Acute poisoning with sarin causes alteration in oxidative homeostasis and biochemical markers in Wistar rats

Proinflammatory cytokines, oxidative stress, and organ function as biomarkers of soman (GD) chronic neurotoxicity

Organophosphate (OP) nerve agents, such as soman (GD), pose great risk to neurological health by inhibiting acetylcholinesterase, leading to seizures, epilepsy, and behavioral deficits. While acute treatment may alleviate immediate symptoms, the long-term consequences, particularly those involving neuroinflammation and systemic toxicity, remain poorly understood. This study used adult male and female Sprague Dawley rats to investigate the chronic effects of a single acute exposure to soman (132 µg/kg, s.c., 1.2 × LD50) on neuroinflammation, behavioral comorbidity, and systemic toxicity. Following exposure, animals were treated with atropine sulfate (2 mg/kg, i.m.) and oxime HI-6 (125 mg/kg, i.m.) to mitigate peripheral cholinergic effects, and with midazolam (3 mg/kg, i.m., 1 h post-exposure) to control seizures. Spontaneously recurring seizures were monitored during handling and with video electroencephalogram (vEEG). Neurobehavioral deficits were assessed 4-8 weeks post-exposure. At 18 weeks post-exposure, brain, serum, and cerebrospinal fluid (CSF) were analyzed for inflammatory and nitro-oxidative stress markers, and the liver and kidney function biomarkers were evaluated. Soman-exposed animals developed epilepsy, confirmed by handling-induced seizures and/or continuous vEEG monitoring. Behavioral assessments revealed significant memory deficits following soman exposure. Proinflammatory cytokines (TNF-α, IL-6, IL-1α, IL-18, IL-17A, and MCP-1) were significantly elevated in both serum and CSF, alongside corresponding increases in their gene expression in the brain. Elevated reactive oxygen/nitrogen species were detected in the serum. Although hematological parameters remained unchanged, a significant increase in total bilirubin and an upward trend in serum blood urea nitrogen (BUN) levels and BUN: Creatinine ratio indicated potential liver and kidney dysfunction. However, no significant structural changes in these organs at the cellular level were observed in histological analyses. This study identifies critical chronic biomarkers of soman exposure affecting the brain, serum, CSF, liver, and kidney. The findings highlight the critical need to monitor systemic and neurological impacts, as well as organ function, to develop effective diagnostic and therapeutic strategies for survivors of nerve agent exposure or OP pesticide poisoning. Behavioral deficits and EEG changes in soman-exposed animals further emphasize the long-term neurological consequences of exposure.

Sarin (GB, O-isopropyl methylphosphonofluoridate) neurotoxicity: critical review

Sarin (GB, O-isopropyl methylphosphonofluoridate) is a potent organophosphorus (OP) nerve agent that inhibits acetylcholinesterase (AChE) irreversibly. The subsequent build-up of acetylcholine (ACh) in the central nervous system (CNS) provokes seizures and, at sufficient doses, centrally-mediated respiratory arrest. Accumulation of ACh at peripheral autonomic synapses leads to peripheral signs of intoxication and overstimulation of the muscarinic and nicotinic receptors, which is described as "cholinergic crisis" (i.e. diarrhea, sweating, salivation, miosis, bronchoconstriction). Exposure to high doses of sarin can result in tremors, seizures, and hypothermia. More seriously, build-up of ACh at neuromuscular junctions also can cause paralysis and ultimately peripherally-mediated respiratory arrest which can lead to death via respiratory failure. In addition to its primary action on the cholinergic system, sarin possesses other indirect effects. These involve the activation of several neurotransmitters including gamma-amino-butyric acid (GABA) and the alteration of other signaling systems such as ion channels, cell adhesion molecules, and inflammatory regulators. Sarin exposure is associated with symptoms of organophosphate-induced delayed neurotoxicity (OPIDN) and organophosphate-induced chronic neurotoxicity (OPICN). Moreover, sarin has been involved in toxic and immunotoxic effects as well as organophosphate-induced endocrine disruption (OPIED). The standard treatment for sarin-like nerve agent exposure is post-exposure injection of atropine, a muscarinic receptor antagonist, accompanied by an oxime, an AChE reactivator, and diazepam.

