Serotonin–dopamine interaction : an overview

Central serotonergic and dopaminergic systems play a critical role in the regulation of normal and abnormal behaviours. Moreover, recent evidence suggests that the dysfunction of dopamine (DA) and serotonin (5-hydroxytriptamine, 5-HT) neurotransmission might underlie the pathophysiology of neuropsychiatric disorders, including depression, schizophrenia, attention deficit hyperactivity disorders, drug abuse, Gilles de la Tourette's syndrome and Parkinson's disease.peer-reviewe

Role of serotonin in central dopamine dysfunction

The interaction between serotonin (5-HT) and dopamine (DA)-containing neurons in the brain is a research topic that has raised the interest of many scientists working in the field of neuroscience since the first demonstration of the presence of monoamine-containing neurons in the mid 1960. The bulk of neuroanatomical data available clearly indicate that DA-containing neurons in the brain receive a prominent innervation from serotonin (5-hydroxytryptamine, 5-HT) originating in the raphe nuclei of the brainstem. Compelling electrophysiological and neurochemical data show that 5-HT can exert complex effects on the activity of midbrain DA neurons mediated by its various receptor subtypes. The main control seems to be inhibitory, this effect being more marked in the mesocorticolimbic DA system as compared to the DA nigrostriatal system. In spite of a direct effect of 5-HT by its receptors located on DA cells, 5-HT can modulate their activity indirectly, modifying γ-aminobutyric (GABA)-ergic and glutamatergic input to the ventral tegmental area (VTA) and substantia nigra pars compacta (SNc). Although 5-HT/DA interaction in the brain has been extensively studied, much work remains to be done to clarify this issue. The recent development of subtype-selective ligands for 5-HT receptors will not only allow a detailed understanding of this interaction but also will lead to the development of new treatment strategies, appropriate for those neuropsychiatric disorders in which an alteration of the 5-HT/DA balance is supposed.peer-reviewe

HEIDEGGER E A PSICANÁLISE: UMA CONVERSA EM SICÍLIA

Pretendo, neste artigo, analisar algumas críticas pontuais que Heidegger dirige à psicanálise freudiana, restringindo-me à conversa que manteve com Medard Boss, nas férias sicilianas de abril-maio 1963. Após uma breve contextualização do que o próprio Heidegger chamou de ‘conversas sicilianas’, procuro identificar os horizontes teóricos dentro dos quais elas se situam, analiso as críticas dirigidas à psicanálise enquanto método, terapia e metapsicologia e concluo tecendo algumas considerações quanto à sua validade e limites

AINDA PREFERIMOS “QUERER O NADA A NADA QUERER”?

Pretendo, nesta Comunicação, partir de uma frase emblemática com que se abre e conclui a III Dissertação da Genealogia da moral: “o homem preferirá ainda querer o nada a nada querer”. O objetivo é testar até que ponto o pensamento de Nietzsche nos pode ajudar para pensar um fenômeno contemporâneo que afeta diretamente ou indiretamente milhões de pessoas: o da depressão. Após uma contextualização e uma justificativa do método de abordagem do texto nietzschiano selecionado, procedo a uma análise da crítica do filósofo ao “ideal ascético” e às figuras culturais do pensamento ocidental que o legitimaram para refletir, em seguida, se e até que ponto ainda hoje, em nosso mundo globalizado, o fenômeno da depressão pode ser caracterizado como “uma vontade de nada”. Finalizo, problematizando a saída terapêutica apenas por uma medicalização da existência

A leitura de Rorty da Reflexão Moral de Freud: uma avaliação

Resumo:Neste artigo, pretendo sondar se e até que ponto a interpretação de Rorty das implicações éticomorais da psicanálise freudiana é pertinente, tendo presentes os vários discursos éticos de Freud. Ao mesmo tempo, procuro explicitar em que sentido a redescrição neopragmática do fenômeno moral não viria apenas enriquecer nosso vocabulário moral, mas - com isso - possibilitar uma ampliação de nós mesmos e tornar “nossas esperanças e desejos mais ricos e mais plenos”. Num primeiro momento, procuro reconstruir a argumentação rortyana para legitimar a relevância do pensamento freudiano e suas implicações para a reflexão moral. Em seguida, teço algumas considerações me posicionando criticamente diante dessa releitura.Palavras-chave: Rorty. Pragmatismo. Psicanálise. Ética.Abstract:In this article I intend to probe if and until what point the interpretation of Rorty on the ethical-moral implications of the freudian psychoanalysis is pertinent based on the several ethical speeches of Freud. At the same time I attempt to explicit in what sense the neopragmatic redescription of the moral phenomenon would not only come to enrich our moral vocabulary but, by that, to make possible an enrichment of ourselves and turn "our hopes and desires richer and fulfilled". At the first moment I aim to reconstruct the rortyan argument to legitimize the relevance of the freudian thought and its implications on the moral reflection. Later on I'll make some regards putting myself on a critic position about this rereading.Keywords: Rorty. Pragmatism. Psychoanalysis. Ethics

