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Effect of Environmental Exposures on the Egg Fertilizing Ability of Human Sperm

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00012480
Recruitment Status : Completed
First Posted : March 12, 2001
Last Update Posted : April 15, 2015
Information provided by:
National Institute of Environmental Health Sciences (NIEHS)

Brief Summary:
Our data indicate that environmental exposure to the heavy metal lead are more widespread than currently appreciated and that such exposures are associated with the production of human male subfertility. Lead's effects are observed in male partners of infertile couples attending an IVF clinical, in men acting as semen donors in an artificial insemination program and in men representative of the general public. Our goal is to identify the mechanism(s) underlying lead's anti-fertility action.

Condition or disease
Male Infertility Testicular Diseases Urologic and Male Genital Diseases Lead Poisoning

Detailed Description:

Our goal is to understand how environmental and occupational exposures to heavy and transition metal ions injure the human male reproductive tract.

The American Urological Association and the American Society for Reproductive Medicine report that ~15% of couples (i.e., more than 6.1 million people in the U.S.) experience infertility at some time. The male is responsible for infertility of 20% of these couples and contributes to the infertility of another 30-40%. However, the cause(s) of male infertility in many cases is unknown. Our data suggest that lead exposures (in the air, in food and in drinking water) underlie a significant fraction of "unexplained" male infertility. We found that blood and seminal plasma lead levels were elevated in 22% of normospermic males from couples seeking infertility treatment, in 29% of semen donors participating in an artificial insemination program and in 23% of unselected semen donors answering an advertisement for research participation. These elevated lead levels were associated with decreased sperm fertility potential in IVF, in artificial insemination and in pregnancy by coitus. The negative effects of lead on sperm function was correlated with expression of specific forms of sperm ion channels (metal binding proteins that allow lead to enter cells), suggesting that such proteins serve as markers for susceptibility or resistance to the reproductive toxic effects of lead. Further, in cases in which human male lead levels changed markedly over time, there were corresponding changes in sperm ion channel, sperm function and sperm fertility potential. These changes were linked to changes in calcium modulated processes in human testis biopsies obtained from infertility patients and could be mimicked in testes of rats experimentally fed lead.

In the current study, we plan to identify changes in gene expression important to the production of the infertile state by comparing the genes expressed in the testis of control and lead exposed rats which are resistant or susceptible to lead. These findings will help to explain how lead exposure kill cells within the testis. We will then determine whether the same changes occur in human testis biopsies and ejaculated sperm from infertile males with high body burdens of lead. The expected outcome of this study is the identification of a possible mechanism explaining male infertility associated with low sperm counts or idiopathic male infertility, tools for diagnosis of male infertility and the hope for rationale treatment.

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Study Type : Observational
Estimated Enrollment : 400 participants
Official Title: Human Sperm Zona Acceptor: Environmental Effects
Study Start Date : August 2002
Actual Primary Completion Date : July 2007
Actual Study Completion Date : July 2007

Information from the National Library of Medicine

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Ages Eligible for Study:   21 Years to 55 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes
  • Otherwise healthy men seeking fertility evaluation, without history of urologic infections or varicocele.
  • Non-smokers.
  • Occupationally exposed to lead or not exposed to lead.
  • Otherwise healthy men undergoing testis biopsy for clinical assessment of spermatogenesis or for sperm retrieval prior to an attempt at assisted reproduction.
  • Otherwise healthy men providing semen specimens for clinical analysis prior to an attempt at assisted reproduction.

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00012480

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United States, California
University of Southern California Women's and Children's Hospital
Los Angeles, California, United States, 90033
United States, New York
North Shore University Hospital
Manhasset, New York, United States, 11030
United States, Pennsylvania
Copper Hospital and Fertility Testing Laboratory and Sperm Bank
Philadelphia, Pennsylvania, United States, 19107
Sponsors and Collaborators
National Institute of Environmental Health Sciences (NIEHS)
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Principal Investigator: Susan H Benoff, PhD North Shore University Hospital
Layout table for additonal information Identifier: NCT00012480    
Other Study ID Numbers: 6100-CP-001
First Posted: March 12, 2001    Key Record Dates
Last Update Posted: April 15, 2015
Last Verified: April 2015
Keywords provided by National Institute of Environmental Health Sciences (NIEHS):
Male infertility
Gene expression
Economics, Medical
Additional relevant MeSH terms:
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Infertility, Male
Testicular Diseases
Genital Diseases, Male
Lead Poisoning
Genital Diseases, Female
Chemically-Induced Disorders
Heavy Metal Poisoning
Gonadal Disorders
Endocrine System Diseases