Oral Estrogen Masculinizes Female Zebra Finch Song System

Quaglino, Allison; Craig-Veit, C.B.; Viant, Mark R.; Erichsen, A; Fry, D. Michael; Millam, James R.

doi:10.1006/hbeh.2001.1752

Cited by 22 publications

(7 citation statements)

References 31 publications

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“…Nonetheless, some individuals responded to the 5 μg dose and had Area X volumes above zero (Figure 1), and two birds in this group had bigger volumes than have ever been reported for control females [16]. A previous study also found that Area X volume was more sensitive to the effects of E2 than other measures [26]. Notably, our results do not preclude the possibility that the male song system could still be exquisitely sensitive to E2's influence.…”

Section: Discussionmentioning

confidence: 58%

“…Estradiol (E2) administration to hatchling females markedly masculinizes the female song system [1,6,10,11,12,14,15,18,20,25,26,28], even to the point where they will produce song as adults [29]. Also, events in the normal masculinization of the song system are directed by estrogen [17].…”

mentioning

confidence: 99%

“…A twenty microgram dose was sufficient to masculinize the brain when given in daily injections [1] and a single two microgram dose was sufficient to produce partial masculinization of HVC soma size when implanted under the skin of the breast [12]. One dose-response study using an oral route of administration gave daily doses of approximately 1.3-3.4 μg/day across an entire week beginning at posthatch day 5 and found only modest masculinization in Area X [26]. Thus, data probing the song system's threshold of sensitivity to estrogen are not available.…”

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confidence: 99%

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A dose–response study of estradiol's effects on the developing zebra finch song system

Grisham

Lee

Mankowski

et al. 2008

Neuroscience Letters

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To gauge the sensitivity of the female zebra finch song system to estradiol (E2), we used subcutaneous implants to administer various doses of E2 to hatchling female zebra finches. Four different doses of E2 were administered: 50, 15, 5 and 0 μg via subcutaneous silicon "ropes" at hatching, and the brains were examined in adulthood. Further, we examined whether masculinization was all-or-none once a threshold was reached or if the morphology of the song system would show a graded response to the various doses of E2. Finally, we asked if the various dependent measures-volume of song nuclei, neuron size, and neuron number-would show differential sensitivity to E2.Fifteen micrograms was sufficient to masculinize many aspects of the song system and was often as effective as 50 μg, causing a dramatic difference relative to the 0 μg group. Different aspects of the song system seemed differentially sensitive to the effects of E2: volumes of song control nuclei, the size of RA neurons, and the number of HVC neurons were significantly masculinized by 15 μg E2, but the number of RA neurons and HVC and lMAN soma sizes required 50 μg. The results suggest that several developmental processes are influenced by E2, possibly because of multiple sites of action or multiple processes that respond to E2.

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Section: Discussionmentioning

confidence: 58%

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confidence: 99%

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confidence: 99%

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A dose–response study of estradiol's effects on the developing zebra finch song system

Grisham

Lee

Mankowski

et al. 2008

Neuroscience Letters

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“…Millam and colleagues focused most of their efforts on the zebra finch, demonstrating that oral administration (to mimic parental feeding) of exogenous estradiol benzoate administered shortly after hatching not only reduced fertility but masculinized the song system in the female (but not in males; Millam et al, 2001;Quaglino et al, 2002). Interestingly, the administration of octylphenol, methoxychlor, and dicofol in the doses given had no effect on fertility.…”

Section: Birds Reptiles and Amphibiansmentioning

confidence: 92%

Environmental Endocrine Disruption of Brain and Behavior

Gore¹,

Crews

2009

Hormones, Brain and Behavior

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“…We recently showed that oral exposure to estrogen also masculinizes female zebra finch chick brain in a doselike fashion [16]. We also found that oral exposure to estrogen severely disrupts adult reproductive performance in sex‐specific ways.…”

Section: Introductionmentioning

confidence: 93%

An avian bioassay for environmental estrogens: The growth response of zebra finch (Taeniopygia guttata) chick oviduct to oral estrogens

Millam

Craig-Veit

Batchelder

et al. 2002

Enviro Toxic and Chemistry

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The rat uterotrophic assay is a recommended tier 1 screening assay for environmental estrogens, but no comparable assay exists for altricial birds. We orally dosed zebra finch chicks daily during their linear growth phase (days 5-11) with estradiol benzoate (EB), genistein, methoxychlor, or octylphenol, all dissolved or suspended in canola oil, or canola oil alone, as a vehicle control. On day 12, oviducts were removed, weighed and examined histologically. All doses of EB (0.1-1,000 nmol/g body wt), genistein at 100 nmol/g. and methoxychlor and octylphenol at 1,000 nmol/g, markedly increased oviduct weight, with the highest dose of EB inducing a 60-fold increase over controls. Oviducts were differentiated in a dose-depedent manner to the point of having tubular glands and a pseudostratified, ciliated epithelium at the higher doses of EB. Our earlier results show that EB at 100 and 1,000 nmol/g impairs reproductive performance of zebra finches. Thus, the zebra finch oviduct bioassay measures estrogenicity over a wide dose range and, for EB exposure, can predict impairment in adult reproductive performance. The responsiveness of chick oviducts to estrogen stimulation may serve as a useful marker of estrogen exposure in wild populations of songbirds.

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Oral Estrogen Masculinizes Female Zebra Finch Song System

Cited by 22 publications

References 31 publications

A dose–response study of estradiol's effects on the developing zebra finch song system

A dose–response study of estradiol's effects on the developing zebra finch song system

Environmental Endocrine Disruption of Brain and Behavior

An avian bioassay for environmental estrogens: The growth response of zebra finch (Taeniopygia guttata) chick oviduct to oral estrogens

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