Which Neurotoxin is the Worst? (Neurotoxin Lore)

That Chemist

3 Mar 202332:41

EducationalLearning

32 Likes 10 Comments

TLDRThis video by 'That Chemist' delves into the realm of neurotoxins, explaining how nerves function and the impact of various chemicals on neuronal activity. Starting with an overview of the nervous system, the script moves on to categorize and discuss the potency and mechanisms of different neurotoxins, such as ethanol, tetrodotoxin, and botulinum toxin. It highlights the irreversible damage some can cause to neurons, the post-mitotic cells, and the importance of understanding these substances for safety and medical applications.

Takeaways

🧠 Nerves and Neurons: The video begins by explaining the fundamental workings of nerves and neurons, which are essential for signal transmission in the body.
🔬 Neurotransmitters: Neurons communicate via neurotransmitters across a synaptic cleft, with the process being one-way due to the nature of the synaptic mechanism.
🐘 Neuron Count: Humans have approximately 86 billion neurons, a significant number compared to other species like elephants with 251 billion and chimpanzees with 22 billion.
🚨 Neuron Damage: Neurons are post-mitotic cells, meaning damage can be irreversible, and some neurotoxins can cause permanent neurotoxicity.
🍻 Ethanol Toxicity: Chronic consumption of high doses of ethanol can lead to thiamine deficiency, resulting in oxidative damage to neurons.
🐡 Tetrodotoxin: A potent neurotoxin found in puffer fish that blocks sodium channels, preventing nerve firing and causing paralysis.
🍽️ Botulinum Toxin: Known as Botox, it can cause paralysis by inhibiting the release of neurotransmitters due to its action as a zinc-containing enzyme.
💊 Tetraethylamonium: A less well-known neurotoxin that blocks potassium channels and nicotinic acetylcholine receptors, potentially recoverable with treatment.
🐟 Methyl Mercury: A neurotoxin that bioaccumulates in food chains, capable of crossing the blood-brain barrier and causing oxidative stress leading to neurotoxicity.
🌿 Toxiferine: A highly toxic plant alkaloid historically used as an arrow poison, acting as a nicotinic acetylcholine receptor antagonist causing paralysis.
🛢️ n-Hexane: A common solvent that becomes neurotoxic after being converted into toxic metabolites, disrupting axonal transport and causing permanent nerve damage.

Q & A

What is the primary function of neurons in the human body?
-Neurons serve two primary roles: receiving signals and sending signals. They detect hormones and signaling molecules transported within blood and send signals to other parts of the body via neurotransmitters in the synaptic cleft.
How does the nervous system send signals throughout the body?
-The nervous system sends signals through the transmission of electrical impulses along nerve cells, known as neurons. These impulses are transmitted through a process involving the opening and closing of sodium and potassium channels, leading to the release of neurotransmitters into the synaptic cleft.
What is the significance of the number of neurons in the human body?
-The human body is comprised of approximately 86 billion neurons. This number is significant as it indicates the complexity of the nervous system and its ability to process and transmit a vast amount of information.
What is the role of neurotransmitters in the synaptic cleft?
-Neurotransmitters in the synaptic cleft play a crucial role in the transmission of signals from one neuron to another. They are released from vesicles in the presynaptic neuron and are detected by the postsynaptic neuron, allowing for the continuation of the signal transmission.
How do neurons handle the neurotransmitters in the synaptic cleft after they have been released?
-After neurotransmitters are released into the synaptic cleft, they can either be reuptaked by the presynaptic neuron for reuse or broken down by enzymes present in the cleft, with their components potentially being reuptaked and reused.
What is the impact of ethanol on the neurotoxicity of a person?
-Ethanol can cause neurotoxicity indirectly by causing thiamine deficiency, which makes it harder for mitochondria to metabolize glucose, leading to the production of more reactive oxygen species that can cause irreversible damage to neurons.
How does tetrodotoxin act as a neurotoxin?
-Tetrodotoxin is a sodium channel blocker, preventing the initial sodium influx into the neuron as it's about to fire. This effectively paralyzes the nerve, preventing it from sending signals and can be lethal if ingested.
What is the mechanism of action of botulinum toxin, also known as Botox?
-Botulinum toxin works by binding to the presynaptic nerve terminal and cleaving the host protein snap 25, which prevents the neuron from fusing vesicles with the cell membrane, thus inhibiting the release of neurotransmitters and causing paralysis.
What is the neurotoxic effect of methylmercury and how does it enter the brain?
-Methylmercury is a neurotoxin that can cross the blood-brain barrier by binding to cysteine residues in LAT transporters. Once in the brain, it interferes with sulfur residues in enzymes, leading to the generation of more reactive oxygen species and causing oxidative stress and neuronal damage.
How does n-hexane cause neurotoxicity and what is its relevance to occupational exposure?
-N-hexane is metabolized in the body to form 2,5-hexanedione, which can react with lysine residues in axonal proteins to form adducts. These adducts can cause cross-linking, disrupting axonal transport and function, leading to permanent damage to nerve cells. Occupational exposure to high levels of n-hexane is a concern due to the potential for chronic neurotoxic effects.
What is the significance of the tier list in the context of the video?
-The tier list in the video serves to categorize various neurotoxins based on their level of toxicity, from less to more severe, providing a comparative understanding of their potential harm to the nervous system and the urgency of avoiding exposure to them.

