Localization of messenger ribonucleic acids for insulin-like growth factor I (IGF-I), IGF-II, and the type 1 IGF receptor in the ovine ovary throughout the estrous cycle.
The distribution pattern of messenger RNAs (mRNAs) for insulin-like growth factor I (IGF-I), IGF-II, and the type 1 IGF receptor and the detection of IGF-binding sites in sections of ovine ovary were demonstrated using in situ hybridization and autoradiography. Ovaries were collected from 30 ewes at time points throughout the estrous cycle. Luteal IGF-II mRNA and IGF-binding site concentrations altered significantly during the cycle, peaking on day 8 (midluteal phase; P < 0.01) and day 15 (late luteal phase; P < 0.001), respectively. In contrast, mRNA expression for IGF-I and the type 1 IGF receptor in the corpus luteum was low and did not vary. IGF-binding sites and mRNAs for IGF-II and the type 1 IGF receptor were also present at low and constant concentrations in ovarian stroma. There was no detectable follicular expression of IGF-I mRNA, although there were high concentrations of IGF-II and the type 1 IGF receptor mRNAs, which both varied significantly with follicular size (P < 0.001 and 0.01, respectively), with the highest concentrations in small follicles (< 2 mm in diameter). Follicular IGF-II expression was confined to the theca, whereas the type 1 IGF receptor was present in both theca and granulosa. IGF-binding site concentrations were significantly higher (P < 0.01) in atretic than healthy follicles, but were uninfluenced by follicular size. These results suggest that IGF-II, in contrast to IGF-I, appears to be the most significant IGF in luteal and, particularly, follicular development in the ewe.
Perks
C M
CM
Department of Anatomy, School of Medical Sciences, Bristol, United Kingdom.
Denning-Kendall
P A
PA
Gilmour
R S
RS
Wathes
D C
DC
D000818:Animals; D001345:Autoradiography; D001483:Base Sequence; D004971:Estrus / Q000378:metabolism*; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000235:genetics*; D007335:Insulin-Like Growth Factor II / Q000235:genetics*; D008969:Molecular Sequence Data; D010053:Ovary / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis*; D017526:Receptor, IGF Type 1 / Q000235:genetics*; D012756:Sheep
D012333:RNA, Messenger; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D017526:Receptor, IGF Type 1