The Effect of Chronic Testosterone Administration on Sturgeon Gonadotropins in Juvenile and Pre-vitellogenic White Sturgeon (Acipenser transmontanus)

Pavlick, Raymond J.; Moberg, Gary P.

doi:10.1006/gcen.1996.6823

Cited by 18 publications

(7 citation statements)

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“…The present results are consistent with a study examining GnRH+T co‐treatment on juvenile and pre‐vitellogenic white sturgeon Acipenser transmontanus Richardson in which long‐term T treatment stimulated the accumulation of pituitary gonadotropins but did not affect basal GnRH‐induced secretions until more than a year later (Pavlick & Moberg, 1997). Although FSH and LH were not measured in this study, the ovarian responses suggests a GnRH+T‐induced accumulation of pituitary gonadotropin (GTH), but release occurred only when other cues (presumably photoperiodic) were perceived by the fish and transduced into the HPG axis.…”

Section: Discussionsupporting

confidence: 92%

Testing the synergistic effects of GnRH and testosterone on the reproductive physiology of pre‐adult pink salmonOncorhynchus gorbuscha

Crossin

Hinch

Cooke

et al. 2010

Journal of Fish Biology

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To test the hypothesis that the hypothalmic gonadotropin-releasing hormone (GnRH) and testosterone (T) co-treatment stimulates both the hypothalmo-pituitary-gonadal (HPG) and hypothalmo-pituitary-interrenal axes, the reproductive and osmoregulatory responses of pre-adult pink salmon Oncorhynchus gorbuscha were compared after GnRH and T administration either alone or in combination. Relative to controls, neither GnRH nor T treatment resulted in significantly greater ovarian or testicular growth, but co-treatment significantly increased ovarian growth after 5 months. Interestingly, the stimulation was undetectable after 3 months. However, once daily photoperiod began shortening after the summer solstice, c. 2 months before the natural spawning date, GnRH+T-treated females were stimulated to produce larger ovaries. Final fish body length and the size of individual eggs did not differ among treatment groups. GnRH+T eggs, however, showed signs of advanced vitellogenesis relative to GnRH-treated and control eggs, whereas T-treated eggs became atretic. Testis size increased significantly from initial values and most males were spermiating, but this growth and development were independent of hormone treatments. Final plasma ion, metabolite and cortisol concentrations did not differ among treatment groups. It is concluded that GnRH+T co-treatment was effective in stimulating female but not male maturation. GnRH and T treatment, however, presumably had little effect on the hypothalmo-pituitary-interrenal axis as observed by ionoregulatory status.

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Section: Discussionsupporting

confidence: 92%

Testing the synergistic effects of GnRH and testosterone on the reproductive physiology of pre‐adult pink salmonOncorhynchus gorbuscha

Crossin

Hinch

Cooke

et al. 2010

Journal of Fish Biology

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“…Pituitary concentrations of both FSH and LH were significantly higher in juvenile or vitellogenic white sturgeon females that were treated with T implants. However, juvenile sturgeon which were injected intraperitoneally with GnRHa showed no change in plasma concentrations of neither of the GTHs [ 69 ]. These variations are probably due to morphological or endocrine differences between the white and the Russian sturgeon resulting in different hormone levels at specific reproductive stages; yet these assumptions need further confirmation.…”

Section: Discussionmentioning

confidence: 99%

Gonadotropins in the Russian Sturgeon: Their Role in Steroid Secretion and the Effect of Hormonal Treatment on Their Secretion

et al. 2016

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In the reproduction process of male and female fish, pituitary derived gonadotropins (GTHs) play a key role. To be able to specifically investigate certain functions of Luteinizing (LH) and Follicle stimulating hormone (FSH) in Russian sturgeon (Acipenser gueldenstaedtii; st), we produced recombinant variants of the hormones using the yeast Pichia pastoris as a protein production system. We accomplished to create in vitro biologically active heterodimeric glycoproteins consisting of two associated α- and β-subunits in sufficient quantities. Three dimensional modelling of both GTHs was conducted in order to study the differences between the two GTHs. Antibodies were produced against the unique β-subunit of each of the GTHs, in order to be used for immunohistochemical analysis and to develop an ELISA for blood and pituitary hormone quantification. This detection technique revealed the specific localization of the LH and FSH cells in the sturgeon pituitary and pointed out that both cell types are present in substantially higher numbers in mature males and females, compared to immature fish. With the newly attained option to prevent cross-contamination when investigating on the effects of GTH administration, we compared the steroidogeneic response (estradiol and 11-Keto testosterone (11-KT) in female and males, respectively) of recombinant stLH, stFSH, and carp pituitary extract in male and female sturgeon gonads at different developmental stages. Finally, we injected commercially available gonadotropin releasing hormone analog (GnRH) to mature females and found a moderate effect on the development of ovarian follicles. Application of only testosterone (T) resulted in a significant increase in circulating levels of 11-KT whereas the combination of GnRH + T did not affect steroid levels at all. The response pattern for estradiol demonstrated a similar situation. FSH levels showed significant increases when GnRH + T was administered, while no changes were present in LH levels.

