Time-dependent sensitization: the odyssey of a scientific heresy from the laboratory to the door of the clinic

IL-4 as a potential biomarker for differentiating major depressive disorder from bipolar depression

We aimed to investigate the differential diagnosis of depressive episodes in patients with major depressive disorder (MDD) and bipolar disorder (BD) using peripheral blood cytokine expression levels. The levels of interleukin (IL)-2, IL-6, IL-10, IL-17, IL4, and IL-12; interferon (IFN)-γ; and tumor necrosis factor (TNF)-α were measured in patients with MDD and BD presenting acute episodes in an inpatient psychiatric setting. The expression levels of IL-6, IL-10, IL-17, and IFN-γ in the MDD and BD groups were higher than those in the control group (P < .05), but there was no significant difference between the patient groups and control group. Only the expression levels of TNF-α and IL-4 were higher in both groups than in the control group, and the BD group had higher levels than the MDD group (P < .05). The expression levels of IL-17, IFN-γ, IL-10, and IL-4 were significantly higher in BD-related manic episodes than in BD-related depressive episodes (P < .05). IL-6, IFN-γ, TNF-α, IL-10, and IL-4 levels were higher in BD-related depressive episodes than in MDD-related depressive episodes (P < .05). The receiver operating characteristic curve test for MDD and BD and the area under the curve for IL-4 revealed good clinical predictability. Patients with MDD and BD exhibited different cytokine profiles when experiencing acute episodes; patients with BD exhibited a more severe immune-inflammatory response system-compensatory immunoregulatory response system (CIRS) imbalance. IL-4 was found to have diagnostic value in differentiating between active depressive episodes in MDD and BD.

Effect of ketamine on the physiological responses to combined hypoglycemic and psychophysical stress

There is evidence that hypoglycemic stress can interact with other stressors, and that ketamine can mitigate the impact of these stressors on behavior and physiology. The current study in male Sprague-Dawley rats investigated whether pre-treatment with 0, 10, or 20 mg/kg ketamine could modulate the interaction between hypoglycemia induced by 0 or 300 mg/kg 2-deoxy-D-glucose (2-DG) and the psychophysical stress of forced swimming (FSS; 6 sessions, 10 min/session) on serum concentrations of corticosterone (CORT) and the pro-inflammatory cytokine, tumor necrosis factor (TNF)-α. It was found that 2-DG enhanced the CORT response to an initial session of FSS, and this effect dissipated after multiple sessions. More importantly, animals displayed significantly higher levels of CORT and lower levels of TNF-α in response to a drug-free test swim conducted 1 week after exposure to the combined stressors, and these responses were not observed in rats that were pre-treated with ketamine. Overall, these findings indicate that ketamine has the potential to reduce the negative impact of interacting stressors on the biological reactivity of the hypothalamic-pituitary-adrenal axis and the immune system.

Animal Models of Drug Relapse and Craving after Voluntary Abstinence: A Review

Relapse to drug use during abstinence is a defining feature of addiction. During the last several decades, this clinical scenario has been studied at the preclinical level using classic relapse/reinstatement models in which drug seeking is assessed after experimenter-imposed home-cage forced abstinence or extinction of the drug-reinforced responding in the self-administration chambers. To date, however, results from studies using rat relapse/reinstatement models have yet to result in Food and Drug Administration-approved medications for relapse prevention. The reasons for this state of affairs are complex and multifaceted, but one potential reason is that, in humans, abstinence is often self-imposed or voluntary and occurs either because the negative consequences of drug use outweigh the drug's rewarding effects or because of the availability of nondrug alternative rewards that are chosen over the drug. Based on these considerations, we and others have recently developed rat models of relapse after voluntary abstinence, achieved either by introducing adverse consequences to drug taking (punishment) or seeking (electric barrier) or by providing mutually exclusive choices between the self-administered drug and nondrug rewards (palatable food or social interaction). In this review, we provide an overview of these translationally relevant relapse models and discuss recent neuropharmacological findings from studies using these models. We also discuss sex as a biological variable, future directions, and clinical implications of results from relapse studies using voluntary abstinence models. Our main conclusion is that the neuropharmacological mechanisms controlling relapse to drug seeking after voluntary abstinence are often different from the mechanisms controlling relapse after home-cage forced abstinence or reinstatement after extinction. SIGNIFICANCE STATEMENT: This review describes recently developed rat models of relapse after voluntary abstinence, achieved either by introducing adverse consequences to drug taking or seeking or by providing mutually exclusive choices between the self-administered drug and nondrug rewards. This review discusses recent neuropharmacological findings from studies using these models and discusses future directions and clinical implications.

Time-course of changes in key catecholaminergic receptors and trophic systems in rat brain after antidepressant administration

Several biochemical parameters within the brain are altered by antidepressants. However, it is still uncertain which parameters are important for the evaluation of the effectiveness of these drugs. What seems certain is that the response of the nervous system is dynamic. The dynamic nature of the nervous system is still poorly understood, although it has implications in clinical management. Criteria for evaluating treatment resistant depression are based on this temporal variability. The present study was designed to evaluate dynamic alterations in catecholaminergic receptors and calcyon (associated with monoaminergic theory of depression) in the rat brain as well as brain-derived neurotrophic factor (BDNF) and tyrosine kinase beta (TRKB; related to neurotrophin theory) induced by three antidepressant drugs (ADs) with various pharmacological profiles (imipramine, desipramine, and citalopram) administered for 21 days or acutely, followed by various drug-free periods. Receptor autoradiography and in situ hybridization studies allowed us to identify changes in various brain regions simultaneously in each rat. Repeated treatment with ADs induced biochemical alterations, which were in agreement with the results of previous studies. These alterations include the downregulation of β1, β2, and α1 adrenergic receptors, upregulation of α2-adrenergic receptors and dopamine D2 receptors, and increased expression of BDNF in the hippocampus. Additionally, we observed dynamic alterations in the measured parameters after acute drug administration, particularly at the level of dopamine receptors, which were extremely sensitive to a single dose of ADs followed by various drug-free periods. All three ADs induced the upregulation of dopamine D2 receptor mRNA levels in the nucleus accumbens. The same effect was induced by single doses of ADs followed by various drug-free periods. The obtained results indicate that alterations in the availability of neurotransmitters at synapses induced by ADs are strong enough to induce immediate and long-lasting adaptive changes in the neuronal network.

