© 1993 Oxford University Press
research-article |
The Effects of Feed Restriction on Reproductive Function in Swiss CD-1 Mice
Developmental and Reproductive Toxicology Group, NIEHS, National Toxicology Program P.O. Box 12233, Research Triangle Park, North Carolina 27709
*Environmental Health Research and Testing 2514 Regency Road, Lexington, Kentucky 40503
Division of Chemistry and Life Sciences, Research Triangle Institute, RTP P.O. Box 12194, North Carolina 27709
Analylical Sciences, 100 Capitola Drive Durham, North Carolina 27713
Received February 12, 1992; accepted July 14, 1992
Many test compounds used in toxicity studies produce a "systemic" toxicity manifested as reduced body weight gain. While it is known that reduced weight gain during juvenile growth reduces or delays reproductive competence, the effects of adultonset feed restriction (FR) and inhibited weight gain on the reproductive system of mice are poorly known. To gain some information on the effects of graded body weight reduction, or reduced body weight gain, on commonly used reproductive end-points, the studies reported below were conducted at two laboratories, using adult mice that were maintained at 90, 80, and 70% of concurrent control body weight (CBW) for up to 21 weeks. Estrous cyclicity and fertility in the females were significantly affected. While male fertility was variably affected, there was a significant decrease in the number of epididymal sperm and in the number of testicular spermatids in the 70% CBW groups. Testis weight was conserved in both studies; relative testis weight increased in all FR groups. These data can improve the interpretation of future studies by helping to separate chemically induced changes from those produced by reduced body weight gain.