Complex sentence: Cold-patches have been used to induce analgesia or relief in pain as result of traumatic injuries; its mechanism remained obscure till the discovery of TRPM8 mediated cold analgesia in rats and mice lacking TRPM8 have seriously impaired cold-detection behavior.
Split into simpler sentences: Cold-patches have traditionally been used to induce analgesia or relief in pain which is caused as result of traumatic injuries. It is now demonstrated using animal models that TRPM8 mediates cold analgesia in rats and mice lacking TRPM8 have seriously impaired cold-detection behavior.