Outlines

00:00

🧠 Neurons and Neurotransmitters: Understanding the Basics

This paragraph introduces the topic of neurotoxins and the importance of understanding nerve cells, or neurons, and their function. It explains that neurons are responsible for receiving and sending signals through neurotransmitters across a synaptic cleft. The paragraph delves into the process of action potential and how neurons fire, including the role of sodium and potassium channels. It also discusses the different types of neurotransmitters and hormones that can influence neurons, setting the stage for the subsequent discussion on neurotoxins.

05:03

🍻 Ethanol: Chronic Neurotoxin and its Effects

The second paragraph focuses on ethanol, commonly known as drinking alcohol, as a neurotoxin. It explains how chronic consumption of ethanol can lead to thiamine deficiency, which in turn makes it harder for mitochondria to metabolize glucose, resulting in the production of more reactive oxygen species that can cause irreversible damage to neurons. The paragraph emphasizes that neurons are post-mitotic and thus not easily replaced, highlighting the permanence of ethanol-induced neurotoxicity.

10:04

🐡 Tetrodotoxin: A Potent Neurotoxin from Puffer Fish

This paragraph discusses tetrodotoxin, a deadly neurotoxin found in puffer fish, which blocks sodium channels and prevents the nerve from firing, leading to paralysis. It mentions the severity of tetrodotoxin poisoning and the importance of early and aggressive medical intervention, including the use of activated charcoal and life support measures, to manage the symptoms until the toxin's effects subside.

15:06

💉 Botox and Tetraethylamonium: Neurotoxins with Medical Uses

The paragraph covers two neurotoxins: botulinum toxin, known commonly as Botox, which is used for cosmetic purposes and has legitimate medical uses, and tetraethylamonium, a less well-known neurotoxin that blocks voltage-dependent potassium channels and nicotinic acetylcholine receptors. It explains the mechanism of action for both substances and their potential for causing paralysis, while also noting that the effects of these neurotoxins can be treated or managed under medical supervision.

20:07

🐟 Methyl Mercury: Bioaccumulation and Neurotoxicity

This paragraph examines the neurotoxic effects of methyl mercury, a chemical that bioaccumulates in food chains and can cross the blood-brain barrier. It discusses how methyl mercury interferes with enzymes involved in the breakdown of reactive oxygen species, leading to oxidative stress and damage to neurons. The paragraph advises caution in consuming foods high in mercury and acknowledges the role of governmental regulations in controlling mercury levels in food.

25:09

🌿 Toxiferine and N-Hexane: Plant Alkaloids and Solvents with Hidden Dangers

The paragraph introduces toxiferine, a highly potent plant alkaloid found in the bush rope plant, which acts as a nicotinic acetylcholine receptor antagonist causing paralysis. It also discusses N-hexane, a common solvent that becomes neurotoxic when metabolized into 2,5-hexanedione, leading to the formation of pearls that disrupt axonal transport and function, causing permanent nerve damage.

30:09

💧 Anatoxin-a and Karenic Acid: Fast-Acting and Kidney-Related Neurotoxins

This paragraph presents anatoxin-a, a rapidly acting neurotoxin produced by cyanobacteria found in contaminated water, which binds irreversibly to nicotinic acetylcholine receptors, causing paralysis and potentially death. It also covers karenic acid found in star fruit, which is dangerous for individuals with kidney problems due to its excretion and potential to cause severe neurotoxic effects.

🌊 Domoic Acid and Strychnine: Excitatory Neurotoxins from Nature

The paragraph discusses domoic acid, a neurotoxin produced by algae that causes amnesic shellfish poisoning by acting as an excitotoxin against ionotropic glutamate receptors, leading to the production of reactive oxygen species and irreversible neuronal damage. It also covers strychnine, found in the strychnine tree, which acts as an antagonist of the glycine receptor, causing muscle contractions that can result in death by asphyxiation.