Techniques in Neuroscience

Microdialysis cerebral technique has been widely employed in order to study neurotransmitter release. This technique presents numerous advantages such as it allows work with sample in vivo from freely moving animals. Different drugs in different points implanted probes in several brain areas can be infused simultaneously by means of microdialysis. Parkinson’s disease (PD) is a progressive neurodegenerative disorder that is primarily characterized by the degeneration of dopamine (DA) neurons in the nigrostriatal system, which in turn produces profound neurochemical changes within the basal ganglia, representing the neural substrate for Parkinsonian motor symptoms. Over the years, a broad variety of experimental models of the disease have been developed and applied in diverse animal species. The two most common toxin models used employ 6-hydroxydopamine (6-OHDA) and the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine/1-methyl-4-phenilpyridinium ion (MPTP/MPP+), either given systemically or locally applied into the nigrostriatal pathway, to resemble PD features in animals. Both neurotoxins selectively and rapidly destroy catecholaminergic neurons, although with different mechanisms. Since in vivo microdialysis coupled to high-performance liquid chromatography (HPLC) is an established technique for studying physiological, pharmacological, and pathological changes of a wide range of low molecular weight substances in the brain extracellular fluid, here we describe a rapid and simple microdialysis technique that allows the direct quantitative study of the damage produced by 6-OHDA and MPP+ toxins on dopaminergic (DAergic) striatal terminals of rat brain.peer-reviewe

Inflammation in Parkinson’s disease : therapeutic implications

Parkinson’s disease (PD) is known to be a chronic and progressive neurodegenerative disease caused by a selective degeneration of dopaminergic (DAergic) neurons in the substantia nigra pars compacta (SNc). A large body of experimental evidence indicates that the factors involved in the pathogenesis of this disease are several, occurring inside and outside the DAergic neuron. Recently, the role of the neuron-glia interaction and the inflammatory process, in particular, has been the object of intense study by the research community. It seems to represent a new therapeutic approach opportunity for this neurological disorder. Indeed, it has been demonstrated that the cyclooxygenase type 2 (COX-2) is up-regulated in SNc DAergic neurons in both PD patients and animal models of PD and, furthermore, non-steroidal anti-inflammatory drugs (NSAIDs) pre-treatment protects against 1-methyl-4- phenyl-1,2,3,6-tetrahydropyridine (MPTP) or 6 hydroxydopamine (6-OHDA)-induced nigro-striatal dopamine degeneration. Moreover, recent epidemiological studies have revealed that the risk of developing PD is reduced in humans who make therapeutical use of NSAIDs. Consequently, it is hypothesized that they might delay or prevent the onset of PD. However, whether or not these common drugs may also be of benefit to those individuals who already have Parkinson’s disease has not as yet been shown. In this paper, evidence relating to the protective effects of aspirin or other NSAIDs on DAergic neurons in animal models of Parkinson’s disease will be discussed. In addition, the pharmacological mechanisms by which these molecules can exert their neuroprotective effects will be reviewed. Finally, epidemiological data exploring the effectiveness of NSAIDs in the prevention of PD and their possible use as adjuvants in the therapy of this neurodegenerative disease will also be examined.peer-reviewe

Central serotonin2C receptor : from physiology to pathology

Since the 1950s, when serotonin (5-HT) was discovered in the mammalian central nervous system (CNS), an enormous amount of experimental evidence has revealed the pivotal role of this biogenic amine in a number of cognitive and behavioural functions. Although 5-HT is synthesized by a small group of neurons within the raphe nuclei of the brain stem, almost all parts of the CNS receive serotonergic projections. Furthermore, the importance of 5-HT modulation and the fine-tuning of its action is underlined by the large number of 5-HT binding sites found in the CNS. Hitherto, up to 15 different 5-HT receptors subtypes have been identified. This review was undertaken to summarize the work that has explored the pathophysiological role of one of these receptors, the 5-HT2C receptor, that has been emerged as a prominent central serotonin receptor subtype. The physiology, pharmacology and anatomical distribution of the 5-HT2C receptors in the CNS will be firstly reviewed. Finally, their potential involvement in the pathophysiology of depression, schizophrenia, Parkinson's disease and drug abuse will be also discussed.peer-reviewe

Effects of transcranial alternating current stimulation on repetitive finger movements in healthy humans

Transcranial alternating current stimulation (tACS) is a noninvasive neurophysiological technique that can entrain brain oscillations. Only few studies have investigated the effects of tACS on voluntary movements. We aimed to verify whether tACS, delivered over M1 at beta and gamma frequencies, has any effect on repetitive finger tapping as assessed by means of kinematic analysis. Eighteen healthy subjects were enrolled. Objective measurements of repetitive finger tapping were obtained by using a motion analysis system. M1 excitability was assessed by using single-pulse TMS and measuring the amplitude of motor-evoked potentials (MEPs). Movement kinematic measures and MEPs were collected during beta, gamma, and sham tACS and when the stimulation was off. Beta tACS led to an amplitude decrement (i.e., progressive reduction in amplitude) across the first ten movements of the motor sequence while gamma tACS had the opposite effect. The results did not reveal any significant effect of tACS on other movement parameters, nor any changes in MEPs. These findings demonstrate that tACS modulates finger tapping in a frequency-dependent manner with no concurrent changes in corticospinal excitability. The results suggest that cortical beta and gamma oscillations are involved in the motor control of repetitive finger movements