Abstract:

The effects of gonad development and age on the serum antioxidant enzyme activities of captive F1 Chinese sturgeon,Acipenser sinensis,were studied.When females in the period of slow gonadal development and males in the period of fast gonadal development were compared,testosterone (T) and the ratio of estrogen (E2)〖DK〗∶testosterone levels were significantly different.Compared to males,the females had a significantly lower malondialdehyde (MDA) level (P<005),but higher activity levels of superoxide dismutase (SOD),glutathione peroxidase (GPX) and SOD/MDA,although these differences were not significant (P＞0.05).For MDA and SOD/MDA in the serum of males and females,high values were found for the correlation coefficients (r=-0915,r=-0818,P<001,respectively).Serum E2/T levels correlated with MDA,SOD/MDA (r=-0635,r=0709,P<005,respectively),while not correlated with SOD or GPX.No significant differences in the activity of serum SOD or MDA were observed in all four different ages(4,8,11 and 12 years old) during the period of slow gonad development.The lowest level of GPX activity was found in the 12-year old age group (P<005),whereas the highest level of the SOD/MDA ratio was observed in this group (P<005).The correlation between the age and the activity of GPX,MDA was negative (r=-0547,P<001,r=-0519,P<005,respectively),while the correlation between the age and the level of the SOD/MDA ratio was positive (r=0569,P<001).These results suggest that the level of oxidant stress in male sturgeons during the period of fast gonad development is higher than those of females during the period of slow gonad development.The antioxidant defense mechanisms of sturgeons gradually increase with increasing age.Therefore,the gonad development and age of the fish should be considered when indexes of antioxidant enzyme activities are used to assess status of fish health.Understanding the biological signaling that underlies these changes will make the use of these parameters even more accurate.