PARENT SESSION
5C Ecological relevance of endocrine disruption
9:00 AM to 7:00 PM, Tuesday, 08 May 2001
Session Chair:

(T/FF218) Tributyltin disrupts the vertebrate reproductive system at multiple sites.

Kime, David¹, Huyskens, Geert², McAllister, Brian¹, Rurangwa, Eugene², Skorkowski, Eduard³, Ollevier, Frans², ^{1 2 3}

ABSTRACT- The induction of imposex in marine gastropods by tributyltin (TBT) is generally considered to be due to it's action as an aromatase inhibitor which blocks conversion of testosterone to estradiol. We show that in teleost fish TBT, at environmentally relevant concentrations, is an inhibitor not only of aromatase, but also of 20HSD (which converts 17-hydroxyprogesterone to the maturation inducing steroid 17,20-dihydroxy-4-pregnen-3-one). Furthermore ppb concentrations of TBT decrease both the motility of teleost sperm and it's ATP content while increasing that of AMP. Since ATP provides the energy source for sperm movement and is an essential component of the monooxygenase system for steroidogenesis we consider that TBT is better termed an ATP disruptor than an aromatase inhibitor. A recent preliminary study showing that TBT is a neurotoxin suggests that it could also alter neuroendocrine activity including hypothalamic function in vertebrates and reproduction in invertebrates. These data suggest that TBT disrupts reproduction in fish at multiple sites by inhibiting steroid hormone production, interfering with pituitary-hypothalamic function and decreasing sperm motility.

Key words: tributyltin, sperm, steroidogenesis, ATP