CALORIE RESTRICTION (CR): ITS EFECTS ON REPRODUCTIVE INDICES





1,2A.M. Handy*, 2A. Black, 2E.M. Tilmont 2D.K. Ingram, 2G.S. Roth, and 2M.A. Lane

1R.O.W. Sciences, Inc./FDC/Logicon, Gaithersburg, MD 2Laboratory of Neurosciences, National Institute on Aging, NIH, Baltimore, MD.




Calorie Restriction (CR) is widely recognized as the only intervention which extends mean and maximal lifespan and prevents or slows the onset of many age-related diseases in short-lived species. Evidence to suggest that many of these benefits can also be seen in longer-lived species is increasing. The effects of CR on reproductive indices in longer-lived species are just beginning to be explored. Long-term CR does not alter the total number of menstrual cycles or the proportion of normal length (24-31d) cycles measured over 2 years in rhesus monkeys, although both were lower in older than younger monkeys. In addition, CR did not alter estradiol or follicle stimulating hormone concentrations although these decreased and increased respectively with age. We have observed a higher incidence of proliferative disease, including endometriosis, in control (CON) females in our colony of 60 female rhesus monkeys, half of which have been on 30% CR for 8 years. No difference in menstrual patterns or early-follicular serum estradiol concentrations has been observed between the two groups. These findings suggest that CR did not alter menstrual cycling or hormones. However, one possible explanation for the reduced incidence of endometriosis in CR monkeys could be lower exposure to estradiol due to a cessation of ovulation. The present study was designed to assess hormonal evidence of ovulation in CON animals as well as those whose calories have been reduced by 30% (CON n=5, CR n=6-on CR for 5 months at the beginning of sample collection; age=9 years). Blood samples were collected three times a week for three weeks following day five of the menstrual cycle. This was done for two consecutive menstrual cycles and blood samples were then analyzed for serum estradiol and progesterone concentrations. Ovulation, evidenced by a sharp peak in estradiol followed by a more gradual rise in progesterone, was observed in both CON and CR groups over the two consecutive cycles. Thus, monkeys on CR for 5 months continue to exhibit hormonal patterns consistent with ovluation. These findings are consistent with our previous findings that CR did not alter menstrual cycle characteristics or early follicular phase hormone levels suggesting that a 30% reduction in calorie intake does not significantly alter reproductive cycling in rhesus monkeys. The present findings also suggest that the reduced endometriosis in CR females is not related to reduced estrogen exposure.







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