| Both CON and CR monkeys are fed a diet low in total fat, saturated fat, and cholesterol, and both have generally low serum cholesterol levels. Moreover, CR seemingly reduces risk factors for several age-associated diseases including diabetes and cardiovascular disease. For example, rhesus monkeys on CR have less abdominal fat and improved glucose tolerance and insulin sensitivity (Lane et al., 1999 a, b). Additionally, CR monkeys have lower systolic blood pressure and serum triglycerides while maintaining higher levels of specific HDLs, all factors which benefit heart health. |
| Recently, NIA has collected blood samples from the female monkeys during 3 consecutive menstrual cycles, daily during the follicular phase and every third day during the luteal phase. Data from this more rigorous sampling procedure are in agreement with our previously published reports and indicate that all young monkeys cycled regularly, regardless of diet group (Lane et al. 2001). Additionally, elevated FSH levels were apparent in the older monkeys, and estradiol was not different between age groups (Wu, et al. 2005). Studies are underway to determine if CR delays the onset of menopause. |
| Several components of sensory function are affected with advanced age in primates. And rhesus monkeys have been an excellent model for study of both vision and hearing. Studies of the NIA monkeys have shown that visual accommodation declines with age but it was not affected by a CR diet (Mattison et al. 2005). Similarly, the monkeys showed an age-related decline in neural function associated with auditory responses that also was not affected by CR (Torre et al. 2004). Future studies when the younger monkeys have reached an advanced age will clarify potential diet differences. |
| Both humans and NHPs experience declines in several cognitive domains including the ability to recall recent events, acquire new information, and shift from one problem solving strategy to another, as well as reduced motor abilities. Tests of delayed responses taxing short-term memory are the best characterized in aging monkeys. The NIA is actively developing and implementing a behavioral program to evaluate age-related changes in memory and function to include tasks such as: object discrimination as an association memory task; delayed match-to-sample as a recognition memory task; object reversal for set shifting; motor movement assessment panel to detect coarse and fine motor movement, and automated locomotor activity detection. Many of these tasks are currently under study. An automated touch screen system is in development. Moreover, further analyses are ongoing including correlating behavioral function with in vivo brain imaging. Age-related declines in the volume of the striatum as well as reduced binding potential of dopamine D2 receptors have been documented (Ingram et al., 2001). |
| In 2001, an RFA was announced soliciting applications from outside scientists to advance the monkey CR studies into new areas of specialization. Projects from 5 groups were funded to work with NIA investigators and have significantly increased our understanding of CR in NHPs. The following projects are nearing completion: |
- Development and Progression of Osteoarthritis
Patricia Kramer (University of Washington, Seattle).
- Effect on the Immune System Specifically Changes in T-cell Subsets, Function, Diversity, Gene Expression Patterns
Janko Nikolich-Zugich (Oregon Health Sciences University, Beaverton, OR).
www.ohsu.edu/vgti/nikolich.htm
- Effect on Lymphocyte Chromosomal Aberrations
Charleen Moore (University of Texas Health Sciences Center, San Antonio, TX).
- Effects on Infection and Inflammation in the Oral Cavity
M. John Novak (University of Kentucky, Lexington, KY)
www.mc.uky.edu/COHR/,
/COHR/clinical_research_center.htm
Mark Reynolds (University of Maryland, College Park).
- Ovarian Aging including Endocrine and Oocyte Changes
Mary Zelinski (Oregon Health Sciences University, Beaverton, OR),
MaryAnn Ottinger (University of Maryland, College Park, MD).
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| While findings emerging from this study appear encouraging regarding the potential beneficial effects of CR on aging processes in monkeys, it is premature to reach a final conclusion. The study is reaching a critical stage as monkeys are approaching geriatric ages that will offer many opportunities for further elucidation of the long-term effects of CR and possible mechanisms that regulate these effects. |
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