Serotonergic (5-HT2) mediation of anxiety-therapeutic effects of serazepine in generalized anxiety disorder

A multicomponent reaction for modular assembly of indole-fused heterocycles

Indoles are privileged chemical entities in natural products and drug discovery. Indole-fused heterocycles, particularly seven-membered ones, have received increasing attention due to their distinctive chemical characteristics and wide spectrum of bioactivities. However, the synthetic access to these compounds is highly limited. Herein, we report a unique multicomponent reaction (MCR) for modular assembly of indole-fused seven-membered heterocycles. In this process, indole, formaldehyde and amino hydrochloride could assemble rapidly to yield indole-fused oxadiazepines, and another addition of sodium thiosulphate would furnish indole-fused thiadiazepines. The biological evaluation disclosed the promising anticancer activity of these compounds. Furthermore, this MCR could be applicable in the late-stage and selective modifications of peptides. Therefore, this work provides a powerful strategy for indole functionalization and valuable tool for construction of seven-membered heterocycles.

Simulation of nanoparticle permeation through a lipid membrane

A metric of nanoparticle toxicity is the passive permeability rate through cellular membranes. To assess the influence of nanoparticle morphology on this process, the permeability of buckyball-sized molecules through a representative lipid bilayer was investigated by molecular-dynamics simulation. When C(60) was compared with a prototypical opened C(60) molecule and a representative combustion-generated particle, C(68)H(29), the calculated free-energy profiles along the permeation coordinate revealed a sizable variation in form and depth. The orientation of the anisotropic molecules was determined by monitoring the principal axis corresponding to the largest moment of inertia, and free rotation was shown to be hindered in the bilayer interior. Diffusion constant values of the permeant molecules were calculated from a statistical average of seven to 10 trajectories at five locations along the permeation coordinate. A relatively minor variation of the values was observed in the bilayer interior; however, local resistance values spanned up to 24 orders of magnitude from the water layer to the bilayer center, due primarily to its exponential dependence on free energy. The permeability coefficient values calculated for the three similarly sized but structurally distinct nanoparticles showed a significant variance. The use of C(60) to represent similarly sized carbonaceous nanoparticles for assessments of toxicity is questioned.

The etiology, biology, and evolving pathology of premenstrual syndromes

Menstrually related symptoms and disorders are multidimensional and affect diverse physiologic systems. Elucidation of the pathophysiologic mechanisms of these disorders should allow for a more precise diagnosis, and provide direction for targeted therapeutic interventions. Several biologic mechanisms that underlie menstrually related symptoms have been proposed. They focus mostly on gonadal hormones, their metabolites and interactions with neurotransmitters and neurohormonal systems, such as serotonin, GABA, cholecystokinin, and the renin-angiotensin-aldosterone system. Altered responses of these systems to gonadal hormone's fluctuations during the menstrual cycle, as well as an increased sensitivity to changes in gonadal hormones may contribute to menstrually related symptoms in vulnerable women. Disrupted homeostasis and deficient adaptation may be core underlying mechanisms. Future directions for clinically-relevant progress include identification of specific subgroups of menstrually-related syndromes, assessment of the genetic vulnerability and changes in vulnerability along the life cycle, the diversified mechanisms by which vulnerability is translated into pathophysiology and symptoms, the normalization process as well as syndromes-based and etiology-based clinical trials.

The neurobiology and control of anxious states

Fear is an adaptive component of the acute "stress" response to potentially-dangerous (external and internal) stimuli which threaten to perturb homeostasis. However, when disproportional in intensity, chronic and/or irreversible, or not associated with any genuine risk, it may be symptomatic of a debilitating anxious state: for example, social phobia, panic attacks or generalized anxiety disorder. In view of the importance of guaranteeing an appropriate emotional response to aversive events, it is not surprising that a diversity of mechanisms are involved in the induction and inhibition of anxious states. Apart from conventional neurotransmitters, such as monoamines, gamma-amino-butyric acid (GABA) and glutamate, many other modulators have been implicated, including: adenosine, cannabinoids, numerous neuropeptides, hormones, neurotrophins, cytokines and several cellular mediators. Accordingly, though benzodiazepines (which reinforce transmission at GABA(A) receptors), serotonin (5-HT)(1A) receptor agonists and 5-HT reuptake inhibitors are currently the principle drugs employed in the management of anxiety disorders, there is considerable scope for the development of alternative therapies. In addition to cellular, anatomical and neurochemical strategies, behavioral models are indispensable for the characterization of anxious states and their modulation. Amongst diverse paradigms, conflict procedures--in which subjects experience opposing impulses of desire and fear--are of especial conceptual and therapeutic pertinence. For example, in the Vogel Conflict Test (VCT), the ability of drugs to release punishment-suppressed drinking behavior is evaluated. In reviewing the neurobiology of anxious states, the present article focuses in particular upon: the multifarious and complex roles of individual modulators, often as a function of the specific receptor type and neuronal substrate involved in their actions; novel targets for the management of anxiety disorders; the influence of neurotransmitters and other agents upon performance in the VCT; data acquired from complementary pharmacological and genetic strategies and, finally, several open questions likely to orientate future experimental- and clinical-research. In view of the recent proliferation of mechanisms implicated in the pathogenesis, modulation and, potentially, treatment of anxiety disorders, this is an opportune moment to survey their functional and pathophysiological significance, and to assess their influence upon performance in the VCT and other models of potential anxiolytic properties.

