Final answer:
Prejunctional receptors prevent overexcitation by inhibiting neurotransmitter release.
Step-by-step explanation:
Prejunctional receptors prevent overexcitation from sustained stimulation of the target tissue by inhibiting neurotransmitter release. Once neurotransmission has occurred, the neurotransmitter needs to be removed from the synaptic cleft, and this can be done through diffusion, degradation by enzymes, or recycling by the presynaptic neuron. However, prejunctional receptors can modulate this process by acting as autoreceptors and inhibiting the release of neurotransmitters. This helps regulate and prevent overexcitation of the target tissue.