Platform Session 16. Dying - The Price of Maturation and Aging
Tuesday, July 26, 2005
2:00 PM–4:00 PM
Location: CCQ 204AB
(126) BENEFITS OF CALORIE RESTRICTION (CR) ON OVARIAN RESPONSE TO EXOGENOUS GONADOTROPINS AND PREIMPLANTATION EMBRYONIC DEVELOPMENT IN OLD RHESUS MONKEYS.
Wu, Julie1, Takahashi, Diana2, Lawson, Maralee2, Pau, Francis2, Mattison, Julie3, Ingram, Donald3, Roth, George3, Lane, Mark4, Ottinger, Mary1, Zelinski-Wooten, Mary2, 1 University of Maryland, College Park, MD2 Oregon Health Sciences University, Beaverton, MD3 National Institute on Aging, Baltimore, MD4 Merck & Co., Rahway, NJ
ABSTRACT- Moderate calorie restriction (CR) remains the only proven non-genetic method of life extension, in addition to delaying reproductive senescence in rodents. Ovarian response to exogenous gonadotropins, oocyte competence and embryogenesis in vitro was assessed in rhesus monkeys during CR. Old (18-24 years) monkeys were maintained on two diets: control (CON; n=9) or calorie restricted at 30% CON (CR; n=7) for 1-2 years. Controlled ovarian stimulation (COS) was performed with recombinant human (r-h) gonadotropins: r-hFSH and r-hLH (Serono), followed by r-h chorionic gonadotropin (r-hCG) to induce ovulatory maturation. Serum estradiol (E2) levels were measured during COS. Ultrasound was performed to confirm the presence of at least three 4 mm follicles/ovary prior to follicle aspiration 27 hours post r-hCG. Based on E2 levels and ultrasound follicle data, monkeys were classified as responders (R; E2>1000 pg/mL), poor responders (PR; E2<600 pg/mL) or non-responders (NR; canceled COS due to lack of follicular growth). There were no differences in age between CON and CR in either R or PR groups, however, the age of PR tended to be younger in CON (21.0±2.0 years) than CR (24.5±0.5 years). Following follicle aspiration, the total number and stage of oocyte maturation was evaluated, and pre-implantation embryonic development in vitro was evaluated following intracytoplasmic sperm injection. No differences were observed in the proportion of immature or mature oocytes collected; fertilization rate of mature oocytes; cleavage rate in fertilized oocytes. A greater (p<0.05) percentage of embryos from CON (60%) compared to CR (40%) arrested by the 8-cell stage. A lower (p<0.05) proportion of embryos from CON relative to CR progressed from 16-cell (46%, 83%, respectively) to the morula stage (40%, 81%). The percentage of blastocysts was similar between CON (20%) and CR (25%), however none of the CON embryos developed to the expanded or hatched blastocyst stages while all of the blastocysts from CR hatched and expanded. Thus, the exposure of preovulatory follicles and/or oocytes to CR in older monkeys has a beneficial effect on subsequent preimplantation embryonic development. Therefore, it appears that CR prolongs ovarian responsiveness to COS as well as supports embryonic development, during aging in nonhuman primates.
KEY WORDS: calorie restriction, ovary, aging, follicle