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Questions and Answers
Which mechanism describes how reserpine affects synaptic transmission?
Which mechanism describes how reserpine affects synaptic transmission?
- Interfering with the storage of neurotransmitters within vesicles. (correct)
- Preventing synaptic transmission by blocking voltage-gated ion channels.
- Inhibiting the synthesis of neurotransmitters by blocking necessary enzymes.
- Blocking axonal transport, preventing the delivery of essential materials.
A drug that inhibits acetylcholinesterase would have what primary effect on synaptic transmission?
A drug that inhibits acetylcholinesterase would have what primary effect on synaptic transmission?
- Blocking the reuptake of acetylcholine from the synapse.
- Prolonging the activity of acetylcholine in the synapse. (correct)
- Decreasing the amount of acetylcholine released into the synapse.
- Inhibiting the synthesis of acetylcholine in the presynaptic neuron.
Which of the following best describes how caffeine alters synaptic transmission?
Which of the following best describes how caffeine alters synaptic transmission?
- By blocking voltage-gated calcium channels, reducing neurotransmitter release.
- By competing with adenosine for presynaptic receptors, preventing its inhibitory effects. (correct)
- By directly stimulating the release of neurotransmitters into the synapse.
- By inhibiting the reuptake of neurotransmitters, prolonging their synaptic activity.
How do drugs like cocaine affect synaptic transmission to produce a stimulant effect?
How do drugs like cocaine affect synaptic transmission to produce a stimulant effect?
If a drug prevents axonal transport within a neuron, which of the following processes would be most directly affected?
If a drug prevents axonal transport within a neuron, which of the following processes would be most directly affected?
How does tetrodotoxin (TTX) affect the function of neurons?
How does tetrodotoxin (TTX) affect the function of neurons?
What is the primary mechanism by which botulinum toxin (Botox) causes muscle paralysis?
What is the primary mechanism by which botulinum toxin (Botox) causes muscle paralysis?
How do MAO inhibitors affect synaptic transmission?
How do MAO inhibitors affect synaptic transmission?
Verapamil, a calcium channel blocker, would have what effect on synaptic transmission?
Verapamil, a calcium channel blocker, would have what effect on synaptic transmission?
Para-chlorophenylalanine (PCPA) inhibits tryptophan hydroxylase. What is the consequence of this action?
Para-chlorophenylalanine (PCPA) inhibits tryptophan hydroxylase. What is the consequence of this action?
Flashcards
Drug Effects on Synaptic Transmission
Drug Effects on Synaptic Transmission
Drugs can alter synaptic transmission by affecting the presynaptic neuron, changing the conversion of electrical signals to chemical signals.
Inhibition of Transmitter Synthesis
Inhibition of Transmitter Synthesis
Inhibiting transmitter synthesis prevents the neuron from producing neurotransmitters.
Blockade of Axonal Transport
Blockade of Axonal Transport
Blocking axonal transport prevents the delivery of essential materials needed to produce neurotransmitters.
Interference with Transmitter Storage
Interference with Transmitter Storage
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Prevention of Synaptic Transmission
Prevention of Synaptic Transmission
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Alteration of Transmitter Release (Calcium Blockade)
Alteration of Transmitter Release (Calcium Blockade)
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Alteration of Transmitter Release (Presynaptic Modulation)
Alteration of Transmitter Release (Presynaptic Modulation)
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Inactivation of Transmitter Reuptake
Inactivation of Transmitter Reuptake
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Blockade of Transmitter Degradation
Blockade of Transmitter Degradation
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Transmitter Production and enzymes
Transmitter Production and enzymes
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Study Notes
- Synaptic transmission can be altered by drugs affecting the presynaptic neuron
- This changes the system that converts an electrical signal (action potential) into a chemical signal (secretion of neurotransmitter)
- Presynaptic drug effects fall into three categories: transmitter production, transmitter release, and transmitter clearance
Effects on Transmitter Production
- Inhibition of transmitter synthesis: para-chlorophenylalanine inhibits tryptophan hydroxylase, preventing serotonin synthesis from its precursor
- Blockade of axonal transport: Colchicine impairs microtubule maintenance and blocks axonal transport
- Interference with transmitter storage: Reserpine blocks the packaging of transmitter molecules within vesicles, leading to enzyme breakdown
Effects on Transmitter Release
- Prevention of synaptic transmission: Tetrodotoxin (puffer fish) blocks voltage-gated Na+ channels, preventing nerve conduction
- Alteration via calcium channel blockade: Verapamil (calcium channel blocker) reduces transmitter release by reducing calcium ion influx
- Modulation of presynaptic activity: Caffeine competes with adenosine for presynaptic receptors, preventing inhibitory effects
- Alteration through other mechanisms:
- Amphetamine stimulates catecholamine transmitter release (DA and NE)
- Botulinum toxin (Botox) disrupts vesicle proteins in motor neurons, inhibiting acetylcholine (ACh) release, causing local paralysis
Effects on Transmitter Clearance
- Inactivation of transmitter reuptake: Cocaine and amphetamine inhibit reuptake, prolonging synaptic activity; certain antidepressants inhibit serotonin or norepinephrine reuptake
- Blockade of transmitter degradation:
- Acetylcholinesterase inhibitors block synaptic enzymes that break down acetylcholine
- MAO inhibitors inhibit the enzyme that breaks down neurotransmitter molecules after reuptake; neurotransmitter remains active longer due to these inhibitors
Transmitter Production
- Presynaptic neurons require a steady supply of raw materials and enzymes at axon terminals to produce neurotransmitters
- Drugs can alter this process
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Description
Drug actions affect presynaptic neurons, modifying electrical to chemical signals. Presynaptic effects: transmitter production, release & clearance. Drugs like reserpine interfere with transmitter storage.
