Meeting Abstract

93.3  Sunday, Jan. 6  Assessments of immuno- and inflamm-aging following a photoperiodic regime that delays female reproductive aging in Siberian hamsters PLACE, NJ*; PARK, S-U; ZYSLING, DA; Cornell University njp27@cornell.edu

Aging and reproductive senescence are thoroughly intertwined, as evident by the ability of calorie restriction to both increase longevity and delay reproductive aging in a variety of animal models of aging. We have previously shown that exposure to short days (SD) between 3 and 9 months of age delayed reproductive aging in 12-month-old, female Siberian hamsters (Phodopus sungorus). Herein we report our initial assessments of somatic aging in male and female hamsters under the same photoperiodic conditions. Because hamsters held in SD decrease food intake and body mass, and also inhibit reproduction, we predicted that 6-months of SD would attenuate the age-associated changes in some biomarkers of somatic aging. We evaluated biomarkers of immuno- and inflamm-aging in hamsters that have been shown to be reliable indicators of aging in mice. The ratio of T-helper (CD4) to total T-cells (CD3) declined with age in hamsters held in long days (LD), as was previously demonstrated in mice. However, 12-month-old hamsters held in SD from 3 to 9 months of age had a CD4:CD3 ratio that was not significantly different than in age-matched hamsters held in LD. Thus, this measure of immuno-aging was not modulated by the previous exposure to SD. Ongoing research is now determining if age-associated changes in pro- and anti-inflammatory cytokines (e.g., interleukin-6 and -10, respectively) occur in Siberian hamsters held in LD, and if 6 months of SD delayed the transition to a pro-inflammatory state in 12-month-old hamsters. The outcomes of these investigations will help determine if the physiological and behavioral changes associated with decreasing photoperiod modulate somatic aging, or if the benefits of SD are limited to a deceleration of reproductive aging in female hamsters.