Effects of sexual maturation, castration, and androgen implants on growth in one‐ and two‐year‐old parr in a Baltic Atlantic salmon (<i>Salmo salar</i> L.) stock

Berglund, I.; Mayer, Ian; Borg, Bertil

doi:10.1111/j.1095-8649.1992.tb02573.x

Cited by 27 publications

(26 citation statements)

References 15 publications

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“…It is, however, also possible that 40H was more effective early in the season (when maturation is decided) when the fish are still small (giving a higher effective dose from the capsules) and when compensatory responses have perhaps not yet occurred. The possibility that ATD and 40H might exert this effect via androgen receptors seems unlikely since the effects of T-administration on maturation in Atlantic salmon parr are quite dissimilar (Berglund et al 1992). Though unspecific effects cannot be excluded, the present results at least suggest that aromatization is not stimulating the onset of maturation as has been suggested by Rowe et al (1991).…”

Section: Discussionmentioning

confidence: 37%

Effects of aromatase inhibitors on sexual maturation in Atlantic salmon, Salmo salar, male parr

Antonopoulou

Mayer

Berglund

et al. 1995

Fish Physiol Biochem

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Atlantic salmon, Salmo salar, male parr were implanted with Silastic capsules filled with different aromatase inhibitors: 1,4,6-androstatriene-3,17-dione (ATD), 4-hydroxy-4-androstene-3,17-dione (4OH), and the non-steroidal CGS16949 A, 4-benzonitrile monohydrochloride (CGS). Aromatization in brain homogenates were lower in salmon implanted with CGS and ATD than in controls. This was not the case for 4OH, but administration of 4OH to brain homogenates reduced the aromatase activity. All three aromatase inhibitors had effected gonadal weights in fish sampled in the summer, but the effects were markedly different among inhibitors. Plasma levels of the androgen 11-ketotestosterone (11KT) and the progestin 17α, 20β-dihydroxy-4-pregnen-3-one (17,20P) were measured by means of radioimmunoassay. CGS and ATD, but not 4OH, significantly decreased the plasma 17,20P levels in the autumn. Plasma levels of 11 KT were not influenced by ATD or CGS treatment, but 4OH had a lowering effect in one autumn sampling. ATD and 4OH (CGS not tested) increased the proportion of maturing males.These findings suggest that aromatization is of physiological importance in different mechanisms controlling reproduction in salmon.

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Section: Discussionmentioning

confidence: 37%

Effects of aromatase inhibitors on sexual maturation in Atlantic salmon, Salmo salar, male parr

Antonopoulou

Mayer

Berglund

et al. 1995

Fish Physiol Biochem

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“…It is likely that incomplete forms of gonad maturation are affected by low growth rate and small body size. On the contrary, defected (incomplete) maturation could not accelerate growth at a level as complete maturation [32,36].…”

Section: Discussionmentioning

confidence: 99%

Body size versus gonad maturation form in under-yearling precocious males of the sea trout (Salmo trutta m. trutta L.)

Dziewulska

Domagała

2006

Reprod. Nutr. Dev.

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-The study was aimed at analysing body size in relation to form of gonad maturation (amount of mature germ cells) in 329 under-yearling sea trout males. The fish, aged 7 months, were caught in late October-early November in 3 streams located in north-western Poland. Each stream supported fish belonging to a different sib group. Standard histological techniques and a computer image analysis programme were used to detect the class of gonad maturation and percentage of the gonad area occupied by tubules with active spermatogenesis. Gonad maturation forms were distinguished based on the latter criteria. Gonads with developing germ cells occupying less than 90% of gonad area were classified as incomplete forms of gonad maturation, others as complete maturation forms. In each sib-groups analysed, even the smallest individual were already precocious, their gonads being incompletely mature. The smallest maturing male measured 7.1 cm in length. The average size of an incompletely maturing individual was slightly smaller than that of the completely mature one but the difference lacked statistical significance (P > 0.05). The sib-group of smaller fish contained less precocious, and the gonads of the more precocious were incompletely mature, compared to the sib-group of larger fish (P < 0.001). It seems that the incomplete form of gonad maturation (defected maturation) occurs at a smaller critical fish size than the complete gonad maturation form. Incomplete maturation is more frequent smaller individuals and possibly in among slow-growing groups of fish.Salmo trutta / testis / precocious / incomplete maturation / partial maturation / attempted maturation

