Can be more than one answer Neurotoxins Which of the followi

Can be more than one answer.

Neurotoxins Which of the following neurotoxins would decrease the rate of neuronal communication (either action potentials or synaptic transmissions). Blowfish toxin: prevents opening of Na^+ channels along the axon Mamba venom: prevents opening of K^+ channels along the axon Scorpion venom: prevents closing of Na^+ channels along the axon Botulinum Toxin: prevents exocytosis of neurotransmitters by pre-synaptic neuron Curare: prevents the binding of neurotransmitters to ligand-gated receptors on post-synaptic cell Conotoxin: prevents opening of Ca^2+ channels at the axon terminal

Solution

1. The blow fish toxin can block neural and skeletal muscle Na+ channels. It imparts a confirmation change that leaves sodium ion channel open and blocking the conduction of nerve impulses along nerve fibres and axon.

2. Mamba venom binds to the node of ranvier of motor neuron and to block the activity of potassium channels. As a result it increase the duration of action potentials and increase the release of acetylcholine at neuromuscular junction.

3. Scorpion venom- 3 types of venom is found in scorpion which affects all 3 channels like Na +,K+ and Ca++.

The alpha-KTx family is considered as the largest of potassium channel toxin family.

4. Botulinum toxin- It is a blocking agent preventing the exocytosis of neurotransmitters specially Acetylcholine from synaptic vesicles in to synaptic cleft , neurotransmitter bind to specific receptors on the plasma membrane of the postsynaptic cell, causing a change in permeability to ions.

5. Curare- A muscle relaxant used in anthesia. It competes with Acetylcholine. It does noy affect neurons.

6. Conotoxin- There are 5 types of conotoxin and omega-conotoxin inhibits N- type voltage dependent calcium channels.

Ans. 2, 4,6