Alterations in BDNF and phospho-CREB levels following chronic oral nicotine treatment and its withdrawal in dopaminergic brain areas of mice

Neuronal changes induced by chronic nicotine in the brain dopaminergic circuits are thought to lead to compulsive nicotine use. When nicotine is given to mice chronically in their drinking water, its intake and effects mimic human smoking. Previously, we have reported that this treatment in mice induces several neurochemical and behavioural changes that are associated with nicotine addiction. Here we studied the effects of chronic oral nicotine treatment and nicotine treatment cessation on two well-characterised markers of neuronal plasticity, brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP-responsive element-binding protein (pCREB), in several dopaminergic brain areas. BDNF levels were not altered by chronic nicotine treatment, but they were significantly increased in the nucleus accumbens (NAc) after 24 h and 29 days of nicotine abstinence and in the ventral tegmental area (VTA) and substantia nigra after 29 days of nicotine abstinence. These findings suggest that nicotine abstinence promotes long-lasting neuroadaptations in dopaminergic neurocircuits by inducing BDNF production. Withdrawal from chronic nicotine treatment oppositely affected pCREB levels in the NAc and in the VTA. Thus, in the NAc, the pCREB levels were significantly elevated and in the VTA significantly decreased as compared with the pCREB levels during the nicotine treatment. These alterations could be compensatory and related to increased dopaminergic signalling during nicotine treatment. In conclusion, the current results suggest the involvement of BDNF- and CREB-related neuronal processes in nicotine-induced neurochemical, behavioural, and neuroplastic changes in dopaminergic neurocircuits.     

Differences in localization of substantia nigra vs interaural line in Wistar and Sprague Dawley rats

The position of substantia nigra anterior to the interaural line has been correlated with body weight in Wistar rats. A regression line y=0.0050x+1.36 makes it possible to locate the substantia nigra in different sized rats ranging between 140 g and 460 g. This equation is not valid for Sprague Dawley rats. The position of bregma anterior to the interaural line has also been examined. A fairly good correlation was found for Sprague Dawley rats while the position of bregma in Wistar rats was much more variable.     

Perinatal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin suppresses contextual fear conditioning-accompanied activation of cyclic AMP response element-binding protein in the hippocampal CA1 region of male rats

We investigated the effect of in utero and lactational exposures to dioxin on adult offspring with contextual fear conditioning, a sex- and hippocampus-dependent learning paradigm; and we measured the conditioning-accompanied activation of cyclic AMP response element-binding protein (CREB) in the hippocampal CA1 region. Pregnant rats were treated with a low dose of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on gestation day 15. TCDD treatment decreased freezing time in conditioning tests of adult male offspring but not of female offspring. A similar, male-specific decrease was observed in the percentage of phosphorylated CREB-immunoreactive neurons in the CA1 region following conditioning in TCDD-treated rats. These results suggest that perinatal TCDD exposure impairs hippocampus-dependent learning in male offspring by suppressing CREB activation.     

Behavioral and neurobiological studies on the male progeny of maternal rats exposed to chronic unpredictable stress before pregnancy

Studies have shown that maternal chronic stress or depression is linked to an increased risk for affective disorders in progeny. However, the impact of maternal chronic stress before pregnancy on their progeny in animal models has not been well studied. We investigated the behaviors and the neurobiology in 60-day-old male progeny of maternal rats exposed to a 21-day chronic unpredictable stress (CUS) before pregnancy, with male progeny of unstressed maternal rats as the control. Sucrose consumption test showed that both sucrose intake and sucrose consumption percentage of the CUS progeny were lower than those of the control progeny (P < 0.05). The number of times crossing the removed hidden platform in the CUS progeny was significantly fewer than that in the control progeny in Morris water maze test (P < 0.05). The level of 5-hydroxytryptamine (5-HT) in the hypothalamus was reduced but the level of norepinephrine (NE) in the hippocampus was increased in CUS progeny when compared to the control (P < 0.05). Western blotting showed that the relative level of phosphorylated CREB (P-CREB) in the CUS progeny was lower than that in the control progeny (P < 0.05). There were significant positive correlations between sucrose consumption percentage and the level of 5-HT in hypothalamus P < 0.05) or the level of P-CREB in hippocampus (P < 0.05). In conclusion, depression or stressful events before pregnancy was also associated with high risk of depression in progeny, and the down-regulation of P-CREB in the hippocampus might be one of the mechanisms underlying depression in the CUS progeny.     