The Psychopharmacology of Obsessive-Compulsive Disorder: A Preclinical Roadmap

This review evaluates current knowledge about obsessive-compulsive disorder (OCD), with the goal of providing a roadmap for future directions in research on the psychopharmacology of the disorder. It first addresses issues in the description and diagnosis of OCD, including the structure, measurement, and appropriate description of the disorder and issues of differential diagnosis. Current pharmacotherapies for OCD are then reviewed, including monotherapy with serotonin reuptake inhibitors and augmentation with antipsychotic medication and with psychologic treatment. Neuromodulatory therapies for OCD are also described, including psychosurgery, deep brain stimulation, and noninvasive brain stimulation. Psychotherapies for OCD are then reviewed, focusing on behavior therapy, including exposure and response prevention and cognitive therapy, and the efficacy of these interventions is discussed, touching on issues such as the timing of sessions, the adjunctive role of pharmacotherapy, and the underlying mechanisms. Next, current research on the neurobiology of OCD is examined, including work probing the role of various neurotransmitters and other endogenous processes and etiology as clues to the neurobiological fault that may underlie OCD. A new perspective on preclinical research is advanced, using the Research Domain Criteria to propose an adaptationist viewpoint that regards OCD as the dysfunction of a normal motivational system. A systems-design approach introduces the security motivation system (SMS) theory of OCD as a framework for research. Finally, a new perspective on psychopharmacological research for OCD is advanced, exploring three approaches: boosting infrastructure facilities of the brain, facilitating psychotherapeutic relearning, and targeting specific pathways of the SMS network to fix deficient SMS shut-down processes. SIGNIFICANCE STATEMENT: A significant proportion of patients with obsessive-compulsive disorder (OCD) do not achieve remission with current treatments, indicating the need for innovations in psychopharmacology for the disorder. OCD may be conceptualized as the dysfunction of a normal, special motivation system that evolved to manage the prospect of potential danger. This perspective, together with a wide-ranging review of the literature, suggests novel directions for psychopharmacological research, including boosting support systems of the brain, facilitating relearning that occurs in psychotherapy, and targeting specific pathways in the brain that provide deficient stopping processes in OCD.

Changes in gut microbiota during development of compulsive checking and locomotor sensitization induced by chronic treatment with the dopamine agonist quinpirole

Long-term treatment of rats with the D2/D3 dopamine agonist quinpirole induces compulsive checking (proposed as animal model of obsessive-compulsive disorder) and locomotor sensitization. The mechanisms by which long-term use of quinpirole produces those behavioral transformations are not known. Here we examined whether changes in gut microbiota play a role in these behavioral phenomena, by monitoring the development of compulsive checking and locomotor sensitization at the same time as measuring the response of gut microbiota to chronic quinpirole injections. Two groups of rats received nine injections of saline (n=16) or quinpirole (n=15; 0.25 mg/kg), at weekly intervals for the first 5 weeks and then two injections per week until the end of treatment. After each injection, rats were placed on a large open field for 55 min, and their behavior was video recorded for subsequent analysis. Fecal matter was collected after each trial and frozen for bacterial community profiling of the 16S rRNA gene, using paired-end reads of the V3 region. The results indicated that the induction of locomotor sensitization and compulsive checking was accompanied by changes in several communities of bacteria belonging to the order Clostridiales (class Clostridia, phylum Firmicutes), and predominantly in Lachnospiraceae and Ruminococcaceae families of bacteria. It is suggested that changes in these microbes may serve to support the energy use requirements of compulsive checking and obsessive-compulsive disorder.

Time-dependent sensitization of antipsychotic effect in adolescent male and female rats

Many behavioral and biological effects of a psychoactive drug often undergo time-dependent change following even one single drug exposure. The present study examined whether one or two exposures of haloperidol, olanzapine or clozapine would also induce a time-dependent change in their behavioral effects in adolescent rats, and whether such a change vary between sexes. Adolescent Sprague-Dawley rats (<40days old) were first treated with one single injection of haloperidol (0.05 and 0.1mg/kg, sc), clozapine (10.0 and 20.0mg/kg, sc), 2 injections of olanzapine (1.0 and 2.0mg/kg, sc) or vehicle, and tested in a conditioned avoidance response (CAR) model or a PCP (3.20mg/kg, sc)-induced hyperlocomotion model to assess the drug's antipsychotic-like behavioral effects. One or three weeks later, rats were challenged with the drug and their avoidance responses and the PCP-induced hyperlocomotion were re-assessed. One-trial haloperidol and 2-trial olanzapine induced a sensitization, while 1-trial clozapine induced a tolerance effect. The 1-trial haloperidol sensitization was significantly higher at the 3-week time point than at 1-week point, especially in the females. Clozapine tolerance in the conditioned avoidance response model also exhibited the time-dependent increase in both sex groups. Olanzapine sensitization in the PCP model showed a time-dependent change in a sex-dependent fashion. Overall, the time-dependent antipsychotic sensitization and tolerance can be demonstrated in adolescent animals. Many pharmacological (e.g. specific drugs, drug doses), individual (e.g. male versus female) and environmental (e.g. specific behavioral models) factors play a role in the modulation of the strength of antipsychotic sensitization and tolerance.

Learning about stress: neural, endocrine and behavioral adaptations

In this review, nonassociative learning is advanced as an organizing principle to draw together findings from both sympathetic-adrenal medullary and hypothalamic-pituitary-adrenocortical (HPA) axis responses to chronic intermittent exposure to a variety of stressors. Studies of habituation, facilitation and sensitization of stress effector systems are reviewed and linked to an animal's prior experience with a given stressor, the intensity of the stressor and the appraisal by the animal of its ability to mobilize physiological systems to adapt to the stressor. Brain pathways that regulate physiological and behavioral responses to stress are discussed, especially in light of their regulation of nonassociative processes in chronic intermittent stress. These findings may have special relevance to various psychiatric diseases, including depression and post-traumatic stress disorder (PTSD).

