Differential expression pattern of inhibin α and βA subunits in the ovaries of postnatal and prepubertal lambs

Abstract

The aim of the present study was to characterize gene and protein expression of follistatin, inhibin α (α) and inhibin βA (βA) subunits in the ovaries of postnatal (3-week-old) and prepubertal (14 and 20–25-week-old) lambs. Northern blot analysis revealed the presence of two α and two βA mRNAs. In postnatal ovary the α 1·2-kb transcript was abundant, its amount gradually falling, while the 2·0-kb mRNA increased and became a major band at 20–25 weeks. Both βA mRNAs, 4·5 kb and 6·0–7·5 kb, were weakly expressed in postnatal ovary, but whereas the 4·5-kb mRNA expression remained at a low level, that of the 6·0–7·5 kb mRNA increased about five fold in prepubertal ovary. The ratio of total α mRNAs to the dominant βA form (6·0–7·5 kb) varied from 1·27 at 3 weeks to 0·33 at 20–25 weeks of age. One major follistatin mRNA of 2·5–3·6 kb was recognized and was constitutively expressed during ovarian growth. Several molecular-mass forms of α and βA subunits with different compositions were seen in prepubertal compared with postnatal ovaries, the latter exhibiting more active follicular growth. In summary, ovine ovaries undergo distinct changes early in life, both morphological and functional, and show a changing pattern of inhibin subunit expression.