Involvement of the NADPH Oxidase NOX2-Derived Brain Oxidative Stress in an Unusual Fatal Case of Cocaine-Related Neurotoxicity Associated With Excited Delirium Syndrome

Hyperactive Delirium with Severe Agitation

Hyperactive delirium with severe agitation is a clinical syndrome of altered mental status, psychomotor agitation, and a hyperadrenergic state. The underlying pathophysiology is variable and often results from sympathomimetic abuse, psychiatric disease, sedative-hypnotic withdrawal, and metabolic derangement. Patients can go from a combative state to periarrest with little warning. Safety of the patient and of the medical providers is paramount and the emergency department should be prepared to manage these patients with adequate staffing, restraints, and pharmacologic sedatives. Treatment with benzodiazepines, antipsychotics, or ketamine is recommended, followed by airway protection, supportive measures, and cooling of hyperthermia.

Response to "Scrutinizing the causal link between excited delirium syndrome and restraint - a commentary on: 'The role of restraint in fatal excited delirium: a research synthesis and pooled analysis' by E.M.F. Strömmer, W. Leith, M.P. Zeegers and M.D. Freeman"

de Boer et al. criticize the conclusions in our 2020 paper on the validity of Excited Delirium Syndrome (ExDS) as "egregiously misleading." Our conclusion was that there "is no existing evidence that indicates that ExDS is inherently lethal in the absence of aggressive restraint." The basis for de Boer and colleague's criticism of our paper is that the ExDS literature does not provide an unbiased view of the lethality of the condition, and therefore the true epidemiologic features of ExDS cannot be determined from what has been published. The criticism is unrelated to the goals or methods of the study, however. Our stated purpose was to investigate "how the term ExDS has evolved in the literature and been endowed with a uniquely lethal quality," and whether there is "evidence for ExDS as a unique cause of a death that would have occurred regardless of restraint, or a label used when a restrained and agitated person dies, and which erroneously directs attention away from the role of restraint in explaining the death." We cannot fathom how de Boer et al. missed this clearly stated description of the study rationale, or why they would endorse a series of fallacious and meaningless claims that gave the appearance that they failed to grasp the basic design of the study. We do acknowledge and thank these authors for pointing out 3 minor citation errors and an equally minor table formatting error (neither of which altered the reported results and conclusions in the slightest), however.

Increased iNOS and Nitrosative Stress in Dopaminergic Neurons of MDMA-Exposed Rats

Several mechanisms underlying 3,4-Methylenedioxy-N-methylamphetamine (MDMA) neurotoxicity have been proposed, including neurochemical alterations and excitotoxicity mediated by reactive oxygen species (ROS), nitric oxide (NO), and reactive nitrogen species (RNS). However, ROS, NO, and RNS sources in the brain are not fully known. We aimed to investigate possible alterations in the expression of the ROS producer NOX enzymes (NOX2, NOX1, and NOX4), NO generators (iNOS, eNOS, and nNOS), markers of oxidative (8-hydroxy-2'-deoxyguanosine, 8OHdG), and nitrosative (3-nitrotyrosine, NT) stress, as well as the colocalization between cells positive for the dopamine transporter (DT1) and cells expressing the neuronal nuclei (NeuN) marker, in the frontal cortex of rats receiving saline or MDMA, sacrificed 6 h, 16 h, or 24 h after its administration. MDMA did not affect NOX2, NOX1, and NOX4 immunoreactivity, whereas iNOS expression was enhanced. The number of NT-positive cells was increased in MDMA-exposed animals, whereas no differences were detected in 8OHdG expression among experimental groups. MDMA and NT markers colocalized with DT1 positive cells. DT1 immunostaining was found in NeuN-positive stained cells. Virtually no colocalization was observed with microglia and astrocytes. Moreover, MDMA immunostaining was not found in NOX2-positive cells. Our results suggest that iNOS-derived nitrosative stress, but not NOX enzymes, may have a crucial role in the pathogenesis of MDMA-induced neurotoxicity, highlighting the specificity of different enzymatic systems in the development of neuropathological alterations induced by the abuse of this psychoactive compound.

Excited Delirium: A Systematic Review

OBJECTIVE

We aimed to clarify the definition, epidemiology, and pathophysiology of excited delirium syndrome (ExDS) and to summarize evidence-based treatment recommendations.

METHODS

We conducted a systematic literature search of MEDLINE, Ovid, Web of Knowledge, and Cochrane Library for articles published to March 18, 2017. We also searched the gray literature (Google Scholar) and official police or medical expert reports to complete specific epidemiologic data. Search results and full-text articles were independently assessed by two investigators and agreements between reviewers assessed with K statistics. We classified articles by study type, setting, and evidence level.

