effect of intrathecal transplantation of adrenal medullary tissue on the sciatic nerve regeneration following chronic constriction injury in the rat

introduction: it has been demonstrated that the adrenal medullary transplants into the spinal subarachnoid space can alleviate neuropathic pain behaviors. the aim of the present study was to test the possibility that histological changes of the sciatic nerve in a neuropathic model as well as sensory dysfunction are repaired by adrenal medullary transplantation. material and methods: left sciatic nerve was ligated in three groups of rats by 4 loose ligatures (cci). after one week of nerve constriction, rats of first group were implanted with adrenal medullary tissue (cci + adrenal medulla) and rats of the second group with striated muscle at the level of l1-l2 (cci + muscle). the third group received only left ligature (cci) and in the fourth group the sciatic nerve was exposed and then muscle and skin sutured (sham). behavioral assessment was evaluated before surgery and 2, 4, 7, 10, 14, 21, 28, 42, and 56 days after the onset of experiment. according to behavioral results, 4 rats in each group were anesthetized and then the distal part of sciatic nerve were isolated and prepared for histological quantitative investigation of nerve regeneration. results: the results showed that cci was accompanied with hyperalgesia and morphological changes in the distal part of sciatic nerve. in animals with adrenal medullary transplantation, not only hyperalgesia was markedly reduced or even eliminated, but also the number of myelinated fibers in the distal segment of nerve increased to nearly normal. conclusions: our findings showed that the implantation of adrenal medullary tissue might have caused regeneration of ligated nerves as well as alleviation of pain behavior.