Ovarian melanotropic peptides and adaptation in two teleostean species: Sparus aurata L. and Dicentrarchus labrax L.

Abstract

The ovarian tissue of Dicentrarchus labrax and Sparus aurata displays two immunoreactive peaks that correspond to the elution time of human des-acetyl α-MSH [ACTH(1–13)-amide] and human α-MSH. In view of the close identity between the primary structure of fish and human α-MSH, these data demonstrate that two MSH-related peptides are present both in sea bream and sea bass ovary. α-MSH-like immunoreactivity was found within both granulosa and thecal layers of mature follicles, as well as in the cytoplasm of oogonia of sea bream and sea bass ovary. Gonadal content of ACTH(1–13)-amide and α-MSH display differences with regard to season, showing the highest peptide levels in reproductive animals. Moreover, the α-MSH content is significantly higher in the ovary of fish farm animals, whereas that of ACTH(1–13)-amide prevails in wild fish ovary.