🌱 Amanitin and Other High-Risk Neurotoxins: The Tier List Overview

This paragraph provides an overview of high-risk neurotoxins, including amanitin, tetraethyllead, chlorpyrifos, and others, which are rated highly due to their immediate or acute risk of causing significant damage or death. It emphasizes the importance of understanding these neurotoxins and their mechanisms of action for safety and research purposes.

🔬 Research Neurotoxins: Tools for Understanding Neuronal Function and Dysfunction

The final paragraph highlights the role of neurotoxins in research, such as dihydroxytryptamine, oxidopamine, perichloroamphetamine, and penuicillium, which are used to selectively destroy specific types of neurons to study their functions and the effects of their destruction on neurological conditions. It underscores the value of these substances in advancing our knowledge of the nervous system and the development of treatments for neurological disorders.

Mindmap

Keywords

💡Neurotoxin

A neurotoxin is a substance that is poisonous or destructive to nerve tissue. In the context of the video, neurotoxins are the central theme, as the script discusses various chemicals that can have detrimental effects on the nervous system, causing paralysis or even death. For example, the script mentions tetradotoxin, a potent neurotoxin found in puffer fish, which blocks sodium channels and prevents nerve impulses.

💡Neuron

Neurons, also known as nerve cells, are the fundamental units of the nervous system, responsible for receiving and sending signals. The video script explains that the human nervous system is comprised of approximately 86 billion neurons, which play a critical role in communication within the body. The script uses neurons to explain how signals are transmitted via neurotransmitters across the synaptic cleft.

💡Neurotransmitter

Neurotransmitters are chemical messengers that transmit signals across a synapse from one neuron to another. The script describes how neurons send signals to other neurons via neurotransmitters, which are released into the synaptic cleft and detected by the postsynaptic neuron, facilitating the continuation of the signal.

💡Action Potential

An action potential is an electrical signal that travels along a neuron's membrane, allowing the neuron to transmit information. The video script explains that neurons have an action potential, which means that a certain threshold of surface receptors must be activated to trigger the neuron to fire, initiating the process of signal transmission.

💡Synaptic Cleft

The synaptic cleft is the small gap between the axon terminal of a presynaptic neuron and the dendrite of a postsynaptic neuron. In the video, the synaptic cleft is described as the location where neurotransmitters are released from the presynaptic neuron and detected by the postsynaptic neuron, enabling the transmission of signals between neurons.

💡Postsynaptic Neuron

A postsynaptic neuron is the neuron that receives a signal from another neuron across a synapse. The script explains that the postsynaptic neuron detects neurotransmitters released by the presynaptic neuron into the synaptic cleft and responds by sending signals to other neurons in the body.

💡Presynaptic Neuron

The presynaptic neuron is the neuron that sends signals across the synaptic cleft to the postsynaptic neuron. The video script describes how the presynaptic neuron releases neurotransmitters into the synaptic cleft, which then bind to receptors on the postsynaptic neuron, initiating a response.

💡Reactive Oxygen Species (ROS)

Reactive oxygen species are chemically reactive molecules containing oxygen. The script discusses how certain neurotoxins, such as ethanol and methylmercury, can lead to an overproduction of ROS, causing oxidative stress and damage to neurons, which can be irreversible due to the post-mitotic nature of nerve cells.

💡Thiamine Deficiency

Thiamine, also known as vitamin B1, is essential for the proper functioning of the nervous system and the metabolism of glucose. The video script explains that chronic consumption of high doses of ethanol can lead to thiamine deficiency, impairing the mitochondria's ability to metabolize glucose and resulting in the production of more ROS, which can cause neurotoxicity.

💡Neuronal Signaling

Neuronal signaling refers to the process by which neurons communicate with each other through electrical and chemical signals. The video script delves into the specifics of how neurons receive and send signals, including the role of neurotransmitters and the importance of the action potential in firing a neuron.

💡Paralysis

Paralysis is the loss of muscle function in one or more limbs due to nerve damage. The script mentions several neurotoxins that can cause paralysis, such as tetradotoxin and botulinum toxin, by disrupting the normal functioning of neurons and preventing the transmission of signals necessary for muscle movement.

💡Oxidative Stress

Oxidative stress occurs when an imbalance exists between the production of ROS and the ability of the body to counteract or detoxify their harmful effects. The video script discusses how neurotoxins can induce oxidative stress, leading to damage to neurons and potentially causing irreversible harm.