The medical benefit of 5-HT research

5-HT research is now more than 50 years old, and it has generated a wealth of therapeutic agents, some of which have had a major impact on disease management. The 5-HT reuptake inhibitors (SSRIs) are among the most widely prescribed drugs for treating depression and a variety of other disorders including anxiety, social phobia and premenstrual dysphoria (PMD). The other major success stories of 5-HT research are the discovery of 5-HT1B/D receptor agonists for treating migraine and 5-HT3 receptor antagonists for chemotherapy and radiation-induced emesis. The role of 5-HT in the mechanism of action of antipsychotic agents remains a topic of intense research, which promises better treatments for schizophrenia in the future. Compounds interacting with 5-HT1F, 5-HT2C, 5-HT6 and 5-HT7 receptors are currently under investigation and may prove to have important therapeutic applications in the future.

The psychobiology of anxiolytic drug. Part 2: Pharmacological treatments of anxiety

Benzodiazepines have been the mainstay of pharmacological treatment of anxiety over the last 4 decades. The problems associated with their use prompted the research for alternative agents that would be useful in anxiety conditions. Old classes of antidepressants, such as tricyclic antidepressants and monoamine oxidase inhibitors, showed effectiveness in some anxiety syndromes, even in areas where benzodiazepines were not very effective. Newer antidepressants, the selective serotonin-reuptake inhibitors, also appear very useful in some anxiety states, and their favourable side-effect profile has elevated them to first-line treatment tools in these conditions. However, the ideal anxiolytic does not exist. Research with other new compounds is very active, and some experimental drugs show promise for the future.

Potential treatment paradigms for anxiety disorders

The current classification system of anxiety disorders allows us to match treatment with the particular form of disorder presented. The first part of this paper presents the main features of each anxiety disorder with the approved pharmacological treatment. Despite progress in this field, treatment has to be improved to resolve resistant symptoms and to eliminate adverse side effects of the drugs currently used. The efficacy of antidepressants in chronic anxiety disorders as compared to classic 'anxiolytics' has been shown. For treatment of acute phase of anxiety, new drugs have been proposed as an alternative to benzodiazepines (BZD), but to date, no individual agent has demonstrated a better effectiveness. Interesting results may be provided by drugs acting on CCK receptors or with 5HT blockers. Preliminary results are listed and prospects in the field are proposed. The discussion focuses on an improved definition of anxiety and on the overlap of anxiety symptoms with those of depression.

Effects of the CCK(B) antagonist CI-988 on responses to mCPP in generalized anxiety disorder

In order to evaluate the effect of the CCK(B) antagonist CI-988 on behavioral, neuroendocrine, and physiologic responses to the mixed, post-synaptic serotonin (5-HT) agonist/antagonist mCPP, 16 patients with a principal DSM-III-R diagnosis of generalized anxiety disorder (GAD) were enrolled in a study that involved two challenge tests. On one day, patients received a single oral dose of CI-988 followed 30 min later by an i.v. infusion of 0.1 mg/kg mCPP. On a second test day patients received placebo CI-988 followed 30 min later by active i.v. mCPP. The sequence of CI-988 was randomly assigned and the testing was conducted in double-blind fashion. In an initial dose-finding phase (N = 6) with a dose of CI-988 of 25 mg, there were no significant between-test differences in behavioral response to mCPP. Accordingly, the second phase of the study was conducted with a CI-988 dose of 100 mg in another of patients (N = 10). CI-988 (100 mg) was well tolerated and had no significant effects on pretest anticipatory anxiety. There was no significant blunting of the anxiety response to mCPP as a result of CI-988 administration, nor did CI-988 affect physiologic or neuroendocrine measures. Correlations between peak changes in plasma levels of CI-988 and mCPP-induced anxiety in the high-dose patient group were not significant. Overall, these findings did not provide evidence of anxiolytic effects of CI-988 in patients with GAD. The lack of effect of CI-988 on neuroendocrine and physiological measures further suggests that CI-988's pharmacological effects could be independent of 5-HT function. However, follow-up studies using higher doses of CI-988 are indicated to confirm this preliminary finding as are studies more closely evaluating the interrelationship between CCK and 5-HT function in GAD.

The prospect of new anxiolytic principles

Novel anxiolytics notwithstanding, in the latest fifteen years there have been no major innovations in the treatment of anxiety disorders. Fascinating research is going on, but real breakthroughs will require adequate models of disease, based on the disordered physiology of each type of pathological anxiety. In this brief overview, we will address both the field of potential anxiolytics in 1997, and the development of new experimental models of anxiety disorders.