Antipsychotic-induced sensitization and tolerance: Behavioral characteristics, developmental impacts, and neurobiological mechanisms

Antipsychotic sensitization and tolerance refer to the increased and decreased drug effects due to past drug use, respectively. Both effects reflect the long-term impacts of antipsychotic treatment on the brain and result from the brain's adaptive response to the foreign property of the drug. In this review, clinical evidence of the behavioral aspect of antipsychotic sensitization and tolerance is selectively reviewed, followed by an overview of preclinical literature that examines these behavioral characteristics and the related pharmacological and nonpharmacological factors. Next, recent work on the developmental impacts of adolescent antipsychotic sensitization and tolerance is presented and recent research that delineates the neurobiological mechanisms of antipsychotic sensitization and tolerance is summarized. A theoretical framework based on "drug learning and memory" principles is proposed to account for the phenomena of antipsychotic sensitization and tolerance. It is maintained that antipsychotic sensitization and tolerance follow basic principles of learning or acquisition ("induction") and memory ("expression"). The induction and expression of both effects reflect the consequences of associative and nonassociative processing and are strongly influenced by various pharmacological, environmental, and behavioral factors. Drug-induced neuroplasticity, such as functional changes of striatal dopamine D2 and prefrontal serotonin (5-HT)2A receptors and their mediated signaling pathways, in principle, is responsible for antipsychotic sensitization and tolerance. Understanding the behavioral characteristics and neurobiological underpinnings of antipsychotic sensitization and tolerance has greatly enhanced our understanding of mechanisms of antipsychotic action, and may have important implications for future drug discovery and clinical practice.

Stress-Induced Reinstatement of Drug Seeking: 20 Years of Progress

In human addicts, drug relapse and craving are often provoked by stress. Since 1995, this clinical scenario has been studied using a rat model of stress-induced reinstatement of drug seeking. Here, we first discuss the generality of stress-induced reinstatement to different drugs of abuse, different stressors, and different behavioral procedures. We also discuss neuropharmacological mechanisms, and brain areas and circuits controlling stress-induced reinstatement of drug seeking. We conclude by discussing results from translational human laboratory studies and clinical trials that were inspired by results from rat studies on stress-induced reinstatement. Our main conclusions are (1) The phenomenon of stress-induced reinstatement, first shown with an intermittent footshock stressor in rats trained to self-administer heroin, generalizes to other abused drugs, including cocaine, methamphetamine, nicotine, and alcohol, and is also observed in the conditioned place preference model in rats and mice. This phenomenon, however, is stressor specific and not all stressors induce reinstatement of drug seeking. (2) Neuropharmacological studies indicate the involvement of corticotropin-releasing factor (CRF), noradrenaline, dopamine, glutamate, kappa/dynorphin, and several other peptide and neurotransmitter systems in stress-induced reinstatement. Neuropharmacology and circuitry studies indicate the involvement of CRF and noradrenaline transmission in bed nucleus of stria terminalis and central amygdala, and dopamine, CRF, kappa/dynorphin, and glutamate transmission in other components of the mesocorticolimbic dopamine system (ventral tegmental area, medial prefrontal cortex, orbitofrontal cortex, and nucleus accumbens). (3) Translational human laboratory studies and a recent clinical trial study show the efficacy of alpha-2 adrenoceptor agonists in decreasing stress-induced drug craving and stress-induced initial heroin lapse.

Incubation of methamphetamine and palatable food craving after punishment-induced abstinence

In a rat model of drug craving and relapse, cue-induced drug seeking progressively increases after withdrawal from methamphetamine and other drugs, a phenomenon termed 'incubation of drug craving'. However, current experimental procedures used to study incubation of drug craving do not incorporate negative consequences of drug use, which is a common factor promoting abstinence in humans. Here, we studied whether incubation of methamphetamine craving is observed after suppression of drug seeking by adverse consequences (punishment). We trained rats to self-administer methamphetamine or palatable food for 9 h per day for 14 days; reward delivery was paired with a tone-light cue. Subsequently, for one group within each reward type, 50% of the lever-presses were punished by mild footshock for 9-10 days, whereas for the other group lever-presses were not punished. Shock intensity was gradually increased over time. Next, we assessed cue-induced reward seeking in 1-h extinction sessions on withdrawal days 2 and 21. Response-contingent punishment suppressed extended-access methamphetamine or food self-administration; surprisingly, food-trained rats showed greater resistance to punishment than methamphetamine-trained rats. During the relapse tests, both punished and unpunished methamphetamine- and food-trained rats showed significantly higher cue-induced reward seeking on withdrawal day 21 than on day 2. These results demonstrate that incubation of both methamphetamine and food craving occur after punishment-induced suppression of methamphetamine or palatable food self-administration. Our procedure can be used to investigate mechanisms of relapse to drug and palatable food seeking under conditions that more closely approximate the human condition.

Nonlinear effects of nanoparticles: biological variability from hormetic doses, small particle sizes, and dynamic adaptive interactions

Researchers are increasingly focused on the nanoscale level of organization where biological processes take place in living systems. Nanoparticles (NPs, e.g., 1-100 nm diameter) are small forms of natural or manufactured source material whose properties differ markedly from those of the respective bulk forms of the "same" material. Certain NPs have diagnostic and therapeutic uses; some NPs exhibit low-dose toxicity; other NPs show ability to stimulate low-dose adaptive responses (hormesis). Beyond dose, size, shape, and surface charge variations of NPs evoke nonlinear responses in complex adaptive systems. NPs acquire unique size-dependent biological, chemical, thermal, optical, electromagnetic, and atom-like quantum properties. Nanoparticles exhibit high surface adsorptive capacity for other substances, enhanced bioavailability, and ability to cross otherwise impermeable cell membranes including the blood-brain barrier. With super-potent effects, nano-forms can evoke cellular stress responses or therapeutic effects not only at lower doses than their bulk forms, but also for longer periods of time. Interactions of initial effects and compensatory systemic responses can alter the impact of NPs over time. Taken together, the data suggest the need to downshift the dose-response curve of NPs from that for bulk forms in order to identify the necessarily decreased no-observed-adverse-effect-level and hormetic dose range for nanoparticles.

