帕罗西汀对心理应激大鼠血浆皮质醇和行为的影响

目的：观察帕罗西汀对心理应激大鼠血浆皮质醇和行为的影响。方法：建立大鼠心理应激模型,观察抗焦虑药物帕罗西汀用药组大鼠下丘脑室旁核c-fos表达、血浆皮质醇和旷场行为。结果：与正常对照组比较,心理应激大鼠下丘脑室旁核c-fos表达显著增加（P〈0.05）,血浆皮质醇含量明显升高（P〈0.05）,在旷场中的穿行格数和直立次数明显增加（P〈0.05）,而帕罗西汀用药能减少大鼠下丘脑室旁核c-fos表达、血浆皮质醇含量和在旷场中的活动（P〈0.05）。结论：帕罗西汀通过抑制c-fos基因表达,下调了下丘脑-垂体-肾上腺（HPA）水平,从而减轻了心理应激所致的焦虑症状。     

帕罗西汀对心理应激大鼠下丘脑室旁核c-fos表达的影响

目的:观察帕罗西汀对心理应激大鼠下丘脑c fos表达的影响,以揭示帕罗西汀治疗心理应激引起焦虑的分子作用机制。方法:建立大鼠心理应激模型,观察抗焦虑药物帕罗西汀用药组大鼠血浆皮质醇和下丘脑c fos的表达。结果:与正常对照组比较,各应激组大鼠血浆皮质醇含量明显升高,下丘脑室旁核c fos表达显著增加,而帕罗西汀单次、连续给药能减少应激大鼠血浆皮质醇含量和下丘脑室旁核c fos表达。结论:帕罗西汀通过抑制c fos基因表达,下调下丘脑垂体肾上腺轴(HPA轴)水平,从而发挥中枢应激调节作用。     

盐酸帕罗西汀对卒中后抑郁大鼠行为和下丘脑室旁核fos蛋白表达的影响

目的:探讨抗抑郁药治疗卒中后抑郁的分子作用机制。方法:应用线栓法致大脑中动脉闭塞制备脑卒中模型结合束缚应激和孤养法复制了卒中后抑郁症(poststroke depression,PSD)大鼠模型。观察PSD大鼠模型行为学改变和下丘脑室旁核c-fos表达,及盐酸帕罗西汀对PSD的干预作用。结果:PSD模型大鼠蔗糖水消耗量降低、Open-Field测定直立评分和水平评分减少,与对照组比较差异有统计学意义(P<0.01);药物组糖水消耗量增加、Open-Field测定水平得分和直立得分增加,与PSD组比较差异有统计学意义(P<0.01)。PSD组下丘脑室旁核c-fos蛋白的表达较卒中组或抑郁组有所增加,且差异有统计学意义(P<0.05);与PSD组比较药物组下丘脑室旁核c-fos蛋白的表达减少,且差异有统计学意义(P<0.01)。结论:盐酸帕罗西汀可以改善PSD大鼠抑郁行为,其抗抑郁作用可能与下调下丘脑室旁核c-fos基因表达有关。     

应激启动下丘脑-垂体-肾上腺轴信号转导机制的实验研究

目的以束缚应激大鼠作为应激研究模型,探讨应激后下丘脑内信号转导分子的变化。方法用Western印迹杂交法研究了应激大鼠下丘脑内c-fos的蛋白表达和p38MAPK的磷酸化情况。结果Western印迹杂交结果显示束缚应激后鼠下丘脑内磷酸化的p38MAPK明显增加,与对照组相比具有非常显著性差异(P<0.01),应激解除后1、3h磷酸化的p38MAPK仍然保持较高的水平(P<0.05),但是应激解除后3h较应激刚结束时下丘脑内磷酸化p38MAPK的水平明显回落(P<0.05);应激后下丘脑内c-fos蛋白表达同样明显增加,与对照组相比具有显著性差异(P<0.01)。应激解除后0、1、3h,c-fos蛋白的表达仍然保持较高的水平(P<0.05)。结论应激发生后,其下丘脑内p38MAPK磷酸化的时相、c-fos蛋白表达时相以及血浆内皮质酮浓度时相具有类似之处,p38MAPK磷酸化、c-fos蛋白很可能是HPA轴活动的上游分子信号。     

