Cyclosporin-A inhibits inducible nitric oxide synthase activity and expression after spinal cord injury in rats.

Nitric oxide is generated from l-arginine by a family of three distinct nitric oxide synthase (NOS) enzymes playing a crucial role in the physiopathology of spinal cord injury (SCI). Cyclosporin-A (CsA), an immunosupressive agent, may be used to inhibit the activity of iNOS and perhaps to protect against neural tissue destruction. Rats were submitted to SCI by contusion, and killed 4, 24 and 72 h after lesion. Results showed an increase in the activity of iNOS at 72 h after the SCI, inhibited by CsA (2.5 mg/kg) administered 12 h after trauma. iNOS Western blot assay showed an increase in the expression of iNOS after trauma, also antagonized by CsA administration.