Endorphins in Kefilins, dinolyns are our endogenous opioids. They bind to opioid receptors like mu, delta and gamma. And when they bind to those receptor, it has a range of effects depending on where the receptor sits. You can get things like euphoria and dysphoria and respiratory depression. But you also get an inhibition of pain or nociceptive signals because it stops the pre-synaptic neuron from sending the neurotransmitter across.