Highlights

The video discusses various neurotoxins and their effects on the nervous system, emphasizing the importance of understanding nerve function.

The human nervous system consists of approximately 86 billion neurons, compared to an elephant's 251 billion and a chimpanzee's 22 billion.

Neurons have two primary roles: receiving signals through hormones or neurotransmitters and sending signals to other neurons.

The synaptic cleft is where neurotransmitters are released to communicate between neurons, highlighting the one-way signal transmission.

Action potential is the threshold for a neuron to fire, involving the opening of sodium channels and the rush of sodium ions into the neuron.

Neurotransmitters are released from vesicles into the synaptic cleft, where they are detected by the postsynaptic neuron.

Different neurons detect various hormones and neurotransmitters, enabling distinct responses to chemical signals in the body.

Ethanol, as a neurotoxin, can cause chronic neurotoxicity through thiamine deficiency and increased reactive oxygen species.

Tetrodotoxin, found in puffer fish, is a sodium channel blocker that prevents nerve firing and can cause paralysis.

Botulinum toxin (Botox) works by cleaving snap 25, inhibiting the release of neurotransmitters and causing muscle paralysis.

Tetraethylamonium is a neurotoxin that blocks voltage-dependent potassium channels and nicotinic acetylcholine receptors.

Methylmercury bioaccumulates in food chains and can cross the blood-brain barrier, leading to neurotoxicity through oxidative stress.

Toxiferine is a potent plant alkaloid used historically as an arrow poison, acting as a nicotinic acetylcholine receptor antagonist.

N-hexane is a common solvent that becomes neurotoxic after being converted into toxic metabolites, causing axonal dysfunction.

MPP+, an impurity in the synthetic opioid MPTP, is a neurotoxin to dopaminergic neurons by disrupting oxidative phosphorylation.

Anatoxin-a, produced by cyanobacteria, is a potent neurotoxin causing rapid paralysis and death by targeting nicotinic acetylcholine receptors.

Karenic acid, found in star fruit, is a recently discovered neurotoxin that can cause severe issues or death in individuals with kidney problems.

Tubocurarine chloride is a neurotoxin historically used as a muscle relaxant during surgery, acting as an antagonist for the nicotinic acetylcholine receptor.

Domoic acid, found in contaminated shellfish, is an excitotoxin causing oxidative damage to neurons through the generation of reactive oxygen species.

Strychnine is a notorious neurotoxin found in the strychnine tree, acting as an antagonist of the glycine receptor and causing muscle contractions leading to asphyxiation.

Anisodamine is a highly toxic neurotoxin that inhibits the nadh dehydrogenase enzyme in mitochondria, leading to cell necrosis.

Tetraethyllead, used as an anti-knock agent in gasoline, is metabolized into triethyllead, which has a long half-life in the brain and causes neuronal damage.

Chlorpyrifos, a pesticide, is a neurotoxin that inhibits acetylcholinesterase, leading to the accumulation of acetylcholine and potential neurological disorders.

TBPO is a research-only neurotoxin that acts as a GABA receptor antagonist, with one of the highest known toxicity levels.

Neo-saxotoxin is a paralytic shellfish toxin that binds to voltage-gated sodium channels, causing paralysis as a potential new local anesthetic.

Carbon disulfide, a common solvent, forms diphyocarbamates in the body that deplete zinc and copper from neurons, leading to increased oxidative stress and neuronal damage.

TETS, a rodenticide, is extremely potent with no known antidote and has been involved in mass poisonings, causing lethal seizures.

Aldicarb, a widely used pesticide, is a fast-acting cholinesterase inhibitor with high environmental toxicity and potential chronic effects.

Batrachotoxin, found in dart frog poison, binds irreversibly to sodium channels, causing continuous nerve firing and paralysis.

Resiniferatoxin is one of the spiciest chemicals known, targeting the TRPV1 ion channel and causing neurotoxicity through calcium overload.

5,7-Dihydroxytryptamine is a research neurotoxin that destroys serotonergic neurons in the brain, used to study Parkinson's-like diseases.

Penetrum A, a mycotoxin found in certain fungi, impairs GABAergic neurotransmission and induces the production of reactive oxygen species, leading to irreversible neuronal damage.

Transcripts

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Related Tags

Neurotoxins Neuroscience Chemistry Health Risks Nervous System Ethanol Tetrodotoxin Botulinum Toxin Environmental Toxins Acute Toxicity Chronic Exposure