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Title: CALORIE RESTRICTION IN YOUNG AND ADULT JAPANESE QUAIL: EFFECTS ON THE REPRODUCTIVE AXIS AND ADRENAL SYSTEMS: RELEVANCE TO MAMMALS.

Author
item OTTINGER, MARY ANN - UNIV. OF MD/NIH
item MOBARAK, MOHAMMED - UNIVERSITY OF MD
item ABDELNABI, MAHMOUD - UNIVERSITY OF MD
item ROTH, GEORGE - NAT'L INST. AGING-NIH
item Proudman, John
item INGRAM, DONALD - NAT'L INST. AGING-NIH

Submitted to: Experimental Gerontology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/15/2005
Publication Date: 9/5/2005
Citation: Ottinger, M., Mobarak, M., Abdelnabi, M., Roth, G., Proudman, J.A., Ingram, D. 2005. Calorie restriction in young and adult japanese quail: effects on the reproductive axis and adrenal systems: relevance to mammals. Experimental Gerontology. 126:967-975.

Interpretive Summary: Feed or nutrient (calorie) restriction is often used to control the body weight of domestic animals used for breeding. Weight control optimizes both health and productivity. In this work, the effects of the amount and the timing of feed restriction on the reproductive system were studied in Japanese quail. This bird, although of limited economic significance in poultry production, matures rapidly and ages quickly. The results showed that a 40% calorie restriction resulted in stress to the animals and an inhibition of the reproductive axis. A 20% calorie restriction, however, had mild effects. These results provide scientists with information that will be useful in determining the mechanisms through which calorie restriction exerts positive effects on the health and longevity of species of different classes of organisms.

Technical Abstract: The benefits of calorie restriction (CR) have been established across a variety of vertebrate and invertebrate species. Similarly, feed restriction (FR) has long been used to optimize health and productivity in domestic species. In birds, many poultry strains highly selected for growth and reproduction are reared and maintained on FR. Although lifespan extension has not been examined in birds, it is clear that reproductive, metabolic, and physiological characteristics are optimized by FR. Our studies have examined the effects of CR in Japanese quail, a small rapidly maturing and aging galliform model in order to assess the effects of degree and timing of CR on reproductive endocrine and neuroendocrine systems. Male Japanese quail were pair fed at 0% (ad libitum), 20%, or 40% CR of the ad lib bird during sexual maturation (3-7 weeks of age). Results showed that both CR groups matured more slowly, with reduced plasma LH in both CR groups. The 40% CR resulted in reduced testes weight, reduced plasma androgen, and elevated plasma corticosterone in adult birds. Both CR groups showed LH release in response to GnRH challenge (20 'g/kg body weight), suggesting inhibition of the HPG system at the level of the hypothalamus. In a subsequent experiment, males (n=10males/treatment) were castrated at 2 weeks of age and then were calorie restricted (0%, 20%, or 40%) until sexual maturity (9 weeks of age). Again, 40% CR resulted in lower circulating LH. However, both CR groups showed LH release with LHRH challenge. Further, the 20% CR exerted relatively mild effects, whereas 40% CR provided significant stress, resulting in central inhibition of the HPG axis. These data are discussed and compared to data collected in mammals, especially the rhesus monkey, particularly relative to timing and degree of CR and impact on reproductive and stress responses.