The efficacy of prazosin for the treatment of posttraumatic stress disorder nightmares in U.S. military veterans

Novel Pharmacological Targets of Post-Traumatic Stress Disorders

Post-traumatic stress disorder (PTSD) is a psychopathological condition with a heterogeneous clinical picture that is complex and challenging to treat. Its multifaceted pathophysiology still remains an unresolved question and certainly contributes to this issue. The pharmacological treatment of PTSD is mainly empirical and centered on the serotonergic system. Since the therapeutic response to prescribed drugs targeting single symptoms is generally inconsistent, there is an urgent need for novel pathogenetic hypotheses, including different mediators and pathways. This paper was conceived as a narrative review with the aim of debating the current pharmacological treatment of PTSD and further highlighting prospective targets for future drugs. The authors accessed some of the main databases of scientific literature available and selected all the papers that fulfilled the purpose of the present work. The results showed that most of the current pharmacological treatments for PTSD are symptom-based and show only partial benefits; this largely reflects the limited knowledge of its neurobiology. Growing, albeit limited, data suggests that the hypothalamic-pituitary-adrenal axis, opioids, glutamate, cannabinoids, oxytocin, neuropeptide Y, and microRNA may play a role in the development of PTSD and could be targeted for novel treatments. Indeed, recent research indicates that examining different pathways might result in the development of novel and more efficient drugs.

The Structural Determinants for α1-Adrenergic/Serotonin Receptors Activity among Phenylpiperazine-Hydantoin Derivatives

Several studies confirmed the reciprocal interactions between adrenergic and serotoninergic systems and the influence of these phenomena on the pathogenesis of anxiety. Hence, searching for chemical agents with a multifunctional pharmacodynamic profile may bring highly effective therapy for CNS disorders. This study presents a deep structural insight into the hydantoin-arylpiperazine group and their serotonin/α-adrenergic activity. The newly synthesized compounds were tested in the radioligand binding assay and the intrinsic activity was evaluated for the selected derivatives. The computer-aided SAR analysis enabled us to answer questions about the influence of particular structural fragments on selective vs. multifunctional activity. As a result of the performed investigations, there were two leading structures: (a) compound 12 with multifunctional adrenergic-serotonin activity, which is a promising candidate to be an effective anxiolytic agent; (b) compound 14 with high α_1A/α_1D affinity and selectivity towards α_1B, which is recommended due to the elimination of probable cardiotoxic effect. The structural conclusions of this work provide significant support for future lead optimization in order to achieve the desired pharmacodynamic profile in searching for new CNS-modulating agents.

Using Prazosin to Treat Posttraumatic Stress Disorder and Associations: A Systematic Review

OBJECTIVE

A central adrenergic hyperactivation is described in the neurobiology of posttraumatic stress disorder (PTSD) with probable variable symptomatic impact. Few studies have evaluated using the alpha-1 adrenergic antagonist prazosin for such symptoms; however, given the likely pathophysiology involved, this drug may play an important role in the pharmacological approach to PTSD.

METHODS

This study assessed articles already published on the use of prazosin through a systematic review along a timeline in view of the symptomatic target of difficult access by standardized treatments. The impact of using this medication for the general symptoms of PTSD is also discussed. Several databases were searched for articles in the literature on the use of prazosin to treat PTSD.

RESULTS

A total of 168 articles were found containing search terms in the title or abstract. Overall, 85 articles met the criteria described, and 48 studies were explored to conduct the present systematic review. Most articles showed some improvement after prazosin administration, especially in relation to sleep symptoms (nightmares and night waking). Only one article demonstrated no improvement after the use of this drug. More randomized studies are needed.

CONCLUSION

Several clinical studies demonstrated the relevant role of prazosin for treating PTSD symptoms. Prazosin is an affordable and cost-effective pharmacological option compared to other drugs used to treat PTSD.

α 2-Adrenoceptors: Challenges and Opportunities-Enlightenment from the Kidney

It was indeed a Don Quixote-like pursuit of the mechanism of essential hypertension when we serendipitously discovered α₂-adrenoceptors (α₂-ARs) in skin-lightening experiments in the frog. Now α₂-ARs lurk on the horizon involving hypertension causality, renal denervation for hypertension, injury from falling in the elderly and prazosin's mechanism of action in anxiety states such as posttraumatic stress disorder (PTSD). Our goal here is to focus on this horizon and bring into clear view the role of α₂-AR-mediated mechanisms in these seemingly unrelated conditions. Our narrative begins with an explanation of how experiments in isolated perfused kidneys led to the discovery of a sodium-retaining process, a fundamental mechanism of hypertension, mediated by α₂-ARs. In this model system and in the setting of furosemide-induced sodium excretion, α₂-AR activation inhibited adenylate cyclase, suppressed cAMP formation, and caused sodium retention. Further investigations led to the realization that renal α₂-AR expression in hypertensive animals is elevated, thus supporting a key role for kidney α₂-ARs in the pathophysiology of essential hypertension. Subsequent studies clarified the molecular pathways by which α₂-ARs activate prohypertensive biochemical systems. While investigating the role of α₁-adrenoceptors (α₁-ARs) versus α₂-ARs in renal sympathetic neurotransmission, we noted an astonishing result: in the kidney α₁-ARs suppress the postjunctional expression of α₂-ARs. Here, we describe how this finding relates to a broader understanding of the role of α₂-ARs in diverse disease states. Because of the capacity for qualitative and quantitative monitoring of α₂-AR-induced regulatory mechanisms in the kidney, we looked to the kidney and found enlightenment.