11β-羟基类固醇脱氢酶1在束缚应激大鼠下丘脑及海马的表达

目的观察应激大鼠下丘脑海马11β-羟基类固醇脱氢酶1(11β-HSD1)的表达变化,探讨11β-HSD1在HPA轴调节中的作用。方法将20只大鼠随机分为对照组、束缚应激组,用Western印迹杂交法观察二组大鼠下丘脑海马内11β-HSD1水平变化。结果束缚应激大鼠海马内11β-HSD1表达水平明显高于对照组(P<0.05),而下丘脑内11β-HSD1表达与对照组比较无统计学差异,但有增加趋势。结论束缚应激能够促进海马内11β-HSD1的表达,其表达增加可能与海马对HPA轴的负反馈调节有关。     

雌激素对卒中后抑郁大鼠血清单胺类递质的影响

目的:探讨雌激素对卒中后抑郁(PSD)大鼠的血清单胺类递质的影响。方法:选用雌性SD大鼠,经Open-Field行为学评分后随机分成对照组、卒中组、PSD组、药物治疗组和雌激素干预组,所有大鼠均行卵巢切除术。对照组为常规饲养;卒中组去卵巢后7d采用线栓法制备局灶性脑缺血大鼠模型;PSD组为卒中大鼠结合孤养、束缚应激制备PSD大鼠模型;药物治疗组对PSD大鼠模型行帕罗西汀灌胃治疗;雌激素干预组对PSD大鼠模型皮下包埋雌激素释放管。观察雌激素对PSD大鼠自发性行为和外周血去甲肾上腺素(NE)和5-羟色胺(5-HT)的影响。结果:与对照组比较,PSD组大鼠旷场实验水平和垂直得分明显减少,外周血NE和5-HT浓度明显降低,差异有统计学意义(P<0.05)。与PSD组比较,雌激素干预组大鼠旷场实验得分增加,外周血5-HT和NE浓度明显升高,差异有统计学意义(P<0.05)。与药物治疗组相较,雌激素干预组大鼠旷场实验得分、外周血5-HT浓度差异无统计学意义(P>0.05)。结论:雌激素能够改善PSD大鼠的行为学、增加血清5-HT浓度,提示对PSD大鼠有脑保护作用。     

抗抑郁剂慢性给药对强迫游泳大鼠下丘脑c-Fos蛋白表达水平的下调作用

应用ｃ－Ｆｏｓ蛋白免疫组织化学定位观察的方法，在强迫游泳大鼠抑郁模型上，观察地昔帕明（５，２０ｍｇ·ｋｇ－１），吗氯贝胺（１０，４０ｍｇ·ｋｇ－１）和氟西汀（５，２０ｍｇ·ｋｇ－１）慢性给药（ｉｐ每日１次，连续７ｄ）对大鼠游泳不动时间和下丘脑核团ｃ－Ｆｏｓ蛋白表达水平的影响．结果表明：强迫游泳可使大鼠下丘脑多个核团的ｃ－Ｆｏｓ蛋白表达水平明显升高，而地昔帕明，吗氯贝胺，氟西汀明显缩短强迫游泳大鼠的不动时间，并选择性地使强迫游泳诱导增加的下丘脑室旁核Ｆｏｓ样免疫阳性神经元数目明显减少．提示下丘脑室旁核可能是介导抗抑郁剂抑制大鼠绝望行为的中枢部位之一．Ｆｏｓ蛋白可能是不同类型抗抑郁剂共同的受体后信号转导物质     

淫羊藿苷对去卵巢大鼠骨和下丘脑不同核团ERβ mRNA表达的影响

目的观察淫羊藿苷对去卵巢大鼠骨和下丘脑不同核团ERβmRNA表达的影响,探讨其治疗绝经后骨质疏松的作用机制。方法将10～11月龄SD♀大鼠60只,随机分为假手术组、去卵巢模型组、淫羊藿苷小、中、大剂量组(每组12只)。以双侧卵巢切除法建立大鼠骨质疏松模型。分别用淫羊藿苷小、中、大剂量给药4个月,采用RT-PCR法,观察各组大鼠骨和下丘脑室旁核、视上核、弓状核ERβmRNA表达的变化。结果大鼠卵巢切除后,血清E2水平、椎骨骨密度、子宫湿重、胫骨和下丘脑弓状核ERβmRNA表达明显降低(P<0.01),下丘脑室旁核、视上核ERβmRNA表达均明显升高(P<0.01)。与去卵巢模型组比较,淫羊藿苷50.0和100.0 mg.kg-1组治疗后,血清E2水平、椎骨骨密度、胫骨和下丘脑弓状核ERβmRNA表达明显升高(P<0.01),下丘脑室旁核、视上核ERβmRNA表达均明显降低(P<0.01),子宫湿重无明显改变(P>0.05)。结论淫羊藿苷可以改善切除卵巢所致的骨质疏松大鼠的骨密度,对子宫无不良反应。其机制可能与其选择性调节去卵巢骨质疏松大鼠下丘脑不同核团ERβmRNA表达水平有关,调节下丘脑功能活动是其途径之一。     

