|Budget Amount *help
¥3,100,000 (Direct Cost : ¥3,100,000)
Fiscal Year 1998 : ¥1,100,000 (Direct Cost : ¥1,100,000)
Fiscal Year 1997 : ¥2,000,000 (Direct Cost : ¥2,000,000)
Follicle-stimulating hormone (FSH) plays an important role in the ovarian follicle maturation. However, the mechanisms of ESH action in the granulosa cells (GC) still remain unclear. Therefore, in order to investigate intracellular signal transduction pathways of FSH in GCs, we determined in vivo and in vitro the expression of mitogen-activated protein kinase (MAPK) activity, and c-fos and Jun family genes. After PMSG was injected to immature female rats, total RNA was extracted from ovaries and subjected to Northern blottings using cDNAs. GCs obtained from porcine small follicles (l-2 mm in diameter) were also incubated in vitro with FSH, P1AA or forskolin. FSII was also added to cell cultures with staurosporine or Rp-cAMP.MAPK activities in cell lysates were determined utilizing specific assay kits. Total RNA was extracted from cultured GCs and subjected to Northern blottings. c-fos and junB mRNAs were significantly expressed in rat ovaries 30 mm after PMSG injection, and reached plateau after 60 min. The expression of junD was minimal, and c-jun was not detected throughout the experimental period. FSH again stimualted c-fos and jun13 mRNAs in cultured GCs 30 mm after ESH addition. Although PMA stimulated the expression of c-fos and junB, forskolin did not influence it. Staurosporine significantly inhibited the increase in mRNAs of these genes by ESH.but Rp-cAMP did not inhibit it, MAPK activiteies were stimulated 5 mm after FSH addition to cultured GCs, and reached plateau after 15 mm. PMA stimulated MAPK activities, while forskolin did not. Staurosporinesignificantly inhibited the increase in NIAPK activities by FSH, whereas Rp-cAMP had no influence.
These data suggest that MAPK, c-fos and junB play an important role in FSH action in granulosa cells, and that protein kinase C pathway is invovled in the signal transduction pathways in granulosa cells,