The effect of cyclooxygenase (COX) inhibitors on Japanese medaka (Oryzias latipes) reproduction parameters fed with high level of arachidonic acid (20:4 n-6)

Abstract

Broodstock of mature Japanese medaka (Oryzias latipes Temminck and Schlegel, 1846) (mean weight 0.45 ± 0.03 g; age 6 months) were maintained in glass aquaria (8 males and 8 females in each aquarium). The fish were fed commercial feed (group C) or this feed was supplemented with arachidonic acid ARA (2 % of total fatty acids in feed; group A) and one of the COX inhibitors: resveratrol (group AR) or NS-398 (group ANS) with amount 20 mg kg−1 BW day−1 of one of the COX inhibitors. The effect of 2 weeks of feeding experimental diets on reproductive parameters (fecundity, embryo and larval survival, hatching rate, and larvae body weight) was analyzed. Larvae (obtained from experimental dietary treatments) were reared for 2 weeks. The percent of spawning female and fecundity was similar in dietary treatments. COX inhibitors in broodstock diet caused a decrease in embryo survival rate. Eggs of medaka from group ANS and AR revealed the lowest hatchability rate. In contrast, group A revealed a higher hatchability rate at the same time. Larval body weight after hatching was significantly the highest in this group. At the end of the experiment, larvae body weight ranged from 1.62 ± 0.43 mg in group AN to 2.89 ± 0.74 mg in group A. These results show that the COX inhibitors decreased gamete and larval quality regardless of high levels of ARA in broodstock diet.