Involvement of Multiple Biotransformation Processes in the Metabolic Elimination of Testosterone by Juvenile and Adult Fathead Minnows (Pimephales promelas)

Parks, Leo W.; LeBlanc, Gerald A.

doi:10.1006/gcen.1998.7131

Cited by 31 publications

(10 citation statements)

References 43 publications

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“…A possible explanation for these results could be that the active steroid environment is controlled not only by the dynamics of secretion in glandular tissue but also by conjugation/deconjugation in target tissues (Cuevas et al, 1992). Differences in clearance rates for the various steroid fractions could also contribute to lower correlations when the various fractions are analyzed separately (Parks and Le Blanc, 1998). However, the role of conjugation in steroid function in physiology and behavior in fishes requires further investigation.…”

Section: Discussionmentioning

confidence: 99%

Endocrine Correlates of Male Polymorphism and Alternative Reproductive Tactics in the Azorean Rock-Pool Blenny, Parablennius sanguinolentus parvicornis

Oliveira

Canário

Grober

et al. 2001

General and Comparative Endocrinology

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In the Azorean rock-pool blenny male sexual polymorphism occurs. Larger and older males (M؉ males) fully express male secondary sex characters (SSC), particularly an anal gland that produces a sex pheromone, whereas smaller and younger sexually active males do not express SSC (M؊ males). Two mating tactic types can be identified among M؉ males: nest-holders that establish nests and court females and floaters that move around in the breeding area and try to achieve parasitic fertilizations and/or to take over nests. Two behavioral tactic types can also be identified within M؊ males: satellites that are associated with particular nests and actively participate in territorial defense (when females go inside the nest to spawn they try to enter to fertilize some of the eggs) and sneakers that do not help nest holders (when spawning occurs they also try to enter the nest to fertilize eggs). It was found that M؉ males have significantly higher levels of 11-ketotestosterone (KT), but not testosterone (T), than M؊ males [M؉ male androgen levels (mean ؎ SE): total T ‫؍‬ 11.6 ؎ 3.0 ng ml ؊1 , total KT ‫؍‬ 4.5 ؎ 1.1 ng ml ؊1 ; M؊ male androgen levels (mean ؎ SE): total T ‫؍‬ 9.6 ؎ 1.0 ng ml ؊1 , total KT ‫؍‬ 2.5 ؎ 1.1 ng ml ؊1 ]. There were no differences in plasma T or KT among individuals using different mating tactics within the same male morph; that is, among M؉ males, nest-holders did not differ in androgen levels from floaters [nest-holder androgen levels (mean ؎ SE): total T ‫؍‬ 12.3 ؎ 4.4 ng ml ؊1 , total KT ‫؍‬ 4.3 ؎ 1.4 ng ml ؊1 ; floater androgen levels (mean ؎ SE): total T ‫؍‬ 5.9 ؎ 0.8 ng ml ؊1 , total KT ‫؍‬ 3.4 ؎ 0.3 ng ml ؊1 ], and among M؊ males, satellites did not differ in androgen levels from sneakers [satellite androgen levels (mean ؎ SE): total T ‫؍‬ 7.7 ؎ 1.5 ng ml ؊1 , total KT ‫؍‬ 1.3 ؎ 0.3 ng ml ؊1 ; sneaker androgen levels (mean ؎ SE): total T ‫؍‬ 8.3 ؎ 1.6 ng ml ؊1 , total KT ‫؍‬ 1.4 ؎ 0.3 ng ml ؊1 ]. Thus, the observed differences appear to be correlated with the expression of different male morphotypes and not with the expression of different behavioral tactics within the morphotype. Androgen levels were not correlated with the behavior activity of nest-holders, except for a negative correlation between KT levels and parental behavior. Furthermore, nestholder males that succeeded in having females spawn in their nests during the observation period had significantly lower KT levels than unsuccessful males. Since behavioral observations preceded blood sampling in time, it is suggested that these results indicate a negative relationship between KT and parental care, since successful males were parenting when blood samples were collected. Male SSC were better correlated with KT than with T and the use of total blood levels (i.e., free ؉ conjugates) yielded higher correlation coefficients than when only the free fraction of each steroid was considered. Since conjugates are nonactive metabolites of the 1 To whom correspondence should be addressed. E-mail:ruiol@ispa.pt. 278free androgen they should r...

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Section: Discussionmentioning

confidence: 99%

Endocrine Correlates of Male Polymorphism and Alternative Reproductive Tactics in the Azorean Rock-Pool Blenny, Parablennius sanguinolentus parvicornis

Oliveira

Canário

Grober

et al. 2001

General and Comparative Endocrinology

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“…The mechanisms behind these actions appear varied, with receptor binding only one of a number of possible responses. For example, contaminants also appear to influence the endocrine system by altering enzymes that enable hormone synthesis (20)(21)(22), hormone metabolism (23,24), and hormone storage on plasma carrier proteins (25,26).…”

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confidence: 99%

Aromatase activity in the ovary and brain of the eastern mosquitofish (Gambusia holbrooki) exposed to paper mill effluent.

