Changes in insulin-like growth factor-binding protein-2 and -3 in follicular fluid during atresia of follicles grown after ovulation in pigs.
In pigs, medium-sized follicles (3-6 mm in diameter), lost during preovulatory maturation, are rapidly replenished after ovulation, increasing tenfold in number between day 3 and day 8 of the oestrous cycle. The incidence of atresia in medium-sized follicles was previously found to increase between day 5 and day 7 after the onset of oestrus (day 0). This study was conducted to determine whether changes in concentrations of insulin-like growth factor binding proteins (IGFBPs) in pig follicular fluid from medium-sized follicles were related to increased incidence of atresia. Individual follicles were isolated on days 5, 6 and 7 after oestrus from eleven pigs. Follicles were defined as atretic when they contained > or = 10% apoptotic granulosa cells (cells containing subdiploid amounts of DNA fluorescence determined by flow cytometry). Concentrations of IGFBP-2 and -3 were determined by ligand blot analysis with 125I-labelled insulin-like growth factor II and quantified by densitometry. The mean percentage of apoptotic cells per follicle increased (P < or = 0.01) from 3.6 to 35.0 and the mean concentration of IGFBP-2 increased (P < or = 0.001) 3.3-fold between day 5 and day 7 after oestrus. The concentration of IGFBP-3 did not differ significantly among days. Mean oestradiol concentration in follicular fluid decreased (P < or = 0.05) from 52.3 to 0.9 ng ml-1 between day 5 and day 7. Androstenedione concentrations in follicular fluid also decreased (P < or = 0.01) between day 5 and day 7, but progesterone did not differ significantly among days.(ABSTRACT TRUNCATED AT 250 WORDS)
D000735:Androstenedione / Q000378:metabolism; D000818:Animals; D017209:Apoptosis; D002352:Carrier Proteins / Q000378:metabolism*; D004958:Estradiol / Q000378:metabolism; D005260:Female; D005496:Follicular Atresia; D015571:Follicular Fluid / Q000378:metabolism*; D006107:Granulosa Cells / Q000502:physiology; D006131:Growth Inhibitors / Q000378:metabolism*; D018971:Insulin-Like Growth Factor Binding Protein 2 / Q000378:metabolism*; D018972:Insulin-Like Growth Factor Binding Protein 3 / Q000378:metabolism*; D011869:Radioligand Assay; D013002:Somatomedins / Q000378:metabolism*; D013552:Swine / Q000378:metabolism*
D002352:Carrier Proteins; D006131:Growth Inhibitors; D018971:Insulin-Like Growth Factor Binding Protein 2; D018972:Insulin-Like Growth Factor Binding Protein 3; D013002:Somatomedins; D000735:Androstenedione; D004958:Estradiol