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.

Os recetores da melatonina como novos alvos de fármacos antidepressivos

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

Considerações sobre o papel da química bioinorgânica na saúde

Projeto de Pós-Graduação/Dissertação apresentado à Universidade Fernando Pessoa como parte dos requisitos para obtenção do grau de Mestre em Ciências Farmacêuticas

Novel insights into the role of the GABAB receptor in depression and anxiety

The GABAB receptor is a functional heterodimer comprising the GABAB1 and GABAB2 subunits, with the GABAB1 subunit displaying two major isoforms, GABAB(1a) and GABAB(1b). Preclinical findings have strongly implicated the GABAB receptor in stress-related psychiatric disorders, however, the precise contribution of the GABAB receptor in depression and anxiety disorders remains unknown. Emerging data suggest that the interaction between adverse environmental conditions, such as early life stress, and a specific genetic composition can increase the risk to develop psychiatric disorders in adulthood. This thesis investigated the role of the GABAB receptor alone or in combination with early-life stress (maternal separation), in modulating antidepressant like and anxiety-related behaviours. Pharmacological blockade of the GABAB receptor with CGP52432 had antidepressant-like behavioural effects. Moreover, mice lacking the GABAB(1b) receptor subunit isoform exhibited antidepressant-like behaviours in adulthood but anxiety-like behaviour in early-life. In response to maternal separation, GABAB(1a)-/- mice exhibited early-life stress-induced anhedonia, a core symptom of depression, while GABAB(1b)-/- mice exhibited a more resilient phenotype. Moreover, when compared with wildtype or GABAB(1a)-/- mice, GABAB(1b)-/- mice that underwent maternal separation exhibited enhanced stressinduced neuronal activation in the hippocampus and in the nucleus accumbens (NAcc), a critical area for anhedonia thus suggesting that enhanced stress-induced neuronal activation in the hippocampus and NAcc in GABAB(1b)-/- mice may be important for their antidepressant-like phenotype and their resilience to stress-induced anhedonia. Pharmacological blockade of GABAB receptor and GABAB(1b) receptor subunit isoform loss of function increased adult hippocampal cell proliferation, thus suggesting that increased hippocampal neurogenesis could be a potential mechanism for the antidepressant-like effects of GABAB receptor antagonists and GABAB(1b) receptor subunit isoform disruption. Finally, this thesis investigated whether the expression of several genes involved in hippocampal neurogenesis or the antidepressant response were altered in the mouse hippocampus following chronic treatment with a GABAB receptor antagonist.

Hippocampus shape analysis and late-life depression.

Major depression in the elderly is associated with brain structural changes and vascular lesions. Changes in the subcortical regions of the limbic system have also been noted. Studies examining hippocampus volumetric differences in depression have shown variable results, possibly due to any volume differences being secondary to local shape changes rather than differences in the overall volume. Shape analysis offers the potential to detect such changes. The present study applied spherical harmonic (SPHARM) shape analysis to the left and right hippocampi of 61 elderly subjects with major depression and 43 non-depressed elderly subjects. Statistical models controlling for age, sex, and total cerebral volume showed a significant reduction in depressed compared with control subjects in the left hippocampus (F(1,103) = 5.26; p = 0.0240) but not right hippocampus volume (F(1,103) = 0.41; p = 0.5213). Shape analysis showed significant differences in the mid-body of the left (but not the right) hippocampus between depressed and controls. When the depressed group was dichotomized into those whose depression was remitted at time of imaging and those who were unremitted, the shape comparison showed remitted subjects to be indistinguishable from controls (both sides) while the unremitted subjects differed in the midbody and the lateral side near the head. Hippocampal volume showed no difference between controls and remitted subjects but nonremitted subjects had significantly smaller left hippocampal volumes with no significant group differences in the right hippocampus. These findings may provide support to other reports of neurogenic effects of antidepressants and their relation to successful treatment for depressive symptoms.

Revisiting the monoamine hypothesis of depression: a new perspective.

