Biomarkers of reproductive toxicity.

A biomarker can be broadly defined as any biological index capable of being measured, which is associated with or indicative of a defined biological endpoint such as a developmental or disease stage. Identification and verification of anatomical, endocrine, cellular and molecular biomarkers is crucial for successful clinical diagnosis and treatment of toxicity and disease, as well as basic toxicological, epidemiological and other research. Various biomarkers of reproductive development and health have been identified, including those associated with pubertal development, adult reproductive health and pregnancy outcome. Herein we discuss those in situ biomarkers which have been more closely associated with toxicant action on the reproductive system. Biomarkers of toxicant exposure and susceptibility are addressed, but the majority of the review focuses on those biomarkers which may prove useful for determining current pathophysiological status or predicting future adverse outcomes. In males these are primarily associated with altered spermatogenesis and sperm parameters, and in females with altered endocrine function. We conclude that although few robust in situ biomarkers are currently available which are specific for toxicant exposure, susceptibility or effect in reproductive systems, there is expectation that post-genomic technologies offer a new paradigm for identifying and verifying such biomarkers as may exist.