In situ analysis of the changes in expression of ovarian inhibin subunit mRNAs during follicle recruitment after ovulation in pigs.
In situ hybridization was used on frozen tissue sections with digoxigenin-labelled antisense riboprobes to inhibin/activin alpha and beta(A) subunits to determine whether inhibin/activin subunit mRNA expression was associated with development of growing, steroidogenically active follicles during follicle recruitment after ovulation. Cell proliferation-associated nuclear antigen Ki-67 protein and cytochrome P450 aromatase expression in granulosa cells were determined immunohistochemically and used as markers for granulosa cell proliferation and steroidogenesis, respectively, on days 3, 5 and 7 after the onset of oestrus. The amounts of inhibin/activin alpha and beta(A) subunit mRNA and P450 aromatase protein were greater (102, 93, and 238%, respectively; P < 0.05) in medium than in small non-atretic follicles and were positively correlated with Ki-67 and with each other. Inhibin/activin alpha and beta(A) mRNA, P450 aromatase, and Ki-67 in granulosa cells were reduced by 66-83% (P < 0.001) in atretic follicles compared with non-atretic follicles. In addition, inhibin/activin alpha and beta(A) mRNA and P450 aromatase in small (1-2 mm) non-atretic follicles decreased (P < 0.05) between day 3 and day 7 independently of morphological or biochemical signs of atresia. The pattern of inhibin/activin subunit mRNA expression supports the notion that activin and inhibin have roles in growth and steroidogenesis in follicle recruitment during the early luteal phase of the oestrous cycle.
Garrett
W M
WM
Germplasm and Gamete Physiology Lab, Agricultural Research Service, United States Department of Agriculture, Beltsville, MD 20705, USA.
Mack
S O
SO
Rohan
R M
RM
Guthrie
H D
HD
D000704:Analysis of Variance; D000818:Animals; D002455:Cell Division; D015925:Cryopreservation; D005260:Female; D005496:Follicular Atresia; D015571:Follicular Fluid / Q000737:chemistry; D005498:Follicular Phase / Q000502:physiology*; D015870:Gene Expression; D006107:Granulosa Cells / Q000166:cytology / Q000378:metabolism; D017403:In Situ Hybridization / Q000379:methods; D007265:Inhibins / Q000032:analysis / Q000235:genetics*; D006080:Ovarian Follicle / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism*; D013552:Swine / Q000502:physiology*
D012333:RNA, Messenger; D007265:Inhibins