Final answer:
Endorphins are the substances released by interneurons that reduce the sensation of pain by binding to opiate receptors on sensory neurons, thus inhibiting pain signal transmission to the brain.
Step-by-step explanation:
The release of endorphins by an interneuron onto opiate receptors on the sensory neuron will reduce the sensation of pain by reducing transmission to the brain. Endorphins bind to the opiate receptors on sensory neurons, which can inhibit the release of neurotransmitters and effectively diminish the perception of pain. This is why endorphins play a crucial role in the body's natural painkilling system and are often referred to as the body's natural opiates.