As the incidence of depression increases, depression continues to inflict additional suffering to individuals and societies and better therapies are needed. Based on magnetic resonance spectroscopy and laboratory findings, gamma aminobutyric acid (GABA) may be intimately involved in the pathophysiology of depression. The isoelectric point of GABA (pI = 7.3) closely approximates the pH of cerebral spinal fluid (CSF). This may not be a trivial observation as it may explain preliminary spectrophotometric, enzymatic, and HPLC data that monoamine oxidase (MAO) deaminates GABA. Although MAO is known to deaminate substrates such as catecholamines, indoleamines, and long chain aliphatic amines all of which contain a lipophilic moiety, there is very good evidence to predict that a low concentration of a very lipophilic microspecies of GABA is present when GABA pI = pH as in the CSF. Inhibiting deamination of this microspecies of GABA could explain the well-established successful treatment of refractory depression with MAO inhibitors (MAOI) when other antidepressants that target exclusively levels of monoamines fail. If further experimental work can confirm these preliminary findings, physicians may consider revisiting the use of MAOI for the treatment of non-intractable depression because the potential benefits of increasing GABA as well as the monoamines may outweigh the risks associated with MAOI therapy.

Antidepressant specificity of serotonin transporter suggested by three LeuT-SSRI structures.

Sertraline and fluoxetine are selective serotonin re-uptake inhibitors (SSRIs) that are widely prescribed to treat depression. They exert their effects by inhibiting the presynaptic plasma membrane serotonin transporter (SERT). All SSRIs possess halogen atoms at specific positions, which are key determinants for the drugs' specificity for SERT. For the SERT protein, however, the structural basis of its specificity for SSRIs is poorly understood. Here we report the crystal structures of LeuT, a bacterial SERT homolog, in complex with sertraline, R-fluoxetine or S-fluoxetine. The SSRI halogens all bind to exactly the same pocket within LeuT. Mutation at this halogen-binding pocket (HBP) in SERT markedly reduces the transporter's affinity for SSRIs but not for tricyclic antidepressants. Conversely, when the only nonconserved HBP residue in both norepinephrine and dopamine transporters is mutated into that found in SERT, their affinities for all the three SSRIs increase uniformly. Thus, the specificity of SERT for SSRIs is dependent largely on interaction of the drug halogens with the protein's HBP.

Low workplace social capital as a predictor of depression - The Finnish public sector study

In a prospective cohort study of Finnish public sector employees, the authors examined the association between workplace social capital and depression. Data were obtained from 33,577 employees, who had no recent history of antidepressant treatment and who reported no history of physician-diagnosed depression at baseline in 2000-2002. Their risk of depression was measured with two indicators: recorded purchases of antidepressants until December 31, 2005, and self-reports of new-onset depression diagnosed by a physician in the follow-up survey in 2004-2005. Multilevel logistic regression analysis was used to explore whether self-reported and aggregate-level workplace social capital predicted indicators of depression at follow-up. The odds for antidepressant treatment and physician-diagnosed depression were 20-50% higher for employees with low self-reported social capital than for those reporting high social capital. These associations were not accounted for by sex, age, marital status, socioeconomic position, place of work, smoking, alcohol use, physical activity, and body mass index. The association between social capital and self-reported depression attenuated but remained significant after further adjustment for baseline psychological distress (a proxy for undiagnosed mental health problems). Aggregate-level social capital was not associated with subsequent depression.

Antenatal depression and anxiety affect postpartum parenting stress:a longitudinal, prospective study

Postpartum depression has been associated with parenting stress, impacting attachment and child development. However, the relation between antenatal depression or anxiety and postpartum parenting stress has not been investigated. We studied the effect of antenatal depression and anxiety and treatment with selective serotonin reuptake inhibitors and selective norepinephrine reuptake inhibitors (antidepressants [ADs]) on postpartum parenting stress.

The difficult-to-treat, therapy-resistant cough: Why are current cough treatments not working and what can we do?

Cough can persist despite exhaustive diagnostic and therapeutic effort and has been termed 'idiopathic' or 'unexplained' but perhaps 'difficult to treat' cough is a more appropriate description. In this article the reasons for poor treatment response are discussed. These include a lack of physician fidelity to management guidelines, patient non-adherence and the lack of effective medicines. A number of randomized controlled trials have been undertaken including low dose opiate therapy, the use of a speech pathology intervention, oral antibiotics and antidepressants. The success or otherwise of such interventions will be discussed. A number of approaches to deal with the problem of 'difficult to treat cough' will be considered.

