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Stacia A. Sower,¹ Karen L. Reed,¹ and Kimberly J. Babbitt²

¹Department of Biochemistry and Molecular Biology, ²Department of Natural Resources, University of New Hampshire, Durham, New Hampshire, USA

Abstract

Declines in amphibian populations, and amphibians with gross malformations, have prompted concern regarding the biological status of many anuran species. A survey of bullfrogs, Rana catesbeiana, and green frogs, Rana clamitans, conducted in central and southern New Hampshire showed malformed frogs at 81% of the sites sampled (13 of 16 sites) . Brain gonadotropin-releasing hormone (GnRH) and the synthesis of androgens and estradiol, hormones essential to reproductive processes, were measured from limb-malformed and normal (no limb malformation) frogs. Normal frogs had significantly higher concentrations (nearly 3-fold) of in vitro produced androgens and of brain GnRH than malformed frogs. Because most malformations are thought to occur during development, we propose that environmental factors or endocrine-disrupting chemicals that may cause developmental abnormalities also act during early development to ultimately cause abnormally reduced GnRH and androgen production in adult frogs. The consequences of reduced GnRH and androgens on anuran reproductive behavior and population dynamics are unknown but certainly may be profound and warrant further research. Key words: amphibians, androgens, endocrine-disrupting chemicals, environmental influences, frogs, gonadotropin-releasing hormone. Environ Health Perspect 108:1085-1090 (2000) . [Online 25 October 2000]

http://ehpnet1.niehs.nih.gov/docs/2000/108p1085-1090sower/ abstract.html

Address correspondence to S.A. Sower, Department of Biochemistry and Molecular Biology, Rudman Hall, University of New Hampshire, Durham, NH 03824 USA. Telephone: (603) 862-2103. Fax: (603) 862-4013. E-mail: sasower@cisunix.unh.edu

We thank C. Gibadlo, K. Suzuki, and C. Chase for skillful technical assistance. We also thank H. Snook and A. Archer of the New Hampshire Department of Environmental Services, L. Eaton-Poole of the U.S. Fish and Wildlife Services, and the many volunteers involved in field sampling. We thank F. Quimby for his review and comments on this manuscript. We also thank J.B.K. Leonard for her assistance and help in editing the manuscript.

This study was supported by a grant from the Sustainability Program, the Colleges of Life Sciences and Agriculture, the Office of Sponsored Research, and the Office of Vice President for Research and Public Service at the University of New Hampshire. This paper is scientific contribution no. 2033 from the New Hampshire Agricultural Experiment Station. The handling of the frogs was in accordance with the University of New Hampshire animal care guidelines.

Received 7 December 1999 ; accepted 13 June 2000.