Changes in carbohydrate metabolism related to the onset of ovarian recrudescence in dmesticated rainbow trout ( Oncorhynchus mykiss)

Abstract

1. 1. A study of several carbohydrate metabolism pathways was carried out in three different tissues—liver, gonad and kidney—from domesticated female rainbow trout ( Oncorhynchus mykiss) at three different stages ofgonadal maturation, i.e. previtellogenesis, endogenous vitellogenesis and the onset of exogenous vitellogenesis. 2. 2. A fall in liver glycogen levels was observed at the beginning of gonadal recrudescence. The glucose obtained by glycogen rupture appears to be used both in liver glycolysis and in generating reducing power. In addition, a decrease in both the use of exogenous glucose and gluconeogenesis was also observed. 3. 3. A large increase in gonad glucose levels was observed at the beginning of gonadal recrudescence. This increase may be due to both a higher use of exogenous glucose (from diet and other tissues) and an increased gluconeogenesis. The higher glucose levels appear to be used not only in glycogen synthesis, but also in producing reducing power. 4. 4. No changes were observed in kidney metabolism that could be related to the initial stages ofgonadal maturation. 5. 5. The onset of the gonadal recrudescence in female rainbow trout is mainly associated with a higher use of glucose in the gonad and increased metabolic activity in the liver.