[Mechanism of deafferentation pain--experimental research using spinal root resection model]

In rats, autotomy of the digits following dorsal root resection has been observed by many researchers and is considered as an animal model of deafferentation pain. Using C5-Th 1 root resection model of rats, we investigated the role of the ventral roots and pain experience given before deafferentation in the development of autotomy. Male Sprague-Dawley rats of eight weeks old, weighing about 200 g, were used. Animals were divided into two major groups; dorsal root resection group and total (both ventral and dorsal) root resection group. Each group was further divided into several sub-groups, according to the use of formalin injection, before or after surgery, and to the side of formalin injection, the forearm of the affected (root resection) side or unaffected side or of both sides. In pre-injection groups, 0.1 ml of 5% formalin was given subcutaneously on the forearm one hour before surgery. In the postinjection groups, formalin was given within one hour after surgery. Dorsal root resection group without formalin injection was used as control. Under anesthesia with intraperitoneal injection of nembutal, left C 5-Th 1 dorsal root resection was performed by C 4-Th 1 laminectomy and left C5-Th 1 total root resection by opening of the corresponding vertebral foramen. After surgery, we checked neurological findings, systemic condition and local changes of all the extremities everyday during the first week and once a week thereafter for at least three months. In control groups, autotomy was not observed at all during the observation period of three months.(ABSTRACT TRUNCATED AT 250 WORDS)