The link between stress and the efficacy of anxiolytics. A new avenue of research

Role of Basolateral Amygdalar Somatostatin 2 Receptors in a Rat Model of Chronic Anxiety

Repeated exposure to stress has been implicated in inducing chronic anxiety states. Stress related increases in anxiety responses are likely mediated by activation of corticotropin-releasing factor receptors (CRFR) in the amygdala, particularly the basolateral amygdala (BLA). Within the BLA, acute injections of the CRFR agonist urocortin 1 (Ucn1) leads to acute anxiety, whereas repeated daily injections of subthreshold-doses of Ucn1 produces a long-lasting, persistent anxiety-like phenotype, a phenomenon referred to as Ucn1-priming. Relative gene expressions from the BLA of vehicle and Ucn1-primed rats were analyzed with quantitative RT-PCR using a predesigned panel of 82 neuroscience-related genes. Compared to vehicle-primed rats, only expression of the somatostatin receptor 2 gene (Sstr2) was significantly reduced in the BLA of Ucn1-primed rats. The contribution of Sstr2 on an anxiety phenotype was tested by injecting a Sstr2 antagonist into the BLA in un-primed rats. The Sstr2 antagonist increased anxiety-like behavior. Notably, pretreatment with Sstr2 agonist injected into the BLA blocked anxiety-inducing effects of acute Ucn1 BLA-injections and delayed anxiety expression during Ucn1-priming. However, concomitant Sstr2 agonist pretreatment during Ucn-1 priming did not prevent either the development of a chronic anxiety state or a reduction of BLA Sstr2 expression induced by priming. The data demonstrate that the persistent anxiety-like phenotype observed with Ucn1-priming in the BLA is associated with a selective reduction of Sstr2 gene expression. Although Sstr2 activation in the BLA blocks acute anxiogenic effects of stress and down-regulation of BLA Sstr2, it does not suppress the long-term consequences of prolonged exposure to stress-related challenges.

STRUCTURED PSYCHOSOCIAL STRESS AND THERAPEUTIC FAILURE

Generalized language-of-thought arguments, appropriate, in the sense of Dretske, to interacting cognitive modules, permit exploration of how disease states interact with medical treatment, given an embedding context of structured psychosocial stress. The interpenetrating feedback between treatment and response creates a kind of idiotypic hall of mirrors generating a synergistic pattern of efficacy, treatment failure, adverse reactions, and patient noncompliance which, from a Rate Distortion perspective, embodies a distorted image of externally-imposed structured stress. For the US, accelerating spatial and social spread of such stress enmeshes both dominant and subordinate populations in a linked system of pathogenic social hierarchy which will express itself, not only in an increasingly unhealthy society, but in the diffusion of therapeutic failure, including, but not limited to, drug-based treatments.

Developing a family-based diabetes program for Latino immigrants: do men and women face the same barriers?

This study examined barriers and facilitators to diabetes self-management among Latino immigrants with diabetes and whether similarities and differences were observed by gender. Eight focus groups were conducted with 24 women and 21 men Latinos; four focus groups involved women only and four involved men only. Themes were identified using a combined deductive/inductive approach and an iterative process of consensus coding. Gender similarities and differences emerged. Barriers to self-management were primarily social for the women, whereas for men, structural aspects related to work were prominent. Interventions aimed at improving diabetes self-management among US Latino immigrants should consider tailored approaches to help men and women overcome distinct barriers.

The health of men: structured inequalities and opportunities

I have summarized in this article data on the magnitude of health challenges faced by men in the United States. Across a broad range of indicators, men report poorer health than women. Although men in all socioeconomic groups are doing poorly in terms of health, some especially high-risk groups include men of low socioeconomic status (SES) of all racial/ethnic backgrounds, low-SES minority men, and middle-class Black men. Multiple factors contribute to the elevated health risks of men. These include economic marginality, adverse working conditions, and gendered coping responses to stress, each of which can lead to high levels of substance use, other health-damaging behaviors, and an aversion to health-protective behaviors. The forces that adversely affect men's health are interrelated, unfold over the life course, and are amenable to change.

The welfare and scientific advantages of non-invasive imaging of animals used in biomedical research

At present, animal experimentation remains central to our understanding of human disease-related processes and of the biological effects of many substances. Traditional experiments have relied heavily on invasive techniques to monitor changes in blood biochemistry, tissue structure or function, or to phenotype or genotype genetically modified animals. In some cases, a proportion or all of the animals used during the course of a study may be sacrificed for histopathological assessment. In most cases, this is to track the progression or regression of a disease over time, or to determine the levels of toxicity evident in specific organs or tissues. However, many of these techniques fail to provide details of how a disease develops or how a substance elicits its effects. In recent years there has been a gradual increase in the application of imaging techniques that were originally developed and used in fundamental research or in medicine. These non-invasive techniques allow diseases, and responses to exogenous substances, to be monitored in a temporal and spatial manner, therefore allowing a greater amount of information to be derived from smaller numbers of animals, which in turn, increases the statistical validity of the data by reducing the level of experimental variation. Non-invasive imaging also allows more informative and humane endpoints to be used and, perhaps most importantly, allows functional details to be studied in the context of a living animal. Some of the recent developments within the field of non-invasive imaging and their significance with respect to animal welfare and the understanding of human physiology are discussed.

