Central nervous system bioaminergic responses to mechanical trauma. An experimental study. Changes in biogenic amines in the brain and spinal cord following penetrating injury were studied in male Wistar rats using high-performance liquid chromatography with electrochemical detection. Rapid increase in hemispheric concentration of these substances was noted beginning shortly after trauma. This trend continued until they were about three to four times control levels by about 24 to 48 hours postinjury. In the spinal cord, however, there was an initial sharp reduction in regional concentrations 2 hours postinjury followed by a slow rise thereafter. By 48 hours postinjury, levels of norepinephrine, dopamine, and serotonin of the cords of injured animals were still less than those of nontraumatized controls. This variation in the central nervous system bioaminergic response with the level of injury raises questions as to its precise role in neurological damage following mechanical insult. 