Rapid postmortem changes of rat striatum dopamine, serotonin, and their metabolites as monitored by brain microdialysis

Brain microdialysis was used to monitor changes in extracelluar dopamine (DA), serotonin (5-HT), and their metabolite levels in the rat striatum at death by cervical dislocation. Maximum respective 450-fold and 150-fold increases in the extracelluar output of DA and 5-HT were observed within the first 30 min of death. DA and 5-HT outputs remained elevated over the following 2 h at levels about 100-fold and 50-fold above pre-death values, respectively. In contrast with monoamine outputs, the outputs of the DA metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), and the 5-HT metabolite, 5-hydroxyindoleacetic acid (5-HIAA), rapidly decreased by 10% and 20%, respectively 1 h after death. 5-Hydroxytryptophol (5-HTOL) gradually decreased after death. Before death both the extracellular DOPAC/DA and 5-HIAA/5-HT ratios were about 400; after death these ratios dropped to 0.56 and 4.0, respectively at 30 min. These observations suggested that regulation of neurotransmitter releases through the neuronal membrane and metabolisms in the rat striatum were seriously disrupted at death. This finding may be helpful in the determination of death in the field of forensic medicine.     

Who's flying the plane: serotonin levels, aggression and free will

The present paper addresses the philosophical problem raised by current causal neurochemical models of impulsive violence and aggression: to what extent can we hold violent criminal offenders responsible for their conduct if that conduct is the result of deterministic biochemical processes in the brain. This question is currently receiving a great deal of attention among neuroscientists, legal scholars and philosophers. We examine our current knowledge of neuroscience to assess the possible roles of deterministic factors which induce impulsive aggression, and the extent to which this behavior can be controlled by neural conditioning mechanisms. Neural conditioning mechanisms, we suggest, may underlie what we consider the basis of responsible (though not necessarily moral) behavior: the capacity to give and take reasons. The models we first examine are based in part upon the role played by the neurotransmitter, serotonin, in the regulation of violence and aggression. Collectively, these results would appear to argue in favor of the view that low brain serotonin levels induce impulsive aggression which overrides mechanisms related to rational decision making processes. We next present an account of responsibility as based on the capacity to exercise a certain kind of reason-responsive control over one's conduct. The problem with such accounts of responsibility, however, is that they fail to specify a neurobiological realization of such mechanisms of control. We present a neurobiological, and weakly determinist, framework for understanding how persons can exercise guidance control over their conduct. This framework is based upon classical conditioning of neurons in the prefrontal cortex that allow for a decision making mechanism that provides for prefrontal cortical control of the sites in the brain which express aggressive behavior that include the hypothalamus and midbrain periaqueductal gray. The authors support the view that, in many circumstances, neural conditioning mechanisms provide the basis for the control of human aggression in spite of the presence of brain serotonin levels that might otherwise favor the expression of impulsive aggressive behavior. Indeed if those neural conditioning mechanisms underlie the human capacity to exercise control, they may be the neural realization of reason-responsiveness generally.     

艾灸干预腹泻型肠易激综合征大鼠miR 24/SERT/5 HT通路改善内脏高敏感状态实验观察

目的 观察艾灸干预对腹泻型肠易激综合征（diarrhea predominant irritable bowel syndrome,IBS-D）大鼠微小RNA-24（micro RNA-24,miR-24）/5-羟色胺转运体（serotonin transporter,SERT）/5-羟色胺（5-hydroxytryptamine,5-HT）通路的影响,探究艾灸改善IBS-D大鼠内脏敏感性的作用机制。方法 将SD大鼠随机分为正常组、模型组、艾灸组共3组,每组12只。采用母子分离＋醋酸刺激＋慢性束缚法制备IBS-D大鼠模型。艾灸组给予艾灸双侧“天枢”“上巨虚”20 min,连续7 d。分别于34、45、53 d检测各组大鼠体质量、稀便率和腹部回撤反射（abdominal withdrawal reflex,AWR）的最小容量阈值;苏木精-伊红染色检测结肠组织病理学变化;ELISA法测定大鼠血清、中脑、结肠组织中5-HT、SERT、5-羟色胺受体4（serotonin receptor 4,5-HT4R）、降钙素基因相关肽（calcitonin gene related peptide,CGRP）、P物质（substance P,SP）水平的变化;Western blot、RT-PCR检测大鼠中脑、结肠组织中SERT、5-HT4R、CGRP、SP的蛋白及mRNA表达水平;RT-PCR检测中脑、结肠组织中miR-24表达水平。结果 与正常组比较,模型组大鼠稀便率升高（P＜0.05）、AWR最小容量阈值下降（P＜0.05）;血清、中脑、结肠组织中5-HT、5-HT4R、CGRP、SP水平均显著升高（P＜0.05）,SERT水平均显著降低（P＜0.05）;miR-24表达水平显著升高（P＜0.05）,SERT蛋白及mRNA表达水平均明显降低（P＜0.05）,5-HT4R、CGRP、SP的蛋白及mRNA表达水平均明显升高（P＜0.05）;与模型组比较,艾灸组大鼠稀便率下降（P＜0.05）,AWR最小容量阈值上升（P＜0.05）;血清、中脑和结肠组织中5-HT、5-HT4R、CGRP、SP水平均显著降低（P＜0.05）,SERT水平显著升高（P＜0.05）;miR-24表达水平显著降低（P＜005）,SERT的蛋白及mRNA表达水平显著升高（P＜0.05）,5-HT4R、CGRP、SP的蛋白及mRNA表达水平显著降低（P＜0.05）。结论 艾灸干预改善IBS-D大鼠内脏高敏感性可能与下调miR-24表达,促进SERT对5-HT的重摄取,降低5-HT水平有关。     