Traumatic brain injury and sleep disturbances in combat-exposed service members and veterans: Where to go next?

OBJECTIVE

To synthesize the current evidence on sleep disturbances in military service members (SMs) and veterans with traumatic brain injury (TBI).

METHODS

An electronic literature search first identified abstracts published from 2008-2018 inclusively referencing sleep, TBI, and military personnel from Operation Enduring Freedom, Operation Iraqi Freedom, Operation New Dawn, and Persian Gulf veterans. Selection criteria eliminated studies on non-combat TBI, open or penetrating injuries, and articles where the relationship between sleep and TBI was not directly examined. Articles on all military branches and components, those currently serving and veterans-ranging from medical chart reviews to clinical trials, were included. Forty-one articles were selected for full text-review.

RESULTS

Twenty-four papers estimated the prevalence of sleep disturbances in TBI. Eight studies demonstrated the contribution of common co-occurring conditions, most notably posttraumatic stress disorder, to the relationship between disrupted sleep and TBI. Ten studies differentiated sleep profiles between military SMs and veterans with and without acute TBI and detected significant differences in sleep disturbances across the course of injury. Longitudinal studies were scarce but helped to establish the temporal relationship between sleep disturbances and TBI and isolate sleep-related mechanisms influencing TBI prognosis. Only three studies reported on interventions for improving sleep quality and TBI symptoms. Systematic research testing assessments and interventions that target sleep disturbances for improving sleep, TBI symptoms, and long-term functional outcomes were identified as critical knowledge gaps.

CONCLUSION

Findings unequivocally establish that sleep disturbances are highly prevalent in SMs and veterans with TBI. However, studies testing the effectiveness of treatments for improving sleep in military groups with TBI have been limited and their results inconsistent. This review highlights a critical opportunity for advancing military medicine through future research aimed at identifying and testing sleep-focused treatments in SMs and veterans with combat-related TBI.

Preclinical characterization of ACH-000029, a novel anxiolytic compound acting on serotonergic and alpha-adrenergic receptors

Anxiety disorders are serious and common mental diseases, yet there is still a need for the development of more effective anxiolytics with better safety profiles than benzodiazepines and serotonin reuptake inhibitors. The serotonergic and noradrenergic systems have reciprocal interactions and are intricately related to the pathogenesis of anxiety. In this study, the anxiolytic-like effect of the novel compound ACH-000029, 3-(2-(4-(2-methoxyphenyl) piperazine-1-yl) ethyl) quinazoline-4(3H)-one, is reported. This compound acts at selected serotonergic (5-HT1A and 5-HT1D partial agonism and 5-HT2A antagonism) and α-adrenergic (α-1A, 1B and 1D antagonism) receptors, with good selectivity over other G-protein-coupled receptors. ACH-000029 exhibited high blood-brain barrier permeation and acute anxiolytic effects in the marble burying (MB) and light-dark box (LDB) models of anxiety over the dose ranges of 8-32 mg/kg i.p. and 16-30 mg/kg p.o. The anxiolytic activity was comparable to that observed for serotonin reuptake inhibitors (paroxetine and fluoxetine) and benzodiazepines (alprazolam, diazepam and clobazam). The analysis of the whole-brain c-fos expression following oral dosing showed that ACH-000029 regulated regions highly associated with the processing of environmental stimuli and anxiety behavior, such as the amygdala, paraventricular nucleus of the thalamus, retrosplenial dorsal, pallidum, bed nuclei of the stria terminalis, and locus ceruleus. No safety concerns were identified for ACH-000029 in the functional observational battery up to 50 mg/kg i.p. and in the nonprecipitated withdrawal test up to 30 mg/kg p.o. twice daily for 20 days. This work supports the further development of ACH-000029 as a drug candidate for the treatment of anxiety disorders. The analysis of the in vitro pharmacology and brain regions regulated by this compound may also lead to the exploration of other indications within the psychiatry field.

Antidepressant-like activity of venlafaxine and clonidine in mice exposed to single prolonged stress - A model of post-traumatic stress disorder. Pharmacodynamic and molecular docking studies

BACKGROUND

Post-traumatic stress disorder (PTSD) is a growing issue worldwide characterized by stress and anxiety in response to re-experiencing traumatic events which strongly impair patient's quality of life and social functions. Available antidepressant and anxiolytic drugs are not efficacious in the majority of treated individuals. This necessitates a significant medical demand to develop novel therapeutic strategies for PTSD.

EXPERIMENTAL APPROACH

Animal model of PTSD was induced using a mouse single prolonged stress protocol (mSPS). To assess the activity of venlafaxine and clonidine, the forced swim test (FST) was used repeatedly 24h, 3days, 8days, 15days and 25days after mSPS. To get insight into a possible mechanism of anti-PTSD action, molecular docking procedure was utilized for the most active drug. This in silico part comprised molecular docking of enantiomers of venlafaxine to human transporters for serotonin (hSERT), norepinephrine (hNET) and dopamine (hDAT).

KEY RESULTS

In mSPS-subjected mice FST revealed the effectiveness of venlafaxine, however in non SPS-subjected mice both venlafaxine and clonidine were active. Molecular docking studies indicated that the affinity of venlafaxine to monoamine transporters is growing in the following rank order: hDAT<hNET<hSERT. Both venlafaxine enantiomers present different selectivity and binding mode.

CONCLUSION AND IMPLICATIONS

Venlafaxine but not clonidine was effective in an animal model of PTSD. Its mechanism of action, i.e., SERT, NET and DAT inhibition indicates potential drug targets for PTSD treatment. We expect that these results will contribute to a broader application of VLX in PTSD patients.