[NADPH-diaphorase-positive nerve cells in heterotopic spinal cord transplants]

The method of ectopic transplantation of embryonic CNS rudiments makes it possible to study the mechanisms underlying adaptation of the transplanted embryonic rudiments. The production of nitric oxide by cells is considered as one of such mechanisms. NADPH-diaphorase is an index of the presence of nitric oxide synthase in cells. It was shown that the nerve cells of rat embryonic spinal cord transplants preserved their capacity to express NADPH-diaphorase after transplantation in the sciatic nerve of an adult animal for six months. The dynamics of NADPH-diaphorase-positive neurons of rat embryonic spinal cord developing after transplantation and in situ were studied. In spinal cord neck region, small bipolar NADPH-diaphorase-positive neurons were visualized on day 17 of prenatal development. After transplantation of the embryonic (day 15) spinal cord in the nerve, NADPH-diaphorase-positive neurons were formed later than in situ: within seven days. The results of histochemical studies carried out within six months after the operation suggest a protective role of NADPH-diaphorase in the neurons of allotransplants developing under the conditions of altered microenvironment and insufficient innervation and also suggest that nitric oxide can cause the death of neurons in long surviving transplants.