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“…been studied in an attempt to discover the most effective type of androgen, the optimal dose and the The growth promoting effects of gonadal steroids, stage of development most receptive to treatment particularly androgens, have long been recognized, (e.g., Higgs et al 1977Higgs et al , 1982Lone and Matty 1980; and their possible applications in aquaculture have Rothbard et al 1988;Berglund et al 1992;Lewis and Sower 1992). Although the application of androgen treatment for growth enhancement is currently limited due to health and environmental restrictions, their effects have been shown quite clearly.…”

Section: Introductionmentioning

confidence: 99%

The effects of gonadal development and sex steroids on growth hormone secretion in the male tilapia hybrid (Oreochromis niloticus � O. aureus)

Melamed

Eliahu

Ofir

et al. 1995

Fish Physiol Biochem

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Profiles of plasma growth hormone (GH) in male tilapia hybrid (Oreochromis niloticus x O. aureus) were measured and compared at different times of the year. The profiles did not appear to be repetitive, however, differences in their nature were observed at the different seasons; the most erratic profiles were seen in the height of the reproductive season (July), while the peaks were more subdued in the spring and disappeared in the autumn. Peaks in male fish were more prominent than in the females when measured in July. Perifused pituitary fragments from fish with a high GSI responded to salmon gonadotropin-releasing hormone (sGnRH) analog (10 nM-1 μM), while those from fish with a low GSI barely responded to even the highest dose. Exposure of perifused pituitary fragments from sexually-regressed fish to carp growth hormone-releasing hormone (cGHRH; 0.1 μM) or sGnRH (I μM) stimulated GH release only after injection of the fish with methyl testosterone (MT; 3 injections of 0.4 mg kg (1)). The same MT pretreatment did not alter the response to dopamine (DA; 1 or 10 μM). GH pituitary content in MT-treated fish was lower than in control fish, which may be explained by the higher circulating GH levels in these fish, but does not account for the increased response to the releasing hormones. Castration abolished the response of cultured pituitary cells to sGnRH (I fM-100 nM) without altering either their basal rate of secretion or circulating GH levels. Addition of steroids to the culture medium (MT or estradiol at 10 nM for 2 days) enabled a GH response to sGnRH stimulation in cells from sexually regressed fish. Pituitary cells which had not been exposed to steroids failed to respond to sGnRH, although their response to forskolin or TPA was similar to that of steroid-exposed cells. It would appear, therefore, that at least one of the effects of the sex steroids on the response to GnRH is exerted proximally to the formation of cAMP, or PKC, presumably at the level of the receptor. An increase in the number of receptors to the GH-releasing hormones, following steroid exposure, would explain also the changing nature of the GH secretory profile in different stages of the reproductive season.

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Effects of sexual maturation, castration, and androgen implants on growth in one‐ and two‐year‐old parr in a Baltic Atlantic salmon (Salmo salar L.) stock

Cited by 27 publications

References 15 publications

Effects of aromatase inhibitors on sexual maturation in Atlantic salmon, Salmo salar, male parr

Effects of aromatase inhibitors on sexual maturation in Atlantic salmon, Salmo salar, male parr

Body size versus gonad maturation form in under-yearling precocious males of the sea trout (Salmo trutta m. trutta L.)

The effects of gonadal development and sex steroids on growth hormone secretion in the male tilapia hybrid (Oreochromis niloticus � O. aureus)

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