硬毛巴豆减弱链脲佐菌素诱导大鼠的神经炎症

Croton hirtus attenuating streptozotocin-induced neuroinflammation in rats

目的本研究旨在探讨硬毛巴豆(CH)提取物在链脲佐菌素(STZ)大鼠中的神经保护作用。方法(1)亚慢性毒性试验包括24只成年大鼠,雌雄不限,体重160~200 g,分为4组,每组6只。第1组大鼠给予二甲基亚砜(DMSO)与生理盐水混合物;第2、3、4组大鼠灌胃给药硬毛巴豆甲醇提取物(MECH),剂量分别为100、200和400 mg/kg,连续28天。将功能观察组合和自发活动分级作为其神经行为活动的一部分,并对脑区(如皮质和海马)进行神经病理学异常分析。(2)研究动物体重为160~200 g的成年雄性Wistar大鼠,分为5组,每组6只,包括对照组(Ⅰ)、STZ组(Ⅱ)、多奈哌齐组(Ⅲ)、MECH组(100 mg/kg,Ⅳ)和MECH组(200 mg/kg,Ⅴ)。第Ⅰ组大鼠口服柠檬酸盐缓冲液和DMSO生理盐水混合物(14天)。第Ⅱ组大鼠在第1天和第3天侧脑室注射链脲佐菌素(3 mg/kg,双侧ICV-STZ),随后给予生理盐水DMSO混合物(14天)。第Ⅲ、Ⅳ和Ⅴ组大鼠在第1天和第3天给予STZ,随后口服多奈哌齐[3 mg/(kg·d)]和MECH[100和200 mg/(kg·d)](14天)。检测大鼠Morris水迷宫(MWM)和被动回避试验(PAT)等学习记忆指标。完成行为学实验后处死动物,取脑,用紫外可见分光光度计测定乙酰胆碱酯酶(AChE)、脂质过氧化(LPO)、谷胱甘肽(GSH)和超氧化物歧化酶(SOD)水平。使用总荧光发射光谱法测定caspase-3水平。通过酶联免疫吸附测定(ELISA)检测β淀粉样蛋白(Aβ)水平,同时对CA1海马区进行组织病理学分析。结果(1)亚慢性毒性结果显示,各组MECH大鼠的旷场试验参数(包括线交叉、直立、进入中广场、排便或排尿)无显著差异(P>0.05)。组织病理学结果显示,与对照组大鼠相比,经过MECH治疗的大鼠两个区域的神经元细胞中均未产生任何病变和炎症。(2)研究主要发现STZ处理大鼠在学习和记忆参数受损显著增加(P<0.001),AChE、caspase-3、Aβ(1-40和1-42)和LPO水平均显著升高(P<0.001),且SOD和GSH水平显著降低(P<0.01)。此外,在海马区发现神经元损伤。相反,STZ诱导大鼠的行为和生化损伤与MECH治疗呈剂量依赖性降低。结论MECH通过其抗氧化作用可显著预防STZ诱导的记忆缺陷,胆碱能功能的恢复可能是行为改善的原因。因此,MECH可能治疗包括阿尔茨海默病在内的认知障碍。

Objective The present study was aimed to investigate the neuroprotective effect of Croton hirtus(CH)extract against streptozotocin(STZ)in rats.Methods(i)The sub-chronic toxicity consisted of 24 adult rats of either sex weighing from 160 to 200 g were divided into four groups with six rats in each group.Rats in group 1 received Dimethyl sulfoxide(DMSO)mixed with saline;rats in groups 2,3,and 4 received 100,200,and 400 mg/kg of methanolic extract of CH(MECH)orally by gavage administration for 28 d,respectively.The functional observation battery and locomotor activity were graded as part of their neurobehavioral activity and the brain regions,including cortex and hippocampus,were analyzed for neuropathological abnormalities.(ii)The main research consisted of 30 adult male Wistar rats weighing from 160 to 200 g,which were divided into five groups and six rats in each group,including control(I),STZ(II),Donepezil(III),MECH(100 mg/kg,IV),and MECH(200 mg/kg,V)groups.Rats in group I received citrate buffer orally and DMSO mixed with saline for 14 d.Rats in group II received STZ via intracerebroventricular injection(3 mg/kg,bilateral ICV-STZ)on days 1 and 3 followed by DMSO mixed with saline for 14 d.Rats in groups III,IV,and V received STZ administration on days 1 and 3 followed by Donepezil[3 mg/(kg·d),p.o.]and MECH[100 and 200 mg/(kg·d),p.o.]for 14 d.Rats were tested for learning and memory parameters such as Morris water maze(MWM)and passive avoidance test(PAT).They were sacrificed after completing behavioural experiments;brains were harvested to estimate the acetylcholinesterase(AChE),lipid peroxidation(LPO),glutathione(GSH),and superoxide dismutase(SOD)by using UV-Visible Spectrophotometer;caspase-3 was evaluated by total fluorescence emission spectra;amyloidβ(Aβ)levels were detected using enzyme-linked immuosorbent assay(ELISA);and histopathological examination was conducted in the CA1 region of the hippocampus.Results(i)The sub-chronic toxicity results revealed that open field test parameters including line crossing,rearing,entering the middle square,defecating,or urinating did not differ significantly in the MECH rats(P>0.05).The histopathological observation did not show any lesions in the neuronal cells and inflammation in both the regions in MECH rats compared with control rats.(ii)The main study findings demonstrated that STZ-treated rats showed a significant increase in impairment in learning and memory parameters(P<0.001),the levels of AChE,caspase-3,Aβ(1-40 and 1-42),and LPO were increased significantly(P<0.001),and significant decrease was found in the levels of SOD(P<0.001)and GSH(P<0.01).Moreover,neuronal damage was found in the hippocampus.In contrast,STZ-induced behavioural and biochemical impairments in rats were considerably decreased by treatment with MECH dosedependently.Conclusion MECH significantly prevented the memory deficit induced by STZ due to antioxidant action.Restoration of cholinergic functioning may be the cause of behavioural improvement.Therefore,MECH may be able to treat cognitive disorders like Alzheimer's disease(AD).