Effect of amitriptyline on the analgesia induced by adrenal medullary tissue transplanted in the rat spinal subarachnoid space as measured by an experimental model of acute pain.

The effect of short and long term amitriptyline (AMI) treatment on the analgesia induced by adrenal medullary autotransplant into the subarachnoid space was investigated in rats. For this purpose, two experiments were carried out. In the first one, the rats were chronically treated for 28 days after transplantation. In the second experiment, rats were treated for 28 days starting 28 days after surgery. Before starting the experiments, basal levels were tested. Tail-flick latencies were checked at Day 4 and Day 28 in the first experiment and at Day 28 and Day 56 in the second. AMI itself did not induce any tail-flick modification after 28 or 56 days. However, it increased the transplantation-induced analgesia at Day 28 in the first experiment and at Day 56 in the second. These results are interpreted in the sense of the ability of AMI to enhance the effects of both monoamine and opioids previously released by the transplantation.