The involvement of gonadotropins and gonadal steroids in the ovulatory dysfunction of the potamodromous Salminus hilarii (Teleostei: Characidae) in captivity

Abstract

Potamodromous teleosts that require migration to reproduce show dysfunctions that block ovulation and spawning while in captivity. To understand the physiological basis of these reproductive dysfunctions, follicle-stimulating hormone b subunit (fshb) and luteinizing hormone b subunit (lhb) gene expression analyses by real-time quantitative PCR, together with measurements of estradiol (E 2), 17α-hydroxyprogesterone (17α-OHP) and 17α,20β-dihydroxy-4-pregnen-3-one (17α,20β-DHP) levels, were carried out throughout the reproductive cycle of the potamodromous Salminus hilarii. The following reproductive stages were evaluated in captive and wild females: previtellogenic (PV), advanced maturation/mature (AM) and regression/spent (REG/SPENT). In the wild females, fshb expression decreased from the PV to the AM stage, and the opposite pattern was detected for E 2, which increased from the PV to the AM stage. fshb was expressed at lower levels in captive than in wild females, and this difference did not change during the reproductive cycle. lhb expression also increased from the PV to the AM stage in both groups, but the wild females at the AM and REG/SPENT stages showed higher lhb expression levels than the captive females. The concentrations of 17α-OHP did not change during the reproductive cycle, and the levels were higher in the captive than in the wild females at all reproductive stages. 17α,20β-DHP levels did not change between wild and captive females. However, in captive females, the transition from PV to AM stage was followed by an increase in 17α,20β-DHP levels. These data indicate that dysfunctions in the gonadotropins and steroids synthesis pathways cause the ovulation failure in captive S. hilarii.

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, ).…”

“…Leporinus piau (Araújo, Oliveira, Costa, & Novaes, 2016), Salminus hilarii (Honji et al, 2009;Moreira et al, 2015), Rhamdia quelen (Reidel et al, 2010), Brycon amazonicus (Hainfellner, is associated with its high fillet yield (Souza & Inhamuns, 2011), 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, 1980). The vitellogenic process of H. marginatus was like that of other tropical Characiformes rheophilic species (Hainfellner, Souza, et al, 2012a;Schorer et al, 2016), occurring in October or November, approximately 2 months before the spawning season (spring/summer).…”

Seasonal changes in hepatosomatic index, gonadosomatic index and plasma estradiol‐17β level in captively reared female rabbit fish ( Siganus guttatus )

“…Since the demand for captive fry of the rabbit fish has been increasing for aquaculture, many studies have been implemented including reproductive biology (Pham & Phan, ; Rahman, Takemura, & Takano, , ; Susilo, Harnadi, & Takemura, ), induced spawning with hormones (Ayson, ) and larval rearing (Hara, Kohno, & Taki, ; Juario, Duray, Duray, Nacario, & Almendras, ) with a view to facilitating artificial propagation of the species. However, further studies on reproductive endocrinology, hormonal regulation and associated reproductive parameters such as HSI, GSI, plasma steroid levels, especially the relationship among those parameters need to be conducted in captivity, especially so as a lot of fishes exhibit some ovulatory dysfunctions such as Salminus hilarii (Moreira et al, ).…”

“…E 2 regulates ovarian development through its stimulation of vitellogenin (Vtg) synthesis in the liver during the oocyte growth (Nagahama & Yamashita, ). Plasma level of E 2 is associated with ovarian development and its level is observed to increase during vitellogenesis in some fish species (Dahle, Taranger, Karlsen, Kjesbu, & Norberg, ; Moreira et al, ; Nagahama, ; Pham, Nguyen, Kjørsvik, Nguyen, & Arukwe, ). In fish, ovarian development can be classified in to different stages, based on the most advanced oocyte batch, which could help fish biologists better understand how fish eggs are formed and grow (Honji, Narcizo, Borella, Romagosa, & Moreira, ; Lubzens et al, ; Parenti & Grier, ).…”

Corticosteroids as inductors of ovulation in Astyanax altiparanae (Characiformes: Characidae) during artificial reproduction

“…In this sense, hormonal therapies are required to provide the final maturation and ovulation in Neotropical migratory species. Thus, several recent studies have attempted to measure the influence of captivity during the reproductive cycle in Neotropical fish species with blocked reproduction in captivity, mainly the potamodromous species, as Prochiloduslineatus (Hainfellneret al, 2012;Souza et al, 2014), Salminushilarii (Honjiet al, 2011(Honjiet al, , 2013Moreira et al, 2015), Steindachneridionparahybae (Honjiet al, 2013(Honjiet al, , 2015 and Piaractusmesopotamicus (Kuradomiet al, 2015) among others.…”