细胞外信号调节蛋白激酶-cAMP反应元件结合蛋白信号通路在应激所致抑郁行为障碍中的作用

Stress is the most important factor in the vulnerability to depression and other behavioral disorders, but the mechanisms that stress signals are transferred into depression are far from understanding. To date, the neurotransmitters, neurotrophins and signal pathway have been concerned in the topic focusing on the pathophysiology of depression, but there are still many puzzles. Increasing evidence has indicated that the alteration in neuronal plasticity is the “trace” of stress-induced damages. The extracellular signal-regulated protein kinase(ERK)-cyclic-AMP-responsive element（CRE）-binding protein(CREB)signal pathway is a powerful intracellular signal transduction pathway participating in neuronal plasticity which is involved in higher brain cognitive functions such as learning and memory. However, so far, little is known about the role of the ERK-CREB signal pathway in response to stress and emotional modulations. Thus the aim of the study was to systematically investigate the role of the ERK-CEB signal pathway in depressive-like behaviors induced by stress. Depression animal models, antidepressant agent treatment and disruption of signal pathway in specific brain regions were applied. In the present study, three experiment sessions were designed to make sure whether the ERK-CREB signal pathway was indeed one of pathophysiological mechanisms of depressive-like behaviors induced by stress. In experiment one, two different stress animal models were applied, chronic forced swim stress and chronic empty water bottle stress. After stress, all animals were tested behaviorally using open-field, elevated-plus maze and saccharine preference test, and brain samples were processed for determination of ERK, P-ERK, CREB and P-CREB using western blot. The relationships between the proteins of ERK, P-ERK, CREB and P-CREB in the brain and the behavioral variables were also analyzed. In experiment two, rats were treated with antidepressant agent fluoxetine once a day for 21 consecutive days, then the brain levels of ERK, P-ERK, CREB and P-CREB was determined, the depressive-like behaviors were also examined. In experiment three, mitogen activated extracellular-signal-regulated kinase kinase (MEK) inhibitor U0126 was administrated to inhabit the activation of ERK in the hippocampus and prefrontal cortex respectively, then behavioral measurements and protein detection were conducted. The main results of the study were as the following: (1) Chronic forced swim stress induced animals to suffer depression and disrupted the ERK-CREB signal pathway in hippocampus and prefrontal cortex. There were significant correlations between P-ERK2, P-CREB and multiple variables of depressive-like behaviors. (2) Chronic empty water bottle stress did not induce depressive-like behaviors. Such stress decreased the brain level of P-ERK2 in hippocampus and prefrontal cortex, but the level of P-CREB in the hippocampus was increased. (3) The antidepressant agent fluoxetine relieved depressive-like behaviors and increased the activities of the ERK-CREB signal pathway in stressed animals. (4) Animals treated with U0126 injection into hippocampus showed decreased activities of the ERK-CREB signal pathway in the hippocampus, and suffered depression comorbid with anxiety. (5) Animals treated with U0126 injection into prefrontal cortex showed decreased activities of the ERK-CREB signal pathway in the prefrontal cortex, and exhibited depressive-like behaviors. In conclusion, The ERK-CREB signal pathway in the hippocampus and prefrontal cortex was involved in stress responses and significantly correlated with depressive-like behaviors; The ERK-CREB signal pathway in the hippocampus and prefrontal cortex participated in the mechanism that fluoxetine reversed stress-induced behavioral disorders, and might be the target pathway of the therapeutic action of antidepressants; The disruption of the ERK-CREB signal pathway in the hippocampus or prefrontal cortex led to depressive-like behaviors in animals, suggesting that disruption of ERK-CREB pathway in the hippocampus or prefrontal cortex was involved in the pathophysiology of depression, and might be at least one of the mechanisms of depression induced by stress.

