Effect of DLF lesions at different spinal levels on morphine induced analgesia

The effect of morphine on tail flick latency was tested in 3 groups of rats. It is shown that in normal rats and in rats with a bilateral DLF lesion at Th10 or lower spinal root segments, morphine increased the tail flick latency. After a bilateral DLF lesion at Th9 or higher segments, morphine did not change the tail flick latency.