A neurotoxin is a toxin that acts specifically on nerve cells – neurons – usually by interacting with membrane proteins such as ion channels. Many of the venoms and other toxins that organisms use in defense against vertebrates are neurotoxins. A common effect is paralysis, which sets in very rapidly. The venom of bees, scorpions, pufferfish, spiders and snakes can contain many different toxins. Many neurotoxins act by affecting voltage-dependent ion channels. For example, tetrodotoxin and batrachotoxin affect sodium channels, maurotoxin, agitoxin, charybdotoxin, margatoxin, slotoxin, scyllatoxin and hefutoxin act on potassium channels, and calciseptine, taicatoxin and calcicludine act on calcium channels. Toxicology (from the Greek words toxicos and logos [1]) is the study of the adverse effects of chemicals on living organisms [2]. It is the study of symptoms, mechanisms, treatments and detection of poisoning, especially the poisoning of people. ... Forensic toxicology is the use of toxicology to aid medicolegal investigation of death, poisoning, and drug use. ... Toxinology is the specialized area of toxicology that deals specifically with biological toxins, such as venoms or poisonous plants. ... The history of poisons (poison being defined as a substance that causes death or injury when swallowed or absorbed)[1] stretches over a period from before 4500 BC to the present day. ... The skull and crossbones symbol (Jolly Roger) traditionally used to label a poisonous substance. ... A toxicant is a chemical compound that has an effect on organisms. ... An antidote is a substance which can counteract a form of poisoning. ... Acceptable Daily Intake or ADI is a measure of a specific substance (usually a food additive) in food or drinking water that can be ingested over a lifetime without an appreciable health risk. ... Acute Toxicity is a property of a substance that has toxic effects on a living organism, when that organism is exposed to a lethal dose of a substance once. ... If the input of a toxic substance to an organism is greater than the rate at which the substance is lost, the organism is said to be bioaccumulating that substance. ... The fixed-dose procedure (FDP) was proposed in 1984 to assess a substances acute oral toxicity using fewer animals with less suffering than the older LD50 test developed in 1927. ... An LD50 test being administered In toxicology, the LD50 or colloquially semilethal dose of a particular substance is a measure of how much constitutes a lethal dose. ... A lethal dose (LD) is an indication of the lethality of a given substance or type of radiation. ... Toxic capacity can mean the toxicity of a substance, possibly in relation to a specific organism and toxic capacity can mean the capacity of an organism, organic system or ecosystem to contain a toxic substance or a selection of toxic substances (a compound) without showing signs of poisoning or dying. ... Toxicity Class refers to a classification system for pesticides created by a national or international government-related or -sponsored organization. ... This article or section does not cite any references or sources. ... Wasp sting, with droplet of venom Venom (literally, poison of animal origin) is any of a variety of toxins used by animals, for the purpose of defense and hunting. ... Necrosis (in Greek Νεκρός = Dead) is the name given to unprogrammed death of cells/living tissue (compare with apoptosis - programmed cell death). ... Hemotoxins are toxins that destroy red blood cells (hemolysis), disrupt blood clotting, and/or cause organ degeneration and generalized tissue damage. ... Mycotoxin (from Gk. ... Chemical structure of aflatoxin B1 Aflatoxins are naturally occurring mycotoxins that are produced by many species of Aspergillus, a fungus, most notably Aspergillus flavus and Aspergillus parasiticus. ... Phototoxins are toxins that can cause allergic reactions in particularly susceptible individuals and which can cause dangerous photosensitivity in a much broader range of subjects. ... This is a list of toxins, poisons and chemical weapons from works of fiction (usually in fantasy and science fiction). ... The Bradford sweets poisoning was the accidental arsenic poisoning of more than 200 people in Bradford, England in 1858; an estimated 20 people died when sweets accidentally made with arsenic were sold from a market stall. ... Minamata disease ), sometimes referred to as Chisso-Minamata disease ), is a neurological syndrome caused by severe mercury poisoning. ... Main article: Minamata disease Niigata Minamata disease ) is a neurological syndrome caused by severe mercury poisoning. ... On November 1, 2006, former lieutenant colonel of the Russian Federations Federal Security Service Alexander Litvinenko suddenly fell ill and was hospitalised. ... The Bhopal Disaster took place in the early hours of the morning of December 3, 1984,[1] in the heart of the city of Bhopal, India, in the state of Madhya Pradesh. ... Dogs and cats have been the main affected pets of the recall. ... This is a list of poisonings in chronological order of victim. ... Lead poisoning is a medical condition, also known as saturnism, plumbism or painters colic, caused by increased blood lead levels. ... It has been suggested that Acrodynia be merged into this article or section. ... Cadmium has no constructive purpose in the human body. ... In high concentrations, as with almost all substances, fluoride compounds are toxic. ... Iron poisoning is caused by an excess of iron in the blood. ... Arsenic poisoning kills by allosteric inhibition of essential metabolic enzymes, leading to death from multi-system organ failure. ... Oxygen toxicity or oxygen toxicity syndrome is severe hyperoxia caused by breathing oxygen at elevated partial pressures. ... There are four syndromes called shellfish poisoning, which share some common features and are primarily associated with bivalve molluscs (such as mussels, clams, oysters and scallops). ... 