Interactions between anxiety, social support, health status and buspirone efficacy in elderly patients

Psychosocial factors are among the etiological factors of anxiety, and have been shown to affect the anxiolytic efficacy of buspirone in laboratory rodents. Disparate human studies suggest that a similar interaction may be valid for anxious patients. However, this interaction is poorly known at present. It was hypothesized that social support and health status are especially relevant psychosocial problems in elderly, and as such, have a large impact on both anxiety and the efficacy of anxiolytic treatment with buspirone. The hypothesis was assessed by three independent studies performed in a total number of 384 elderly in-patients (109 males, 275 females, age approximately 80 years). A low number of social contacts associated with a large number of diseases proved to be a strong risk factor for anxiety, whereas the reverse condition (many contacts/few diseases) was associated with considerably lower Hamilton Rating Scale for Anxiety (HAM-A) scores. Buspirone ameliorated anxiety significantly in general, but the "many contacts/many diseases" condition was associated with twice as much improvement as the "few contacts/few diseases" condition. The patient's self-evaluation of health status was predicted strongly by the disease score used in the above two studies. Taken conjointly, data suggest that the major Axis-IV problems faced by the age class studied (social support and health status) have a strong effect on both anxiety and buspirone responsiveness in elderly patients. Thus, drug responses appear to be modulated by nonpharmacological factors, and research directed towards identifying such factors would provide information important to a more appropriate patient targeting of certain medications.

Chronic stress alters behavior in the conditioned defensive burying test: role of the posterior paraventricular thalamus

In the present studies, we examined the effects of chronic restraint on behavior in the conditioned defensive burying paradigm, a well-validated test of anxiety. This test is based on the findings that rodents tend to cover or bury the source of a noxious or aversive stimulus. However, little is known about whether prior chronic stress exposure can alter this anxiety-related behavior. In the present study, we examined whether chronic restraint affects indices of behavior in the conditioned defensive burying paradigm. Furthermore, since the posterior division of the paraventricular thalamus (pPVTh) regulates neuroendocrine activity specifically in chronically stressed but not control rats, we hypothesized that the pPVTh may also regulate any chronic stress-induced changes in behavior observed in the defensive burying test. Chronically stressed rats (30-min restraint per day for seven consecutive days) exhibited decreased latency to bury compared to control rats regardless of the presence of lesions suggesting increased reactivity to the shock in these animals. Importantly, pPVTh-lesioned chronically stressed rats exhibited increased duration and height of burying compared to control rats with pPVTh lesions, whereas no differences existed between sham-lesioned control and chronically stressed rats. Since both burying height and duration of burying are considered indices of anxiety in the defensive burying test, the present results suggest that the intact pPVTh may be important in dampening behaviors related to anxiety in chronically stressed rats.

Behavioral and physiological mouse models for anxiety: effects of flesinoxan in 129S6/SvEvTac and C57BL/6J mice

Serotonin(1A) (5-HT(1A)) receptors are involved in anxiety. This study focuses on the role of genetic factors on the anxiety-related effects of 5-HT(1A) receptor stimulation using both a within subject design. The effects of 5-HT(1A) receptor activation were studied in high- and low-anxiety mice (129S6/SvEvTac (S6) and C57BL/6J (B6), respectively) in behavioral and physiological anxiety-related assays. These two strains were also selected because they are frequently used in gene-targeting studies. Mice were treated with the selective 5-HT(1A) receptor agonist flesinoxan (0-0.3-1.0-3.0 mg/kg s.c.) and tested in either the open-field activity test, the light-dark exploration test, or the stress-induced hyperthermia paradigm. Flesinoxan unexpectedly increased anxiety, but also decreased activity on several behavioral measures in B6 mice. Flesinoxan produced only minimal effects in the behavioral tests in the high-anxiety S6 strain. In contrast, the physiological hyperthermia response showed anxiolytic-like effects of flesinoxan in both strains. Our data indicate that the role of 5-HT(1A) receptor activation on anxiety-related responses is dependent on genetic background and selected paradigm used to assess anxiety. These findings indicate that it is critical to use a multi-level approach to develop mouse models for human diseases. In addition, the implication of such findings for studies on genetically modified mice is discussed.

