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Effects of altered food intake during pubertal development in male and female Wistar rats
Citation:
LAWS, S. C., T. E. STOKER, M. G. HOTCHKISS, J. M. FERRELL, AND R. L. COOPER. Effects of altered food intake during pubertal development in male and female Wistar rats . TOXICOLOGICAL SCIENCES. Society of Toxicology, RESTON, VA, 100(1):194-202, (2007).
Impact/Purpose:
To find the optimum endpoints and protocols for the assays that will be used in a Tier I Screening Battery to detect endocrine disrupting chemicals.
Description:
The U.S.EPA is currently validating assays that will be used in a Tier I Screening Battery to detect endocrine disrupting chemicals. A primary concern with the Protocols for the Assessment of Pubertal Development and Thyroid Function in Juvenile Male and Female Rats is that a nonspecific reduction in body weight (BWT) during the exposure period may potentially confound the interpretation of effects on the endocrine endpoints. Wistar rats were underfed 10, 20, 30 or 40% less than the ad libitum food consumed by controls from postnatal days (PND) 22 -42 (females) or PND 23-53 (males). Terminal BWT of females and males were 2, 4, 12 ,19% and 2, 6, 9,19% lower than controls, respectively. In the females, neither the age of pubertal onset nor any of the thyroid hormone endpoints were affected by FR that led to a 12% decrease in BWT. Similarly, none of the male reproductive endpoints examined were altered by FR that led to a 9% BWT decrease. However, decreased T3 and T4 was observed in FR males with a 9% reduced BWT. While these data support the use of the maximum tolerated dose (MTD) for BWT (10%) for the female protocol, effects on the male thyroid endpoints indicate that a slightly lower limit ( 6% BWT loss) may be appropriate for the male pubertal protocol, and in cases where the BWT loss approaches 9-10%, additional studies and/or a weight of evidence approach should be used when interpreting the data for the thyroid endpoints.
URLs/Downloads:
Effects of Altered Food Intake during Pubertal Development in Male and Female Wistar Rat