negative regulation of neuronal action potential

Definition

Target type: biologicalprocess

Any process that stops, prevents or reduces the frequency, rate or extent of neuronal action potential. [GO_REF:0000058, GOC:TermGenie, PMID:25126967]

Negative regulation of neuronal action potential is a crucial process for controlling the flow of information within the nervous system. It involves a complex interplay of mechanisms that act to decrease the likelihood or intensity of action potentials, ensuring precise and controlled neuronal communication. Here's a detailed description of the process:

1. **Hyperpolarization:** This involves increasing the membrane potential of the neuron, making it more negative than its resting potential. Hyperpolarization reduces the likelihood of an action potential occurring by increasing the threshold that needs to be reached for depolarization. This can be achieved through:
* **Increased potassium permeability:** Opening of potassium channels allows potassium ions to flow out of the neuron, making the inside more negative.
* **Decreased sodium permeability:** Closing of sodium channels reduces the influx of positive sodium ions, further contributing to hyperpolarization.
* **Activation of hyperpolarizing neurotransmitters:** Some neurotransmitters, like GABA and glycine, bind to receptors on the postsynaptic neuron, leading to the opening of chloride channels and influx of negative chloride ions, causing hyperpolarization.

2. **Inhibition of Sodium Channels:** Action potentials rely on the rapid influx of sodium ions through voltage-gated sodium channels. Inhibiting these channels directly prevents the rapid depolarization necessary for an action potential to occur. This inhibition can be achieved through:
* **Inactivation of sodium channels:** After a period of sustained depolarization, sodium channels undergo a temporary inactivation, preventing further sodium influx.
* **Blockage of sodium channels:** Certain toxins and drugs, like tetrodotoxin, can directly bind to and block sodium channels, inhibiting action potential generation.

3. **Activation of Potassium Channels:** Potassium channels play a key role in repolarizing the membrane after an action potential. By increasing potassium permeability, these channels enhance the outward flow of potassium ions, restoring the negative membrane potential. This repolarization phase makes the neuron less susceptible to further excitation.

4. **Regulation of Calcium Influx:** Calcium ions play a critical role in synaptic transmission and neurotransmitter release. However, excessive calcium influx can disrupt neuronal function. Negative regulation of neuronal action potentials often involves mechanisms that reduce calcium influx, such as:
* **Inhibition of voltage-gated calcium channels:** Some neurotransmitters, like GABA, can activate receptors that suppress calcium influx through voltage-gated calcium channels, thereby reducing neurotransmitter release.
* **Activation of calcium-activated potassium channels:** Increased intracellular calcium can activate potassium channels, leading to hyperpolarization and reduction in neuronal excitability.

5. **Presynaptic Inhibition:** This involves reducing the release of excitatory neurotransmitters from the presynaptic neuron, thereby decreasing the likelihood of generating an action potential in the postsynaptic neuron. This can be achieved by:
* **Activation of inhibitory interneurons:** These neurons release inhibitory neurotransmitters that suppress the release of excitatory neurotransmitters from the presynaptic neuron.
* **Modulation of presynaptic receptors:** Some neurotransmitters can bind to receptors on the presynaptic terminal, influencing the release of excitatory neurotransmitters.

6. **Feedback Inhibition:** This mechanism involves the postsynaptic neuron providing feedback to the presynaptic neuron, reducing its activity. This feedback can be mediated by:
* **Axon collateral inhibition:** Axons of some neurons can branch back and synapse on their own dendrites or soma, providing inhibitory feedback.
* **Retrograde signaling:** The postsynaptic neuron can release retrograde messengers that travel back to the presynaptic neuron, modulating its activity.

In summary, negative regulation of neuronal action potentials is a complex and multi-faceted process that plays a crucial role in fine-tuning neuronal communication. These mechanisms ensure that neuronal activity is controlled, preventing uncontrolled firing and maintaining the integrity of information transmission within the nervous system.'
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Proteins (1)

Compounds (28)