11-Ketotestosterone induces silvering-related changes in immature female short-finned eels, Anguilla australis

Effect of thermal regime on the expression of key reproductive genes during hormonally-induced vitellogenesis in female European eels

“…GSI increase is the result of gonad maturation, while increase in eye dimensions is supposed to be an adaptive response to the increased darkness during the maturational oceanic migration (Rohr et al, 2001). …”

“…In the decreasing temperature group, early ovarian development was stimulated as evidenced by the increase in GSI, oocyte diameter and oil droplet number, and by the higher 11-KT plasma level. In fact, 11-KT plays a role in early ovarian development and lipid accumulation in oocyte and it is probably responsible for the changes recorded in the decreasing temperature group (Rohr et al, 2001;Matsubara et al, 2003b;Lokman et al, 2007;Sudo et al, 2012). On the other hand, in the decreasing temperature group low values of FSHβ and LHβ mRNA were registered, indicating that low temperatures inhibit vitellogenesis (Sudo et al, 2011).…”

“…Apart from estrogens, it was demonstrated that also steroids traditionally considered more involved in male physiology, play an important role in female eel maturation, as 11-KT which promotes the previtellogenic ovarian growth (Rohr et al, 2001;Matsubara et al, 2003a Matsubara et al., ,b, 2005Lokman et al, 2007; Kazeto et al, 2011;Setiawan et al, 2012).…”

“…In the gonads, an increase in aa-arb expression has been recorded and it can be related with the previtellogenic oocyte growth, due to the role that androgens play in this event (Rohr et al, 2001;Matsubara et al, 2003a,b;2004;Lokman et al, 2007;Kazeto et al, 2011;Setiawan et al, 2012).…”

“…In teleosts, two paralogous genes of P450arom have been found, cyp19a1b, mainly expressed in the brain and cyp19a1a, mainly expressed in the gonad (Chang et al, 1997a;Gelinas et al, 1998; 5 Kishida and Callard, 2001;Blázquez and Piferrer, 2004;Choi et al, 2005). In European and Japanese eels, however, only one aromatase cDNA has been identified (termed cyp19a1), and is expressed in ovary, brain and pituitary Tzchori et al, 2004).Apart from estrogens, it was demonstrated that also steroids traditionally considered more involved in male physiology, play an important role in female eel maturation, as 11-KT which promotes the previtellogenic ovarian growth (Rohr et al, 2001;Matsubara et al, 2003a Matsubara et al., ,b, 2005Lokman et al, 2007; Kazeto et al, 2011;Setiawan et al, 2012).The effect of the androgens can be also mediated by binding to ARs. The gonadal steroids are essential for the teleost reproduction and they are able to affect practically all tissues.…”