烟草依赖者的注意偏向研究

Relapse has been a great challenge in clinical treatment and experimental studies of drug addiction. Recent studies suggest that psychological dependence may play a major role in addiction relapse, even more important than physiological dependence. Then a fundamental question arises: how to measure the psychological dependence? How to examine whether an addict has psychologically quitted when leaving drug rehabilitation centers? Self-report, a commonly used evaluation approach, is inevitably vulnerable to various cognitive influences, particularly in explicit tasks. Therefore, an objective index is necessary to evaluate the subliminal psychological drug dependence level. The objective of the current study was to develop such a psychological paradigm to probe the unaware attentional bias of in smoking addicts. Experiment 1 adapted the interocular suppression technique of binocular rivalry to study the attentional bias to cigarette pictures in smokers and age-matched nonsmoker. Results show that the smokers demonstrated similar attentional bias in both visible and unaware conditions, while non-smokers showed attentional bias only in the visible condition, and there was a significant interaction between experiment conditions and subject groups. These results provide compelling evidence for addiction-specific attentional bias in cigarette smokers, by minimizing the influence of confounding conscious factors. Furthermore, attentional bias of smokers in unawareness state was negatively correlated with their cigarette dependence levels, while their pre-test cigarette craving levels was positively correlated with their attnetional bias in the visible condition. This pair of correlations further demonstrated the advantages of unawareness state in disclosing stable dependence states, therefore supporting the effectiveness of the paradigm used in this study. Another interesting finding of Experiment 1 is that non-smokers also showed attentional bias in the visible condition. To exclude the possibility that the attentional bias found in experiment 1 was task-specific, experiment 2 adapted the most commonly-used visual dot probe task with smoking scenes as in relevant reference. The result in experiment 1 was well replicated, i.e., nonsmokers in experiment 2 also showed significant attentional bias to smoking-related stimuli, We interpenetrate this interesting finding as an effect of environmental influence, as the participants of the current study live in a highly smoking-exposed and smoking-encouraged environment, which is quite different with the participants of studies reported in the literature. A series of questionnaires and scales administered in the current study indeed show that most smokers smoked due to influence of the environment. They also acknowledged that smoking as an important media of social communication in China, and even considered that away from the smoking environment would effectively help them to quit. The current study also found that the disgust level towards cigarette pictures and smoking-related scenes of non-smokers was positively correlated with their attnentional bias in the visible condition of experiment 1. It is likely that in a highly smoking-encouraged environment, the remaining few on-smokers have severe disgust to cigarettes and smoking scenes; and their attentional bias might be caused by disgust avoidance. In conclusion, the current study represents the first study showing the existence of unaware attentional bias to smoking related stimuli in cigarette smokers by applying the interocular suppression paradigm, providing a reference to study of dependence of other drugs. The current study also found that our non-smoking participants also showed attentional bias to smoking related stimuli, which may be due to the possible influence of highly smoking-exposed environment of our participants.

No accelerated evolution of 3 ' UTR region in human for brain-expressed genes

The difference in cognitive skills between humans and nonhuman primates is one of the major characters that define our own species. It was previously hypothesized that this divergence might be attributable to genetic differences at gene expression level,

Abnormal regional homogeneity of drug-naive obsessive-compulsive patients

To explore the possible abnormal resting-state activity in patients with obsessive-compulsive disorder (OCD), the regional homogeneity (ReHo) of 22 pairs of patients and well-matched healthy controls was calculated. Compared with controls, the patients showed higher ReHo in the left anterior cingulate cortex, but lower ReHo in the left inferior temporal gyrus. These findings supported the abnormal resting-state brain activity in drug-naive OCD patients. No significant correlations between ReHo value and four clinical characteristics were found, suggesting that abnormal ReHo might be trait-related in OCD. NeuroReport 21:786-790 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Effects of adrenergic agonists on the extrahepatic expression of vitellogenin Ao1 in heart and brain of the Chinese rare minnow (Gobiocypris rarus)