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“…In mammals, pulsatile administration of LHRH during the prepubertal stages results in the release of LH and in the onset of puberty [4][5][6][7]. In juvenile fish, however, the levels of the LH-like gonadotropin II (GtH II) in the pituitary are low, and a GnRH treatment alone is often unsuccessful in inducing GtH II release [8][9][10][11]. Since GtH II synthesis in immature fish is under the positive feedback control of gonadal steroids, pituitary GtH II content can be increased by the administration of aromatizable androgens or estrogens [8,9,11,12].…”

Section: Introductionmentioning

confidence: 99%

“…In juvenile fish, however, the levels of the LH-like gonadotropin II (GtH II) in the pituitary are low, and a GnRH treatment alone is often unsuccessful in inducing GtH II release [8][9][10][11]. Since GtH II synthesis in immature fish is under the positive feedback control of gonadal steroids, pituitary GtH II content can be increased by the administration of aromatizable androgens or estrogens [8,9,11,12]. This is unlike the situation in mammals, in which steroids primarily exert inhibiting effects on LH levels during prepubertal stages [13,14].…”

Section: Introductionmentioning

confidence: 99%

“…Although the reproductive axis of most fishes studied can be activated before puberty by the administration of different combinations of steroids, GnRH, and dopamine antagonists, the effectiveness of the various treatments varies among species and may depend on age and developmental stage. In the steroidprimed, immature, female white sturgeon, for instance, a GnRH treatment does not result in GtH II release [11], and immature black carp ovaries do not respond to gonadotropic stimulation [10]. ), rainbow trout (Oncorhynchus mykiss), and African catfish (Clarias gariepinus) [35,36].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of Long-Term Testosterone, Gonadotropin-Releasing Hormone Agonist, and Pimozide Treatments on Gonadotropin II Levels and Ovarian Development in Juvenile Female Striped Bass (Morone saxatilis)1

Holland

Hassin

Zohar

1998

Biology of Reproduction

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The ability of the juvenile female reproductive axis to respond to hormonal stimulation was investigated in a Perciform fish, the striped bass (Morone saxatilis) using various combinations of testosterone (T), GnRH agonist (GnRHa), and pimozide. A long-term treatment with T alone, or T in combination with GnRHa, increased pituitary gonadotropin II (GtH II) levels 2- and 3-fold, respectively, suggesting that T and GnRHa each stimulate GtH II accumulation. Release of the accumulated GtH II could be induced only by high doses of GnRHa in combination with T, indicating that GtH II synthesis and release require different levels of GnRH stimulation. The addition of the dopamine antagonist pimozide did not affect pituitary and plasma GtH II levels but, in response to an additional acute GnRHa challenge, inhibited the release of GtH II. Although ovarian development was slightly stimulated by a combined T and GnRHa treatment, vitellogenesis was generally not initiated. The present study demonstrated that the juvenile striped bass pituitary is responsive to hormonal stimulation, resulting in elevated levels of GtH II in the pituitary and plasma. However, increased plasma levels of GtH II did not result in precocious puberty, suggesting that additional factors are required for the initiation of ovarian development in this teleost.

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The Effect of Chronic Testosterone Administration on Sturgeon Gonadotropins in Juvenile and Pre-vitellogenic White Sturgeon (Acipenser transmontanus)

Cited by 18 publications

References 0 publications

Testing the synergistic effects of GnRH and testosterone on the reproductive physiology of pre‐adult pink salmonOncorhynchus gorbuscha

Testing the synergistic effects of GnRH and testosterone on the reproductive physiology of pre‐adult pink salmonOncorhynchus gorbuscha

Gonadotropins in the Russian Sturgeon: Their Role in Steroid Secretion and the Effect of Hormonal Treatment on Their Secretion

Effects of Long-Term Testosterone, Gonadotropin-Releasing Hormone Agonist, and Pimozide Treatments on Gonadotropin II Levels and Ovarian Development in Juvenile Female Striped Bass (Morone saxatilis)1

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