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

April 14, 2015 updated by: National Institute of Environmental Health Sciences (NIEHS)

Human Sperm Zona Acceptor: Environmental Effects

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.

Study Overview

Status

Completed

Conditions

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.

Study Type

Observational

Enrollment (Anticipated)

400

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • California
      • Los Angeles, California, United States, 90033
        • University of Southern California Women's and Children's Hospital
    • New York
      • Manhasset, New York, United States, 11030
        • North Shore University Hospital
    • Pennsylvania
      • Philadelphia, Pennsylvania, United States, 19107
        • Copper Hospital and Fertility Testing Laboratory and Sperm Bank

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

21 years to 55 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

Male

Description

  • 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.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

National Institute of Environmental Health Sciences (NIEHS)

Investigators

  • Principal Investigator: Susan H Benoff, PhD, North Shore University Hospital

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

August 1, 2002

Primary Completion (Actual)

July 1, 2007

Study Completion (Actual)

July 1, 2007

Study Registration Dates

First Submitted

March 9, 2001

First Submitted That Met QC Criteria

March 9, 2001

First Posted (Estimate)

March 12, 2001

Study Record Updates

Last Update Posted (Estimate)

April 15, 2015

Last Update Submitted That Met QC Criteria

April 14, 2015

Last Verified

April 1, 2015

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 6100-CP-001

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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