Teleost vitellogenins (VTGs) are large multidomain apolipoproteins and traditionally considered as the estrogen responsive precursors of the major egg yolk proteins. We identified five clones encoding VTGs, about 16% of the random EST clones from our constructed cDNA library from Chinese rare minnow liver tissue treated with 17 beta-estradiol (E2). Full-length vtgAo1 has been obtained based on the sequence information of four partial cDNA inserts by RACE. The inducibility of the vtgAo1 expression in liver by E2 was confirmed by RT-PCR. The presence of vtgAo1 transcripts have been observed primarily in liver. However. a significant level of the vtgAo1 was found in an unexpected location, heart, particularly in atrial cells by RT-PCR and whole mount in situ hybridization analyses. The vtgAo1 mRNA expression in heart and liver tissue could be suppressed by both alpha-adrenergic agonist, phenylephrine (PE) and beta-adrenergic agonist, isoproterenol (ISO). The expression of VTG in the heart observed in the present studies suggested it may provide protection from surplus intracellular lipids in fish cardiomyocytes as triglyceride transport proteins do in mammals. The results also indicated that the production of teleost vtg in vivo can be regulated by riot only estrogenic agents, but adrenergic signals as well. (c) 2008 Elsevier B.V. All rights reserved.

Effects of hexachlorobenzene on antioxidant status of liver and brain of common carp (Cyprinus carpio)

Hexachlorobenzene (HCB)-induced oxidative damages have been published in rats while the effects have not yet been reported in fishes. Juvenile common carps (Cyprinus carpio) were exposed to waterborne HCB from 2 to 200 mu g l(-1) for 5, 10 or 20 days. Liver and brain were analyzed for various parameters of oxidative stress. There were no significant changes of glutathione (GSH) content and superoxide dismutase (SOD) activity in liver after 5 or 10 days exposure, whereas obvious drops were observed at higher concentrations after 20 days exposure. Significant decreases of GSH content and SOD activity in brain were found during all the exposure days. In brain, HCB also significantly elevated the contents of reactive oxygen species (ROS), thiobarbituric acid-reactive substances (TBARS, as an indicator of lipid peroxidation products), glutathione disulfide (GSSG), and activities of nitric oxide synthase (NOS), glutathione peroxidase (GPx), and glutathione reductase (GR), and inhibited activities of acetylcholinesterase (AchE) and glutathione S-transferase (GST). The results clearly demonstrated that environmentally possible level of HCB could result in oxidative stress in fish and brain was a sensitive target organ of HCB toxicity. (c) 2006 Elsevier Ltd. All rights reserved.

Adaptive hormetic response of pre-exposure of mouse brain with low-dose C-12(6+) ion or Co-60 gamma-ray on growth hormone (GH) and body weight induced by subsequent high-dose irradiation

The brain of the Kun-Ming strain mice were irradiated with 0.05 Gy of C-12(6+) ion or Co-60 gamma-ray as the pre-exposure dose, and were then irradiated with 2 Gy of 12C6+ ion or Co-60 gamma-ray as challenging irradiation dose at 4 h after per-exposure. Body weight and serum growth hormone (GH) concentration were measured at 35th day after irradiation. The results showed that irradiation of mouse brain with 2 Gy of C-12(6+) ion or Co-60 gamma-ray significantly diminished mouse body weight and level of serum GH. The relative biological effectiveness values of a 2 Gy dose of C-12(6+) ion calculated with respect to Co-60 gamma-ray were 1.47 and 1.34 for body weight and serum GH concentration, respectively. Pre-exposure with a low-dose (0.05 Gy) of C-12(6+) ion or Co-60 gamma-ray significantly alleviated reductions of mouse body weight and level of serum GH induced by a subsequent high-dose (2 Gy) irradiation. The data suggested that low-dose ionizing irradiation can induce adaptive hormetic responses to the harmful effects of pituitary by subsequent high-dose exposure.