Adult response to olanzapine or clozapine treatment is altered by adolescent antipsychotic exposure: a preclinical test in the phencyclidine hyperlocomotion model

This study examined how repeated olanzapine (OLZ) or clozapine (CLZ) treatment in adolescence alters sensitivity to the same drug in adulthood in the phencyclidine (PCP) hyperlocomotion model. Male adolescent Sprague-Dawley rats (postnatal day (P) 44-48) were first treated with OLZ (1.0 or 2.0 mg/kg, subcutaneously (sc)) or CLZ (10.0 or 20.0 mg/kg, sc) and tested in the PCP (3.2 mg/kg, sc)-induced hyperlocomotion model for five consecutive days. Then a challenge test with OLZ (0.5 mg/kg) or CLZ (5.0 mg/kg) was administered either during adolescence (~P 51) or after the rats matured into adults (~P 76 and 91). During adolescence, repeated OLZ or CLZ treatment produced a persistent inhibition of PCP-induced hyperlocomotion across the five test days. In the challenge test during adolescence, rats previously treated with OLZ did not show a significantly stronger inhibition of PCP-induced hyperlocomotion than those previously treated with vehicle (VEH). In contrast, those previously treated with CLZ showed a weaker inhibition than the VEH controls. When assessed in adulthood, the enhanced sensitivity to OLZ and the decreased sensitivity to CLZ were detected on ~P 76, even on ~P 91 in the case of OLZ. These findings suggest that adolescent OLZ or CLZ exposure can induce long-term alterations in antipsychotic response that persist into adulthood.

Homeopathic medications as clinical alternatives for symptomatic care of acute otitis media and upper respiratory infections in children

The public health and individual risks of inappropriate antibiotic prescribing and conventional over-the-counter symptomatic drugs in pediatric treatment of acute otitis media (AOM) and upper respiratory infections (URIs) are significant. Clinical research suggests that over-the-counter homeopathic medicines offer pragmatic treatment alternatives to conventional drugs for symptom relief in children with uncomplicated AOM or URIs. Homeopathy is a controversial but demonstrably safe and effective 200-year-old whole system of complementary and alternative medicine used worldwide. Numerous clinical studies demonstrate that homeopathy accelerates early symptom relief in acute illnesses at much lower risk than conventional drug approaches. Evidence-based advantages for homeopathy include lower antibiotic fill rates during watchful waiting in otitis media, fewer and less serious side effects, absence of drug-drug interactions, and reduced parental sick leave from work. Emerging evidence from basic and preclinical science research counter the skeptics' claims that homeopathic remedies are biologically inert placebos. Consumers already accept and use homeopathic medicines for self care, as evidenced by annual US consumer expenditures of $2.9 billion on homeopathic remedies. Homeopathy appears equivalent to and safer than conventional standard care in comparative effectiveness trials, but additional well-designed efficacy trials are indicated. Nonetheless, the existing research evidence on safety supports pragmatic use of homeopathy in order to “first do no harm” in the early symptom management of otherwise uncomplicated AOM and URIs in children.

Time-dependence of risperidone and asenapine sensitization and associated D2 receptor mechanism

When an antipsychotic drug is given repeatedly and intermittently, there is often a long-term increase in its behavioral efficacy, termed antipsychotic sensitization. With the passage of time, the magnitude of antipsychotic sensitization may increase or decrease based on the principle of time-dependent sensitization (TDS) or memory decay, respectively. In the present study, we examined the time-dependent feature and possible dopamine D2 receptor mechanism of sensitization induced by risperidone and asenapine in the conditioned avoidance response test. Well-trained male adult Sprague-Dawley rats were first repeatedly treated with risperidone (1.0mg/kg) or asenapine (0.2mg/kg) and tested for avoidance response daily for 5 consecutive days. Eight, 18 or 38 days after the 5th drug treatment, all rats were retested drug-free to assess the long-term impact of prior risperidone or asenapine treatment. Drug-pretreated rats had significantly lower avoidance than vehicle-pretreated ones on this test, and the group differences increased with the passage of time. In the subsequent drug challenge test at 10, 20 or 40 days after the 5th drug treatment, all rats were injected with a low dose of risperidone (0.3mg/kg) or asenapine (0.1mg/kg). Drug-pretreated rats again made significantly fewer avoidances than controls, confirming the antipsychotic sensitization effect. Finally, in the quinpirole (a D2/3 receptor agonist, 1.0mg/kg, sc)-induced hyperlocomotion test, risperidone-pretreated rats exhibited a significantly higher level of motor activity than the vehicle-pretreated ones. These findings suggest that risperidone and asenapine sensitization is long-lasting, follows the TDS principle, and is likely mediated by D2 receptor supersensitivity.

A dynamic network model of the similia principle

The use of drugs in high dilutions and the principle of similarity (or "similia") are two basic tenets of homeopathy. However, the plausibility of both is a subject of debate. Although several models have been proposed to explain the similia principle, it can be best understood and appreciated in the framework of complexity science and dynamic systems theory. This work applies a five-node Boolean network to show how self-organization and adaptation are relevant to rationalizing this traditional medical principle. Simulating the trajectories and attractors of the network system in the energy state-space provides a rudimentary and qualitative illustration of how targeted external perturbations can have pathological effects, leading to permanent, self-sustaining alterations. Similarly, changes that conversely enable the system to find its way back to the original state can induce therapeutic effects, by causing specific shifts in attractors when suitable conditions are satisfied. Extrapolating these mechanisms to homeopathy, we can envisage how major changes in the evolution of homeodynamic systems (and, eventually, healing of the entire body) can be achieved through carefully selected remedies that reproduce the whole symptom pattern of the ill state.

