Clonidine immediately after immobilization stress prevents long-lasting locomotion reduction in the rat

Inhibition of Protein Synthesis Attenuates Formation of Traumatic Memory and Normalizes Fear-Induced c-Fos Expression in a Mouse Model of Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a debilitating psychosomatic condition characterized by impairment of brain fear circuits and persistence of exceptionally strong associative memories resistant to extinction. In this study, we investigated the neural and behavioral consequences of inhibiting protein synthesis, a process known to suppress the formation of conventional aversive memories, in an established PTSD animal model based on contextual fear conditioning in mice. Control animals were subjected to the conventional fear conditioning task. Utilizing c-Fos neural activity mapping, we found that the retrieval of PTSD and normal aversive memories produced activation of an overlapping set of brain structures. However, several specific areas, such as the infralimbic cortex and the paraventricular thalamic nucleus, showed an increase in the PTSD group compared to the normal aversive memory group. Administration of protein synthesis inhibitor before PTSD induction disrupted the formation of traumatic memories, resulting in behavior that matched the behavior of mice with usual aversive memory. Concomitant with this behavioral shift was a normalization of brain c-Fos activation pattern matching the one observed in usual fear memory. Our findings demonstrate that inhibiting protein synthesis during traumatic experiences significantly impairs the development of PTSD in a mouse model. These data provide insights into the neural underpinnings of protein synthesis-dependent traumatic memory formation and open prospects for the development of new therapeutic strategies for PTSD prevention.

Propranolol versus Other Selected Drugs in the Treatment of Various Types of Anxiety or Stress, with Particular Reference to Stage Fright and Post-Traumatic Stress Disorder

Propranolol, a non-cardioselective β_1,2 blocker, is most commonly recognised for its application in the therapy of various cardiovascular conditions, such as hypertension, coronary artery disease, and tachyarrhythmias. However, due to its ability to cross the blood–brain barrier and affinity towards multiple macromolecules, not only adrenoreceptors, it has also found application in other fields. For example, it is one of the very few medications successfully applied in the treatment of stage fright. This review focuses on the application of propranolol in the treatment of various types of anxiety and stress, with particular reference to stage fright and post-traumatic stress disorder (PTSD). Both mechanisms of action as well as comparison with other therapies are presented. As those indications for propranolol are, in most countries, considered off-label, this review aims to gather information that can be useful while making a decision about the choice of propranolol as a drug in the treatment of those mental conditions.

Myocardial hypersensitivity to ischemic injury is not reversed by clonidine or propranolol in a predator-based rat model of posttraumatic stress disorder

Individuals with posttraumatic stress disorder (PTSD) are at increased risk for cardiovascular disease. We previously reported that a predator-based model of PTSD increases myocardial sensitivity to ischemic injury. Heightened sympathetic signaling has a well-established role in the formation of anxiety associated with PTSD and may also contribute to worsening of myocardial injury in the ischemic heart. Thus, we examined whether suppression of sympathetic tone protects the ischemic heart in rats subjected to this model of PTSD. Rats were treated with saline or clonidine throughout the 31-day stress paradigm. Behavior on the elevated plus maze (EPM) was assessed on Day 32, and hearts were subjected to an ischemic insult on day 33. Stressed rats exhibited increased anxiety on the EPM and significantly larger myocardial infarcts following ischemia. Clonidine reversed the anxiety-like behavior but had no impact on infarct size. In a subsequent experiment, rats were treated with propranolol in their drinking water throughout the stress paradigm. Propranolol had no effect on either anxiety or myocardial sensitivity to ischemic injury. These findings suggest that the myocardial hypersensitivity to ischemic injury observed in this model is not caused by increased sympathetic tone or chronic β-adrenergic receptor signaling.

Buspirone along with melatonin attenuates oxidative damage and anxiety-like behavior in a mouse model of immobilization stress

AIM

Stress is recognized to precipitate anxiety and related psychological problems characterized by a wide range of biochemical and behavioral changes. The present study was carried out to investigate the protective effects of melatonin and buspirone, and their combination, against six hours immobilization stress-induced, anxiety-like behavioral and oxidative damage in mice.

