Effects of high hydrostatic pressure on the pituitary–gonad axis in the European eel, Anguilla anguilla (L.)

Sébert, Marie-Emilie; Amérand, Aline; Vettier, Aurélie; Weltzien, Finn‐Arne; Pasqualini, Catherine; Sébert, Philippe; Dufour, Sylvie

doi:10.1016/j.ygcen.2007.01.009

Cited by 39 publications

(18 citation statements)

References 48 publications

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“…Eels were escaping light by ascending during dusk and descending during dawn at depths between 200 and 700 m, both in continental and deep-sea waters which probably persists as far as the spawning grounds. So, besides the effects of swimming as discussed in this study, the diel vertical migration in the ocean can be expected to have effects on sexual maturation through the alternation in pressure [46], temperature (Tsukamoto K, presented at the Aquaculture Europe 2008 symposium organised by the European Aquaculture Society in Krakow, Poland; [38]) and avoidance of light [47]. …”

Section: Discussionmentioning

confidence: 99%

Swimming suppresses hepatic vitellogenesis in European female silver eels as shown by expression of the estrogen receptor 1, vitellogenin1 and vitellogenin2 in the liver

Palstra

Schnabel

Nieveen

et al. 2010

Reprod Biol Endocrinol

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BackgroundWhen European silver eels (Anguilla anguilla) venture into the Atlantic Ocean for their 6,000 km semelparous spawning run to the Sargasso Sea, they are still in a prepubertal stage. Further sexual development appears to be blocked by dopaminergic inhibition of hypothalamus and pituitary activity. Recently, we found that swimming for several weeks in freshwater stimulated the incorporation of fat droplets in the oocytes. So, it was hypothesized that long term swimming in seawater would release the inhibition further and would also stimulate the production of vitellogenin by the liver.MethodsFor this study a swim-flume was constructed to allow simulated migration of migratory female silver eels for 3 months (1,420 km) in natural seawater at 20 degrees C. Primers were designed for polymerase chain reactions to measure the mRNA expression of estrogen receptor 1 (esr1), vitellogenin1 (vtg1) and vitellogenin2 (vtg2) genes in the liver of European female silver eels.ResultsIn comparison to resting eels, swimming eels showed a diminished expression of esr1, vtg1 and vtg2 in the liver. They also had lower plasma calcium (Ca; indicative of vitellogenin) levels in their blood. This showed that vitellogenesis is more strongly suppressed in swimming than in resting eels. However, when eels were subsequently stimulated by 3 weekly carp pituitary extract injections, the expression of the same genes and plasma levels of Ca strongly increased in both groups to similar levels, thus equalizing the initial differences between resting and swimming.ConclusionsIt is concluded that vitellogenesis remains suppressed during resting and even more during swimming. The fact that swimming stimulates fat deposition in the oocytes but suppresses vitellogenesis indicates that these events are separated in nature and occur sequentially. Swimming-suppressed vitellogenesis may imply that in nature eels undergo vitellogenesis and final maturation near or at the spawning grounds.

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Section: Discussionmentioning

confidence: 99%

Swimming suppresses hepatic vitellogenesis in European female silver eels as shown by expression of the estrogen receptor 1, vitellogenin1 and vitellogenin2 in the liver

Palstra

Schnabel

Nieveen

et al. 2010

Reprod Biol Endocrinol

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“…Only CAT activity significantly increases (Table 3) which is probably not sufficient to compensate the expected high increase in HO • during swimming activity under pressure. However, estrogens, which are known to exhibit antioxidant properties (Vina et al 2006;Sugioka et al 1987), increase in females after pressure exposure (Sébert et al 2007). So the hypothesis is that during migration females could use (among others) sexual hormones as antioxidant systems when males would use the reversal effect of hydrostatic pressure to preserve themselves against ROS.…”

Section: Malesmentioning

confidence: 99%

Sex-related differences in aerobic capacities and reactive oxygen species metabolism in the silver eel

Amérand

Vettier

Moisan

et al. 2010

Fish Physiol Biochem

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Silver European eels (Anguilla anguilla L.) need to develop important aerobic capacities to cope with their long fasting spawning migration at depth, particularly males which are about half the size of females. Moreover, they have to face potential oxidative stress because reactive oxygen species (ROS) production is linked to the increase in metabolic rate. Thus, aerobic metabolism was globally evaluated in male and female silver eels exposed to a 10.1 MPa hydrostatic pressure (1,000 m depth). Oxygen consumption (MO(2)), ROS production and antioxidant enzyme activities were measured in the muscle fibres. Males showed a trend in both higher rate of aerobic metabolism and ROS production than females. After pressure exposure, ROS production was inversely correlated to metabolic rate only in males. By facilitating MO(2) rise with no harmful effects by ROS, the supposed enhanced aerobic capacities of males could speed up the sustained swimming. In females, the tendency to lower metabolic rate and higher catalase activity would make them less vulnerable to ROS effects. These results are in agreement with the hypothesis for different migration depths between genders.

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“…Much remains to be understood about the endocrine pathways controlling aspects of reproduction such as puberty and gametogenesis in teleosts. Gonad development and gametogenesis are influenced by external signals such as temperature and photoperiod (Zanuy et al, 1986;Taranger et al, 2010) and, in eels, can be influenced by swimming behavior and hydrostatic pressure (Sébert et al, 2007;Palstra et al, 2008). These external signals trigger the release of gonadotropin releasing hormone (GNRH) by the hypothalamus which controls the release of pituitary follicle stimulation hormone (FSH) and luteinizing hormone (LH).…”

Section: Introductionmentioning

confidence: 99%

Transcriptomic profiling of male European eel ( Anguilla anguilla ) livers at sexual maturity

Churcher

Pujolar

Milan

et al. 2015

Comparative Biochemistry and Physiology Part D: Genomics and Pr

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Effects of high hydrostatic pressure on the pituitary–gonad axis in the European eel, Anguilla anguilla (L.)

Cited by 39 publications

References 48 publications

Swimming suppresses hepatic vitellogenesis in European female silver eels as shown by expression of the estrogen receptor 1, vitellogenin1 and vitellogenin2 in the liver

Swimming suppresses hepatic vitellogenesis in European female silver eels as shown by expression of the estrogen receptor 1, vitellogenin1 and vitellogenin2 in the liver

Sex-related differences in aerobic capacities and reactive oxygen species metabolism in the silver eel

Transcriptomic profiling of male European eel ( Anguilla anguilla ) livers at sexual maturity

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