星形胶质细胞内三羧酸循环在福尔马林诱导的大鼠脊髓中枢敏化中的作用

目的:探讨星形胶质细胞内的三羧酸循环在福尔马林诱导的大鼠炎性持续性痛、慢性痛和脊髓中枢敏化中的作用。方法:在大鼠右后肢足底注射福尔马林(5%,0.05 ml)制备炎性持续性痛大鼠模型,鞘内注射100 nmol/ml氟代柠檬酸(fluorocitrate,FC)和/或5×104nmol/ml谷氨酸(L-glutamate,Glu)后,观察大鼠的行为学变化。结果:(1)急性期:与对照组相比,鞘内注射FC对大鼠自发伤害性行为(舔咬爪和缩腿反射)有抑制作用,而鞘内注射了Glu部分翻转了该抑制效应;(2)在慢性期,与对照组相比较,单次鞘内注射FC在3 h~2 d的时间点上显著提高大鼠同侧的50%爪缩阈值(P0.01,P0.05),而对侧50%爪缩阈值仅在第1 d时间点显示提高(P0.05)。随后在福尔马林注射后第9 d,再次鞘内注射FC,与对照组相比,能在3 h提高大鼠的同侧和对侧的50%爪缩阈值(P0.05),而在6 h阈值恢复到对照组水平(P0.05)。多次鞘内注射FC后,能够在3~7 d时间点上显著提高大鼠同侧的50%爪缩阈值(P0.01,P0.05),在2~7 d时间点上显著提高大鼠对侧的50%爪缩阈值(P0.01,P0.05)。随后在福尔马林注射后第9、10、11 d连续3 d鞘内注射FC,大鼠同侧的50%爪缩阈值的提高仅在鞘内注射日当天发生(P0.01,P0.05),次日即恢复到对照组水平(P0.05),而对侧的50%爪缩阈值在鞘内注射日第11 d及第12 d有所提高(P0.05),第13 d恢复到对照组水平(P0.05)。结论:星形胶质细胞内的三羧酸循环参与福尔马林诱导的急性痛和慢性痛的形成,但是在慢性痛的维持方面不起主导作用。     

Effects of sex, hindpaw injection site and stimulus modality on nociceptive sensitivity in arthritic rats

Injection of Complete Freund's adjuvant (CFA) into the hindpaw produces inflammation and alterations in nociceptive sensitivity. The present study was designed to compare the effects of CFA injection into the dorsal and plantar surfaces of the hindpaw on nociceptive sensitivity of the hindpaw to mechanical pressure, warm-water and a hotplate stimulus in male and female rats. CFA or vehicle (VEH) was injected into the dorsal or plantar surface of the right hindpaw on day 0 and tests were conducted on days 4, 6, 8, 10, 11 and 18. Up until day 11 the inflammation was confined to the injected hindpaw (monoarthritic state), whereas by day 18 both hindpaws were inflamed (polyarthritic state). The site of the CFA injection had minimal effects on thermal or mechanical sensitivity with the following exceptions. On days 11 and 18 males had higher hotplate latencies when injected in the dorsal as compared to the plantar surface. For both males and females, warm-water paw withdrawal latencies were longer in those rats injected in the dorsal versus the plantar surface on day 18. No sex differences in paw pressure thresholds were observed on days 11 and 18 in CFA-treated rats. In the warm-water paw withdrawal test CFA-treated males exhibited longer latencies than CFA-treated females on day 11, but similar latencies on day 18. In the hotplate test CFA-treated females exhibited shorter latencies than CFA-treated males on days 11 and 18. The present results demonstrate that nociceptive sensitivity is the result of the interplay among sex, CFA injection site (plantar vs. dorsal), arthritic state (mono- vs. polyarthritic) and stimulus modality (mechanical vs. thermal).     

cAMP反应元件结合蛋白(CREB)与细胞凋亡

cAMP反应元件结合蛋白(CREB)是真核细胞内核转录调节因子,受多因素的激活而调控靶基因,调节细胞凋亡.细胞凋亡与机体生长发育、内环境稳定、防御反应等功能相关.     

奥曲肽对福尔马林诱导的大鼠痛反应和脊髓背角pCREB表达的抑制作用

目的:本研究旨在观察局部应用奥曲肽对福尔马林诱发的痛反应以及脊髓背角磷酸化的c AMP反应元件结合蛋白(phosphorylated c AMP response element binding protein,p CREB)表达的影响。方法:实验采用行为学观察和外周神经单纤维记录的方法,研究足底注射2.5%福尔马林50μl诱发的SD大鼠痛反应;同时采用免疫组织化学染色观察脊髓背角p CREB的表达。结果:福尔马林足底注射可以引起大鼠典型的双相性痛行为,敏化C和Aδ类初级传入单位,包括机械阈值的下降和传入放电率的增加(P0.001);同时福尔马林注射还可以明显增加双侧脊髓背角p CREB的表达,以注射侧最为显著(P0.05和P0.01)。足底注射生长抑素类似物奥曲肽(20μmol/L,50μl)可明显降低福尔马林诱发的第二相特异性伤害行为评分,减少C和Aδ类单位的传入放电率;同时局部应用奥曲肽还可以部分抑制福尔马林诱发的脊髓背角p CREB表达增加。结论:结果提示,局部应用奥曲肽可以显著抑制福尔马林诱发的痛反应,脊髓背角p CREB参与了此过程。     