Psychiatric pharmaceuticals in the environment

Psychiatric pharmaceuticals, such as anxiolytics, sedatives, hypnotics, and antidepressants, are among the most prescribed active substances throughout the world. The occurrence of these widely used compounds in environmental matrices (wastewaters, surface, ground and drinking waters, soils, sediments, bio-solids and tissue), as well as the first studies indicating their high persistence and toxicity to non-target organisms, justify the growing concern about these emerging environmental pollutants. Despite this increasing interest, there is a considerable lack of knowledge about the environmental fate of a large number of psychiatric pharmaceuticals and further research about this topic is needed. This paper aims to review the literature data related to the occurrence, persistence, environmental fate and toxicity for non-target organisms of this group of pharmaceuticals. The analytical methods developed for the determination of psychiatric medicines in environmental matrices are also highlighted.

Photodegradation of sertraline by solar radiation and influencing factors

Photodegradation is considered to be one of the most important processes of elimination of pharmaceutical drugs from natural water matrices. The high consumption and discharge of these substances, in particular antidepressants, to the aquatic environment supports the need to study degradation processes. This dissertation aimed at studying the direct and indirect photodegradation of sertraline, an antidepressant known for its persistence in the environment, and the evaluation of the influence of environmentally relevant factors in its photodegradation. The photodegradation experiments were developed under simulated solar light and the irradiation times converted to summer sunny days (SSD), an equivalent time in natural environmental conditions. The direct photodegradation was evaluated in solutions of sertraline prepared in ultrapure water and the indirect photodegradation was studied through the addition of photosensitizers (humic substances, Fe(III), nitrates and oxygen). Further irradiation studies were perfomed in aqueous samples collected from two wastewater treatment plants, Vouga river and Ria de Aveiro. The samples were chemically characterized (dissolved organic carbon, nitrates and nitrites and iron determination and UV/Vis spectroscopy). The quantification of sertraline was done by HPLC-UV and photoproducts from direct photodegradation were identified by electrospray mass spectrometry. An observed direct photodegradation rate of sertraline of 0.0062 h-1 was determined, corresponding to a half-life time of 111 h (equivalent to 29 SSD). A significant influence of photosensitizers was observed, the best results being achieved in irradiations of sertraline with humic acids, obtaining a half-life time of 12 h. This was attributed to the hydrophobicity of this substance and higher absortivity in the UV/Vis wavelength, which promote processes of indirect photodegradation. The degradation of sertraline in natural samples was also enhanced comparatively to the direct photodegradation, achieving half-life times between 10 and 25h; the best results were achieved in samples from the primary treatment of a wastewater treatment plant and Ria de Aveiro, with half-life times of 10 and 16 h, respectively. A total of six photoproducts formed during the direct photodegradation of sertraline were identified, three of which were not yet identified in the literature. The main factors contributing to the degradation of sertraline were analysed but this was not fully accomplished, requiring further studies of the composition of the natural matrices and the combined influence of distinct photosensitizers during the irradiation. Nevertheless, it was concluded that the photodegradation of sertraline is greatly influenced by indirect photodegradation processes, promoted by the presence of photosensitizers.

Operacionalização para Portugal: Critérios de Beers de medicamentos inapropriados nos doentes idosos

Introdução: A terapêutica medicamentosa do doente idoso requer cuidados acrescidos tendo em conta as suas alterações fisiopatológicas e múltiplas patologias, que o tornam mais susceptível a eventos adversos. Têm sido criados diversos instrumentos para avaliação do uso de medicamentos inapropriados no idoso, sendo o mais frequentemente utilizado, os Critérios de Beers, cuja última actualização data de 2002. Objectivos: Operacionalização dos Critérios de Beers para alertar os profissionais de saúde em Portugal. Métodos: Análise dos fármacos e grupos de fármacos dos Critérios de Beers, comercializados em Portugal, identificação das substâncias pertencentes aos grupos assinalados por Beers que não foram incluídas nestes Critérios. Resultados: Ajustaram-se as dois quadros dos Critérios de Beers, com referência às substâncias comercializadas em Portugal e inclusão das substâncias pertencentes aos grupos de fármacos indicados na escala de Beers, com respectivos graus de inapropriação e efeitos que podem ocorrer com a administração dos medicamentos aos idosos. No quadro 1 de Beers haviam 34 substâncias sem Autorização de Introdução no Mercado (AIM) e quatro possuem designações diferentes. No quadro 2, por possuírem AIM e não estarem mencionadas, incluíram-se três antidepressivos tricíclicos, 12 antipsicóticos convencionais, doses máximas de cinco benzodiazepinas de curta acção, não se tendo encontrado referência a doses de duas, e 28 AINEs, sendo que dois são Coxibs. Conclusão: A operacionalização para Portugal dos Critérios de Beers permite a criação de um instrumento que auxilie o médico na escolha de medicamentos e doses a prescrever ao idoso garantindo um aumento de segurança da terapêutica. Esta operacionalização permite ainda a comparação de resultados de estudos sobre terapêutica inapropriada no doente idoso realizados em países diferentes e que apliquem os Critérios de Beers.

