P2X receptors in sensory neurons co-cultured with cancer cells exhibit a decrease in opioid sensitivity.

Opioids are known to control the activity of P2X receptors in the sensory neurons of rats. These receptors are important in persistent pain signaling. However, there are extremely severe pain states, such as those associated with metastatic diseases, that are refractory to opioid treatment.

Opioids inhibit purinergic nociceptors in the sensory neurons and fibres of rat via a G protein-dependent mechanism.

We have found that opioid and P2X receptors are functionally coupled in the sensory nerve fibres and neurons of rat. When examined in the skin-nerve preparation, the ATP-evoked discharges of nerve fibres belonging to n. saphenous were inhibited by various opiates in a naloxone-dependent manner.