外周注射福尔马林诱导大鼠前扣带皮层中ERK-CREB的激活

目的研究外周福尔马林刺激诱导的大鼠前扣带皮层中细胞外信号调节激酶（ERK）和cAMP反应元件结合蛋白（CREB）的激活。方法大鼠单侧足底皮下注射5％的福尔马林,在刺激后的不同时间点将大鼠进行灌注固定或直接取前扣带皮层组织,用免疫组织化学和Western blotting方法观察前扣带皮层中磷酸化ERK和磷酸化CREB的激活情况。结果单侧足底皮下注射福尔马林能诱导双侧前扣带皮层中ERK和CREB的磷酸化。磷酸化的ERK和磷酸化CREB的表达高峰分别在刺激后的3min和30min。非磷酸化的CREB和ERK没有显著变化。结论大鼠前扣带皮层能够接受外周伤害性信息的传人,激活的ERK和CREB可能与疼痛的原发性不愉快有关。     

缬草对慢性应激导致的抑郁大鼠大脑海马p-CREB阳性神经元数量的影响

目的探讨最佳剂量缬草对慢性应激导致的抑郁大鼠行为及其大脑海马磷酸化cAMP反应元件结合蛋白(phosphorylated cAMP responsive element-binding protein,p-CREB))阳性神经元的影响。方法将35只大鼠随机均分为正常对照组、未用药模型组、阴性对照模型组、阳性对照模型组、低剂量缬草模型组、中剂量缬草模型组和高剂量缬草模型组。在用药期间,每周测试大鼠体质量、自来水及1%糖水摄取量1次。用药后,计数大脑海马神经元数量,确定缬草最佳剂量。然后根据前述方法,在灌药结束后灌注和固定所有大鼠。采用中性红染色、免疫组化等方法对大鼠海马p-CREB和脑源性神经营养因子(brain-derived neurotrophic factor,BDNF)阳性神经元进行检测。结果高剂量(100mg·kg-1·d-1)缬草能促使抑郁大鼠1%糖水摄取量恢复至正常水平,还可使抑郁大鼠大脑海马神经元以及p-CREB阳性神经元数量恢复到正常水平。正常对照组大鼠大脑海马神经元的BDNF染色较浅淡,其余各组大鼠大脑海马神经元的BDNF阳性染色没有明显差异。结论本研究高剂量(100mg·kg-1·d-1)缬草可能是治疗慢性应激导致大鼠抑郁症的最佳剂量。缬草可以改善抑郁大鼠的行为活动,恢复大脑海马神经元以及p-CREB阳性神经元数量到正常水平。     

磷酸化的cAMP反应元件结合蛋白1在糖尿病大鼠肾小球中表达增强

目的探讨磷酸化的cAMP反应元件结合蛋白1(P-CREB1)在糖尿病大鼠肾组织中的表达特征及与细胞外基质积聚的关系。方法雄性Wistar大鼠切除右肾2周后随机分为对照组和糖尿病组,用链脲佐菌素复制糖尿病模型。分别于1、2、4、8和12周用免疫组化检测纤维黏连蛋白(FN)、层黏连蛋白(LN)及P-CREB1的表达,Western印迹和RT-PCR检测肾皮质CREB1磷酸化(活性)及mRNA的表达。结果糖尿病组FN与LN在4周时开始升高,并持续到12周。CREB1的活性及其mRNA在2、4和8周增高,在12周时降至正常。结论CREB1可能在糖尿病肾病细胞外基质积聚中发挥一定作用。     

NGF对局灶性脑缺血再灌注大鼠海马和顶叶皮质内CREB mRNA表达的影响

探讨外源性神经生长因子(nervegrowthfactor,NGF)对局灶性脑缺血再灌注大鼠海马和顶叶皮质内的cAMP反应元件结合蛋白(cyclicAMPresponseelementbindingprotein,CREB)mRNA表达的影响。用线栓法制作大鼠局灶性脑缺血再灌注模型,运用原位杂交和图像分析技术检测大鼠缺血侧海马CA1区和顶叶皮质内CREBmRNA的表达。结果显示:缺血再灌注组缺血侧海马CA1区和顶叶皮质CREBmRNA阳性反应产物平均光密度(OD)比假手术组减少(P<0.05),NGF组CA1区和顶叶皮质内的CREBmRNA阳性产物平均光密度高于缺血再灌注组(P<0.05)。本研究结果提示NGF可以上调局灶性脑缺血再灌注大鼠海马和顶叶皮质缺血神经元CREBmRNA的表达,NGF对缺血神经元的保护作用可能通过激活CREB的转录与翻译,从而启动一系列信号通路来实现。     

