CA1区MMP-2、MMP-9的表达情况。结果①假手术组、模型组,尼莫地平组和人参皂甙Rg110、20、40mg/kg组神经功能缺损评分,分别为0、2.8±0.9、1.5±0.7、2.1±0.9、1.5±0.7及1.3±1.1,差异均有统计学意义（P〈0.05）。人参皂甙Rg120、40mg/kg组与模型组比较,差异有统计学意义（P〈0.05）。人参皂甙Rg110、20、40mg/kg组与尼莫地平组比较,差异均无统计学意义（P〉0.05）。②免疫组化和免疫印迹结果显示各组均有MMP-2、MMP-9的表达,其中假手术组仅有少量表达,模型组表达量最多。与模型组比较,人参皂甙Rg110、20、40mg/kg组及尼莫地平组MMP-2、MMP-9的表达量减少,差异有统计学意义（P〈0.05）;与尼莫地平组比较,人参皂甙Rg110mg/kg组的MMP-2、MMP-9表达量显著增高,40mg/kg组显著降低（P〈0.05）,而20mg/kg组则差异无统计学意义（P〉0.05）。结论人参皂甙Rg1防治大鼠脑缺血-再灌注损伤的机制可能与抑制脑组织MMP-2、MMP-9表达有关,且以高剂量组效果较好。     

Prognostic significance of p53 and matrix metalloproteinase-9 expression in follicular lymphoma

Objectives: p53 mutations and high protein expression are associated with adverse prognosis in several lymphoma subtypes. Matrix metalloproteinase‐9 (MMP‐9) has also been found to correlate with poor survival in all lymphomas studied. The data concerning the clinical role of protein expression of p53 or gelatinases and their inhibitors in follicular lymphoma are rare. The purpose of this study was to evaluate the prognostic and clinical implications of the immunoreactive proteins p53, MMP‐2, MMP‐9, tissue inhibitor of matrix metalloproteinase‐1 (TIMP‐1) and TIMP‐2 in follicular lymphoma. Methods: The material consisted of 67 patients with primarily non‐transformed follicular lymphoma. Diagnostic lymph node tissue sections of patients were stained by immunohistochemical method using specific monoclonal antibodies. Results: p53 over‐expression was detected in 8 (12%) out of 67 cases. p53 over‐expression correlated with high grade (P = 0.011), bulky tumour (P = 0.031) and forthcoming transformation (P = 0.001). It also correlated with poor overall (P = 0.001) and cause‐specific survival (P = 0.010) in multivariate analysis and had a strong inverse correlation with time to transformation (P < 0.001). MMP‐2, MMP‐9 and TIMP‐2 expression correlated with high grade. MMP‐9 positivity in centroblasts correlated with good chemotherapy response (P = 0.019), but it was not prognostic for survival. MMP‐2, TIMP‐1 or TIMP‐2 did not associate with survival, either. Conclusions: In this study, p53 over‐expression predicted both transformation to diffuse large B‐cell lymphoma and poorer overall and cause‐specific survival of patients with follicular lymphoma. Expression of gelatinases or their inhibitors did not have any significant correlations with prognosis, although MMP‐9 predicted a good response to first‐line chemotherapy.     

Role of melatonin in regulating matrix metalloproteinase-9 via tissue inhibitors of metalloproteinase-1 during protection against endometriosis

Abstract:  Endometriosis is a gynecological disease of women and plausibly regulated by matrix metalloproteinases (MMPs). However, mechanisms of alterations in MMPs during endometriosis remain unclear. Human endometriotic tissues possessing varying degrees of severity were examined for expression of MMPs and tissue inhibitors of metalloproteinase (TIMP)-1. In addition, endometriosis was generated in mice and endometriotic tissues were tested for MMP-9 activity. Results show significant upregulation of secreted and synthesized proMMP-9 activity with duration and severity of endometriosis. Along with upregulation of activity, the expression of proMMP-9 was found increased while TIMP-1 expression followed an inverse trend. The effect of melatonin, a major secretory product of the pineal gland, on endometriosis was examined in preventive and therapeutic models in mice. The results show that melatonin arrested lipid peroxidation and protein oxidation and downregulated proMMP-9 activity and expression in a time and dose-dependent manner while protecting and regressing peritoneal endometriosis. Moreover, the attenuated activity and expression of proMMP-9 were associated with subsequent elevation in the expression of TIMP-1. Our study reveals for the first time the role of melatonin in arresting peritoneal endometriosis in mice and a novel marker, expression ratio of proMMP-9 versus TIMP-1, was identified for assessing severity and progression of endometriosis.     

Melatonin protects against transient focal cerebral ischemia in both reproductively active and estrogen-deficient female rats: the impact of circulating estrogen on its hormetic dose-response

Melatonin (5-15 mg/kg) protects male animals against ischemic stroke. We explored the potential interactions and synergistic neuroprotection of melatonin and estrogen using a panel of lipid peroxidation and radical-scavenging assays, primary neuronal cultures subjected to oxygen-glucose deprivation (OGD), and lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. Neuroprotective efficacy of melatonin was also evaluated in both reproductively active and ovariectomized female rats subjected to transient focal cerebral ischemia. Relative to melatonin or estradiol (E2) alone, a combination of the two agents exhibited robust, synergistic antioxidant and radical-scavenging actions (P<0.05, respectively). Additionally, the two agents, when combined at large doses, showed synergistic inhibition in the production of tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) in the LPS-stimulated RAW 264.7 cells (P<0.05, respectively). Alternatively, co-treatment with melatonin and E2 independently, but not combined, showed a U-shaped dose-responsive (hormetic) cytoprotection for neuronal cultures subjected to OGD. When combined at a dosage either positively or negatively skewed from each optimal dosage, however, co-treatment caused synergistic neuroprotection. Relative to vehicle-injected controls, melatonin given intravenously at 1-5 mg/kg, but not 0.1 or 15 mg/kg, significantly reduced brain infarction and improved neurobehavioral outcomes (P<0.05, respectively) in reproductively active female rats. In ovariectomized stroke rats, melatonin was only effective at a large dosage (15-50 mg/kg). These results demonstrate complex interactions and synergistic antioxidant, radical-scavenging, and anti-inflammatory actions between estradiol and melatonin, and highlight the potential need to rectify the melatonin's hormetic dose-response by the level of circulating estradiol in the treatment of female stroke patients.