Journal Article

Postulated Human Sperm Count Decline May Involve Historic Elimination of Juvenile Iodine Deficiency: A New Hypothesis with Experimental Evidence in the Rat

James W. Crissman, Paul S. Cooke, Rex A. Hess, M. Sue Marty and Ashley B. Liberacki

in Toxicological Sciences

Volume 53, issue 2, pages 400-410
Published in print February 2000 | ISSN: 1096-6080
Published online February 2000 | e-ISSN: 1096-0929 | DOI: http://dx.doi.org/10.1093/toxsci/53.2.400
Postulated Human Sperm Count Decline May Involve Historic Elimination of Juvenile Iodine Deficiency: A New Hypothesis with Experimental Evidence in the Rat

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Human sperm count studies, historic dietary iodination, and an animal model where neonatal goitrogen administration causes unprecedented testis enlargement, together suggest an hypothesis relevant to the postulated fall in human sperm counts. We present the hypothesis with a supporting study extending the model to include iodine deficiency. In a one-generation rat reproduction study, dams were fed an iodine sufficient (control, 200 ppb I) or deficient (low iodine diet [LID], <20 ppb I) diet from prebreeding through weaning, when male offspring were divided into three groups: 1) controls from iodine sufficient dams, 2) neonatal LID (NLID) from the LID dams, fed control diet postweaning, and 3) chronic LID (CLID) from LID dams, fed a moderate LID (40 ppb I) postweaning. F1 males were euthanized on postnatal day (PND) 133 ± 1. Each of the three diet groups comprised two subgroups in which testicular parameters were evaluated: 1) daily sperm production (DSP), sperm motility, morphology, and histopathology, and 2) Sertoli cell and round spermatid morphometry. In the first subgroup, NLID and CLID testes weights were 8.5% and 14.0% heavier than their unusually heavy controls (3.921 g; historical control mean ≅ 3.5 g), with proportional DSP increases. Sperm motility, morphology, and testis histopathology were unaffected. In the morphometry subgroup, respective increases in NLID and CLID rats included testes weights (+28.6% and +20.3%), Sertoli cells (+24.8% and +23.9%), and round spermatids (+20.4% and +15.8%). The results indicate that neonatal iodine deficiency can significantly increase spermatogenic function in rats, and support our hypothesis concerning human sperm counts.

Keywords: iodine deficiency; hypothyroidism; sperm count; sertoli cells; rat; human; testes.

Journal Article.  9828 words.  Illustrated.

Subjects: Medical Toxicology ; Toxicology (Non-medical)

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