氟西汀对慢性应激大鼠前额叶谷氨酸转运体GLT-1表达的影响

目的研究氟西汀对慢性应激大鼠前额叶谷氨酸转运体1(GLT-1)的影响,进一步探讨氟西汀抗抑郁作用可能的分子机制。方法正常SD大鼠60只,随机分为对照组、慢性不可预见性应激(CUS)组和氟西汀组。对CUS组和氟西汀组大鼠进行CUS应激后,氟西汀组给予氟西汀治疗,对照组和CUS组给予生理盐水。实验结束后进行糖水偏好和旷场行为测试,并使用免疫组织化学法和蛋白印迹分析检测大鼠前额叶GLT-1的表达水平。结果 (1)行为学测试结果显示,CUS组大鼠糖水偏好、总行程、平均移动速度及直立次数均低于对照组(P<0.01);氟西汀组上述指标均高于CUS组(P<0.01)。(2)免疫组织化学法分析显示,CUS组与对照组比较,大鼠前额叶GLT-1表达下降(P<0.01);经氟西汀治疗后,大鼠前额叶GLT-1表达比CUS组明显升高(P<0.01)。(3)蛋白印迹分析显示,CUS组与对照组比较,大鼠前额叶GLT-1表达下降(P<0.01);经氟西汀治疗后,大鼠前额叶GLT-1表达比CUS明显升高(P<0.01)。结论慢性应激下调大鼠前额叶GLT-1表达水平,而氟西汀上调GLT-1表达水平,GLT-1表达增加可能是氟西汀抗抑郁作用的分子机制之一。     

帕罗西汀抗抑郁作用涉及改善氧化应激状态、HPA轴功能和海马脑源性神经营养因子表达

目的:研究帕罗西汀抗慢性轻度不可预见刺激(CUMS)致大鼠抑郁症作用与调节氧化应激平衡和下丘脑-垂体-肾上腺皮质(HPA)轴功能及脑源性神经营养因子(BDNF)表达的关系。方法:♂SD大鼠60只,随机分为正常对照组(NG)、模型组(MG)、帕罗西汀(1.8mg.kg-1.d-1)灌胃处理模型组及对照组。采用孤养结合CUMS方式建立大鼠抑郁症模型。以开场实验及糖水消耗试验评价大鼠抑郁行为,试剂盒测定血清丙二醛(MDA)含量及过氧化物歧化酶(SOD)、过氧化氢酶(CAT)活性变化;放射免疫法分析血清皮质酮(CORT)浓度,RT-PCR法测定大鼠海马BDNF及下丘脑CRFmRNA表达。结果:与NG组相比,MG组大鼠在开场实验中水平得分、垂直得分和理毛次数以及糖水消耗均明显降低,血清MDA含量明显升高,SOD和CAT活性降低,血清COTR含量及下丘脑CRF表达明显升高,海马BDNF表达降低。给予帕罗西汀能够显著阻遏CUMS诱导的上述变化,但对正常组大鼠无明显影响。结论:帕罗西汀抗抑郁作用可能与减轻CUMS所致氧化应激损伤和改善HPA轴功能及阻遏神经细胞BDNF表达降低有关。     

Acute effects of nicotine on restraint stress-induced anxiety-like behavior, c-Fos expression, and corticosterone release in mice