Orlando

Davis

Guillette

2002

Environ Health Perspect

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Endocrine DisruptorsStudies have shown that female mosquitofish living downstream of a paper mill located on the Fenholloway River, Florida, have masculinized secondary sex characteristics, including altered anal fin development and reproductive behavior. Masculinization can be caused by exposure to androgens in the water or from an alteration in aromatase activity in the fish. We hypothesized that aromatase activity would be inhibited by a component(s) of the paper mill effluent. Aromatase inhibition could masculinize the hormonal profile and, subsequently, secondary sex characteristics of the exposed females. Therefore, we predicted that ovarian and brain aromatase activity would be lower in the female mosquitofish from the Fenholloway River compared with the reference site, the Econfina River. Adult females were collected and standard length, body mass, anal fin length, and segment number were measured. Ovarian and brain aromatase activity were determined using a tritiated water assay.

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“…Homeostasis could be disrupted by xenobiotic-induced alterations of sex steroid-metabolizing cytochrome P450 enzymes. By inducing or blocking these enzymes, the natural balance of circulating sex steroids could conceivably be altered from normal [5,6].…”

Section: Introductionmentioning

confidence: 98%

“…This sexual dimorphism is imprinted during development, a process mediated by sex steroids. Fish, birds, and marine mammals are among the other groups that have demonstrated sexual dimorphism in cytochrome P450 enzymes [5]. Possible mechanisms through which normal endocrine homeostasis could be disrupted by hormonally active agents include altering (a) the hypothalamic-pituitary axis; (b) the activity of steroidogenic enzymes (developmentally or directly); (c) the function of steroid-binding molecules such as sex hormone-binding globulin; (d) the activity of hormone receptors by acting as hormone agonists or antagonists; (e) the rate of hepatic steroid inactivation; or (f) renal clearance.…”

Section: Introductionmentioning

confidence: 99%

Sex‐specific effects of gestational and lactational coexposure to lead and cadmium on hepatic phase I and phase II xenobiotic/steroid‐metabolizing enzymes and antioxidant status

Pillai

Patel

Pandya

et al. 2009

J Biochem & Molecular Tox

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Liver has evolved complex enzymatic mechanisms to detoxify a wide array of xenobiotic substances, ranging from dietary components to environmental toxins to pharmaceuticals. Activities of many steroid-metabolizing enzymes in adult rat liver microsomes are sexually differentiated. Toxic effects of lead and cadmium on hepatic tissue have been well established in our earlier studies. We thus monitored the effects of gestational and lactational coexposure to lead and cadmium on hepatic phase I and phase II xenobiotic- and steroid-metabolizing enzyme activities in both male and female F1 generation postnatal day (PND) 56 rats. Adult pregnant female rats were treated subcutaneously [0.05 mg/(kg body wt. day)] with sodium acetate (control group), lead acetate, and cadmium acetate separately and in combination throughout the gestational and lactational period. Hepatic phase I xenobiotic-metabolizing enzymes (NADPH- and NADH-cytochrome c reductase) activities significantly decreased significantly in all the metal-treated groups in both PND 56 male and female rats as compared with the control group. Hepatic phase II enzymes (uridine diphosphate-glucuronosyl transferase, gamma-glutamyl transpeptidase, glutathione-S-transferase, 17-beta-hydroxysteroid oxidoreductase) were also highly susceptible to all the metal-treated groups. The observed alterations in the oxidative stress and biochemical parameters in the liver of F1 generation male and female rats resulted from an independent effect of lead and/or cadmium and also from their interaction. Results suggest that early developmental exposure to lead and cadmium both alone and in combination can suppress the hepatic xenobiotic-metabolizing enzyme activities in the liver of F1 generation male and female rats in a sex-dependent manner.

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Involvement of Multiple Biotransformation Processes in the Metabolic Elimination of Testosterone by Juvenile and Adult Fathead Minnows (Pimephales promelas)

Cited by 31 publications

References 43 publications

Endocrine Correlates of Male Polymorphism and Alternative Reproductive Tactics in the Azorean Rock-Pool Blenny, Parablennius sanguinolentus parvicornis

Endocrine Correlates of Male Polymorphism and Alternative Reproductive Tactics in the Azorean Rock-Pool Blenny, Parablennius sanguinolentus parvicornis

Aromatase activity in the ovary and brain of the eastern mosquitofish (Gambusia holbrooki) exposed to paper mill effluent.

Sex‐specific effects of gestational and lactational coexposure to lead and cadmium on hepatic phase I and phase II xenobiotic/steroid‐metabolizing enzymes and antioxidant status

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