Reproduction in aging normal and neonatally androgenized female rats

Decline in reproductive success was compared in normal and neonatally androgenized female rats permitted to receive 1 or 5 ejaculations during each of 7, 5, 3, or 1 mating test. Exposing the females to .5 microgram of testosterone propionate on Day 3 of life increased their age-related rate of decline in the number of successful pregnancies and offspring born in each litter as well as in behavioral receptivity. In both normal and neonatally androgenized animals, fertility and receptivity were greater in animals receiving five ejaculations rather than one ejaculation and in those having multiple pregnancies rather than a single or no prior pregnancy. Perinatally androgenized animals appear to provide a useful model for studying factors influencing age-dependent reproductive processes.