Acute tamoxifen treatment increases nitric oxide level but not total antioxidant capacity and adenosine deaminase activity in the plasma of rabbits.

Tamoxifen is a synthetic non steroidal anti-estrogen used to treat patients with breast cancer and healthy subjects with high risk of breast cancer. It was aimed to study the short term effects of tamoxifen on the plasma total antioxidant capacity (TAC), nitric oxide (NO) and the adenosine deaminase activity (ADA) in healthy rabbits. Sixteen healthy New Zealand rabbits were allocated to 2 groups including controls and tamoxifen treated animals. Controls received a single application of 0.9% saline via oral route while the treated rabbits received orally tamoxifen (dissolved in 0.9% saline, at a dose of 5 mg/kg). Blood samples were collected at 6 and 24 hours following the treatments. Plasma TAC and ADA were not affected by Tamoxifen treatment. However, NO level in tamoxifen treated group was increased at 24 hours following tamoxifen treatment as compared to controls. In conclusion, acute tamoxifen treatment may not affect the antioxidant status and cellular immunity, as evidenced by unaltered TAC and ADA. However, NO level was increased as early as 24 hours following tamoxifen treatment.