Thienylphencyclidine protection for the spinal cord of adult rats against extension of lesions secondary to a photochemical injury.

The purpose of this study was to evaluate treatment with the N-methyl-D-aspartate antagonist thienyl-phencyclidine (TCP) after spinal cord injury for its behavioral, electrophysiological, morphological, and immunohistochemical effects. Five minutes after a photochemical lesion was produced in rats at the T-8 level, the animals received TCP (1 mg/kg, intravenously) or TCP vehicle (saline). The animals were evaluated on Day 18 for neurological recovery by testing motor and sensory functions. The TCP-treated group showed less neurological impairment than the untreated group (p < 0.05 for inclined-plane stability and withdrawal reflex to extension). Somatosensory evoked potential testing was performed on Days 21 to 23 and the wave amplitude between the onset and P1 in the TCP-treated group was higher than in the untreated group (p < 0.05). Mean arterial blood pressure was not significantly modified after TCP injection. Morphometric studies of the lesion area in cross section revealed a significantly reduced spinal cord infarction in the TCP-treated group (p < 0.05). Immunohistochemical evaluation of the spinal cord in lumbar area showed an increased level of serotonin immunoreactivity in the dorsal horn of animals treated by TCP. These results demonstrate the efficacy of TCP in reducing secondary lesions after spinal cord injury in rats.