In silico toxicity as a tool for harm reduction: A study of new psychoactive amphetamines and cathinones in the context of criminal science

The emergence of new psychoactive substances (NPS) has raised many issues in the context of law enforcement and public drug policies. In this scenario, interdisciplinary studies are crucial to the decision-making process in the field of criminal science. Unfortunately, information about how NPS affect people's health is lacking even though knowledge about the toxic potential of these substances is essential: the more information about these drugs, the greater the possibility of avoiding damage within the scope of a harm reduction policy. Traditional analytical methods may be inaccessible in the field of forensic science because they are relatively expensive and time-consuming. In this sense, less costly and faster in silico methodologies can be useful strategies. In this work, we submitted computer-calculated toxicity values of various amphetamines and cathinones to an unsupervised multivariate analysis, namely Principal Component Analysis (PCA), and to the supervised techniques Soft Independent Modeling of Class Analogy and Partial Least Square-Discriminant Analysis (SIMCA and PLS-DA) to evaluate how these two NPS groups behave. We studied how theoretical and experimental values are correlated by PLS regression. Although experimental data was available for a small amount of molecules, correlation values reproduced literature values. The in silico method efficiently provided information about the drugs. On the basis of our findings, the technical information presented here can be used in decision-making regarding harm reduction policies and help to fulfill the objectives of criminal science.     

The relation of ADHD and violent aggression: What can we learn from epidemiological and genetic studies?

Disruptive behavior includes psychopathological and behavioral constructs like aggression, impulsivity, violence, antisociality and psychopathy and is often closely related with diagnostic categories like conduct disorder (CD), attention deficit disorder (ADHD) and antisocial personality disorder (ASP). There is now clear evidence that neurobiological and environmental factors contribute to these phenotypes. A mounting body of evidence also suggests interactive effects of genetic and environmental risks.In this selective review we give an overview over epidemiological aspects of the relation between ADHD and antisocial behavior, including violent aggression and psychopathy. Moreover, we summarize recent findings from molecular genetic studies and particularly discuss pleiotropic effects of a functional polymorphism of the serotonin transporter promoter gene (5HTTLPR) and childhood adversity on ADHD and violent behavior. The reported gene–environment interactions are not only informative for understanding the neurobiological underpinnings of disruptive behavior, but also throw some light on the relation between ADHD and violent behavior from a genetic perspective. The impact of genetic research on forensic psychiatry and future directions of neurobiological research are discussed.     

Understanding human aggression: New insights from neuroscience

The present paper reviews and summarizes the basic findings concerning the nature of the neurobiological and behavioral characteristics of aggression and rage. For heuristic purposes, the types of aggression will be reduced to two categories — defensive rage (affective defense) and predatory attack. This approach helps explain both the behavioral properties of aggression as well as the underlying neural substrates and mechanisms of aggression both in animals and humans. Defensive rage behavior is activated by a threatening stimulus that is real or perceived and is associated with marked sympathetic output. This yields impulsivity with minimal cortical involvement. Predatory attack behavior in both animals and humans is generally planned, taking minutes, hours, days, weeks, months, or even years (with respect to humans) for it to occur and is directed upon a specific individual target; it reflects few outward sympathetic signs and is believed to require cortical involvement for its expression. Predatory attack requires activation of the lateral hypothalamus, while defensive rage requires activation of the medial hypothalamus and midbrain periaqueductal gray (PAG). Both forms of aggressive behavior are controlled by components of the limbic system, a region of the forebrain that is influenced by sensory inputs from the cerebral cortex and monoaminergic inputs from the brainstem reticular formation. Control of aggressive tendencies is partly modifiable through conditioning and related learning principles generated through the cerebral cortex.     

The Media and the Chemical Imbalance Theory of Depression

The cause of mental disorders such as depression remains unknown. However, the idea that neurotransmitter imbalances cause depression is vigorously promoted by pharmaceutical companies and the psychiatric profession at large. We examine media reports referring to this chemical imbalance theory and ask reporters for evidence supporting their claims. We then report and critique the scientific papers and other confirming evidence offered in response to our questions. Responses were received from multiple sources, including practicing psychiatrists, clients, and a major pharmaceutical company. The evidence offered was not compelling, and several of the cited sources flatly stated that the proposed theory of serotonin imbalance was known to be incorrect. The media can play a positive role in mental health reporting by ensuring that the information reported is congruent with the peer-reviewed scientific literature.