4 distinct shellfish-poisoning syndromes have been identified: Paralytic shellfish poisoning (PSP) Neurologic shellfish poisoning (NSP) Diarrheal shellfish poisoning (DSP) Amnestic shellfish poisoning (ASP) All 4 syndromes share some common features and primarily are associated with bivalve mollusks (eg, mussels, clams, oysters, scallops). ... Diarrheal shellfish poisoning (DSP) is one of the four recognised symptom types of shellfish poisoning, the others being paralytic shellfish poisoning, neurologic shellfish poisoning and amnesic shellfish poisoning. ... Amnesic shellfish poisoning (ASP) is one of the four recognised syndromes of shellfish poisoning (the others being neurotoxic shellfish poisoning [1], diarrhetic shellfish poisoning [2] and paralytic shellfish poisoning). ... Chemical structure of the ciguatoxin CTX1B Ciguatera is a foodborne illness poisoning in humans caused by eating marine species whose flesh is contaminated with a toxin known as ciguatoxin, which is present in many micro-organisms (particularly, the micro-algae Gambierdiscus toxicus) living in tropical waters. ... Scombroid is a foodborne illness poisoning associated with eating seafood that has been stored improperly. ... Tetrodotoxin (anhydrotetrodotoxin 4-epitetrodotoxin, tetrodonic acid, TTX) is a potent neurotoxin with no known antidote, which blocks action potentials in nerves by binding to the pores of the voltage-gated, fast sodium channels in nerve cell membranes. ... Pesticide poisonings, where chemicals intended to control a pest affect non-target organisms such as humans, wildlife, or bees. ... Many organophosphates are potent neurotoxins, functioning by inhibiting the action of acetylcholinesterase (AChE) in nerve cells. ... Historically, most cases of nicotine poisoning have been the result of its use as an insecticide; however, such use is less frequent now than previously. ... Theobromine poisoning or chocolate poisoning is an adverse reaction to the alkaloid theobromine, found in chocolate, tea, cola beverages, and some other foods. ... Carbon monoxide poisoning occurs after the inhalation of carbon monoxide gas. ... Vitamin poisoning, or hypervitaminosis, refers to a condition of high storage levels of vitamins, which can lead to toxic symptoms. ... A drug overdose occurs when a drug is ingested in quantities and/or concentrations large enough to overwhelm the homeostasis of a living organism, causing severe illness or death. ... The current version of the article or section is written like a magazine article instead of the formal tone expected of an encyclopedia. ... This is a list of plants containing poisonous parts that pose a serious risk of illness, injury, or death to humans. ... This is a list of organisms that are dangerous to humans. ... The skull and crossbones, a common symbol for poison. ... The hazard symbol for carcinogenic chemicals in the Globally Harmonized System. ... In biology, a mutagen (Latin, literally origin of change) is a physical or chemical agent that changes the genetic information (usually DNA) of an organism and thus increases the number of mutations above the natural background level. ... This is a list of Extremely Hazardous Substances as defined by Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act. ... For the use of biological agents by terrorists, see bioterrorism. ... This article or section does not cite any references or sources. ... Drawing by Santiago Ramón y Cajal of neurons in the pigeon cerebellum. ... A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle. ... Ion channels are pore-forming proteins that help to establish and control the small voltage gradient that exists across the plasma membrane of all living cells (see cell potential) by allowing the flow of ions down their electrochemical gradient. ... It has been suggested that Snake poison be merged into this article or section. ... This article does not cite any references or sources. ... For other uses, see Western honey bee and Bee (disambiguation). ... Superfamilies Pseudochactoidea Buthoidea Chaeriloidea Chactoidea Iuroidea Scorpionoidea See classification for families. ... Genera Amblyrhynchotes Arothron Auriglobus Canthigaster Carinotetraodon Chelonodon Colomesus Contusus Ephippion Feroxodon Fugu Gastrophysus Javichthys Lagocephalus Liosaccus Marilyna Monotretus Omegaphora Pelagocephalus Polyspina Reicheltia Sphoeroides Takifugu Tetractenos Tetraodon Torquigener Tylerius Xenopterus For species see Genera articles. ... Diversity 111 families, 40,000 species Suborders Mesothelae Mygalomorphae Araneomorphae  See table of families Wikispecies has information related to: Spiders Spiders are predatory invertebrate animals that have two body segments, eight legs, no chewing mouth parts and no wings. ... blue: sea snakes, black: land snakes Superfamilies and Families Henophidia Aniliidae Anomochilidae Boidae Bolyeriidae Cylindrophiidae Loxocemidae Pythonidae Tropidophiidae Uropeltidae Xenopeltidae Typhlopoidea Anomalepididae Leptotyphlopidae Typhlopidae Xenophidia Acrochordidae Atractaspididae Colubridae Elapidae Hydrophiidae Viperidae A snake is a scaly, limbless, elongate reptile from the order Squamata. ... Tetrodotoxin (anhydrotetrodotoxin 4-epitetrodotoxin, tetrodonic acid, TTX) is a potent neurotoxin with no known antidote, which blocks action potentials in nerves by binding to the pores of the voltage-gated, fast sodium channels in nerve cell membranes. ... Batrachotoxins are extremely potent cardiotoxic and neurotoxic steroidal alkaloids found in certain species of frogs (poison dart frog), Melyridae beetles and birds (Pitohui, Ifrita kowaldi). ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ... There are very few or no other articles that link to this one. ... Summary Charybdotoxin (CTX) is a 37 amino acid neurotoxin extracted from the venom of the scorpion that blocks calcium-activated potassium channels. ... // Margatoxin ( synonym MgTx) is a toxin that was first found in, and isolated from, the South American scorpion called Centruroides Margaritatus. ... // Slotoxin is a peptide from Centruroides noxius Hoffmann scorpion venom. ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ... There are very few or no other articles that link to this one. ... There are very few or no other articles that link to this one. ... The references in this article would be clearer with a different and/or consistent style of citation, footnoting or external linking. ... // Calcicludine (CaC) is a protein toxin from the venom of the green mamba that inhibits high-voltage-activated calcium channels, especially L-type calcium channels. ...

