Abstract
Serotonin (5-HT) immunoreactivity was investigated at the injury site of the rat spinal cord by light and electron microscopic immunohistochemistry. The animals were perfused with fixative immediately, 1–5 min, 7–60 min, and 1–48 h after a 3-sec extradural compression of the thoracic cord with a Sugita aneurysm clip. Five minutes after injury, abundant hemostatic plugs containing platelets with high 5-HT immunoreactivity appeared at the traumatized cord segment, whereas 5-HT-containing varicose fibers became less immunoreactive. The 5-HT-immunoreactive platelets initially were localized to the periphery of the hemostatic plugs. By 30 min after injury, the platelets had decreased 5-HT, but neural fibers and terminals began to show increased 5-HT immunoreactivity, which increased and lasted as long as 48 h. These results indicate that platelets contributed to the initial 5-HT concentration increase at the injury site but that later 5-HT accumulation occurred in the neural elements.
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