Leporinus elongatus induced spawning using carp pituitary extract or mammalian GnRH analogue combined with dopamine receptor antagonists

Abstract

Several studies have been developed to support the replacement of the crude carp pituitary extract (CPE) by synthetic products for induced reproduction of South American rheophilic species. However, results have been quite heterogeneous and there is no consensus or a routine use of synthetic products in these species. Thus, the aim of this study was to evaluate the ovulatory process in L. elongatus using different protocols of hormonal induction. Thus, fifteen wild mature females maintained at the Experimental Fish Station, Salto Grande, SP, Brazil were submitted to three different hormonal treatments: CPE (fractioned dose: 0.5 and 5.0 mg kg -1 ); mGnRHa (single dose: 3.5 µg kg -1 ) and mGnRHa (single dose: 5.0 µg kg -1 ). The spawning rate and absolute fecundity were similar among the treatments, but fertility rates were higher for CPE treatment (23.60 ± 9.40) then for mGnRHa treatments (close to or zero zero). Although females ovulated in all treatments, none of them provided viable embryos, showing hatching rates close to zero or zero. Both mGnRHa treatments were more potent for inducing the ovulatory process then CPE treatment, which was evidenced by the fact that the formers showed higher volume density of postovulatory follicles (POF). Accordingly, E 2 and 17α-OHP plasma levels were higher for the mGnRHa treated females compared to the CPE one at the time of ovulation. In this study we confirmed previous scientific evidence that, regardless of whether promoting ovulation, the use of conventional CPE and GnRH doses are not appropriate for some South American migratory species, due to the nonattainment of viable embryos. Moreover, we have brought new information about the relationship between reproductive performance and gonadal steroids concentrations using different hormonal therapies, contributing to understand the reasons for Leporinus elongatus embryo loss in induced spawning.

Resumption and progression of meiosis and circulating levels of steroids and prostaglandin F 2α of Piaractus mesopotamicus induced by hypophysation with prostaglandin F 2α

“…Regarding this concern, studies developed in our laboratory have shown that the failures occur as a result of the hormonal induction process causing final maturation with migration and breakdown of the germinal vesicle (GVBD), but it is insufficient to cause ovulation (Criscuolo‐Urbinati et al., 2012). This type of failure had previously been demonstrated in carps (Jalabert et al., 1977), in other tropical rheophilic species, such as matrinxã ( Brycon amazonicus ) (Hainfellner et al., 2012), piau ( Leporinus friderici ) (De Souza et al., 2020), piapara ( Leporinus elongatus ) (Pereira et al., 2018) and piaçu ( Leporinus macrocephalus ) (Pereira et al., 2017), and all these descriptions shows the presence of unovulated GVBD oocytes retained in the ovaries.…”

Reproductive performance of lambari ( Astyanax altiparanae ) in a seminatural system using different protocols

“…Moreover, the intermediate reproductive performance obtained using 1,000 μg sGnRHa/kg highlights that future approaches testing dopamine inhibitors together with sGnRHa may change the current scenario. Even unusual and much higher than that the doses used for hormonal induction for neotropical (Acuña & Rangel, 2009; Pereira et al., 2016, 2018; Souza et al., 2018, 2020; Viveiros et al., 2013), cyprinids (Podhorec et al., 2016; Podhorec, Socha, Sokolowska‐Mikolajczyk, Policar, Svinger, Drozd, et al., 2012; Podhorec, Socha, Sokolowska‐Mikolajczyk, Policar, Svinger, Gosiewski, et al., 2012) and salmonids fishes (Arabaci et al., 2004), the 1,000 μg sGnRHa/kg treatment resulted in fertility and hatching rates above 90%, indicating that the use of this synthetic treatment is not a problem for this species in this concern.…”

“…Concerning possible reasons for ovulation failures, we observed that only the unspawned females of the fractioned CPE group (and all individuals) retained GVBD oocytes (meiosis resumption) in the ovaries, while all unspawned females from other groups retained only oocytes with intact germinal vesicles. This specific type of failure, which causes GVBD but not ovulation, was in deep studied using fractioned CPE doses in common carp (Jalabert et al., 1977) and in some tropical reophilic species, such as matrinxã ( Brycon amazonicus ) (Hainfellner et al., 2012), piau ( Leporinus friderici ) (Souza et al., 2020), piapara ( Leporinus elongatus ) (Pereira et al., 2018) and piaçu, ( Leporinus macrocephalus ) (Pereira et al., 2016). All of these descriptions mentioned unovulated GVBD oocytes retained in the ovaries, but it is still unknown the reasons for such partial failure.…”

Reproductive cycle of the Amazonian planktivorous catfish Hypophthalmus marginatus (Siluriformes, Pimelodidae)

“…For the congener species H. edentatus (Carvalho, ), GSI values reported for mature females were also relatively low (6.4%), indicating that the maparás may present small GSI values in comparison to other tropical migratory fish. The GSI values of mature females of Brycon orbignyanus (Ganeco et al, ), Piaractus mesopotamicus (Romagosa, Paiva, Godinho, & Storfer, ), Pseudoplatystoma fasciatum (Romagosa et al, ), Prochilodus lineatus (Hainfellner, Souza, et al, ), Leporinus piau (Araújo, Oliveira, Costa, & Novaes, ), Salminus hilarii (Honji et al, ; Moreira et al, ), Rhamdia quelen (Reidel et al, ), Brycon amazonicus (Hainfellner, de Souza, Munoz, & Batlouni, ) and Leporinus elongatus (Pereira, Boscolo, Moreira, & Batlouni, ) were 15%, 15%, 15%, 19%, 20%, 16%, 10%, 15% and 16% respectively. The relatively small GSI values of species belonging to the Hypophthalmus genus may be associated with the small celomic cavity and the displacement of the organs towards the ventral part of the animal, whereas the caudal portion of the animal is entirely occupied by muscles, which is associated with its high fillet yield (Souza & Inhamuns, ), and also attributable to the fact that these species do not form fat deposits; rather, the fat is diffused in muscle tissue, giving the fillet its high fat content (Carvalho, ).…”