Metabolism of glucose, pyruvate, and glutamine during the maturation of oocytes derived from pre-pubertal and adult cows

The aim of the study was to compare the energy metabolism of oocytes from p re-pubertal (2 to 3 months) and adult cows during maturation, to identify t he cause of poor developmental potential in many pre-pubertal oocytes. The metabolism of [5-H-3] glucose, [2-C-14]pyruvate, and [G-H-3] glutamine was measured at 0 hr, 12 hr, and 24 hr maturation. Oxidative metabolism was imp ortant during maturation of oocytes from both pre-pubertal and adult cows, with pyruvate metabolism peaking at 12 hr and glutamine metabolism increasi ng linearly and peaking at 24 hr. Peak oxidative metabolism was significant ly lower in oocytes from pre-pubertal animals, for both pyruvate and glutam ine (P < 0.05). Glucose metabolism increased significantly during oocyte ma turation in both groups (0hr to 24 hr). Glucose metabolism was significantl y lower in oocytes from pre-pubertal cows at 12 hr (P < 0.05). Oocytes from pre-pubertal animals were significantly smaller than oocytes from adult co ws at 0 hr, 12 hr, and 24 hr maturation (P < 0.05). When metabolic rates we re corrected for oocyte volume, there were no significant differences in su bstrate metabolism between oocytes from pre-pubertal and adult cows. There was however, a delay in the increase in glucose metabolism in prepubertal o ocytes 0 hr to 12 hr maturation. Germinal vesicle breakdown was slower in o ocytes from pre-pubertal animals with more oocytes still at the germinal ve sicle stage approximately 5 hr post-aspiration, compared to oocytes from ad ult cows (P < 0.05). By 24 hr, development to metaphase II was equivalent f or prepubertal and adult oocytes. This study identified differences in ener gy metabolism, oocyte size, and meiotic progression between the oocytes fro m prepubertal and adult cows that may account for the poor developmental po tential of many prepubertal oocytes. (C) 1999 Wiley-Liss, Inc.