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BROMOCHLOROACETIC ACID EXERTS QUALITATIVE EFFECTS ON RAT SPERM: IMPLICATIONS FOR A NOVEL BIOMARKER
Citation:
Klinefelter, G R., L F. Strader, J D. Suarez, AND N L. Roberts. BROMOCHLOROACETIC ACID EXERTS QUALITATIVE EFFECTS ON RAT SPERM: IMPLICATIONS FOR A NOVEL BIOMARKER. TOXICOLOGICAL SCIENCES 68(1):164-173, (2002).
Description:
ABSTRACT
Disubstituted haloacid by-products of drinking water disinfection such as dibromoacetic acid and dichloroacetic acid have been shown to perturb spermatogenesis and fertility in adult male rats. In the present study we sought to establish whether equimolar exposures to bromochloroacetic acid (BCA), a prevalent by-product in finished drinking water, is also capable of disrupting these endpoints; and if so, to determine whether the novel biomarker of fertility (SP22) would be correlated with subfertility induced by testicular toxicity. A dose range finding study indicated that body weight was not affected by exposure to 14 daily doses of 72 mg/kg BCA while numerous male reproductive parameters were altered including decreases in the number and progressive motility of cauda epididymal sperm. In addition, there was an increased incidence of delayed spermiation in the testes of males exposed to 72 mg/kg BCA. In the definitive study, exposures ranged from 8 to 72 mg/kg, the fertility of cauda epididymal sperm was evaluated by in utero insemination, and the two dimensional profile of cauda sperm membrane proteins was evaluated quantitatively. The morphology of both caput and cauda epididymal sperm was altered by 72 mg/kg BCA. The fertility of cauda epididymal sperm, the percentages of progressively motile sperm and progressive tracks, and two sperm membrane proteins (SP22 and SP9) were decreased signficantly by each BCA exposure. While the two sperm proteins and the two measures of progressive motility were each signficantly correlated with fertility, only one of these measures, i.e. SP22, had a R value of greater than 0.5. When data for SP22 and fertility were fit to a non-linear model, r2 was 0.84. Using this exposure paradigm, the no observed effect level for BCA is less than 8 mg/kg. Moreover, SP22 may be useful in predicting compromised fertility after exposure to by-products of drinking water disinfection.
Key Words: Disinfection By-Products, Fertility, Spermatogenesis, Sperm Biomarker