Anxiolytic properties of the antipsychotic alkaloid alstonine

Anxiolytic properties may be a crucial feature of newer antipsychotics associated with the improvement of negative symptoms in schizophrenic patients. The indole alkaloid alstonine acts as an atypical antipsychotic in behavioral models, but differs in its dopamine and serotonin binding profile. The purpose of this study was to verify if alstonine possesses anxiolytic properties in mice. The hole-board and light/dark models were used; moreover, the participation of D(1), 5-HT(2), NMDA and gamma-aminobutyric acid (GABA) receptors was likewise investigated. Alstonine clearly behaves as anxiolytic in both hole-board and light/dark situations. Pretreatment with the 5-HT(2A/2C) serotonin receptor antagonist ritanserin reverted the effects of alstonine in both the hole-board and light/dark models, suggesting the involvement of these receptors in the alstonine mechanism of action. The involvement of glutamate NMDA receptors should also be considered, given that alstonine partially reversed the increase in locomotion induced by MK-801 in the hole board, as well as MK-801-induced hyperlocomotion in motor activity apparatus.

The effect of social factors on the anxiolytic efficacy of buspirone in male rats, male mice, and men

Earlier findings suggest that housing conditions in laboratory animals and life events in humans influence the efficacy of anxiolytic drugs. Here we report on the impact of social isolation on buspirone efficacy in male mice and rats as assessed by the elevated plus-maze. In addition, the impact of social support on buspirone efficacy was assessed in male patients. When administered 30 min before testing and irrespective of housing conditions, buspirone significantly suppressed locomotor activity both in mice (6 mg/kg) and rats (10 mg/kg) and, as such, other behavioral changes observed at this time point must be seen as behaviorally nonselective. However, these locomotor disruptive effects of buspirone were not evident in either species at longer injection-test intervals (2 and 4 h). When given 2 h prior to testing, a low (3 mg/kg) but not high (10 mg/kg) dose of buspirone increased the frequency of open arm exploration in rats (but not mice) irrespective of housing conditions. At the longest injection-test interval used (4 h), buspirone increased the duration of open arm exploration in individually housed, but not group-housed, rats. Similar, though somewhat less robust, effects were observed in male mice at this time. In a double-blind placebo-controlled study with male patients, chronic buspirone treatment (3 x 10 mg daily for 6 weeks) produced a highly significant reduction in scores on the Hamilton Rating Scale for Anxiety (HAM-A). Multiple regression analysis of social support received by patients indicated that the support of nonrelatives (but not of family or other relatives) was a strong positive predictor of buspirone efficacy. Taken together, our data support the hypothesis that social conditions affect the anxiolytic efficacy of buspirone. Results are discussed in relation to differences in the social organization of the three species investigated.

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 health of men: structured inequalities and opportunities

I have summarized in this article data on the magnitude of health challenges faced by men in the United States. Across a broad range of indicators, men report poorer health than women. Although men in all socioeconomic groups are doing poorly in terms of health, some especially high-risk groups include men of low socioeconomic status (SES) of all racial/ethnic backgrounds, low-SES minority men, and middle-class Black men. Multiple factors contribute to the elevated health risks of men. These include economic marginality, adverse working conditions, and gendered coping responses to stress, each of which can lead to high levels of substance use, other health-damaging behaviors, and an aversion to health-protective behaviors. The forces that adversely affect men's health are interrelated, unfold over the life course, and are amenable to change.

Social stress in laying hens: differential effect of stress on plasma dopamine concentrations and adrenal function in genetically selected chickens

Genetic selection for high or low group productivity and survivability (HGPS, LGPS) has created two phenotypically distinct chicken lines. Each line has unique characteristics in behavioral and physiological adaptability to multiple-bird cage system. The present study was designed to examine whether these differences reflect genetic variation in the control of plasma dopamine (DA) concentrations and adrenal function in response to social stress. Chickens from the HGPS and LGPS lines were randomly assigned to single- or 10-bird cages at 17 wk of age. The 10-bird cages were the same as those used in the development of the two lines. Differences in regulation of DA concentrations and adrenal function in response to different social environments were measured between the two lines when the study was conducted at 24 wk of age. In the 10-bird cages, the HGPS line had lower levels of DA (P < 0.05) and heavier adrenal glands (AG, P < 0.05) than those of the LGPS line, but concentrations of corticosterone (CORT) from the two lines were not significantly different. In the single-bird cages, DA levels in both lines were greater than in that of their siblings in the 10-bird cages, but a greater increase was found in the LGPS line (P < 0.01 and P < 0.05, 405% vs. 293%). Likewise, both lines had lower concentrations of CORT (P < 0.05) in the single- vs. 10-bird cages, but the AG were less heavy in the LGPS line but not in HGPS line in the single-bird cages (P < 0.05). The results indicated that the two strains reacted differently in terms of their stress hormone levels in the two different environments. These differences could contribute to the behavioral and physiological differences existing between the two lines.