Distribution of nerve lesions in serotonin-induced acute ischemic neuropathy.

We have developed a new model of an acute ischemic nerve injury in rat produced by the combined effects of right femoral artery ligation and intraperitoneal injection of serotonin. Light microscopic studies were performed on the right sciatic, tibial, plantar and sural nerves dissected from rats 7 days to 6 months after serotonin injection. Ischemic lesions occurred mostly in the middle tibial nerve and involved either a part or the whole transverse nerve section. Partial tibial nerve lesions appeared mainly as small subperineurial or large wedge-shaped areas of fiber loss or regeneration. No well-delineated central fascicular lesions were seen. Sural nerves were less damaged than tibial nerves. The predominantly subperineurial fascicular distribution of ischemic lesions seen in the present model differs from the central fascicular distribution found in previous experimental studies on nerve ischemia. The different distribution of lesions is probably related to the small fascicular size and local microvascular architecture of the affected nerve segment, as well as to the method of producing ischemia.