Antioxidant defense in the follicular fluid of water buffalo.

Oxidative damages to the oocyte or follicular cells were suggested to trigger atresia. In water buffalo, loss of the blood-follicle barrier sieving effect on the diffusion of plasma haptoglobin was previously found associated with atretic oocytes. The red-ox status of water buffalo follicles was evaluated by measuring in follicular fluid both the total antioxidant capacity (TAC), expressed as Trolox equivalents, and the concentration of specific free radical scavengers, determined by HPLC. Among follicles at random stages of the reproductive cycle (N=74), a number (N=32) were analyzed also for the cumulus-oocyte morphology or plasma haptoglobin penetration. The haptoglobin follicular concentration compatible with the barrier selectivity function was calculated to be less than 53% of the concentration in plasma. The data on TAC, retinol, -tocopherol, -tocopherol, ascorbic acid and uric acid fluctuated in a wide range of values. The relative (follicular vs plasmatic) levels of -tocopherol were found negatively correlated with those of retinol (P<0.01). In the follicles, the -tocopherol levels were 1.250.35 or 1.990.72 M when the haptoglobin concentration was <53% or >53% of the concentration in plasma respectively. The concentration of ascorbic acid or uric acid was higher (up to 10- or 30-fold respectively) in follicular fluid than in plasma. Fluids containing haptoglobin >53% or associated with cumulus-oocyte complexes of bad quality displayed levels of uric acid about 20-fold higher than in plasma. The results suggest that high penetration of haptoglobin in the follicle and cumulus-oocyte degradation are associated with alteration of the level of the major antioxidants, particularly with the enhancement of uric acid concentration.