A self-explanatory term for a venom produced by scorpions* which contains multiple toxins and other compounds.
Toxins and chemicals in scorpion venom-SV Neurotoxin, cardiotoxin, nephrotoxin, haemolytic toxin, phosphodiesterases, phospholipases, hyaluronidases, glycosaminoglycans, histamine, serotonin*, tryptophan, and cytokine releasers.
*Which may contribute to the pain of with scorpion envenomation.
Pathophysiology SV has neuromuscular and autonomic effects, and causes local tissue damage. Its primary targets are voltage-dependent ion channels, leading to prolonged neural activity, cardiopulmonary and end-organ effects secondary to autonomic excitation. Somatic and cranial nerve hyperactivity result from neuromuscular overstimulation.
Neurotoxins are the most potent toxins: they are heat-stable, have low molecular weight, and impair activity in nerves, muscles, and the heart by altering ion channel permeability. They are divided into two broad groups:
• Long-chain polypeptide neurotoxins Lock voltage-dependent sodium channels in the open position, leading to continuous, prolonged, repetitive firing of the somatic, sympathetic, and parasympathetic neurons, symptoms of autonomic and neuromuscular overexcitation and prevention of normal nerve impulse transmissions, in addition to flooding the region with neurotransmitters–e.g., epinephrine, norepinephrine, acetylcholine, glutamate, and aspartate.
• Short polypeptide neurotoxins Block potassium channels.
The binding of neurotoxins to the host is reversible, but different neurotoxins have different affinities.
The stability of the neurotoxin is due to the 4 disulfide bridges that fold the neurotoxin into a very compact 3-dimensional structure, thus making it resistant to pH and temperature changes. However, reagents that can break the disulfide bridges can inactivate this toxin by causing it to unfold. Also, the antigenicity of this toxin is dependent on the length and number of exposed regions that are sticking out of the 3-dimensional structure.