Testing the nanoparticle-allostatic cross-adaptation-sensitization model for homeopathic remedy effects

Key concepts of the Nanoparticle-Allostatic Cross-Adaptation-Sensitization (NPCAS) Model for the action of homeopathic remedies in living systems include source nanoparticles as low level environmental stressors, heterotypic hormesis, cross-adaptation, allostasis (stress response network), time-dependent sensitization with endogenous amplification and bidirectional change, and self-organizing complex adaptive systems. The model accommodates the requirement for measurable physical agents in the remedy (source nanoparticles and/or source adsorbed to silica nanoparticles). Hormetic adaptive responses in the organism, triggered by nanoparticles; bipolar, metaplastic change, dependent on the history of the organism. Clinical matching of the patient's symptom picture, including modalities, to the symptom pattern that the source material can cause (cross-adaptation and cross-sensitization). Evidence for nanoparticle-related quantum macro-entanglement in homeopathic pathogenetic trials. This paper examines research implications of the model, discussing the following hypotheses: Variability in nanoparticle size, morphology, and aggregation affects remedy properties and reproducibility of findings. Homeopathic remedies modulate adaptive allostatic responses, with multiple dynamic short- and long-term effects. Simillimum remedy nanoparticles, as novel mild stressors corresponding to the organism's dysfunction initiate time-dependent cross-sensitization, reversing the direction of dysfunctional reactivity to environmental stressors. The NPCAS model suggests a way forward for systematic research on homeopathy. The central proposition is that homeopathic treatment is a form of nanomedicine acting by modulation of endogenous adaptation and metaplastic amplification processes in the organism to enhance long-term systemic resilience and health.

The neuroprogressive nature of major depressive disorder: pathways to disease evolution and resistance, and therapeutic implications

In some patients with major depressive disorder (MDD), individual illness characteristics appear consistent with those of a neuroprogressive illness. Features of neuroprogression include poorer symptomatic, treatment and functional outcomes in patients with earlier disease onset and increased number and length of depressive episodes. In such patients, longer and more frequent depressive episodes appear to increase vulnerability for further episodes, precipitating an accelerating and progressive illness course leading to functional decline. Evidence from clinical, biochemical and neuroimaging studies appear to support this model and are informing novel therapeutic approaches. This paper reviews current knowledge of the neuroprogressive processes that may occur in MDD, including structural brain consequences and potential molecular mechanisms including the role of neurotransmitter systems, inflammatory, oxidative and nitrosative stress pathways, neurotrophins and regulation of neurogenesis, cortisol and the hypothalamic-pituitary-adrenal axis modulation, mitochondrial dysfunction and epigenetic and dietary influences. Evidence-based novel treatments informed by this knowledge are discussed.

Advances in Integrative Nanomedicine for Improving Infectious Disease Treatment in Public Health

INTRODUCTION

Infectious diseases present public health challenges worldwide. An emerging integrative approach to treating infectious diseases is using nanoparticle (NP) forms of traditional and alternative medicines. Advantages of nanomedicine delivery methods include better disease targeting, especially for intracellular pathogens, ability to cross membranes and enter cells, longer duration drug action, reduced side effects, and cost savings from lower doses.

METHODS

We searched Pubmed articles in English with keywords related to nanoparticles and nanomedicine. Nanotechnology terms were also combined with keywords for drug delivery, infectious diseases, herbs, antioxidants, homeopathy, and adaptation.

RESULTS

NPs are very small forms of material substances, measuring 1-100 nanometers along at least one dimension. Compared with bulk forms, NPs' large ratio of surface-area-to-volume confers increased reactivity and adsorptive capacity, with unique electromagnetic, chemical, biological, and quantum properties. Nanotechnology uses natural botanical agents for green manufacturing of less toxic NPs.

DISCUSSION

Nanoparticle herbs and nutriceuticals can treat infections via improved bioavailability and antiinflammatory, antioxidant, and immunomodulatory effects. Recent studies demonstrate that homeopathic medicines may contain source and/or silica nanoparticles because of their traditional manufacturing processes. Homeopathy, as a form of nanomedicine, has a promising history of treating epidemic infectious diseases, including malaria, leptospirosis and HIV/AIDS, in addition to acute upper respiratory infections. Adaptive changes in the host's complex networks underlie effects.

CONCLUSIONS

Nanomedicine is integrative, blending modern technology with natural products to reduce toxicity and support immune function. Nanomedicine using traditional agents from alternative systems of medicine can facilitate progress in integrative public health approaches to infectious diseases.

Nonlinear dynamical systems effects of homeopathic remedies on multiscale entropy and correlation dimension of slow wave sleep EEG in young adults with histories of coffee-induced insomnia

BACKGROUND

Investigators of homeopathy have proposed that nonlinear dynamical systems (NDS) and complex systems science offer conceptual and analytic tools for evaluating homeopathic remedy effects. Previous animal studies demonstrate that homeopathic medicines alter delta electroencephalographic (EEG) slow wave sleep. The present study extended findings of remedy-related sleep stage alterations in human subjects by testing the feasibility of using two different NDS analytic approaches to assess remedy effects on human slow wave sleep EEG.

METHODS

Subjects (N=54) were young adult male and female college students with a history of coffee-related insomnia who participated in a larger 4-week study of the polysomnographic effects of homeopathic medicines on home-based all-night sleep recordings. Subjects took one bedtime dose of a homeopathic remedy (Coffea cruda or Nux vomica 30c). We computed multiscale entropy (MSE) and the correlation dimension (Mekler-D2) for stages 3 and 4 slow wave sleep EEG sampled in artifact-free 2-min segments during the first two rapid-eye-movement (REM) cycles for remedy and post-remedy nights, controlling for placebo and post-placebo night effects.

RESULTS

MSE results indicate significant, remedy-specific directional effects, especially later in the night (REM cycle 2) (CC: remedy night increases and post-remedy night decreases in MSE at multiple sites for both stages 3 and 4 in both REM cycles; NV: remedy night decreases and post-remedy night increases, mainly in stage 3 REM cycle 2 MSE). D2 analyses yielded more sporadic and inconsistent findings.

CONCLUSIONS

Homeopathic medicines Coffea cruda and Nux vomica in 30c potencies alter short-term nonlinear dynamic parameters of slow wave sleep EEG in healthy young adults. MSE may provide a more sensitive NDS analytic method than D2 for evaluating homeopathic remedy effects on human sleep EEG patterns.

