Document Detail

Effects of larval-juvenile treatment with perchlorate and co-treatment with thyroxine on zebrafish sex ratios.
MedLine Citation:
PMID:  17196199     Owner:  NLM     Status:  MEDLINE    
The objective of this study was to determine the effect of larval-juvenile exposure to perchlorate, a thyroid hormone synthesis inhibitor, on the establishment of gonadal sex ratios in zebrafish. Zebrafish were exposed to untreated water or water containing perchlorate at 100 or 250 ppm for a period of 30 days starting at 3 days postfertilization (dpf). Recovery treatments consisted of a combination of perchlorate and exogenous thyroxine (T4; 10 nM). Thyroid histology was assessed at the end of the treatment period (33 dpf), and gonadal histology and sex ratios were determined in fish that were allowed an additional 10-day period of growth in untreated water. As expected, exposure to perchlorate caused changes in thyroid histology consistent with hypothyroidism and these effects were reversed by co-treatment with exogenous T4. Perchlorate did not affect fish survival but co-treatment with T4 induced higher mortality. However, relative to the corresponding perchlorate concentration, co-treatment with T4 caused increased mortality only at a perchlorate concentration of 100 ppm. Perchlorate alone or in the presence of T4 suppressed body length at 43 dpf relative to control values. Perchlorate exposure skewed the sex ratio toward female in a concentration-dependent manner, and co-treatment with T4 not only blocked the feminizing effect of perchlorate but also overcompensated by skewing the sex ratio towards male. Moreover, co-treatment with T4 advanced the onset of spermatogenesis in males. There was no clear association between sex ratios and larval survival or growth. We conclude that endogenous thyroid hormone plays a role in the establishment of gonadal sex phenotype during early development in zebrafish.
Sandeep Mukhi; Leticia Torres; Reynaldo Patiño
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-12-28
Journal Detail:
Title:  General and comparative endocrinology     Volume:  150     ISSN:  0016-6480     ISO Abbreviation:  Gen. Comp. Endocrinol.     Publication Date:  2007 Feb 
Date Detail:
Created Date:  2007-01-08     Completed Date:  2007-02-27     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0370735     Medline TA:  Gen Comp Endocrinol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  486-94     Citation Subset:  IM    
Department of Environmental Toxicology and Texas Cooperative Fish and Wildlife Research Unit, Texas Tech University, Lubbock, TX 79409-1160, USA.
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MeSH Terms
Age Factors
Analysis of Variance
Dose-Response Relationship, Drug
Drug Interactions
Environmental Pollutants / administration & dosage,  pharmacology*
Gonads / drug effects*,  growth & development
Larva / drug effects,  growth & development
Perchloric Acid / administration & dosage,  pharmacology*
Sex Differentiation / drug effects*
Sex Ratio
Statistics, Nonparametric
Thyroid Gland / drug effects,  growth & development,  metabolism
Thyroxine / administration & dosage,  metabolism*
Zebrafish / growth & development,  metabolism*
Reg. No./Substance:
0/Environmental Pollutants; 0/perchlorate; 7488-70-2/Thyroxine; 7601-90-3/Perchloric Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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