NGF对局灶性脑缺血再灌注大鼠顶叶皮质CREB表达的上调作用

为探讨外源性神经生长因子(NGF)对局灶性脑缺血再灌注大鼠顶叶皮质cAMP反应元件结合蛋白(CREB)和磷酸化CREB(p-CREB)表达的影响,用线栓法制作局灶性脑缺血再灌注模型,应用免疫组织化学、WesternBlotting和图像分析方法检测大鼠缺血侧顶叶皮质CREB和p-CREB的表达。结果显示:缺血再灌注组CREB表达较假手术组减少,p-CREB表达高于假手术组(P<0.05);NGF组CREB和p-CREB表达高于缺血再灌注组(P<0.05)。以上结果表明NGF明显上调局灶性脑缺血再灌注大鼠顶叶皮质CREB和p-CREB的表达,NGF对缺血神经元的保护作用可能通过上调CREB和p-CREB的表达来实现。     

活化蛋白-1和cAMP反应元件结合蛋白在脂多糖注射大鼠肺组织中的变化及地塞米松的影响

目的：探讨活化蛋白-1(AP-1)和cAMP反应元件结合蛋白(CREB)在急性肺损伤(ALI)发生发展中的可能作用,以及地塞米松的抗炎作用机制。方法：采用脂多糖（LPS）5mg/kg颈静脉注射复制ALI大鼠模型,用凝胶电泳迁移率改变分析法(EMSA)观察ALI大鼠肺组织AP-1和CREB的改变和地塞米松的影响。结果：ALI大鼠肺组织AP-1的DNA结合活性在2h达到峰值,12h后接近正常水平。CREB的活性在1h即到达峰值,但直到12h并未完全达到正常水平。地塞米松对AP-1和CREB的DNA结合活性均有显著抑制作用。结论：AP-1和CREB可能在大鼠的急性肺损伤的发生中发挥重要作用,在转录水平的调节可能是糖皮质激素发挥抗炎作用的重要机制之一。     

降钙素基因相关肽对局灶性脑缺血再灌注大鼠脑cAMP反应元件结合蛋白mRNA表达的影响

目的 探讨外源性降钙素基因相关肽(CGRP)对局灶性脑缺血再灌注大鼠海马和顶叶皮质cAMP反应元件结合蛋白(CREB)mRNA表达的影响.方法 用线栓法制作大鼠局灶性脑缺血再灌注模型,应用原位杂交和图像分析技术检测大鼠缺血侧海马CA1区和顶叶皮质CREB mRNA表达.结果 假手术组右侧海马CAl区和顶叶皮质CREB mRNA有明显表达,缺血再灌注组右侧海马CAl区和顶叶皮质CREB mRNA阳性产物吸光度值减少,CGRP组缺血侧海马CAl区和顶叶皮质CREB mRNA表达的吸光度值比缺血再灌注组增高(P＜0.05).结论 CGRP上调局灶性脑缺血再灌注大鼠海马和顶叶皮质CREB mRNA的表达,CGRP对缺血神经元的保护作用可能通过激活CREB的转录与翻译,从而启动一系列信号通路来实现.     

气味对小鼠学习记忆能力及海马cAMP反应元件结合蛋白的影响

摘要目的:探讨不同气味(苹果、香水、樟脑)对小鼠学习记忆能力及海马cAMP反应元件结合蛋白(CREB)和磷酸化的CREB(pCREB)的影响。方法:让小鼠在不同气味的环境下生活14d,在第7d开始方形水迷宫训练,3d后进行测试,连续测试5d。测试完后断髓处死动物,取出脑组织,用免疫组织化学染色观察海马pCREB和CREB表达情况,并进行图像分析。结果:樟脑组和香水组水迷宫的潜伏期较对照组延长,错误次数增多(P＜0.05)。免疫组化染色显示鼠海马CREB的磷酸化水平大大降低(P＜0.05),但对CREB的表达无明显影响。苹果组与对照组比各指标均无显著差异(P＞0.05)。结论:樟脑气味和香水气味对小鼠记忆能力有负面作用,且这种作用可能是通过降低CREB磷酸化水平而实现的。苹果气味对小鼠记忆能力无明显影响。