RESULTS

After reviewing the title and abstract of 3,604 references, we fully reviewed 284 potentially relevant references, from which 66 were selected for final review. Six contributed to the definition of ExDS, 24 to its epidemiology, 38 to its pathophysiology, and 27 to its management. The incidence of ExDS varies widely with medical or medicolegal context. Mortality is estimated to be as much as 8.3% to 16.5%. Patients are predominantly male. Male sex, young age, African-American race, and being overweight are independent risk factors. Pathophysiology hypotheses mostly implicate dopaminergic pathways. Most cases occur with psychostimulant use or among psychiatric patients or both. Proposed treatments are symptomatic, often with rapid sedation with benzodiazepines or antipsychotic agents. Ketamine is suggested as an alternative.

CONCLUSION

The overall quality of studies was poor. A universally recognized definition is lacking, remaining mostly syndromic and based on clinical subjective criteria. High mortality rate may be due to definition inconsistency and reporting bias. Our results suggest that ExDS is a real clinical entity that still kills people and that has probably specific mechanisms and risk factors. No comparative study has been performed to conclude whether one treatment approach is preferable to another in the case of ExDS.

The NADPH oxidase NOX2 mediates loss of parvalbumin interneurons in traumatic brain injury: human autoptic immunohistochemical evidence

Pharmacological interventions for traumatic brain injury (TBI) are limited. Together with parvalbumin (PV) loss, increased production of reactive oxygen species (ROS) by the NADPH oxidase NOX enzymes represents a key step in TBI. Here, we investigated the contribution of NOX2-derived oxidative stress to the loss of PV immunoreactivity associated to TBI, performing immunohistochemistry for NOX2, 8-hydroxy-2′-deoxyguanosine (8OHdG) and PV on post mortem brain samples of subjects died following TBI, subjects died from spontaneous intracerebral hemorrhage (SICH) and controls (CTRL). We detected an increased NOX2 expression and 8OHdG immunoreactivity in subjects died from TBI with respect to CTRL and SICH. NOX2 increase was mainly observed in GABAergic PV-positive interneurons, with a minor presence in microglia. No significant differences in other NADPH oxidase isoforms (NOX1 and NOX4) were detected among experimental groups. NOX2-derived oxidative stress elevation appeared a specific TBI-induced phenomenon, as no alterations in the nitrosative pathway were detected. Our results suggest that NOX2-derived oxidative stress might play a crucial role in the TBI-induced loss of PV-positive interneurons.

Blockade of Serotonin 5-HT2A Receptors Suppresses Behavioral Sensitization and Naloxone-Precipitated Withdrawal Symptoms in Morphine-Treated Mice

The increasing prescription of opioids is fueling an epidemic of addiction and overdose deaths. Morphine is a highly addictive drug characterized by a high relapse rate - even after a long period of abstinence. Serotonin (5-HT) neurotransmission participates in the development of morphine dependence, as well as the expression of morphine withdrawal. In this study, we examined the effect of blockade of 5-HT_2A receptors (5-HT_2ARs) on morphine-induced behavioral sensitization and withdrawal in male mice. 5-HT_2AR antagonist MDL 11,939 (0.5 mg/kg, i.p.) suppressed acute morphine (5.0 mg/kg, s.c.)-induced increase in locomotor activity. Mice received morphine (10 mg/kg, s.c.) twice a day for 3 days and then drug treatment was suspended for 5 days. On day 9, a challenge dose of morphine (10 mg/kg) was administered to induce the expression of behavioral sensitization. MDL 11,939 (0.5 mg/kg, i.p.) pretreatment suppressed the expression of morphine-induced behavioral sensitization. Another cohort of mice received increasing doses of morphine over a 7-day period to induce morphine-dependence. MDL 11,939 (0.5 mg/kg, i.p.) prevented naloxone-precipitated withdrawal in morphine-dependent mice on day 7. Moreover, chronic morphine treatment increased 5-HT_2AR protein level and decreased the phosphorylation of extracellular signal-regulated kinases in the prefrontal cortex. Together, these results by the first time demonstrate that 5-HT_2ARs modulate opioid dependence and blockade of 5-HT_2AR may represent a novel strategy for the treatment of morphine use disorders.

HIGHLIGHTS

(i)Blockade of 5-HT_2A receptors suppresses the expression of morphine-induced behavioral sensitization.(ii)Blockade of 5-HT_2A receptors suppresses naloxone-precipitated withdrawal in morphine-treated mice.(iii)Chronic morphine exposure induces an increase in 5-HT_2A receptor protein level and a decrease in ERK protein phosphorylation in prefrontal cortex.