Modification of the oestrous cycle hormonal profile by dietary restriction.

In fully fed female CFY Sprague-Dawley rats there was a significant increase in oestrous cycle length with increasing age and a decrease in the percentage of rats with cycles of regular duration. Modification of the rate of reproductive decline could be achieved by restriction of food intake from weaning. Such animals showed retention of regular cycles to a greater age and there was no age-associated change in the length of the oestrous cycle. In dietary restricted females the serum LH peak occurred earlier in the cycle and serum oestradiol-17 beta rose later than in fully fed animals. Both peaks were of reduced amplitude. Serum progesterone values were reduced overall by dietary restriction. Underfeeding resulted in both an increase in serum FSH values and a significant modification of the serum FSH profile.