Clinical evidence suggests that nicotine reduces anxiety in stressful situations. In the present study, we investigated the effect of nicotine on restraint-enhanced anxiety-like behavior, c-Fos expression, an index of neuronal activation in the brain, and plasma corticosterone. Two-hour restraint stress-enhanced anxiety-like behavior in the elevated plus-maze (EPM) and nicotine hydrogen tartrate (0.25 mg/kg, i.p.) attenuated the stress-induced changes. Pretreatment with the centrally acting nicotinic antagonist, mecamylamine (2 mg/kg), blocked nicotine's effects. In addition, restraint led to significant increases of c-Fos expression in several brain regions related to stress or anxiety including paraventricular hypothalamic nucleus (PVN), lateral hypothalamic area (LH), central amygdaloid nucleus (CeA), medial amygdaloid nucleus (MeA) and cingulate and retrosplenial cortices (Cg/RS), paraventricular thalamic nucleus (PVT), and basolateral amygdaloid nucleus (BLA). Nicotine attenuated the restraint-induced expression of c-Fos in the PVN, LH, CeA, MeA, and Cg/RS, while leaving the BLA and PVT unaffected. In contrast, nicotine did not reverse the increased levels of plasma corticosterone induced by restraint. These findings suggest that nicotine may modify the stress-induced behavioral changes via regulating the neuronal activation in selected brain regions rather than affecting hypothalamo-pituitary-adrenocortical axis hormone responses.     

Effects of morphine and morphine withdrawal on brainstem neurons innervating hypothalamic nuclei that control the pituitary-adrenocortical axis in rats

Different data support a role for brainstem noradrenergic inputs to the hypothalamic paraventricular nucleus (PVN) in the control of hypothalamus - pituitary - adrenocortical (HPA) axis. However, little is known regarding the functional adaptive changes of noradrenergic afferent innervating the PVN and supraoptic nucleus (SON) during chronic opioid exposure and upon morphine withdrawal. Here we have studied the expression of Fos after administration of morphine and during morphine withdrawal in the rat hypothalamic PVN and SON. Fos production was also studied in brainstem regions that innervate hypothalamic nuclei: the nucleus of solitary tract (NTS - A2) and the ventrolateral medulla (VLM - A1) and combined with immunostaining for tyrosine hydroxylase (TH) for immunohistochemical identification of active neurons during morphine withdrawal. Male rats were implanted with s.c. placebo or morphine (tolerant/dependent) pellets for 7 days. On day 8 rats received an injection of saline i.p., morphine i.p., saline s.c. or naloxone s.c. Acute morphine administration produced an increase in Fos expression at hypothalamic nuclei and in the brainstem regions, and tolerance developed towards this effect. Precipitated morphine withdrawal induced marked Fos immunoreactivity within the PVN and SON. Concomitantly, numerous neurons in the brainstem were stimulated by morphine withdrawal. Moreover, catecholaminergic-positive neurons in the brainstem showed a significant increase in Fos expression in response to morphine withdrawal. These findings demonstrate that chronic activation of opioid receptors results in altered patterns of immediate-early genes (IEG) expression in the PVN and SON, which occurs concurrently with an increased activity of their inputs from the brainstem.     

Altered glutamate receptor and corticoliberin gene expression in brain regions related to hedonic behavior in rats

Present experiments in rats were aimed to verify the hypothesis that glutamatergic neurotransmission and stress hormones play a role in impairment of hedonic behavior, a sign of depression-like state. On the basis of individual variability in sucrose preference, test rats were divided into anhedonic and hedonic groups. Anhedonic animals showed higher basal concentrations of adrenocorticotropin and corticosterone but reduced hormonal responses during novelty stress compared to hedonic animals. Acute administration of citalopram (10 mg/kg ip) induced similar effects in both groups. Corticotropin-releasing hormone (CRH) mRNA levels in hypothalamic paraventricular nucleus (PVN) were higher in anhedonic rats. Oxytocin (OT) and vasopressin gene expression in the PVN and proopiomelanocortin (POMC) expression in the anterior pituitary failed to show any significant differences. Gene expression of NR1 receptor subunit of N-methyl-D-aspartate (NMDA) glutamate receptor in the ventral tegmental area (VTA) was found to be lower in anhedonic rats. In the nucleus accumbens (NAc) and the hippocampus of anhedonic animals, higher mRNA levels of NR2A subunit compared to those of hedonic rats were detected. Thus, low sucrose preference is associated with altered HPA axis activity, NMDA receptor subunits and CRH gene expression in selected brain regions. These mechanisms may operate in the disposition to develop hedonic deficit in some mental disorders.     

