Comparative effects of human chorionic gonadotropin (hCG) and gonadotropin-releasing hormone agonist (GnRHa) treatments on the stimulation of male Senegalese sole (Solea senegalensis) reproduction

Abstract

The aquaculture of Senegalese sole (Solea senegalensis) is limited by the failure of cultured breeders (G1 generation) to produce fertilized spawning. Critical reproductive dysfunctions have been observed in both female and male Senegalese sole cultured breeders, including reduced fecundity and diminished sperm production. The present work aimed to study the effectiveness of different hormonal treatments on the stimulation of male reproduction. Male Senegalese sole cultured breeders were treated with 1) saline injections (controls), 2) gonadotropin-releasing hormone agonist ). Each group of males was placed in separated spawning tanks together with females treated with GnRHa implants.All three hormonal treatments increased plasma testosterone (T) and 11-ketotestosterone (11-KT) levels and the gonadosomatic index (GSI), with highest effects exerted by the hCG treatment. Histological examination of the testes showed no effect of the GnRHa injection, but a clear stimulation of germ cell proliferation and testicular maturation by GnRHa implants and hCG injections. As expected, GnRHa implantation of females induced egg release in all experimental tanks and interestingly, female fecundity increased in tanks containing GnRHa-or hCG-treated males. A fertilized spawning was obtained only from the group containing hCG-treated males. In conclusion, hormonal treatments stimulated steroidogenesis and spermatogenesis in male Senegalese sole, with highest efficiency of the hCG multiple injection treatment.

New developments and biological insights into the farming of Solea senegalensis reinforcing its aquaculture potential

“…; Guzmán et al . ). Combined treatment of GnRHa with 11‐ketoandrostenedione, an 11KT precursor (Agulleiro et al .…”

Reproduction, olfaction and dominance behaviour in Senegalese sole (Solea senegalensis)

“…Moreover, there was a couple which spawned formed of only cultured breeders in 2014 and the same cultured female spawned with one wild male, which had reproduced with another wild female. This is not the first report of cultured Senegalese sole participating in the spawning season, Guzmán et al (2011) observed 1 fertilised spawn of a total of 60 spawns after GnRHa implants applied into the females and hCG treatment in males, however, the two spawns obtained in the present study were naturally achieved. Furthermore, found a fidelity of mating couples over years, which this situation has been also observed in our study showing the importance of the mate choice in this species.…”

“…For example, and applied Gonadotropin-Releasing Hormone analogue (GnRHa) implants and injections in cultured Senegalese sole obtaining spontaneous spawning but the eggs were not fertilized. The same researchers Guzmán et al, 2011) also applied human Chorionic Gonadotropin (hCG) and different doses of GnRHa in cultured males obtaining significantly more production of sperm, however, the spawned eggs were still mainly unfertilized with just one spawn obtained from cultured animals after applying double GnRHa treatment in cultured females and hCG in cultured males (Guzmán et al, 2011). These results suggested that hormonal issues in the control of gametogenesis were not the reason of the reproductive dysfunction in cultured breeders .…”

“…For example, and used GnRHa (Gonadotropin-Releasing Hormone analogue) in cultured sole acquiring large increases in spontaneous spawning, however, the eggs were also not fertilized. Another study applying hCG (human Chorionic Gonadotropin) and different concentrations of GnRHa in cultured males obtained positive results in terms of sperm production, however, the eggs were again not fertilised Guzmán et al, 2011), just one spawn was obtained from cultured animals after applying double GnRHa treatment in cultured females and hCG in cultured males. These studies suggest that hormonal dysfunctions in the control of gametogenesis are not the cause of the reproduction failure in cultured breeders, due to this species achieves gametogenesis and produces viable gametes (Guzmán et al, 2009a;.…”

“…However, Senegalese sole reproduction in captivity depends on wild-origin broodstocks since hatchery reared or cultured sole fail systematically to release fertilised eggs García-López et al, 2006) in spite of having the capacity to produce viable gametes suitable for in vitro fertilization García-López et al, 2006;Rasines et al, 2012). Hormonal therapies were unsuccessful to correct this dysfunction and behavioural studies have demonstrated that the lack of proper courtship behaviour in cultured males appears to be behind this problem Guzmán et al, 2011). The olfactory system represents a key organ that controls hormonal communication for reproductive priming and/or synchronization courtship behaviour in several teleosts (Moore, 2002;Moore and Waring, 1996;Sorensen, 1992;Sorensen et al, 1990).…”