The possible role of intravenous lipid emulsion in the treatment of chemical warfare agent poisoning

Organophosphates (OPs) are cholinesterase inhibitors that lead to a characteristic toxidrome of hypersecretion, miosis, dyspnea, respiratory insufficiency, convulsions and, without proper and early antidotal treatment, death. Most of these compounds are highly lipophilic. Sulfur mustard is a toxic lipophilic alkylating agent, exerting its damage through alkylation of cellular macromolecules (e.g., DNA, proteins) and intense activation of pro-inflammatory pathways. Currently approved antidotes against OPs include the peripheral anticholinergic drug atropine and an oxime that reactivates the inhibited cholinesterase. Benzodiazepines are used to stop organophosphate-induced seizures. Despite these approved drugs, efforts have been made to introduce other medical countermeasures in order to attenuate both the short-term and long-term clinical effects following exposure. Currently, there is no antidote against sulfur mustard poisoning. Intravenous lipid emulsions are used as a source of calories in parenteral nutrition. In recent years, efficacy of lipid emulsions has been shown in the treatment of poisoning by fat-soluble compounds in animal models as well as clinically in humans. In this review we discuss the usefulness of intravenous lipid emulsions as an adjunct to the in-hospital treatment of chemical warfare agent poisoning.

Cardiac and renal nitrosative-oxidative stress after acute poisoning by a nerve agent Tabun

We hypothesized that Tabun poisoning, as well as other organophosphorous treatment, cause specific organs' oxidative changes that have not previously been substantiated investigated. In this regard, a marker for nitrosative-oxidative stress in the main haemodynamic organs (heart and kidney) could reveal the existence of such changes. In this study, for the first time we studied the nitrosative/oxidative stress in heart and kidney after acute Tabun (Ethyl N,N- Dimethylphosphoramidocyanidate) poisoning measuring by immunohistochemistry the expression of 3-nitrotyrosine--a marker for nitrosative-oxidative stress. We investigated nitrotyrozine expression in three different groups of animals (with at least 3 animals in each group): the first group was treated with 0.5 LD50 Tabun and organs were collected after 24 h; the second group received vehicle for the same period; in the third group a highly specific re-activator was applied immediately after Tabun application. Heart and kidney were collected after 24 h. The levels of nitrotyrozine production significantly increased (more than 3 times) in cardiomyocytes after Tabun. The application of re-activator slightly reduced these levels not reaching the basal heart levels. Nitrotyrozine expression in kidney increased more than 2 times after Tabun and application of re-activator did not change it significantly. In conclusion, our study evidently demonstrated that Tabun trigger oxidative-nitrosative stress in heart and kidney and these cellular effects should be protected by an additional anti-oxidant therapy, since acetylcholinesterase re-activator is not efficient in this manner.

Toxicity induced by chemical warfare agents: insights on the protective role of melatonin

Chemical Warfare Agents (CWAs) are substances that can be used to kill, injure or incapacitate an enemy in warfare, but also against civilian population in terrorist attacks. Many chemical agents are able to generate free radicals and derived reactants, excitotoxicity process, or inflammation, and as consequence they can cause neurological symptoms and damage in different organs. Nowadays, taking into account that total immediate decontamination after exposure is difficult to achieve and there are not completely effective antidotes and treatments against all CWAs, we advance and propose that medical countermeasures against CWAs poisoning would benefit from a broad-spectrum multipotent molecule. Melatonin, a versatile and ubiquitous antioxidant molecule, originally discovered as a hormone synthesized mainly in the pineal gland, has low toxicity and high efficacy in reducing oxidative damage, anti-inflammatory effects by regulation of multiple cellular pathways and properties to prevent excitotoxicity, among others. The purpose of this review is to show the multiple and diverse properties of melatonin, as a pleiotropic indole derivative, and its marked potential for improving human health against the most widely used chemical weapons.