The effects of synthetic and endogenous imidazoline binding site ligands on neuronal activity in discrete brain regions of naive and restraint-stressed rats

We have mapped Fos expression to investigate brain regions activated by synthetic selective I₂ (BU224) and endogenous (harmane) imidazoline binding site ligands in naive and restraint-stressed rats. Systemic administration of BU224 or harmane to naive rats increased Fos-like immunoreactivity (FLI) in the hypothalamic paraventricular nucleus (PVN), hippocampal dentate gyrus (DG), central and medial nuclei of the amygdala (CeA, MeA) and the locus coeruleus (LC). FLI in restraint-stressed rats was increased in all 5 regions by harmane, and in the CeA, MeA and LC by BU224. Dual-labelling of FLI cells in the PVN of naive rats showed an increase in the number of corticotrophin-releasing-factor-containing cells (CRF) activated by BU224 and harmane. Several CRF-containing neurons in the PVN expressed α₁-adrenoceptors and were densely surrounded by catecholaminergic axons and terminals. Our results provide a functional neuroanatomical framework which may explain the stimulatory effects of imidazoline ligands on basal and stress-induced neuronal and neuroendocrine activity.     

Paraventricular nucleus of the hypothalamus glutamate neurotransmission modulates autonomic,neuroendocrine and behavioral responses to acute restraint stress in rats

In the present study, the involvement of paraventricular nucleus of the hypothalamus (PVN) glutamate receptors in the modulation of autonomic (arterial blood pressure, heart rate and tail skin temperature) and neuroendocrine (plasma corticosterone) responses and behavioral consequences evoked by the acute restraint stress in rats was investigated. The bilateral microinjection of the selective non-NMDA glutamate receptor antagonist NBQX (2 nmol/ 100 nL) into the PVN reduced the arterial pressure increase as well as the fall in the tail cutaneous temperature induced by the restraint stress, without affecting the stress-induced tachycardiac response. On the other hand, the pretreatment of the PVN with the selective NMDA glutamate receptor antagonist LY235959 (2 nmol/100 nL) was able to increase the stress-evoked pressor and tachycardiac response, without affecting the fall in the cutaneous tail temperature. The treatment of the PVN with LY235959 also reduced the increase in plasma corticosterone levels during stress and inhibited the anxiogenic-like effect observed in the elevated plus-maze 24 h after the restraint session. The present results show that NMDA and non-NMDA receptors in the PVN differently modulate responses associated to stress. The PVN glutamate neurotransmission, via non-NMDA receptors, has a facilitatory influence on stress-evoked autonomic responses. On the other hand, the present data point to an inhibitory role of PVN NMDA receptors on the cardiovascular responses to stress. Moreover, our findings also indicate an involvement of PVN NMDA glutamate receptors in the mediation of the plasma corticosterone response as well as in the delayed emotional consequences induced by the restraint stress.     

Inhibition of reactive oxygen species in hypothalamic paraventricular nucleus attenuates the renin–angiotensin system and proinflammatory cytokines in hypertension

Aims

To explore whether reactive oxygen species (ROS) scavenger (tempol) in the hypothalamic paraventricular nucleus (PVN) attenuates renin–angiotensin system (RAS) and proinflammatory cytokines (PICs), and decreases the blood pressure and sympathetic activity in angiotensin II (ANG II)-induced hypertension.

Methods and results

Male Sprague–Dawley rats were infused intravenously with ANG II (10 ng/kg per min) or normal saline (NS) for 4 weeks. These rats were treated with bilateral PVN infusion of oxygen free radical scavenger tempol (TEMP, 20 μg/h) or vehicle (artificial cerebrospinal fluid, aCSF) for 4 weeks. ANG II infusion resulted in increased mean arterial pressure (MAP) and renal sympathetic nerve activity (RSNA). These ANG II-infused rats also had higher levels of gp91^phox (a subunit of NAD(P)H oxidase), angiotensin-converting enzyme (ACE), and interleukin-1beta (IL-1β) in the PVN than the control animals. Treatment with PVN infusion of TEMP attenuated the overexpression of gp91^phox, ACE and IL-1β within the PVN, and decreased sympathetic activity and MAP in ANG II-infused rats.

Conclusion

These findings suggest that ANG II infusion induces elevated PICs and oxidative stress in the PVN, which contribute to the sympathoexcitation in hypertension. Inhibition of reactive oxygen species in hypothalamic paraventricular nucleus attenuates the renin–angiotensin system, proinflammatory cytokines and oxidative stress in ANG II-induced hypertension.