Isolation of a toxin from Centruroides infamatus infamatus Koch scorpion venom that modifies Na+ permeability on chick dorsal root ganglion cells

When Venom Meets the Heart: A Rare Case of Scorpion Sting-Induced Acute Myocardial Infarction

Scorpion sting cases are everyday encounters in the Emergency Department (ED). However, scorpion sting-induced systemic manifestations are rarely seen. Signs and symptoms of envenomation involve the central nervous system, stimulation of the autonomic nervous system and rarely respiratory and heart failure leading to death. Cardiovascular manifestations are particularly prominent following stings by the Indian red scorpion. This case report is of an 18-year-old male patient who presented to ED with complaints of scorpion sting. Twelve lead electrocardiography (ECG) done was suggestive of acute inferior wall myocardial infarction with raised cardiac markers. He also had autonomic dysfunction in the form of hypertension, hypothermia and priapism. He was treated with an alpha-blocker, dual antiplatelets and analgesics. ECG changes reverted to normal the next day, and he was discharged. So, the anticipation of life-threatening complications of scorpion stings plays a vital role in the treatment and prognosis of patients presenting to ED.

Scorpion venom and the inflammatory response

Scorpion venoms consist of a complex of several toxins that exhibit a wide range of biological properties and actions, as well as chemical compositions, toxicity, and pharmacokinetic and pharmacodynamic characteristics. These venoms are associated with high morbility and mortality, especially among children. Victims of envenoming by a scorpion suffer a variety of pathologies, involving mainly both sympathetic and parasympathetic stimulation as well as central manifestations such as irritability, hyperthermia, vomiting, profuse salivation, tremor, and convulsion. The clinical signs and symptoms observed in humans and experimental animals are related with an excessive systemic host inflammatory response to stings and stings, respectively. Although the pathophysiology of envenomation is complex and not yet fully understood, venom and immune responses are known to trigger the release of inflammatory mediators that are largely mediated by cytokines. In models of severe systemic inflammation produced by injection of high doses of venom or venoms products, the increase in production of proinflammatory cytokines significantly contributes to immunological imbalance, multiple organ dysfunction and death. The cytokines initiate a cascade of events that lead to illness behaviors such as fever, anorexia, and also physiological events in the host such as activation of vasodilatation, hypotension, and increased of vessel permeability.

Structural and functional comparison of toxins from the venom of the scorpions Centruroides infamatus infamatus, Centruroides limpidus limpidus and Centruroides noxius

Two novel toxins containing 66 amino acid residues each were isolated from the venom of the scorpions Centruroides infamatus infamatus and Centruroides limpidus limpidus, respectively. Their full amino acid sequences were determined. Comparison of primary structures showed that they share 97% similarity among themselves and 83% to that of toxin 2 from Centruroides noxius. The three toxins studied compete with each other for the same binding sites on membranes prepared from rat brain synaptosomes, suggesting that they are all beta-scorpion toxins. Toxin action was assayed into the microI-2 rat skeletal muscle Na+ channel heterologously expressed into Xenopus oocytes. All three toxins block this Na+ channel in a similar fashion, without affecting inactivation, and showed IC50 values in the micromolar concentration range.