METHOD

Male Laca mice were pre-treated with melatonin (2.5, 5 mg·kg(-1)), buspirone (5, 10 mg·kg(-1)), and their combination for consecutive five days. On the 6(th) day, animals were immobilized for six hours, and thereafter various behavioral tests were performed followed by biochemical tests.

RESULTS

Immobilization stress significantly impaired body weight, locomotor activity, and caused anxiety-like behavior, along with increased oxidative damage. Pretreatment with melatonin and buspirone significantly improved the loss in body weight and locomotor activity, attenuated anxiety-like behavior (in both the mirror chamber and plus maze performance tasks), further restored the levels of brain total proteins, and caused antioxidant-like effects, as evidenced by reduced lipid peroxidation, nitrite concentration, and restoration of reduced glutathione and catalase activity, as compared to control animals. In addition, combination of melatonin (2.5, 5 mg·kg(-1)) with buspirone (5 mg·kg(-1)) significantly potentiated their protective effects, as compared to their effects individually.

CONCLUSION

The present study suggests that melatonin potentiates the beneficial effect of buspirone against immobilization stress-induced, anxiety-like behavioral and oxidative damage in mice possibly by involving a serotonergic mechanism.

Sympathetic system modulation to treat post-traumatic stress disorder (PTSD): a review of clinical evidence and neurobiology

A review of clinical evidence and neurobiology on the effects of modulation of sympathetic system modulation to treat post-traumatic stress disorder (PTSD) is being presented . The review provides an overview of currently available treatments followed by efficacy of orally effective sympathetic blocking agents. The main focus of the review is the application of stellate ganglion blocks (SGBs) or a local anesthetic blockade of the sympathetic ganglion in the neck.

Response variation following trauma: a translational neuroscience approach to understanding PTSD

Exposure to traumatic stress is a requirement for the development of posttraumatic stress disorder (PTSD). However, because the majority of trauma-exposed persons do not develop PTSD, examination of the typical effects of a stressor will not identify the critical components of PTSD risk or pathogenesis. Rather, PTSD represents a specific phenotype associated with a failure to recover from the normal effects of trauma. Thus, research must focus on identifying pre- and posttraumatic risk factors that explain the development of the disorder and the failure to reinstate physiological homeostasis. In this review, we summarize what is known about the clinical and biological characteristics of PTSD and articulate some of the gaps in knowledge that can be addressed by basic neuroscience research. We emphasize how knowledge about individual differences related to genetic and epigenetic factors in behavioral and brain responses to stress offers the hope of a deeper understanding of PTSD.

Pharmacologic reduction of CNS noradrenergic activity in PTSD: the case for clonidine and prazosin

This article reviews the neurobiologic rationale for and presents clinical guidance concerning the use of medications that reduce central nervous system noradrenergic activity in the treatment of intrusive symptoms of posttraumatic stress disorder. The authors reviewed neurobiological studies, nonclinical studies using animal models, clinical case reports, open-label drug studies, and blinded, placebo-controlled drug studies. This review of the basic science and clinical literature, and the authors' clinical experience with culturally and demographically diverse populations, indicate that clonidine and prazosin can play a useful role in treating sleep disturbance and hyperarousal in posttraumatic stress disorder, with minimal adverse effects and low financial cost.

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.

Timing of stress and testing influence the long-lasting behavioral performance in rats

Three exposures (Days 1, 2 and 3) of rats to immobilization or immobilization combined with cold induced an alteration of exploratory behavior in an open space arena. When tested 1h after both stressors exposure, rats displayed a decrease in locomotor and rearing score. The deficit disappeared when rats were tested five days later and the performance remained unchanged in trials performed on days 9, 10, 15, 22 and 29 of the study. When testing was postponed five days after the third stressor exposure, a gradual reduction of the performance developed and the deficit persisted until the last trial on Day 29. Amphetamine, in a dose of 0.3 mg/kg revealed a sensitized response to the drug in the stressed animals. The results showed short- and long-lasting behavioral consequences of the used stressors, the long-term manifestation of the sequelae being dependent on the sequence and timing of stressor exposure and open space testing.