Plasma levels of follicle-stimulating and luteinizing hormones during the reproductive cycle of wild and cultured Senegalese sole (Solea senegalensis)

9 pages, 4 figures, 1 table
The intensive culture of the Senegalese sole (Solea senegalensis) is hampered by the low or null fertilization rates exhibited by the first generation (F1) of reared males. To investigate the regulation of the reproductive processes in this species by the pituitary gonadotropins follicle-stimulating and luteinizing hormones (Fsh and Lh, respectively), we developed a highly sensitive and specific enzyme-linked immunosorbent assay (ELISA) for Lh measurements. Quantification of the Fsh and Lh plasma levels in cultured sole using the Lh ELISA developed here, and a previously developed ELISA for Fsh, indicated that in both males and females circulating Fsh steadily increased during autumn and winter and prior to the major spawning in spring, whereas an Lh surge occurred specifically during spawning. The increase in Fsh was associated with a rise of plasma levels of the steroid hormones testosterone (T), 11-ketotestosterone (11-KT) and estradiol-17β (E2), but that of Lh was concomitant with a strong decline of the levels of E2 in females and of 11-KT in males, possibly reflecting a rapid steroidogenic shift promoting the final maturation of gametes. Comparison of the plasma levels of gonadotropins and steroids between wild and F1 fish during autumn and spring revealed that F1 males showed significantly lower plasma Lh titres compared to wild males, whereas the levels of T and 11-KT were similar or more elevated in the F1 fish. These data suggest that an impaired Lh secretion during spawning, and perhaps altered Lh-mediated mechanisms in the testis, may be underlying causes for the low reproductive performance of Senegalese sole F1 males. © 2015 Elsevier Inc
This work was funded by the Spanish Fundación Ramón Areces (to J.C.), and partially supported by the Spanish Ministry of Science and Innovation (MICINN) Aquagenomics project (CSD2007-00002 to S.Z.) and the Spanish National Institute for Agronomic Research (INIA) project RTD2011-00050 (to N.D). Participation of E.F. was financed by a predoctoral fellowship from INIA