In vivo steroid regulation of aromatase and 5α-reductase in goldfish brain and pituitary

Pasmanik, Metsada; Schlinger, Barney A.; Callard, Gloria V.

doi:10.1016/0016-6480(88)90308-5

Cited by 79 publications

(31 citation statements)

References 18 publications

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“…Estrogens can lead to the aetivation of brain aromatase [29], whieh in turn has a role in the regulation of gonadotropin-releasing hormone or inhibitors of gonadotropin-releasing hormone. This mechanism may explain why both male and female trout showed elevated gonad size.…”

Section: Discussionmentioning

confidence: 99%

Stimulation of reproductive growth in rainbow trout (Oncorhynchus mykiss) following exposure to treated sewage effluent

Höger

Taylor

Hitzfeld

et al. 2006

Enviro Toxic and Chemistry

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Abstract-Ralnbow trout (Oncorhynchus mykiss) were exposed to 1.5 and 15% viv secondary treated sewage etlluent for 32 wecks in ftow-through mesocosms. The exposure encompassed the full periocl of reproductive development for rainbow traut. Traut dicl not show any evidence of a dose-c1ependent change in growth. Fish exposed to 15% effluent were the only group to show morlality (5%) over the duration of the experiment. Trout at the highest effluent concentratlon had significantly higher liver size than reference water fish. Both male and femalc trom in the 15% cxposure group also exhibited significantly higher gonad wcight tban thc rcfcrcnce graul'. In female trout, this gonad size increase could be explained by higher egg numbers. Female antt male traut both displayed a significant increase in plasma 17ß-estradiollevels after exposure to 15% effluent, while neither sex had dose-dependent differences in plasma testosterone. Male trout displayed elevated vitellogenin levels and reduced plasma 11-ketotestosterone concentration after exposure to 15% eftluent. Chemical examination of steraidal compounds, including both estrogens and androgens, in the wastewater revealed that only estrane was detectable at a mean concentratioll of 4.5 ng/L. It is assumed that the effects observed in trout exposed to 15% eftluent were consistent witb stimulation 01' reproductive development due to very low levels of estrogens. Overall, long-term exposure to treated sewage eftluent containing low levels of estrogen did not have significant negative implications for reproductive development in rainbow trout.

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Section: Discussionmentioning

confidence: 99%

Stimulation of reproductive growth in rainbow trout (Oncorhynchus mykiss) following exposure to treated sewage effluent

Höger

Taylor

Hitzfeld

et al. 2006

Enviro Toxic and Chemistry

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“…Rats that are genetically deficient for androgen receptors exhibit significantly reduced hypothalamic AA [ 13]. Together these data suggest that androgens regulate estrogen formation in brain through a receptor-mediated mech anism.In several other species estradiol stimulates brain aromatase [14][15][16][17][18]. We have been unable to demonstrate an effect of estra diol alone in the rat [3,19], However, our recent observation that estradiol treatment significantly increases androgen recep tor levels in the POA of castrate rats [20] suggests that estrogens and androgens might act together to regulate AA in the POA.…”

mentioning

confidence: 84%

Synergistic Induction of Aromatase Activity in the Rat Brain by Estradiol and 5α-Dihydrotestosterone

Roselli

1991

Neuroendocrinology

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Estrogens are produced locally from androgen precursors by cells within the hypothalamus and preoptic area (POA). The activity of the aromatase enzyme complex responsible for this intracellular conversion is controlled by gonadal steroids. The purpose of this study was to determine: whether estrogen acts together with androgen to regulate aromatase activity (AA) and whether nuclear androgen receptor levels are increased after exposure to combined treatment with estradiol benzoate (EB) and dihydrotestosterone (DHT). Thus, adult male rats were castrated and treated for 1 week with either vehicle (0.1 ml sesame oil, s.c), EB (2 µg/day), testosterone (3-cm Silastic implant), DHT (3-cm Silastic implant) or EB + DHT. These treatments produced hormone levels in the physiologic range. We found that both testosterone and DHT significantly stimulated AA (p < 0.05 vs. castrated rats). However, testosterone induced AA significantly more than DHT in the POA (p < 0.05; castrated + testosterone vs. castrated + DHT). EB alone did not affect AA but synergized with DHT to stimulate AA in the POA to levels equivalent with the testosterone-treated group. By comparison, EB alone did not enhance the induction of AA by DHT in the hypothalamus. Combined treatment with EB and DHT had no effect on the concentrations of nuclear androgen receptors in either tissue suggesting that the effect of EB was not mediated through an androgen receptor mechanism. These results suggest that both androgens and estrogens play a physiologic role in the control of estrogen formation in the rat brain. Furthermore, the anatomical specificity that we observed indicates that critical differences in enzyme responsiveness are present in different areas of the brain.

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“…The brain of adult fish is well knownfor its high aromatase activity (Pasmanik and Callard, 1985;Pasmanik et al, 1988) corresponding to the strong expression of the cyp19a1b gene, that encodes CYP19A1B (or aromatase B), the brain form of aromatase in fish (Chiang et al, 2001;Tchoudakova et al, 2001). Although the functional significance for this unique feature of the fish brain is not fully understood, the mechanisms underlying this high expression are starting to be well deciphered.…”

Section: Introductionmentioning

confidence: 99%

Early regulation of brain aromatase (cyp19a1b) by estrogen receptors during zebrafish development

Mouriec

Lareyre

Tong

et al. 2009

Developmental Dynamics

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In vivo steroid regulation of aromatase and 5α-reductase in goldfish brain and pituitary

Cited by 79 publications

References 18 publications

Stimulation of reproductive growth in rainbow trout (Oncorhynchus mykiss) following exposure to treated sewage effluent

Stimulation of reproductive growth in rainbow trout (Oncorhynchus mykiss) following exposure to treated sewage effluent

Synergistic Induction of Aromatase Activity in the Rat Brain by Estradiol and 5α-Dihydrotestosterone

Early regulation of brain aromatase (cyp19a1b) by estrogen receptors during zebrafish development

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