Enhanced PON1 activity in the kidneys of cyclophosphamide treated rats may play a protective role as an antioxidant against cyclophosphamide induced oxidative stress.

Recent studies have shown that paraoxanase (PON1) has protective effect against oxidative stress and hence can act as an antioxidant. A time course study was carried out in order to find out alterations in PON1 activity in cyclophosphamide (CYP) induced renal injury. Eight to ten weeks old female rats were administered CYP at the dose of 150 mg/kg body wt. (i.p.) and sacrificed at 6, 16, or 24 h after treatment. Saline treated rats served as control. CYP exposure for 6 h caused a dramatic increase in PON1 activity (83%), which escalated to 160% at 16 h. The renal PON1 activity reached control values 24 h after treatment with CYP. The renal malondialdehyde level was unaltered 6 h after treatment with CYP and an increase by 35% was observed 16 h after treatment with CYP. The present investigation shows for the first time that an increase in renal PON1 activity is an early biochemical event in cyclophosphamide induced renal damage. It is suggested that this enzyme may have a role within the antioxidant systems of the kidney.