Toxins ingested from the environment are described as exogenous and include gases (such as carbon monoxide), metals (such as mercury), liquids (ethanol) and an endless list of solids. When exogenous toxins are ingested, the effect on neurons is largely dependent on dosage. Thus, ethanol (alcohol) is inebriating in low doses, only producing mild neurotoxicity. Prolonged exposure to "safe" alcohol levels slowly weakens and kills neurons. This article does not cite any references or sources. ... Carbon monoxide, with the chemical formula CO, is a colorless, odorless, and tasteless gas. ... General Name, Symbol, Number mercury, Hg, 80 Chemical series transition metals Group, Period, Block 12, 6, d Appearance silvery Standard atomic weight 200. ... A liquid will usually assume the shape of its container A liquid is one of the main states of matter. ... Ethanol, also known as ethyl alcohol, drinking alcohol or grain alcohol, is a flammable, colorless, slightly toxic chemical compound, and is best known as the alcohol found in alcoholic beverages. ... A solid is a state of matter, characterized by a definite volume and a definite shape (i. ... Ethanol, also known as ethyl alcohol, drinking alcohol or grain alcohol, is a flammable, colorless, slightly toxic chemical compound, and is best known as the alcohol found in alcoholic beverages. ...

Neurotoxicity also occurs from substances produced within the body - endogenous neurotoxins. A prime example of a neurotoxin in the brain is glutamate^{[citation needed]}, which is paradoxically also a primary neurotransmitter. When the glutamate concentration around a neuron reaches a critical point the neuron kills itself by a process called apoptosis^{[citation needed]}. This whole process is called excitotoxicity, so named because glutamate normally acts as an excitatory neurotransmitter at lower levels.^{[citation needed]} The term neurotoxic is used to describe a substance, condition or state that damages the nervous system and / or brain, usually by killing neurons. ... Glutamic acid (Glu, E), is the protonated form of glutamate (the anion). ... Chemical structure of D-aspartic acid, a common amino acid neurotransmitter. ... A section of mouse liver showing an apoptotic cell indicated by an arrow // Apoptosis is a process of deliberate life relinquishment by a cell in a multicellular organism. ... Excitotoxicity is the pathological process by which nerve cells are damaged and killed by glutamate and similar substances. ...

