Induction of vitellogenesis by 17-hydroxyprogesterone and methyl farnesoate during post-reproductive period, in the estuarine crab Neohelice granulata

Abstract

Adult females of the crab Neohelice granulata was treated during the post-reproductive period with both 17-hydroxyprogesterone (17PG) and methyl farnesoate (MF). During the 4-wk in vivo assay, animals were fed on hormone (17PG or MF) enriched pellet food twice a week, at a dose of 2 nmol/g of body weight. Additionally, ovarian pieces were in vitro incubated with every hormone for 24 h, at a concentration of 15μM. At the end of the in vivo assay, both the gonadosomatic index (GSI) and the vitellogenic protein (Vg) content of crabs treated with either 17PG or MF was significantly (p<0.05) higher than the values of the concurrent control. In addition, hemolymphatic vitellogenin level of both groups hormonally treated was higher at that time. At the end of the in vitro assay, a significantly (p<0.05) higher increase in both protein synthesis and content of Vg proteins was verified in the ovaries incubated with 17PG, with respect to control, but not in those incubated with MF. The involvement of the studied hormones in the regulation of ovarian growth during the reproductive cycle of N. granulata is discussed.