Parametric studies of antipsychotic-induced sensitization in the conditioned avoidance response model: roles of number of drug exposure, drug dose, and test-retest interval

Repeated haloperidol and olanzapine treatment produces an enhanced disruption of avoidance responding, a validated measure of antipsychotic activity. Experimental parameters affecting this sensitization-like effect have not been thoroughly examined. The present study investigated the role of three parameters (number of injections, dose, and interval between initial exposure and challenge) in antipsychotic sensitization in the conditioned avoidance response paradigm. Well-trained Sprague-Dawley rats received different numbers of drug treatment (1-5 days) or different doses of haloperidol (0.025-0.10 mg/kg, subcutaneously) or olanzapine (0.5-2.0 mg/kg, subcutaneously). After certain time intervals (4, 10 or 17 days), they were tested for the expression of haloperidol or olanzapine sensitization in a challenge test in which all rats were injected with a lower dose of haloperidol (0.025 mg/kg) or olanzapine (0.5 mg/kg). Throughout the drug-treatment period, both haloperidol and olanzapine dose-dependently enhanced their disruption of avoidance responding. Three days later, the sensitization induced by a low dose of haloperidol (0.025 mg/kg) or olanzapine (0.5 mg/kg) was only apparent in rats that received treatment for 5 days, but not in those that received treatment for 1-4 days. The sensitization induced by the medium and high doses of haloperidol (0.05 and 0.10 mg/kg) or olanzapine (1.0 and 2.0 mg/kg) was still robust even with only 3 days of treatment. The sensitization induced by a 3-day haloperidol (0.10 mg/kg) and olanzapine (2.0 mg/kg) treatment was long-lasting, still detectable 17 days after the last drug treatment. This study suggests that antipsychotic sensitization is a robust behavioral phenomenon. Its induction and expression are strongly influenced by parameters such as number of drug exposures, drug dose, and test-retest interval. Given the importance of antipsychotic sensitization in the maintenance of antipsychotic effects in the clinic, this study introduces a paradigm that can be used to investigate the behavioral and neurobiological mechanisms underlying antipsychotic sensitization.

A model for homeopathic remedy effects: low dose nanoparticles, allostatic cross-adaptation, and time-dependent sensitization in a complex adaptive system

Background

This paper proposes a novel model for homeopathic remedy action on living systems. Research indicates that homeopathic remedies (a) contain measurable source and silica nanoparticles heterogeneously dispersed in colloidal solution; (b) act by modulating biological function of the allostatic stress response network (c) evoke biphasic actions on living systems via organism-dependent adaptive and endogenously amplified effects; (d) improve systemic resilience.

Discussion

The proposed active components of homeopathic remedies are nanoparticles of source substance in water-based colloidal solution, not bulk-form drugs. Nanoparticles have unique biological and physico-chemical properties, including increased catalytic reactivity, protein and DNA adsorption, bioavailability, dose-sparing, electromagnetic, and quantum effects different from bulk-form materials. Trituration and/or liquid succussions during classical remedy preparation create “top-down” nanostructures. Plants can biosynthesize remedy-templated silica nanostructures. Nanoparticles stimulate hormesis, a beneficial low-dose adaptive response. Homeopathic remedies prescribed in low doses spaced intermittently over time act as biological signals that stimulate the organism’s allostatic biological stress response network, evoking nonlinear modulatory, self-organizing change. Potential mechanisms include time-dependent sensitization (TDS), a type of adaptive plasticity/metaplasticity involving progressive amplification of host responses, which reverse direction and oscillate at physiological limits. To mobilize hormesis and TDS, the remedy must be appraised as a salient, but low level, novel threat, stressor, or homeostatic disruption for the whole organism. Silica nanoparticles adsorb remedy source and amplify effects. Properly-timed remedy dosing elicits disease-primed compensatory reversal in direction of maladaptive dynamics of the allostatic network, thus promoting resilience and recovery from disease.

Summary

Homeopathic remedies are proposed as source nanoparticles that mobilize hormesis and time-dependent sensitization via non-pharmacological effects on specific biological adaptive and amplification mechanisms. The nanoparticle nature of remedies would distinguish them from conventional bulk drugs in structure, morphology, and functional properties. Outcomes would depend upon the ability of the organism to respond to the remedy as a novel stressor or heterotypic biological threat, initiating reversals of cumulative, cross-adapted biological maladaptations underlying disease in the allostatic stress response network. Systemic resilience would improve. This model provides a foundation for theory-driven research on the role of nanomaterials in living systems, mechanisms of homeopathic remedy actions and translational uses in nanomedicine.

Analysis of region-specific changes in gene expression upon treatment with citalopram and desipramine reveals temporal dynamics in response to antidepressant drugs at the transcriptome level

RATIONALE

The notion that the onset of action of antidepressant drugs (ADs) takes weeks is widely accepted; however, the sequence of events necessary for therapeutic effects still remains obscure.

OBJECTIVE

We aimed to evaluate a time-course of ADs-induced alterations in the expression of 95 selected genes in 4 regions of the rat brain: the prefrontal and cingulate cortices, the dentate gyrus of the hippocampus, and the amygdala.

METHODS

We employed RT-PCR array to evaluate changes during a time-course (1, 3, 7, 14, and 21 days) of treatments with desipramine (DMI) and citalopram (CIT). In addition to repeated treatment, we also conducted acute treatment (a single dose of drug followed by the same time intervals as the repeated doses).

RESULTS

Time-dependent and structure-specific changes in gene expression patterns allowed us to identify spatiotemporal differences in the molecular action of two ADs. Singular value decomposition analysis revealed differences in the global gene expression profiles between treatment types. The numbers of characteristic modes were generally smaller after CIT treatment than after DMI treatment. Analysis of the dynamics of gene expression revealed that the most significant changes concerned immediate early genes, whose expression was also visualized by in situ hybridization. Transcription factor binding site analysis revealed an over-representation of serum response factor binding sites in the promoters of genes that changed upon treatment with both ADs.

CONCLUSIONS

The observed gene expression patterns were highly dynamic, with oscillations and peaks at various time points of treatment. Our study also revealed novel potential targets of antidepressant action, i.e., Dbp and Id1 genes.

Multiweek resting EEG cordance change patterns from repeated olfactory activation with two constitutionally salient homeopathic remedies in healthy young adults

OBJECTIVES

Electroencephalography (EEG) offers psychophysiologic tools to improve sensitivity for detecting objective effects in complementary and alternative medicine. This current investigation extended prior clinical research studies to evaluate effects of one of two different homeopathic remedies on resting EEG cordance after an olfactory activation protocol on healthy young adults with remedy-relevant, self-perceived characteristics.