A potent neurotoxin such as batrachotoxin affects the nervous system by causing depolarization of nerve and muscle fibres due to increased sodium ion permeability of the excitable cell membrane. Batrachotoxins are extremely potent cardiotoxic and neurotoxic steroidal alkaloids found in certain species of frogs (poison dart frog), Melyridae beetles and birds (Pitohui, Ifrita kowaldi). ... In biology, depolarization is the event a cell undergoes when its membrane potential grows more positive with respect to the extracellular solution. ... General Name, Symbol, Number sodium, Na, 11 Chemical series alkali metals Group, Period, Block 1, 3, s Appearance silvery white Standard atomic weight 22. ... An electrostatic potential map of the nitrate ion (NO3−). Areas coloured red are lower in energy than areas colored yellow An ion is an atom or group of atoms which have lost or gained one or more electrons, making them negatively or positively charged. ... Permeability has several meanings: In electromagnetism, permeability is the degree of magnetisation of a material in response to a magnetic field. ... The cell membrane (also called the plasma membrane, plasmalemma or phospholipid bilayer) is a semipermeable lipid bilayer common to all living cells. ...

A number of artificial neurotoxins, known as nerve agents, have been developed for use as chemical weapons. Nerve agents (also known as nerve gases, though these chemicals are liquid at room temperature) are a class of phosphorus-containing organic chemicals (organophosphates) that disrupt the mechanism by which nerves transfer messages to organs. ... Dressing the wounded during a gas attack by Austin O. Spare, 1918. ...

The most potent nuerotoxin is tetrodotoxin. This chemical acts to block sodium channels in nuerons, preventing action potentials. This leads to paralysis and eventually death (Wski) Tetrodotoxin (anhydrotetrodotoxin 4-epitetrodotoxin, tetrodonic acid, TTX) is a potent neurotoxin with no known antidote, which blocks action potentials in nerves by binding to the pores of the voltage-gated, fast sodium channels in nerve cell membranes. ...

See also

• Neurotoxicity
• Teratogenesis, many birth defects are essentially caused by neurotoxicity in developing neurons
• Penitrem A