Question

Draw an axon and synapse with all the necessary components for neurotransmission and then explain (a) how a specific neurotoxin (you find choose one: don’t usew-conotoxin, it’ used below) affects this system and (b) how selective serotonin reuptake inhibitors work on this system and briefly explain how they would be effective as antidepressants.

Answer 1

a) Neurotoxin are toxins that are destructive to nerve tissue and also called as neurotoxicity.Common examples of neurotoxins include lead, ethanol (drinking alcohol), glutamate, nitric oxide, botulinum toxin (e.g. Botox), tetanus toxin, and tetrodotoxin.

Neurotoxins are absorbed through inhalation, ingestion, skin contact, or injection and can have immediate or long-lasting impacts by causing neurons to malfunction or by disrupting interneuron communication.

Specific effect:-Botulinum toxin-Inhibitors of synaptic vesicle :- produce by bacteria

Glutamate, nitric oxide:-Endogenous neurotoxin sources -acquired by ingestion

Alcohol:-Neurotoxins with multiple effects also by drinking

Tetrodotoxin-Na channel inhibitors:- It is produce by the ingestion of fish mostly .It reduces the functional capacity of neuron communication. Tetratoxin will bind sodium channels on neurons and reduce their membrane permeability to sodium. This results in an increased effective threshold of required excitatory signals in order to induce an action potential in a postsynaptic neuron. The effect of this increased signaling threshold is a reduced excitability of postsynaptic neurons, and subsequent loss of motor and sensory function which can result in paralysis and death. LEAD -Ca-mediated cytotoxicity:-Calcium ions, as concentrated Lead will lead to cellular uptake of calcium which disrupts cellular homeostasis and induces apoptosis.

similiary process occur in other neurotoxin.

b) Selective serotonin reuptake inhibitors treat depression by increasing levels of serotonin in the brain. Serotonin is one of the chemical messengers (neurotransmitters) that carry signals between brain nerve cells (neurons).

Selective serotonin reuptake inhibitors block the reabsorption (reuptake) of serotonin into neurons. This makes more serotonin available to improve transmission of messages between neurons. Selective serotonin reuptake inhibitors are called selective because they mainly affect serotonin, not other neurotransmitters and may called it specific neurotoxin.