METHODS

Ninety-seven (7) young adults (N=97, mean age 19 years, 55% women) with good self-rated global health and screened for homeopathic constitutional types consistent with one of two remedies (either Sulphur or Pulsatilla) underwent three weekly laboratory sessions. At each visit, subjects had 5-minute resting, eyes-closed EEG recordings before and after a placebo-controlled olfactory activation task with their constitutionally relevant verum remedy. One remedy potency (6c, 12c, or 30c) used per week, was presented in a randomized order over the 3 sessions. Prefrontal resting EEG cordance values at Fp1 and Fp2 were computed from artifact-free 2-minute EEG samples from the presniffing and postsniffing rest periods. Cordance derives from an algorithm that incorporates absolute and relative EEG values.

RESULTS

The data showed significant two-way oscillatory interactions of remedy by time for ß, α, θ, and δ cordance, controlling for gender and chemical sensitivity.

CONCLUSIONS

EEG cordance provided a minimally invasive technique for assessing objective nonlinear physiologic effects of two different homeopathic remedies salient to the individuals who received them. Time factors modulated the direction of effects. Given previous evidence of correlations between cordance and single-photon emission computed tomography, these findings encourage additional neuroimaging research on nonlinear psychophysiologic effects of specific homeopathic remedies.

Depression and sickness behavior are Janus-faced responses to shared inflammatory pathways

It is of considerable translational importance whether depression is a form or a consequence of sickness behavior. Sickness behavior is a behavioral complex induced by infections and immune trauma and mediated by pro-inflammatory cytokines. It is an adaptive response that enhances recovery by conserving energy to combat acute inflammation. There are considerable phenomenological similarities between sickness behavior and depression, for example, behavioral inhibition, anorexia and weight loss, and melancholic (anhedonia), physio-somatic (fatigue, hyperalgesia, malaise), anxiety and neurocognitive symptoms. In clinical depression, however, a transition occurs to sensitization of immuno-inflammatory pathways, progressive damage by oxidative and nitrosative stress to lipids, proteins, and DNA, and autoimmune responses directed against self-epitopes. The latter mechanisms are the substrate of a neuroprogressive process, whereby multiple depressive episodes cause neural tissue damage and consequent functional and cognitive sequelae. Thus, shared immuno-inflammatory pathways underpin the physiology of sickness behavior and the pathophysiology of clinical depression explaining their partially overlapping phenomenology. Inflammation may provoke a Janus-faced response with a good, acute side, generating protective inflammation through sickness behavior and a bad, chronic side, for example, clinical depression, a lifelong disorder with positive feedback loops between (neuro)inflammation and (neuro)degenerative processes following less well defined triggers.

Long-term body weight outcomes of antidepressant-environment interactions

Both obesity rates and antidepressant use have escalated in the last 20 years. Most people who start antidepressant treatment discontinue it on their own. Meanwhile, obesity rates continue to increase. To test the hypothesis that antidepressant use is a risk factor for obesity, even after long-term discontinuation, we developed a novel animal paradigm consisting of short-term exposure to stress and antidepressants, followed by long-term high-fat diet. We show here that recurrent restraint stress (RRS)-related weight loss is recovered 2 weeks after the end of stress in young growing rats receiving a high-fat diet. It is noteworthy that animals that received short-term antidepressant treatment with either imipramine or fluoxetine during 7 days of RRS showed behavioral evidence of antidepressant effects. When exposed to a high-fat diet after stress and when antidepressant treatment had ended, the animals had significant increases in caloric intake, body weight (BW) and size from 17 to 22 weeks following antidepressant discontinuation when compared with (control) RRS animals treated with saline and fed with a high-fat diet. These data are consistent with the previously described phenomenon of time-dependent sensitization, and support the notion that enduring effects of short-term antidepressant treatment become manifest on a long-term basis after antidepressant discontinuation, during conditions of high stress followed by high-fat intake. Analyses of open field and body size measurements obtained in a small subset of animals show that animals previously exposed to antidepressant had no deficits in locomotor activity and were larger. Antidepressant exposure may therefore be a covert, insidious and enduring risk factor for obesity, even after discontinuation of antidepressant treatment. Our data support the concept of persistent, long-term effects of pharmacological-environment interactions on BW regulation.

Stressors can affect immobility time and response to imipramine in the rat forced swim test

We subjected Wistar rats to the forced swim test (FST) to compare the effects of two doses of imipramine in physically stressed rats (P: unavoidable electric footshocks), emotionally stressed rats (E: odors), or non-stressed rats (C). Stress or control sessions lasted 35 days. Drug treatments began on day 21 and continued for the next 14 days. E rats were placed for 10 min, once per day for 35 days, in a small non-movement-restricting cage impregnated with urine collected from a P rat. E and P rats exhibited opposite changes in locomotion. After 21 days of stress sessions, P rats displayed the longest immobility times in the FST, followed by E rats. In the P group, on day 7 of treatment (day 28 of the study), imipramine (2.5 mg/kg) reduced immobility time to baseline values. In the E group, immobility time decreased only after 14 days of treatment with the low imipramine dose. The high dose of imipramine (5.0 mg/kg) reduced immobility time at day 7 of treatment in all groups. In conclusion, physical and emotional stress similarly increased immobility time in the FST, but emotional stress appears to be more resistant to imipramine treatment.

PTSD and stress sensitisation: a tale of brain and body Part 2: animal models

Animal models that are characterised by long-lasting conditioned fear responses as well as generalised behavioural sensitisation to novel stimuli following short-lasting but intense stress have a phenomenology that resembles that of PTSD in humans. These models include brief sessions of shocks, social confrontations, and a short sequence of different stressors. Subgroups of animals with different behavioural traits or coping styles during stress exposure show a different degree or pattern of long-term sensitisation. Weeks to months after the trauma, treated animals on average also show a sensitisation to novel stressful stimuli of neuroendocrine, cardiovascular and gastrointestinal motility responses as well as altered pain sensitivity and immune function. Functional neuroanatomical and pharmacological studies in these animal models have provided evidence for involvement of amygdala and medial prefrontal cortex, and of brain stem areas regulating neuroendocrine and autonomic function and pain processing. They have also generated a number of neurotransmitter and neuropeptide targets that could provide novel avenues for treatment in PTSD.

