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PLASMA CLEARANCE OF VITELLOGENIN IN SHEEPSHEAD MINNOWS AFTER CESSATION OF EXPOSURE TO 17BETA-ESTRADIOL AND PARA-NONYLPHENOL
Citation:
Hemmer, R L., M J. Hemmer, S D. Friedman, D T. Marcovich, K. J. Kroll, AND N D. Denslow. PLASMA CLEARANCE OF VITELLOGENIN IN SHEEPSHEAD MINNOWS AFTER CESSATION OF EXPOSURE TO 17BETA-ESTRADIOL AND PARA-NONYLPHENOL. Presented at SETAC 20th Annual Meeting, Philadelphia, PA, November 14-18, 1999.
Description:
Two experiments were performed to determine the rate of vitellogenin plasma accumulation and clearance in male sheepshead minnows (Cyprinodon variegatus) during and after exposure to either 17b-estradiol (E2) or para-nonylphenol (p-NP). Adult fish were continuously exposed to aqueous concentnrations of 100 and 1000 ng E2/L, and 10 and 100 |g p-NP/L for 16 days in duplicate experiments using an intermittent flow-through dosing apparatus. E2 exposure concentrations were monitored weekly by radioimmunoassay and p-NP by GC-flame ionization throughout the 16-day dosing periods. Separate triethylene glycol treatments at 50 |l/L served as the negative solvent control for both tests. Fish were sampled on days 8 and 16 of exposure followed by sampling 2,4,8, 13 and 21 days post-exposure in the first experiment, and 2,4,8,13,16,21,26,30 and 55 days post-exposure in the second experiment. At each time period, five fish were randomly sampled from each concentration and the serum vitellogenin level for individual fish determined by direct ELISA. Exposure to E2 and p-NP resulted in a dose dependent increase in plasma vitellogenin over the course of the 16-day exposure period. Vitellogenin levels began decreasing with 2 days after exposure cessation and exhibited an exponential rate of elimination from the plasma. Clearance curves were comparable between E2 and p-NP at both the high and low concentrations tested. Our results indicate that in sheephead minnows clearance of plasma vitellogenin is concentration and time dependent and may be detectable for weeks after initial exposure to an estrogenic chemical.