Somatostatin in the ovary of an African lungfish (Protopterus annectens): An in situ hybridisation, immunohistochemical, and autoradiographical study

In mammals, somatostatin seems to be involved in the control of ovarian ste roidogenesis. There have been no studies on the presence or actions of soma tostatin in the ovary of nonmammalian vertebrates. The localisation of soma tostatin-14 was examined immunohistochemically using the antibody to somato statin-14 in the ovary of the African lungfish Protopterus annectens. Immun oreactivity was present in the granulosa cells of mature ovarian follicle e xamined by light microscopy. Using an oligonucleotide probe complementary t o mRNA for somatostatin-ll and labelled at the 3'-end with alpha-S-35, in s itu hybridisation demonstrated somatostatin-14 mRNA distributed in cells sh owing the same localisation as that of the immunoreactive cells. Binding si tes for SST-14 were identified with autoradiography using [I-125]somatostat in-14. Binding sites were localised on granulosa and theca cells. Somatosta tin-14 may be thus synthesised in the lungfish ovary. (C) 1999 Academic Pre ss.