Toward developing recombinant gonadotropin-based hormone therapies for increasing fertility in the flatfish Senegalese sole

Abstract

Captive flatfishes, such as the Senegalese sole, typically produce very low volumes of sperm. This situation is particularly prevalent in the first generation (F1) of reared sole males, which limits the development of artificial fertilization methods and the implementation of selective breeding programs. In this study, we investigated whether combined treatments with homologous recombinant follicle-stimulating (rFsh) and luteinizing (rLh) hormones, produced in a mammalian host system, could stimulate spermatogenesis and enhance sperm production in Senegalese sole F1 males. In an initial autumn/winter experiment, weekly intramuscular injections with increasing doses of rFsh over 9 weeks resulted in the stimulation of gonad weight, androgen release, germ cell proliferation and entry into meiosis, and the expression of different spermatogenesis-related genes, whereas a subsequent single rLh injection potentiated spermatozoa differentiation. In a second late winter/spring trial corresponding to the sole’s natural prespawning and spawning periods, we tested the effect of repeated rLh injections on the amount and quality of sperm produced by males previously treated with rFsh for 4, 6, 8 or 10 weeks. These latter results showed that the combination of rFsh and rLh treatments could increase sperm production up to 7 times, and slightly improve the motility of the spermatozoa, although a high variability in the response was found. However, sustained administration of rFsh during spawning markedly diminished Leydig cell survival and the steroidogenic potential of the testis. These data suggest that in vivo application of rFsh and rLh is effective at stimulating spermatogenesis and sperm production in Senegalese sole F1 males, setting the basis for the future establishment of recombinant gonadotropin-based hormone therapies to ameliorate reproductive dysfunctions of this species.

In silico analysis, temporal expression and gonadotropic regulation of receptors for follicle‐stimulating hormone and luteinizing hormone in testis of spotted snakehead Channa punctata

“…This explanation may be seen in light of the fact that proliferation of Sertoli cells is reported to cease when SG enter meiosis, thereby many fold progressive increase in ratio of germ cells to Sertoli cells have been observed with the differentiation of SC and ST in several teleosts, O. niloticus(Matta et al, 2002;Schulz et al, 2005;Vilela et al, 2003), C. gariepinus(Schulz et al, 2005), Poecilia reticulata Peters 1859(Billard & Escaffre, 1969) and D. rerio(Leal et al, 2009). The inference proposed in the present study that germ cell mRNA diluted somatic cell mRNA and consequently cpfshra and cplhcgr appeared to decrease during preparatory and early/mid spawning phases is further substantiated by a sharp increase in expression of cpfshra and cplhcgr during post spawning phase when germ cell number markedly reduced and the lobules contained only SG at the periphery and residual SZ in the lumen(Basak et al, 2016).Gonadotropic regulation of testicular fshra and lhcgr expression in teleosts has been least explored and the available studies show inconsistent results(Chauvigne et al, 2014b(Chauvigne et al, , 2017García-López et al, 2010). In S. senegalensis, recombinant homologous Fsh (rFsh) is reported to be ineffective in influencing the expression of either fshra or lhcgr while rLh increased the expression of only lhcgr(Chauvigne et al, 2014b).…”

“…Gonadotropic regulation of testicular fshra and lhcgr expression in teleosts has been least explored and the available studies show inconsistent results (Chauvigne et al ., , ; García‐López et al ., ). In S. senegalensis , recombinant homologous Fsh (rFsh) is reported to be ineffective in influencing the expression of either fshra or lhcgr while rLh increased the expression of only lhcgr (Chauvigne et al ., ).…”

“…In S. senegalensis, recombinant homologous Fsh (rFsh) is reported to be ineffective in influencing the expression of either fshra or lhcgr while rLh increased the expression of only lhcgr(Chauvigne et al, 2014b). A combined treatment of rFsh and rLh, however, stimulated expression of both the gonadotropin receptors(Chauvigne et al, 2017). In D. rerio as well, homologous rFSH failed to affect the expression of either gonadotropin receptors.…”

Low sperm to egg ratio required for successful in vitro fertilisation in a pair-spawning teleost, Senegalese sole (Solea senegalensis)

“…In the present study, 61% of the males checked for sperm had the required quantity and quality needed for the experiments and in vitro fertilisations. This availability of males, has already be improved as therapies with recombinant gonadotropins exist that both increase sperm production and quality (Chauvigné et al, 2018(Chauvigné et al, , 2017. These recombinant gonadotropin therapies, significantly increased sperm production by up to seven times and significantly increased the sperm quality parameters, percentage motility, progressivity and velocity of spz.…”

Providing recombinant gonadotropin-based therapies that induce complete oogenesis and produce viable larvae from an immature teleost, flathead grey mullet (Mugil cephalus)

“…Chinese hamster ovary (CHO) cells (Chauvigné et al, 2017;Choi et al, 2005;Giménez et al, 2015;Molés et al, 2011;Peñaranda et al, 2018;So et al, 2005). The application of rGths based therapies has shown promise to control gametogenesis in different teleost (Chauvigné et al, 2018(Chauvigné et al, , 2017Giménez et al, 2015;Kamei et al, 2006;Peñaranda et al, 2018) and, therefore, could be an effective method to induce gametogenesis in cultured mullet arrested in the early stages of sexual maturation.…”