Comparison of the maturation of the adrenergic and serotonergic neurotransmitter systems in the brain: implications for differential drug effects on juveniles and adults

Our understanding of the development of neurotransmitter systems in the central nervous system has increased greatly over the past three decades and it has become apparent that drug effects on the developing nervous system may differ considerably from effects on the mature nervous system. Recently it has become clear there are significant differences in the effectiveness of antidepressant drug classes in children and adolescents compared to adults. Whereas the selective serotonin reuptake inhibitors are effective in treating all ages from children to adults, the tricyclic antidepressants, many of which inhibit norepinephrine reuptake, have been shown to be ineffective in treating children and adolescents even though they are effective in adults. We review here the development of the noradrenergic and serotonergic nervous systems, both in terms of neurotransmitter system markers and function. Both of these neurotransmitter systems are primary targets of antidepressant medications as well as of central nervous system stimulants. It is clear from a comparison of their development that the serotonin system reaches maturity much earlier than the norepinephrine system. We suggest this may help explain the differences in response to antidepressants in children and adolescents compared to adults. In addition, these differences suggest that drugs acting preferentially on either neurotransmitter system may impact the normal course of CNS development at different time points. Consideration of such differences in the development of neurotransmitter systems may be of significance in optimizing treatments for a variety of centrally mediated disorders.

Delayed effects of antidepressant drugs in rats

The present study has addressed the question of what is more important for the occurrence of adaptive changes observed in the organism treated with antidepressant drugs: a daily dosing of the drug or the period of time necessary for the plastic events to develop. Here, we report on the effects of desipramine given to rats acutely (and tested following 2 drug-free weeks) as when the drug was administered repeatedly, on behavior in the forced swim test (i.e. significant shortening of immobility time by ca. 60%) and on the binding of [3H]CGP12177 to beta-adrenergic receptors in the rat brain cortex (significant decrease of the binding by ca. 15%). Additionally, using the procedure of the repeated forced swim test (six times over 21 days), we show that the shortening of immobility time induced by a single dose of imipramine persisted throughout the whole experimental period and was similar to that seen in a group of animals treated repeatedly with the drug. Also, the effects of citalopram on immobility and climbing were similar after acute treatment and delayed testing to those seen after repeated drug exposure. The results obtained in the present study may question some conclusions that are usually drawn from the behavioral and, especially, biochemical studies concerning the need for repeated treatment with antidepressant drugs to induce various adaptive changes in the brain, which are thought to be responsible for the therapeutic efficacy of these drugs.

Toward a model of drug relapse: an assessment of the validity of the reinstatement procedure

BACKGROUND AND RATIONALE

The reinstatement model is widely used to study relapse to drug addiction. However, the model's validity is open to question.

OBJECTIVE

We assess the reinstatement model in terms of criterion and construct validity.

RESEARCH HIGHLIGHTS AND CONCLUSIONS

We find that the reinstatement model has adequate criterion validity in the broad sense of the term, as evidenced by the fact that reinstatement in laboratory animals is induced by conditions reported to provoke relapse in humans. The model's criterion validity in the narrower sense, as a medication screen, seems promising for relapse to heroin, nicotine, and alcohol. For relapse to cocaine, criterion validity has not yet been established primarily because clinical studies have examined medication's effects on reductions in cocaine intake rather than relapse during abstinence. The model's construct validity faces more substantial challenges and is yet to be established, but we argue that some of the criticisms of the model in this regard may have been overstated.

Adaptations or pathologies? Long-term changes in brain and behavior after a single exposure to severe threat

The experience of a single threatening situation may alter the behavior of an animal in a long-lasting way. Long-lasting changes in behavior have been induced in laboratory animals to model and investigate the development and neural substrate of human psychopathologies. Under natural conditions, however, changes in behavior after an aversive experience may be adaptive because behavioral modifications allow animals to adjust to a threat for extended periods of time. In the laboratory setting, properties of the aversive situation and the potential of the animal to respond to the threat may be altered and lead to extensive, prolonged changes, indicating a failure in behavioral regulation. Such long-term changes seem to be mediated by neuronal alterations in components of the fear pathway. To understand psychopathologies, determinants of exaggerated responsivity and the underlying molecular and neural processes have to be analyzed in a comparative way under conditions that produce normal and abnormal fear and anxiety.

Preclinical models: status of basic research in depression

Approximately one half-century ago several classes of medications, discovered by serendipity, were introduced for the treatment of depression and bipolar disorder. These highly effective medications revolutionized our approach to mood disorders and helped launch the modern era of psychiatry. Yet our progress since those serendipitous discoveries has been disappointing. We still do not understand with certainty how those medications produce their desired clinical effects. We have not introduced newer medications with fundamentally different mechanisms of action than the older agents. We have not identified the genetic and neurobiological mechanisms underlying depression and mania, nor do we understand the mechanisms by which nongenetic factors influence these disorders. We have only a rudimentary understanding of the circuits in the brain responsible for the normal regulation of mood and affect, and of those circuits that function abnormally in mood disorders. In approaching these gaps in our knowledge, this workgroup highlighted four major areas for future investment. These include developing better animal models of mood disorders; identifying genetic determinants of normal and abnormal mood in humans and animals; discovering novel targets and biomarkers of mood disorders and treatments; and increasing the recruitment of investigators from diverse backgrounds to mood disorders research.

Developmental sources of variation in liability to adolescent substance use disorders

This review provides a synthesis of the literature on the complex sequence of maturational, psychosocial, and neuroadaptive processes that lead to substance use disorders (SUD) in adolescence. A brief overview introduces the concepts of liability to SUD and epigenesis. A theory is presented explaining how affective, cognitive, and behavioral dysregulation in late childhood is exacerbated during early and middle adolescence by family and peer factors, as well as puberty, leading to substance use. Continued exacerbation of the three components of dysregulation by drug and non-drug stressors during late adolescence is posited to result in neuroadaptations that increase the likelihood of developing SUD, particularly in high-risk individuals. Implications for etiologic research as well as clinical and preventive interventions are discussed.