Starting antidepressant use: a qualitative synthesis of UK and Australian data

Objective To explore people's experiences of starting antidepressant treatment. Design Qualitative interpretive approach combining thematic analysis with constant comparison. Relevant coding reports from the original studies (generated using NVivo) relating to initial experiences of antidepressants were explored in further detail, focusing on the ways in which participants discussed their experiences of taking or being prescribed an antidepressant for the first time. Participants 108 men and women aged 22–84 who had taken antidepressants for depression. Setting Respondents recruited throughout the UK during 2003–2004 and 2008 and 2012–2013 and in Australia during 2010–2011. Results People expressed a wide range of feelings about initiating antidepressant use. People's attitudes towards starting antidepressant use were shaped by stereotypes and stigmas related to perceived drug dependency and potentially extreme side effects. Anxieties were expressed about starting use, and about how long the antidepressant might begin to take effect, how much it might help or hinder them, and about what to expect in the initial weeks. People worried about the possibility of experiencing adverse effects and implications for their senses of self. Where people felt they had not been given sufficient time during their consultation information or support to take the medicines, the uncertainty could be particularly unsettling and impact on their ongoing views on and use of antidepressants as a viable treatment option. Conclusions Our paper is the first to explore in-depth patient existential concerns about start of antidepressant use using multicountry data. People need additional support when they make decisions about starting antidepressants. Health professionals can use our findings to better understand and explore with patients’ their concerns before their patients start antidepressants. These insights are key to supporting patients, many of whom feel intimidated by the prospect of taking antidepressants, especially during the uncertain first few weeks of treatment.

FAS -670A>G genetic polymorphism Is associated with Treatment Resistant Depression

Background Hippocampal neurogenesis has been suggested as a downstream event of antidepressants (AD) mechanism of action and might explain the lag time between AD administration and the therapeutic effect. Despite the widespread use of AD in the context of Major Depressive Disorder (MDD) there are no reliable biomarkers of treatment response phenotypes, and a significant proportion of patients display Treatment Resistant Depression (TRD). Fas/FasL system is one of the best-known death-receptor mediated cell signaling systems and is recognized to regulate cell proliferation and tumor cell growth. Recently this pathway has been described to be involved in neurogenesis and neuroplasticity. Methods Since FAS -670A>G and FASL -844T>C functional polymorphisms never been evaluated in the context of depression and antidepressant therapy, we genotyped FAS -670A>G and FASL -844T>C in a subset of 80 MDD patients to evaluate their role in antidepressant treatment response phenotypes. Results We found that the presence of FAS -670G allele was associated with antidepressant bad prognosis (relapse or TRD: OR=6.200; 95% CI: [1.875–20.499]; p=0.001), and we observed that patients carrying this allele have a higher risk to develop TRD (OR=10.895; 95% CI: [1.362–87.135]; p=0.008).Moreover, multivariate analysis adjusted to potentials confounders showed that patients carrying G allele have higher risk of early relapse (HR=3.827; 95% CI: [1.072–13.659]; p=0.039). FAS mRNA levels were down-regulated among G carriers, whose genotypes were more common in TRD patients. No association was found between FASL-844T>C genetic polymorphism and any treatment phenotypes. Limitations Small sample size. Patients used antidepressants with different mechanisms of action. Conclusion To the best of our knowledge this is the first study to evaluate the role of FAS functional polymorphism in the outcome of antidepressant therapy. This preliminary report associates FAS -670A>G genetic polymorphism with Treatment Resistant Depression and with time to relapse. The current results may possibly be given to the recent recognized role of Fas in neurogenesis and/or neuroplasticity.