Alterations in the Estrogen Environment of the Testis Contribute to Declining Sperm Production

Date of Award


Degree Name

Master of Science


Biological Sciences

First Advisor

Dr. Christopher A. Pearl

Second Advisor

Dr. John Spitsbergen

Third Advisor

Dr. Cindy Linn

Access Setting

Masters Thesis-Abstract Only


Testis function declines with age, both in terms of spermatogenesis and steroidogenesis. Estrogen concentrations also fall with age, but little research has studied this correlation. This study investigated the estrogen environment of the aging rat testis and elucidated possible mechanisms for how estrogen and sperm decline are connected by comparing natural aging with an estrogen treatment protocol during the same aging window. Steroid hormone concentrations, estrogen receptor expression and localizations, testis morphology, apoptosis levels, and pituitary hormone levels were all studied in connection with aging and with estrogen treatment. Aging causes a decline in sperm production, testosterone and estrogen concentrations, and reduces estrogen receptor alpha expression. Estrogen treatment was shown to prevent approximately 50% of the age-dependent loss of sperm production and was able to restore youthful estrogen concentrations and estrogen receptor expression levels.


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