Quantifying intrinsic specificity: A potential complement to affinity in drug screening

We report here the investigation of a novel description of specificity in protein-ligand binding based on energy landscape theory. We define a new term, intrinsic specificity ratio (ISR), which describes the level of discrimination in binding free energies of the native basin for a protein-ligand complex from the weaker binding states of the same ligand. We discuss the relationship between the intrinsic specificity we defined here and the conventional definition of specificity. In a docking study of molecules with the enzyme COX-2, we demonstrate a statistical correspondence between ISR value and geometrical shapes of the small molecules binding to COX-2. We further observe that the known selective (nonselective) inhibitors of COX-2 have higher (lower) ISR values. We suggest that intrinsic specificity ratio may be a useful new criterion and a complement to affinity in drug screening and in searching for potential drug lead compounds.

条件反射性免疫抑制及其脑机制的c-fos研究

To explore the neural mechanisms underlying conditioned immunomodulation, this study employed the classical taste aversion (CTA) behavioral paradigm to establish the conditioned humoral and cellular immunosuppression (CIS) in Wistar rats, by paring saccharin (CS) with intraperitoneal (i.p.) injection of an immunosuppressive drug cyclophophamide (UCS). C-fos immunohistochemistry method was used to observe the changes of the neuronal activities in the rat brain during the acquisition, expression and extinction of the conditioned immunosuppression (CIS). The followings are the main results: 1. Five days after one trial of CS-UCS paring, reexposure to CS alone significantly decreased the level of the anti-ovalbumin (OVA) IgG in the peripheral serum. Two trials of CS-UCS paring and three reexposures to CS not only resulted in further suppression of the primary immune response, but also reduced the numbers of peripheral lymphocytes and white blood cells. This finding indicates that CS can induce suppression of the immune function, and the magnitude of the effects is dependent on the intensity of training. 2. On day 5 following two trials of CS-UCS pairing, CS suppressed the spleen lymphocytes responsiveness to mitogens ConA, PHA and PWM, and decreased the numbers of peripheral lymphocytes and white blood cells. On day 15, only PHA induced lymphocyte proliferation was suppressed by CS. On day 30, presentation of CS did not have any effect on these immune parameters. These results suggest that the conditioned suppression of the cellular immune function can retain 5-15 days, and extinct after 30 days. 3. CTA was easily induced by one or two CS-UCS parings, and remained robust even after 30 days. These data demonstrate that CIS can be dissociated from CTA, and they may be mediated by different neural mechanisms. 4. Immunohistochemistry assays revealed a broad pattern of c-fos expression throughout the rat brain following the CS-UCS pairing and reexposure to CS, suggesting that many brain regions are involved in CIS. Some brain areas including the solitary tract nucleus (Sol), lateral parabrachial nucleus (LPB) and insular cortex (IC), showed high level c-fos expressions in response to both CS and UCS, suggesting that they may be involved in the transmission and integration of the CS and UCS signals in the brain. There were dense c-FOS positive neurons in the paraverntricular nucleus (PVN) and supraoptic nucleus (SO) of hypothalamus, subfornical organ (SFO) and area postrema (AP) etc. after two trials of CS-UCS paring and after the reexposure to CS 5 days later, but not in the first training and after the extinction of CIS (30 days later). The results reflect that these nuclei may have an important role in CIS expression, and may also response to the immunosuppression of UCS. The conditioned training and reexposure to CS 5 days later induced high level c-fos expression in the cingulate cortex (Cg), central amygdaloid nucleus (Ce), intermediate part of lateral septal nucleus (LSI) and ventrolateral parabrachial nucleus (VLPB) etc. But c-fos induction was not apparent when presenting CS 30 days later. These brain regions are mainly involved in CIS, and may be critical structures in the acquisition and expression of CIS. Some brain regions, including the frontal cortex (Fr), ventral orbital cortex (VO), IC, perirhinal cortex (PRh), LPB and the medial part of solitary nucleus (SolM), showed robust c-FOS expression following the conditioning training and reexposure to CS both on day 5 and day 30, suggesting that they are critically involved in CTA.